Packaged grilled cod roe and its manufacturing method

Abstract

To provide roasted salted Alaska pollack roe which is excellent in taste and a texture relative to packed roasted salted Alaska pollack roe which is subjected to low temperature sterilization processing, and is reduced in bacterial contamination at a degree in which the roasted salted Alaska pollack roe can be distributed to the market as roasted salted Alaska pollack roe, and a production method of the same.SOLUTION: There is provided packed roasted salted Alaska pollack roe in which roasted salted Alaska pollack roe subjected to aging and salting, is packaged in a pack, the roasted salted Alaska pollack roe is excellent in taste and texture relative to roasted salted Alaska pollack roe which is packaged in a pack after salting, aging, roasting and is subjected to low temperature sterilization processing until a bacteria number level becomes a prescribed bacteria number level, and the roasted salted Alaska pollack roe of the invention has a general viable cell number measured after opening the pack and immediately after taking out the same from the pack of 10000 CFU / g or less, and a coliform group is negativity. There is also provided a production method of the same.SELECTED DRAWING: Figure 2

Description

Technical Field

[0004] ,

[0001] The present invention relates to packed grilled pollock roe and a method for producing the same.

Background Art

[0002] Grilled pollock roe is a kind of processed fish egg product obtained mainly by salting the ovaries of Alaska pollock and then baking them. Different from non-baked salted pollock roe, grilled pollock roe, whose surface is baked and slightly hard, can be enjoyed for its texture, umami, and flavor that leave a fresh feeling and a delicate grainy feeling of fish eggs inside. It has been widely eaten not only as a side dish for rice but also as an ingredient for onigiri. Grilled pollock roe can be easily cooked by baking salted pollock roe in an oven toaster, grill, frying pan, etc., so it is popular in households and is one of the popular ingredients that people want to put in onigiri, along with pickled ume, salmon, kelp, etc. (Non-Patent Document 1, Non-Patent Document 2).

[0003] As long as salted pollock roe is available, grilled pollock roe can be made relatively easily at home. However, special considerations for hygiene are required to supply grilled pollock roe for use as an ingredient for onigiri sold at convenience stores, supermarkets, etc. (hereinafter referred to as "conveniences, etc."). That is, different from grilled pollock roe produced at home, which is usually eaten immediately after cooking, grilled pollock roe used in foods such as onigiri sold at conveniences, etc. is processed into the intended food form, then transported to retail stores, displayed on product shelves, and eaten after consumers purchase it. Therefore, more thorough hygiene management is required so that consumers can eat it with confidence. Regarding this point, various methods for sterilizing pollock roe have been proposed conventionally. For example, Patent Document 1 discloses a sterilization method that does not impair the taste of salted pollock roe by packing and sealing non-sterilized salted pollock roe and treating it at a heating temperature of 60°C to 80°C for about 20 minutes to 3 hours, at which the eggs do not boil.

[0004] To the best of the applicant's knowledge, the grilled cod roe currently sold as a filling for rice balls in convenience stores and other places is also pasteurized by heating the package in a water bath at around 63°C after grilling. However, according to the inventors' own findings, packaged grilled cod roe that is pasteurized after grilling and packaging is significantly inferior to grilled cod roe obtained by grilling commercially available salted cod roe in an oven toaster, grill, or frying pan, in other words, grilled cod roe prepared by cooking at home. In particular, the contrast between the slightly firm texture of the grilled surface of the cod roe and the raw texture of the uncooked interior, as well as the popping umami of the fish roe, are significantly diminished. Reflecting this, when we investigated the popularity ranking of rice balls sold at convenience stores using internet media, we were surprised to find that the top spots were dominated by tuna mayonnaise, pickled plum, and salmon, with grilled cod roe being almost completely absent (Non-Patent Literature 3, Non-Patent Literature 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-273636 [Patent Document 2] Japanese Patent Publication No. 2012-034616 [Non-patent literature]

[0006] [Non-Patent Document 1] "Ranking of Popular Onigiri Fillings! Easy Recipes Also Introduced," [online], Jelly, February 17, 2019, [Accessed June 23, 2019], Internet<URL:https: / / jelly-media.jp / posts / 1928> [Non-Patent Document 2] "[National Food] Top 20 Onigiri Fillings, What's Your Favorite Onigiri Now?", [online], Naver Matome, July 31, 2012, [Searched June 23, 2019], Internet<URL:https: / / matome.naver.jp / odai / 2134359745609300101> [Non-Patent Document 3] "2018 Convenience Store Onigiri Popularity Survey: The trend is 'a surge in health consciousness.' 'Hearty' onigiri makes a comeback as a variation. 'Salmon, Tuna, and Plum' remain popular," [online], Japan Onigiri Association, June 15, 2018 [Retrieved June 23, 2019], Internet<URL:https: / / www.onigiri.or.jp / archives / 4620> [Non-Patent Document 4] "Top 85 Popular Convenience Store Onigiri Ranking! A Thorough Comparison Focusing on the 3 Major Companies [Latest]", [online], Rank Best, October 23, 2018, [Searched June 23, 2019], Internet<URL:https: / / ranking-best.net / 1465> [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This invention was made to solve the problems of the conventional grilled cod roe products described above, and aims to provide grilled cod roe and a method for producing it that have the same texture and flavor as grilled cod roe obtained by grilling cod roe in a toaster oven, grill, or frying pan at home, and that have less bacterial contamination to the extent that they can be distributed to the market as grilled cod roe products. [Means for solving the problem]

[0008] As a result of diligent research efforts to solve the above problems, the inventors have come to the conclusion that the reason why pasteurized grilled cod roe, which replicates the grilled cod roe currently distributed in the market, often falls short of grilled cod roe obtained by grilling commercially available salted cod roe at home in terms of texture, umami, and flavor, is due to the following reasons in the pasteurization process. In other words, in order to thoroughly sterilize thick grilled cod roe all the way to the inside, it is necessary to heat the inside of the grilled cod roe thoroughly, even at a low temperature of around 60°C. Therefore, in the pasteurization process, the grilled cod roe is subjected to a situation that is, so to speak, like being boiled for a long time, so the protein in the grilled cod roe is denatured by the heat, and the protein inside the egg membrane and in the roe grains is also denatured, resulting in a dry and crumbly texture, and it is thought that the moisture contained in the grilled cod roe seeps out into the bag. As a result, grilled cod roe that has undergone a low-temperature pasteurization process after grilling loses not only the savory aroma after grilling, but also the contrast in texture—a slightly firm surface with a raw interior—and even the popping texture of the fish eggs. Furthermore, the grilled cod roe becomes watery overall, and its savory flavor is also diminished.

[0009] Based on the above findings, and through further trial and error, the inventors focused on the fact that in the process of roasting cod roe, only the surface of the cod roe is heated and sterilized. They conceived the idea that by suppressing bacterial contamination inside the cod roe sacs to a level that poses no hygiene problems before the roasting process, it might be possible to obtain roasted cod roe in a package that remains sufficiently hygienic during storage and after opening, without the need for pasteurization after roasting.

[0010] However, in order to fully bring out the flavor, umami, and texture of cod roe, a salting process and a maturation process are necessary, and conventionally, it was thought that some degree of contamination inside the cod roe sacs was unavoidable during these salting and maturation processes. For example, Patent Document 2 discloses a technique for coexisting with kefir bacteria during the salting and maturation process of cod roe, but this is merely a technique to suppress bacterial growth, and not a technique to reduce bacterial contamination itself.

[0011] Under these circumstances, the inventors, through further trial and error, discovered that by improving the pre-treatment process before roasting the cod roe, particularly the salting process, it is possible to fully bring out the original flavor, umami, and texture of the cod roe while suppressing bacterial contamination inside the cod roe sacs to an extremely low level. Furthermore, after salting and maturation, the inventors discovered that by roasting only the surface of the cod roe with superheated steam and packaging the roasted cod roe while it is still at a relatively high temperature, it is possible to obtain packaged roasted cod roe with a level of bacterial contamination that is completely acceptable for distribution to the market, without going through the pasteurization process that was previously considered essential, and with a texture and umami that is indistinguishable from roasted cod roe cooked and produced at home. Thus, the inventors completed the present invention.

[0012] In other words, the present invention solves the above problem by providing packaged grilled cod roe, which is made by grilling salted and aged cod roe and then sealing the grilled cod roe in a pack, characterized in that the grilled cod roe has superior texture and flavor compared to grilled cod roe that has been salted, aged, and grilled, then sealed in a pack and pasteurized at a low temperature until it reaches a predetermined bacterial count level, and the total viable bacteria count measured immediately after opening the pack and removing the cod roe from the pack is 10,000 CFU / g or less, and coliform bacteria are negative.

[0013] The specified bacterial count level mentioned above refers to a bacterial count level that has been suppressed to a degree sufficient for distribution in the market. Specifically, for example, it is a level in which the total bacterial count measured after removing the grilled cod roe from the package and storing it at 25°C for 48 hours is 10,000 CFU / g or less, and coliform bacteria are negative. More preferably, it is a level in which the total bacterial count measured after removing the grilled cod roe from the package and storing it at 25°C for 72 hours is 10,000 CFU / g or less, and coliform bacteria are negative. If the total bacterial count and coliform bacteria count are at this level, as described later, the packaged grilled cod roe can be removed from the package and used as an ingredient in rice balls, etc., and can be displayed and sold on the shelves of convenience stores, etc., which are normally under room temperature conditions.

[0014] From another perspective, the packaged grilled cod roe according to the present invention has the same texture and flavor as grilled cod roe that has been salted and aged and then grilled without pasteurization. Here, salted and aged cod roe refers to what is commonly known as salted cod roe, such as the salted cod roe sold in supermarkets. In other words, grilled cod roe that has been salted and aged and then grilled without pasteurization is equivalent to grilled cod roe that can be obtained in a typical household by grilling commercially available salted cod roe using appropriate cooking equipment such as an oven toaster, grill, or frying pan. Therefore, the fact that the packaged grilled cod roe according to the present invention has the same texture and flavor as grilled cod roe that has been salted and aged and then grilled without pasteurization means that, as described later, the packaged grilled cod roe according to the present invention has the same texture and flavor as grilled cod roe that is handmade in ordinary households, while having its total bacterial count and coliform bacteria count reduced to a level sufficient for distribution in the market.

[0015] Furthermore, the packaged grilled cod roe according to the present invention has a total bacterial count of 10,000 CFU / g or less and is negative for coliform bacteria when measured immediately after removal from the package. In one preferred embodiment, the total bacterial count measured immediately after removal from the package is 1,000 CFU / g or less and is negative for coliform bacteria. In a more preferred embodiment, the total bacterial count measured immediately after removal from the package is 100 CFU / g or less and is negative for coliform bacteria. In an even more preferred embodiment, the total bacterial count measured immediately after removal from the package is 30 CFU / g or less and is negative for coliform bacteria.

[0016] Packaged grilled cod roe that meets the above-mentioned total bacterial count and coliform count requirements meets the standards for frozen foods (total bacterial count of 100,000 CFU / g or less, coliform negative) as described in each article of the "Standards and Specifications for Foods, Food Additives, etc." (Ministry of Health and Welfare Notification No. 370 of 1959), and can be shipped and distributed as a frozen food.

[0017] In one preferred embodiment, the packaged grilled cod roe according to the present invention has a total bacterial count of 10,000 CFU / g or less and is negative for coliform bacteria, measured after being removed from the package and stored at 25°C for 48 hours. In a more preferred embodiment, the total bacterial count is 5,000 CFU / g or less and is negative for coliform bacteria, measured after being removed from the package and stored at 25°C for 48 hours. In an even more preferred embodiment, the total bacterial count is 1,000 CFU / g or less and is negative for coliform bacteria, measured after being removed from the package and stored at 25°C for 48 hours. Packaged grilled cod roe having a total bacterial count of 10,000 CFU / g or less and being negative for coliform bacteria, measured after being removed from the package and stored at 25°C for 48 hours, can be consumed without any food hygiene issues, even 48 hours after the package is opened. This means that the packaged grilled cod roe according to the present invention can be used as an ingredient in rice balls and other products, and can be displayed and sold on shelves in convenience stores and other retail stores that are normally in a room temperature environment.

[0018] In a more preferred embodiment, for the grilled pollack roe in a pack according to the present invention, after being taken out of the pack and stored at 25°C for 72 hours, the total viable count of the grilled pollack roe measured is 10,000 CFU / g or less, and the coliform group is negative. In a more preferred embodiment, under the same conditions, the total viable count measured is 5,000 CFU / g or less, and the coliform group is negative. In an even more preferred embodiment, the total viable count is 1,000 CFU / g or less, and the coliform group is negative. Such grilled pollack roe in a pack can be eaten without any hygienic problems even after 72 hours at room temperature from the time of opening the pack, and thus is more preferred from the perspective of extending the expiration date.

[0019] Incidentally, the grilled pollack roe in a pack according to the present invention is superior in texture and flavor compared to grilled pollack roe that is salted, aged, baked, sealed in a pack, and then subjected to low-temperature sterilization treatment until it reaches a predetermined bacterial count level. Furthermore, it has a texture almost equivalent to that of grilled pollack roe produced by cooking at home. This is also confirmed by the fact that the difference in the moisture content between the egg membrane part and the ovarian part of the grilled pollack roe measured immediately after taking it out of the pack is 1.0% by mass or more and 2.5% by mass or less, more preferably 1.5% by mass or more and 2.0% by mass or less. The above moisture content is measured in a state where the grilled pollack roe in a pack is thawed and returned to room temperature when it is in a frozen state.

[0020] That is, as described above, grilled pollack roe produced by cooking at home has two different textures at the same time: the surface is baked and slightly firm, while the inside remains soft with a raw feeling and a small granular feeling of fish eggs. However, the difference in the moisture content between the egg membrane part and the ovarian part, as measured by the present inventor, is about 1.8% by mass as described later, and the moisture content of the egg membrane part is less than that of the ovarian part. Thus, it is considered that the fact that the egg membrane part has a lower moisture content than the ovarian part and the difference is about 1.8% by mass reflects the unique texture of grilled pollack roe, namely, the slightly firm baked feeling on the surface of the pollack roe and the raw feeling inside the pollack roe.

[0021] Therefore, if the difference in moisture content between the egg membrane and the inside of the roe clusters of the packaged grilled cod roe according to the present invention is between 1.0% and 2.5% by mass, more preferably between 1.5% and 2.0% by mass, with approximately 1.8% by mass being the central amount, and the egg membrane has less moisture content than the inside of the roe clusters, it can be reasonably inferred that the texture will be almost the same as grilled cod roe produced by cooking at home. Furthermore, in grilled cod roe that has been pasteurized at low temperature after being sealed in a package after salting, aging, and grilling, the difference in moisture content between the egg membrane and the inside of the roe clusters is small, less than 1.0% by mass, and this is thought to be related to the loss of texture and flavor. Therefore, if the difference in moisture content between the egg membrane and the inside of the roe sac of the packaged grilled cod roe according to the present invention is between 1.0% and 2.5% by mass, more preferably between 1.5% and 2.0% by mass, with the above-mentioned 1.8% by mass being the central amount, and the egg membrane has a lower moisture content than the inside of the roe sac, it can be reasonably inferred that the texture and flavor are superior to grilled cod roe that has been pasteurized at low temperature until a predetermined bacterial count level is reached.

[0022] Furthermore, the present invention provides a method for producing packaged grilled cod roe, comprising: (1) a salting step of soaking cod roe in a salting solution at a predetermined ambient temperature for a predetermined time; (2) a maturation step of maturing the cod roe that has undergone the salting step at a predetermined ambient temperature for a predetermined time; (3) a baking step of baking the cod roe that has undergone the maturation step; and (4) a packaging step of sealing the cod roe that has undergone the baking step into a pack, wherein the salting step in (1) includes (1A) a first salting step in which the predetermined ambient temperature is 15°C or more and 25°C or less and the predetermined time is 20 hours or more and 30 hours or less, and (1B) a second salting step in which the predetermined ambient temperature is 5°C or more and 15°C or less and the predetermined time is 20 hours or more and 30 hours or less, in this order, and furthermore, the baking step in (3) is superheated steam baking using superheated steam, thereby solving the above problems.

[0023] The manufacturing method of salted pollock roe in packs of the present invention is characterized in that a first salting process at a relatively high temperature and a second salting process at a relatively low temperature are carried out in this order. By doing so, while fully fulfilling the original role of the salting process of bringing out the graininess of the fish eggs in the pollock roe, it is possible to suppress an increase in the number of general viable bacteria and the number of coliforms inside the pollock roe after the salting process and further after the aging process.

[0024] The predetermined ambient temperature in the first salting process (1A) is preferably 15°C or higher and 25°C or lower, more preferably 16°C or higher and 24°C or lower, and still more preferably 17°C or higher and 23°C or lower. The predetermined time in the first salting process (1A) is preferably 18 hours or longer and 30 hours or shorter, more preferably 20 hours or longer and 28 hours or shorter, and still more preferably 22 hours or longer and 26 hours or shorter.

[0025] On the other hand, the predetermined ambient temperature in the second salting process (1B) is preferably 5°C or higher and 15°C or lower, more preferably 7°C or higher and 13°C or lower, and still more preferably 9°C or higher and 11°C or lower. The predetermined time in the second salting process (1B) is preferably 18 hours or longer and 30 hours or shorter, more preferably 20 hours or longer and 28 hours or shorter, and still more preferably 22 hours or longer and 26 hours or shorter.

[0026] Although there is a partially overlapping part in the preferable ranges of the ambient temperature in the first salting process and the second salting process, the second salting process is carried out at a lower ambient temperature than the first salting process, and the ambient temperature at which both salting processes are carried out will not be the same. Also, the implementation times of the first salting process and the second salting process may be different, but it is preferable that they are the same, and the total salting time for both processes is more preferably about 48 hours in total.

[0027] The method for producing packaged grilled cod roe according to the present invention is further characterized in that the grilling step in (3) is carried out by superheated steam grilling, and does not include the low-temperature pasteurization step by water bath, which was previously considered indispensable. In other words, by incorporating the two-stage salting step described above, in the method for producing packaged grilled cod roe according to the present invention, the total number of viable bacteria inside the cod roe sacs subjected to the grilling step in (3) is suppressed to 100 CFU / g or less, and coliform bacteria are suppressed to a negative level. If the total number of viable bacteria and coliform bacteria inside the sacs is at this level, the total number of viable bacteria and coliform bacteria can be reduced to a level sufficient to allow the product to be distributed to the market as grilled cod roe simply by grilling the surface of the cod roe with superheated steam in the grilling step in (3), without going through a low-temperature pasteurization step. This is a finding that could not have been predicted at all from conventional manufacturing methods in which low-temperature pasteurization was carried out by immersing the packaged cod roe in hot water. As is well known, superheated steam is steam heated to over 100°C. In addition to the latent heat of steam, it possesses sensible heat due to superheating, and has the advantage of being able to cook the target substance, cod roe, more uniformly and efficiently compared to conventional grilling methods.

[0028] Furthermore, in a preferred embodiment of the method for producing packaged grilled cod roe according to the present invention, the predetermined ambient temperature in the cod roe maturation step (2) is 5°C to 15°C, more preferably 7°C to 13°C, and even more preferably 9°C to 11°C, and the predetermined time in (2) is 36 hours to 60 hours, more preferably 40 hours to 56 hours, and even more preferably 44 hours to 52 hours. By including the maturation step (2) under such conditions, it is possible to fully and uniformly bring out the texture, umami, and preferably flavor of the cod roe while suppressing the increase in the total number of viable bacteria and the number of coliform bacteria.

[0029] In a preferred embodiment, the method for producing packaged grilled cod roe according to the present invention is carried out by having the cod roe to be grilled remain in a space from which superheated steam at 240°C to 260°C is blown for 2 minutes to 3 minutes during the grilling process in (3) above. By grilling with superheated steam under the conditions described above, the surface of the cod roe can be thoroughly grilled and sterilized, and grilled cod roe with excellent texture, umami, and preferably flavor can be produced.

[0030] If the temperature of the superheated steam is too high, the surface of the cod roe will be excessively grilled, resulting in a hard texture. Therefore, from the viewpoint of obtaining grilled cod roe with an excellent texture, the temperature of the superheated steam is preferably less than 270°C, and more preferably 260°C or lower. On the other hand, if the temperature of the superheated steam is too low, the surface of the cod roe will not be sufficiently grilled, and sufficiently sterilized grilled cod roe cannot be obtained. Therefore, the temperature of the superheated steam is preferably 230°C or higher, and more preferably 240°C or higher.

[0031] On the other hand, the time that the cod roe to be roasted is kept in the space from which the superheated steam is blown should not be too short from the viewpoint of sufficient surface sterilization by uniform roasting, and should not be too long from the viewpoint of avoiding deterioration of texture due to over-roasting. Therefore, the time that the cod roe to be roasted is kept in the space from which the superheated steam is blown is preferably 1 minute or more and 4 minutes or less, more preferably 1 minute 30 seconds or more and 3 minutes 30 seconds or less, and even more preferably 2 minutes or more and 3 minutes or less.

[0032] Furthermore, in a preferred embodiment of the method for producing packaged grilled cod roe according to the present invention, the grilled cod roe that has undergone the grilling step of (3) above is filled and sealed into a packaging container (pack) while it is still maintained at a relatively high predetermined temperature immediately after grilling. This reduces bacterial contamination during the packaging process. In a more preferred embodiment of the method for producing packaged grilled cod roe according to the present invention, the predetermined temperature is 60°C or higher, in a more preferred embodiment, the predetermined temperature is 70°C or higher, and in an even more preferred embodiment, the predetermined temperature is 80°C or higher.

[0033] In the present invention, the pack into which the grilled cod roe is filled only needs to have an opening that can be closed, and there are no particular restrictions on the material, type, or size of the pack. The pack may be made of flexible material, or it may be made of hard material such as glass, plastic, or metal, or it may be made of two or more materials. However, since the method for manufacturing packaged grilled cod roe according to the present invention involves filling a pack with grilled cod roe that has been grilled by appropriate means while maintaining it at a predetermined temperature or higher, it is desirable to use a pack made of a material with excellent heat resistance. Furthermore, the pack may be a vacuum pack with the inside evacuated, or it may have some air remaining, or it may be filled with an inert gas.

[0034] The cod roe targeted by this invention can be any fish ovary that can be roasted to make grilled cod roe. It can be any fish ovary belonging to the Gadidae or Hakeidae families that have been used conventionally, and preferably the ovaries of Alaska pollock, Pacific cod, southern cod, and hoki, and more preferably the ovaries of Alaska pollock. In addition, there are various grades of cod roe such as gamuko, mako, and mizuko depending on the degree of maturity and thickness, but the cod roe targeted by this invention can be any cod roe that can be roasted to make grilled cod roe, and there are no particular restrictions on the grade of the cod roe. In this invention, grilled cod roe can be any cod roe obtained by roasting the surface of salted and aged cod roe, and so-called grilled mentaiko and grilled spicy mentaiko are naturally included in the grilled cod roe as defined herein. [Effects of the Invention]

[0035] The present invention provides packaged grilled cod roe and a method for producing the same, which have superior texture and flavor compared to pasteurized grilled cod roe, and which have minimal bacterial contamination to the extent that they can be distributed to the market without any problems as a grilled cod roe product. [Brief explanation of the drawing]

[0036] [Figure 1] This process diagram shows a comparison of the method for producing packaged grilled cod roe according to the present invention (Example 1) (A), an existing method for producing packaged grilled cod roe (Comparative Example 1) (B), and a production method that omits the pasteurization step from the existing method for producing packaged grilled cod roe (Comparative Example 2) (C). [Figure 2] This is a photograph of a cross-section of the packaged grilled cod roe of the present invention. [Figure 3] This is a photograph of a cross-section of existing packaged grilled cod roe that has undergone a pasteurization process. [Figure 4] This is a photograph of a cross-section of grilled cod roe prepared in a typical home kitchen. [Modes for carrying out the invention]

[0037] 1. Method for producing packaged grilled cod roe The following describes the packaged grilled cod roe and its manufacturing method according to the present invention. While this specification describes grilled cod roe made from the ovaries of the Alaska pollock, it goes without saying that the packaged grilled cod roe and its manufacturing method according to the present invention are not limited to grilled cod roe made from the roe of the Alaska pollock. Furthermore, the present invention is not limited to the examples specifically disclosed herein.

[0038] 1.1. Existing methods for packaging grilled cod roe The existing method for manufacturing packaged grilled cod roe is shown in Figure 1(B), and involves the following steps: bringing in frozen cod roe as raw material (Step 1), thawing the frozen cod roe brought in as raw material (Step 2), washing the thawed cod roe (Step 3), removing foreign matter and intestinal tract from the washed cod roe (Step 4), soaking the washed cod roe in a salt solution containing a predetermined concentration of salt (the so-called salting process) (Step 5), removing parasites, peritoneum, fins, bones, etc. from the salted cod roe (Step 6), and salting. The process consists of the following steps: maturing the prepared cod roe (the so-called maturation process) (step 7), grilling the matured cod roe (step 8), vacuum packaging the grilled cod roe (step 9), pasteurization by immersing the vacuum-packaged grilled cod roe in warm water maintained at approximately 63°C for about 40 minutes (step 10), and cooling, freezing, and packaging the pasteurized grilled cod roe (steps 11-13). Packaged grilled cod roe is manufactured through the above steps.

[0039] 1.2. Method for producing packaged grilled cod roe according to the present invention On the other hand, the method for producing packaged grilled cod roe according to the present invention is as shown in Figure 1(A), and steps 1 to 4, steps 6 and 7, and steps 11 to 13 are common to the existing method for producing packaged grilled cod roe shown in Figure 1(B).

[0040] However, the present invention provides a salting process for packaged grilled cod roe that differs from the existing manufacturing method shown in Figure 1(B) in that, instead of the conventional salting process 5 in which washed cod roe is soaked in a salt solution of a predetermined salt concentration and is consistently carried out at an ambient temperature of around room temperature (20°C), the present invention provides a first salting process (step 5Aα) in which salting is carried out at a relatively high ambient temperature of around room temperature (20°C), and a second salting process (step 5Aβ) in which salting is carried out at an ambient temperature lower than room temperature (20°C). By combining the first salting process (step 5Aα) and the second salting process (step 5Aβ) of the present invention, the salting process of the packaged grilled cod roe manufacturing method can fully bring out the texture of the fish eggs while suppressing the increase in the number of general bacteria and coliform bacteria during the salting process, particularly the increase in the number of general bacteria and coliform bacteria inside the roe sacs.

[0041] Furthermore, the method for manufacturing packaged grilled cod roe of the present invention shown in Figure 1(A) differs from the existing method for manufacturing packaged grilled cod roe shown in Figure 1(B) in that it includes a baking step 8A using a superheated steam baking machine instead of a baking step 8 using a grilling machine. Using a superheated steam baking machine has the advantage that the surface of the cod roe can be baked and sterilized more efficiently and uniformly by exposing the cod roe to a space filled with superheated steam that has sensible heat due to superheating in addition to latent heat of vaporization.

[0042] Furthermore, the method for manufacturing packaged grilled cod roe according to the present invention, shown in Figure 1(A), differs from the existing method for manufacturing packaged grilled cod roe shown in Figure 1(B) in that it includes a step 9A in which the grilled cod roe is packaged while being kept at a predetermined temperature or higher, instead of the vacuum packaging step 9. By packaging the grilled cod roe while it is kept at a predetermined temperature or higher, in other words, while it is still in the high-temperature state immediately after grilling, bacterial contamination between grilling and packaging can be reduced. It should be noted that the method for manufacturing packaged grilled cod roe according to the present invention does not include a pasteurization step 10, as will be described later. Therefore, the packaging container used to package the cod roe after grilling only needs to be able to be closed, and it is not necessary to vacuum package the cod roe so that it is in close contact with the packaging container in order to increase the sterilization efficiency in the pasteurization step, as in the existing method shown in Figure 1(B), nor is it necessary to seal the packaging container.

[0043] In addition, the method for producing packaged grilled cod roe of the present invention shown in Figure 1(A) differs from the existing method for producing packaged grilled cod roe shown in Figure 1(B) in that it does not include a pasteurization step 10. That is, the method for producing packaged grilled cod roe of the present invention, having the manufacturing process described above, can reduce the total number of viable bacteria and coliform bacteria in the grilled cod roe to a level that is acceptable for use as a frozen food and as an ingredient for rice balls, without having to go through a pasteurization (water bath) step 10. Therefore, according to the method for producing packaged grilled cod roe of the present invention, it is possible to produce packaged grilled cod roe that has the same texture, umami, and preferably flavor as grilled cod roe that has not been pasteurized after salted and aged cod roe has been grilled, in other words, grilled cod roe that is obtained by grilling salted cod roe at home.

[0044] In the method for producing packaged grilled cod roe according to the present invention, in the step of thawing the frozen cod roe (step 2), an appropriate thawing method, including thawing with air at room temperature as is commonly practiced, can be used. However, it is desirable to use a thawing method that minimizes the risk of bacterial contamination of the cod roe during thawing, and in particular, thawing in salt water is desirable.

[0045] Furthermore, in the method for producing packaged grilled cod roe of the present invention, the salt concentration of the brine used in the brine curing process (steps 5, 5Aα, and 5Aβ) is not particularly limited, but depending on the size of the cod roe clusters, a brine with a salt concentration of preferably 5 to 20% by mass, more preferably 8 to 15% by mass, can be suitably used. In addition, colorants, seasonings, chili peppers, etc., may be added to the brine as needed.

[0046] The method for producing packaged grilled cod roe according to the present invention does not fundamentally require the use of a bacteriostatic agent, and it is not necessary to use one, however, the use of a bacteriostatic agent when necessary is not excluded. The type of bacteriostatic agent used is not particularly limited, but organic acids and organic acid salts are preferably used. More preferably, glacial acetic acid (acetic acid), acetate, citrate, gluconate, lactate, fumarate, and sorbate can be used, and even more preferably, glacial acetic acid (acetic acid), sodium acetate, and sodium gluconate can be used. By adding these bacteriostatic agents to the salting solution at a concentration of, for example, less than 1.0% by mass, more preferably 0.9% by mass or less, and even more preferably 0.7% by mass or less relative to the mass of the cod roe, it is possible to suppress variations in the number of bacteria between products while maintaining excellent texture, umami, and preferably flavor of the resulting grilled cod roe.

[0047] 2. Method for measuring total viable cell count and coliform bacteria count Before describing the present invention in more detail through experiments, we will first explain the methods for measuring the total viable cell count and coliform bacteria count used in the following experiments.

[0048] In this specification, the total bacterial count was measured using the standard agar culture method in accordance with the method for measuring the total bacterial count described in the "Food Hygiene Inspection Guidelines 2018," and the coliform count was measured using deoxycholate agar medium in accordance with the method for measuring the coliform count described in the "Food Hygiene Inspection Guidelines 2018."

[0049] Total viable cell count and coliform bacteria count were measured either in the entire cod roe or by separating the egg membrane and the inside of the roe sac. The amount of sample used for measurement was 10 g in all cases: the entire cod roe, the egg membrane, and the inside of the roe sac. Unless otherwise specified in this specification, the measurement results and reference values ​​for total viable cell count and coliform bacteria count refer to the measurement results or reference values ​​for the entire cod roe.

[0050] In this specification, "whole cod roe" means the entire cod roe, including both the egg membrane portion and the interior of the roe cluster, without distinction. On the other hand, in this specification, "egg membrane portion" means the egg membrane portion that encloses the cod roe. However, in the case of baked cod roe, the fish eggs present near the egg membrane undergo thermal denaturation during baking and adhere to the egg membrane, and are peeled off together with the egg membrane. Therefore, in the case of baked cod roe, the egg membrane portion includes not only the egg membrane portion itself but also the fish eggs that are peeled off together with the egg membrane. The thickness of the egg membrane portion peeled off from the baked cod roe was in the range of approximately 1 to 2 mm in all cases of Sample 1, Control 1, Control 2, and Control 3 described later. On the other hand, in this specification, "interior of the roe cluster" means the interior portion of the cod roe that is located inside the egg membrane portion.

[0051] 3. Experiment 1: Effects of different manufacturing methods on total viable cell count and coliform bacteria count. This study investigated the effects of the differences between the present invention's method for producing packaged grilled cod roe and existing methods for producing packaged grilled cod roe on the total viable bacterial count and coliform bacteria count of the cod roe during the manufacturing process and the resulting packaged grilled cod roe. First, the specific manufacturing methods of Sample 1 and Control Samples 1-3, which were the samples to be measured, will be described. [Examples]

[0052] <Sample 1: Packaged grilled cod roe according to the present invention> As an example of packaged grilled cod roe according to the present invention, sample 1 was manufactured according to the process shown in Figure 1(A). Specifically, the frozen roe of the Alaska pollock, which is the raw material, was thawed by soaking it in 5% by mass saline solution overnight (step 2). Next, the thawed cod roe was rinsed in a chlorine bath with a chlorine concentration of 200 ppm for about 10 seconds, and then rinsed again in a saline bath with a salt concentration of 3% by mass for about 10 seconds to wash the cod roe (step 3). For washing, half the weight of the cod roe was chlorine water (chlorine concentration 200 ppm) and a saline solution with a salt concentration of 3% by mass was used. After removing foreign matter and intestinal tract from the washed cod roe (step 4), the cod roe was soaked in a saline solution with a salt concentration of 13.8% by mass (hereinafter referred to as "salting solution" in this example) at room temperature, i.e., at an ambient temperature of 20°C, for 24 hours (step 5Aα). The temperature of the brine solution at the start of salting in step 5Aα was set to 20°C. After turning and kneading as appropriate, the cod roe was then moved to a chilled storage room at a temperature of 10°C while still immersed in the brine solution, and left to stand for another 24 hours (step 5Aβ). The salted cod roe was then placed in a shallow basket, and after removing the cod roe from the brine solution, the peritoneum, fins, bones, and parasites were removed by appropriate methods (step 6). Then, it was left to stand in the chilled storage room at a temperature of 10°C for 48 hours to mature (step 7). The aged cod roe was roasted using a commercially available superheated steam oven (model "QFB-5980C", manufactured by Naomoto Kogyo Co., Ltd., model name "Steam DC Oven") under the conditions of a superheated steam temperature of 250°C blown into the oven and a roasting time of 2 minutes and 30 seconds for the cod roe (step 8A). After roasting, the cod roe was filled into packaging containers (packs) while maintaining a product temperature of 80°C or higher, and the opening of the packaging containers was closed to seal them (step 9A). After being cooled to room temperature (approximately 20°C), it was frozen in a commercially available tunnel freezer (model "MMF-2512FL", manufactured by Maekawa Seisakusho Co., Ltd., model name "Microcomputer Mesh Freezer"). The packaged roasted cod roe thus produced was designated as Sample 1. Comparative Example 1

[0053] <Comparison product 1: Existing packaged grilled cod roe that has undergone a low-temperature pasteurization process> As a reproduction of existing packaged grilled cod roe, Control Product 1 was manufactured according to the process shown in Figure 1(B). Steps 1 to 4 involved processing the cod roe in the same manner as in Example 1, and then soaking it in a saline solution with a salt concentration of 13.8% by mass (hereinafter referred to as "salting solution" in this comparative example) for 48 hours at an ambient temperature of 20°C (Step 5). The temperature of the salting solution at the start of salting was 20°C. A commercially available bacteriostatic agent (product name "SM-P", manufactured by Ueno Food Techno Co., Ltd.) was added to the salting solution at an amount of 0.4% by mass relative to the cod roe. Subsequently, in the same manner as in Example 1, the salted cod roe was placed in a shallow basket, and after removing the cod roe from the salting solution, the peritoneum, fins, bones, and parasites were removed by appropriate methods (Step 6). Then, it was left to mature for 48 hours in a chilled storage room at an internal temperature of 10°C (Step 7). The aged cod roe was roasted using a commercially available far-infrared roasting machine (model "ICB-20S-WB", manufactured by Ishino Seisakusho Co., Ltd., model name "Far-Infrared Ceramic Burner") at an internal temperature of 250°C and a roasting time of 3 minutes (step 8). The roasted cod roe was vacuum-packed in appropriate packaging containers (step 9), and pasteurized by immersing the packaging containers in a 63°C water bath for 40 minutes (step 10). After removing the packaged roasted cod roe from the water bath, it was cooled to room temperature (approximately 20°C) and then frozen using a commercially available tunnel freezer (model "MMF-2512FL", manufactured by Maekawa Seisakusho Co., Ltd., model name "Microcomputer Mesh Freezer"). The packaged roasted cod roe thus produced was designated as control product 1. Comparative Example 2

[0054] <Comparison product 2: Existing packaged grilled cod roe without pasteurization> To investigate the effect of pasteurization on the total bacterial count and coliform count of packaged grilled cod roe, packaged grilled cod roe was manufactured in the same manner as Comparative Example 1, except that (1) a bacteriostatic agent was not added to the curing solution and (2) the pasteurization process (step 10) of the packaged grilled cod roe was not performed, according to the process shown in Figure 1(C). The packaged grilled cod roe thus manufactured was designated as Control Product 2. Comparative Example 3

[0055] <Comparison item 3: Grilled cod roe prepared in a typical home> As a reproduction of grilled cod roe prepared in a typical household, control product 3 was prepared using the following procedure. The surface of commercially available salted cod roe was grilled in a commercially available oven toaster (model "ET-FA28", manufactured by Zojirushi Corporation) at a heat setting of 1300W and a grilling time of 3 minutes. The grilled cod roe was vacuum-packed in an appropriate packaging container and frozen in a commercially available tunnel freezer (model "MMF-2512FL", manufactured by Maekawa Seisakusho Co., Ltd., model name "Microcomputer Mesh Freezer"). The packaged grilled cod roe thus produced was designated as control product 3.

[0056] The following describes the effects of differences in the manufacturing process for packaged grilled cod roe on the cod roe during the manufacturing process and on the packaged grilled cod roe obtained by each manufacturing method, i.e., Sample 1 and Control Products 1-3, referring to Example 1 (Sample 1) and Comparative Examples 1-3 (Control Products 1-3) as appropriate.

[0057] 3.1. Total bacterial count and coliform count of cod roe after salting process First, we investigated the effect of differences in the salting process on the total bacterial count and coliform count of cod roe after salting. The salting process was carried out using the methods described in Example 1, Comparative Example 1, and Comparative Example 2, and the total bacterial count and coliform count of the cod roe immediately after salting were measured separately in the inside of the roe sac and the egg membrane. In Example 1, Comparative Example 1, and Comparative Example 2, steps 1 to 4 leading up to the salting process were common to all. The results are shown in Table 1.

[0058] [Table 1]

[0059] As shown in Table 1, the cod roe that underwent the salting process of Example 1, which consisted of a first salting process in which the cod roe was immersed in a salting solution at an ambient temperature of 20°C for 24 hours and a second salting process in which the cod roe was immersed in a salting solution at an ambient temperature of 10°C for 24 hours, had a total bacterial count of less than 10 CFU / g inside the cod roe sac and was negative for coliform bacteria, and the same was true for the cod roe egg membrane.

[0060] In contrast, the cod roe that underwent the salting process of Comparative Example 1, in which the cod roe was immersed for 48 hours at an ambient temperature of 20°C in a salt solution containing 0.4% by mass of a bacteriostatic agent relative to the mass of the cod roe, showed a total bacterial count of 210 CFU / g and a coliform count of 60 CFU / g inside the roe sac, while the total bacterial count in the egg membrane of the cod roe was 1300 CFU / g and the coliform count was 280 CFU / g. These measurements are significantly higher than those of the cod roe that underwent the salting process of Example 1, both in the egg membrane and inside the sac. The total bacterial count inside the sac exceeded 100 CFU / g, and coliform bacteria were also detected, which is a major difference from the cod roe that underwent the salting process of Example 1.

[0061] Furthermore, Comparative Example 2, which underwent the same salting process as Comparative Example 1 except that a bacteriostatic agent was not added to the salting solution, showed a total bacterial count of 120 CFU / g and a coliform count of 40 CFU / g inside the roe sac, while the total bacterial count in the egg membrane of the roe was 1000 CFU / g and the coliform count was 160 CFU / g. These measurements were significantly higher than those of the roe that underwent the salting process of Example 1, both in the egg membrane and inside the sac. The total bacterial count inside the sac exceeded 100 CFU / g, and coliform bacteria were also detected, which is a major difference from the roe that underwent the salting process of Example 1. It should be noted that the measurements of Comparative Example 2 were close to those of Comparative Example 1, and no significant difference was observed in the total bacterial count and coliform count immediately after salting, regardless of whether a bacteriostatic agent was added.

[0062] The results above demonstrate that differences in the salting process significantly affect the total bacterial count and coliform count in the roe sac and egg membrane immediately after salting. This indicates that by performing the salting process in two stages—a first salting process at a relatively high temperature and a second salting process at a relatively low temperature—the total bacterial count and coliform count in the roe sac and egg membrane immediately after salting can be significantly suppressed.

[0063] 3.2 Total bacterial count and coliform count after maturation process Next, using the cod roe that had undergone the salting process as described in 3.1 above, the maturation process was further carried out using the methods described in Example 1, Comparative Example 1, and Comparative Example 2. The total number of viable bacteria and coliform bacteria in the cod roe immediately after the maturation process were measured separately in the inside of the roe sac and in the egg membrane. Note that the maturation process was the same for all three: Example 1, Comparative Example 1, and Comparative Example 2. The results are shown in Table 2.

[0064] [Table 2]

[0065] As shown in Table 2, the cod roe that underwent the salting process in Example 1 was further subjected to a maturation process in which it was aged for 48 hours at an ambient temperature of 10°C. The total bacterial count measured immediately afterward was 10 CFU / g in both the inside of the cod roe sac and the egg membrane, and coliform bacteria were negative in both the inside of the cod roe sac and the egg membrane. Thus, with the manufacturing method of Example 1, the total bacterial count and coliform bacteria count remained almost unchanged from the values ​​immediately after the salting process even after the maturation process.

[0066] In contrast, the cod roe from Comparative Example 1 and Comparative Example 2 after the salting process was subjected to a further maturation process in which it was aged for 48 hours at an ambient temperature of 10°C. Immediately afterward, the total bacterial count and coliform count were measured. The total bacterial count inside the cod roe sacs was 250 CFU / g (Comparative Example 1) and 180 CFU / g (Comparative Example 2), the coliform count was 90 CFU / g (Comparative Example 1) and 90 CFU / g (Comparative Example 2), the total bacterial count in the egg membrane of the cod roe was 1500 CFU / g (Comparative Example 1) and 1200 CFU / g (Comparative Example 2), and the coliform count was 350 CFU / g (Comparative Example 1) and 200 CFU / g (Comparative Example 2). Thus, in both Comparative Example 1 and Comparative Example 2, the measurement results for the total bacterial count after the maturation process were approximately 20% higher than the measurements after the salting process, and the coliform count was approximately 20-50% higher than the measurements after the salting process.

[0067] In contrast, in the cod roe after the salting process in Example 1, which is an example of the method for producing packaged grilled cod roe according to the present invention, the total number of viable bacteria was suppressed to less than 10 CFU / g and the coliform bacteria were negative. Therefore, even after the maturation process, the total number of viable bacteria and coliform bacteria could be kept low at a level of 10 CFU / g and negative. In other words, the salting process in the method for producing packaged grilled cod roe according to the present invention can suppress the total number of viable bacteria and coliform bacteria after the salting process, which is an upstream process, to a very low level, and the growth of general viable bacteria and coliform bacteria in the subsequent maturation process can be significantly reduced.

[0068] 3.3. Total bacterial count and coliform count of packaged grilled cod roe Next, using each of the cod roe samples that had undergone the maturation process as described in 3.2 above, the cod roe was further roasted, packaged, pasteurized (Comparative Example 1 only), and frozen using the methods described in Example 1, Comparative Example 1, and Comparative Example 2 to produce packaged roasted cod roe, i.e., Sample 1 of Example 1, Control 1 of Comparative Example 1, and Control 2 of Comparative Example 2. For each sample, the total number of viable bacteria and coliform bacteria were measured separately in the inside of the roe sac and in the egg membrane immediately after opening the package, after storage at 25°C for 48 hours after opening the package, and after storage at 25°C for 72 hours after opening the package. The results are shown in Table 3. Note that Table 3 also includes the measurement results after the salting process and after the maturation process shown in Tables 1 and 2.

[0069] [Table 3]

[0070] As shown in Table 3, Sample 1, a packaged roasted cod roe according to the present invention, was produced by a two-stage salting process consisting of a first salting process and a second salting process. The total bacterial count inside the roe sac immediately after the salting process was 100 CFU / g or less, and coliform bacteria were negative inside the roe sac immediately after the salting process. Subsequently, the sample underwent roasting with superheated steam, and the total bacterial count inside the cod roe sac immediately after opening the package was less than 10 CFU / g, and coliform bacteria were negative. The total bacterial count in the cod roe membrane was also less than 10 CFU / g, and coliform bacteria were negative. On the other hand, comparing the total bacterial count immediately after opening and after the maturation process, the total bacterial count in the egg membrane decreased due to the roasting process with superheated steam, suggesting that the surface of the cod roe was heated and sterilized. The above results regarding total viable count and coliform bacteria fully meet the standards for frozen foods (total viable count of 100,000 CFU / g or less, coliform bacteria negative) described in each article of the "Standards and Specifications for Foods, Food Additives, etc." (Ministry of Health and Welfare Notification No. 370 of 1959). This indicates that the packaged grilled cod roe according to the present invention can be shipped and used as a frozen food without any hygiene issues, even though it has not been pasteurized.

[0071] Furthermore, after opening the packaged grilled cod roe sample 1 and storing it at 25°C for 48 hours, the total bacterial count inside the roe sac and in the egg membrane was measured to be less than 10 CFU / g in both cases, and the coliform count was negative in both cases. Even after storing it at 25°C for 72 hours after opening the package, the total bacterial count inside the roe sac and in the egg membrane remained below 10 CFU / g, and the coliform count remained negative. These results indicate that the packaged grilled cod roe according to the present invention has such low levels of total bacterial count and coliform count that it can be consumed without any problems even 48 or 72 hours after opening the package.

[0072] On the other hand, in control product 1, which corresponds to existing packaged grilled cod roe produced by conventional manufacturing methods, the total bacterial count immediately after the salting process exceeded 100 CFU / g in both the inside of the roe sac and the egg membrane, and the coliform count was 60 CFU / g (inside the sac) or 280 CFU / g (inside the egg membrane). However, after subsequent roasting and pasteurization processes, the total bacterial count inside the cod roe sac immediately after opening the package was less than 10 CFU / g, and the coliform count was negative, with the same result observed in the cod roe egg membrane. Furthermore, after opening control product 1 and storing it at 25°C for 48 hours, the total bacterial count inside the sac and the egg membrane was less than 10 CFU / g, and the coliform count was negative, with the same result observed after 72 hours of storage at 25°C.

[0073] The above results regarding the total bacterial count and coliform bacteria of sample 1 produced by the manufacturing method of the present invention are almost equivalent to the corresponding measurement results of control product 1, which corresponds to existing pasteurized packaged grilled cod roe. This indicates that, according to the method for producing packaged grilled cod roe of the present invention, the total bacterial count and coliform bacteria can be reduced to a level equivalent to that of pasteurized grilled cod roe produced by existing methods for producing packaged grilled cod roe, even without pasteurization.

[0074] In contrast, control product 2, which was roasted cod roe produced through the same process as control product 1 except that it was not pasteurized, showed a total bacterial count of 90 CFU / g and coliform bacteria of 10 CFU / g inside the roe sac immediately after opening the package. The total bacterial count in the roe membrane was also less than 60 CFU / g and coliform bacteria of 30 CFU / g. Comparing this to the measurement results after the maturation process, the total bacterial count in the roe membrane decreased to 1 / 20 after the roasting process, but the total bacterial count inside the cod roe sac only decreased to 1 / 2 even after the roasting process. In addition, coliform bacteria were not sterilized to the point of becoming negative in either the roe membrane or inside the roe sac. These results indicate that for cod roe where the total bacterial count after the salting and aging processes exceeded 100 CFU / g in both the inside of the egg sac and the egg membrane, and coliform bacteria were also detected, surface roasting alone, which is normally used in the production of grilled cod roe, is insufficient to adequately sterilize both the egg membrane and the inside of the egg sac. Therefore, to produce packaged grilled cod roe products, a pasteurization process, which involves maintaining a predetermined temperature for a certain period of time or longer, is essential. In particular, the roasting process does not sufficiently heat the inside of the cod roe sac, resulting in extremely low sterilization efficiency inside the sac.

[0075] Furthermore, after opening the Control Product 2 pack and storing it at 25°C for 48 hours, the total bacterial count and coliform count were measured. The total bacterial count inside the cod roe sac increased to 21,000 CFU / g and the coliform count to 1,200 CFU / g, while the total bacterial count in the cod roe membrane increased to 35,000 CFU / g and the coliform count to 1,500 CFU / g. After storage at 25°C for 72 hours, the total bacterial count inside the cod roe sac reached 64,000 CFU / g and the coliform count reached 9,800 CFU / g, while the total bacterial count in the cod roe membrane reached 78,000 CFU / g and the coliform count reached 12,000 CFU / g. In other words, Control Product 2 is completely unsuitable as an ingredient for rice balls that are expected to be consumed after being stored at room temperature for 48 or 72 hours.

[0076] In summary, the two-stage salting process employed in this invention, which combines a first salting process carried out under a relatively high ambient temperature and a second salting process carried out under a relatively low ambient temperature, has been shown to significantly reduce the total bacterial count and coliform count compared to the single salting process carried out under a relatively high constant temperature ambient temperature used in conventional methods for manufacturing packaged grilled cod roe. As a result, the method for manufacturing packaged grilled cod roe of this invention makes it possible to produce packaged grilled cod roe with a total bacterial count and coliform count that is completely acceptable for shipment as frozen food or as an ingredient for rice balls, simply by surface baking with superheated steam. Furthermore, as will be evident from the sensory tests described below, the salting process in the method for manufacturing packaged grilled cod roe of this invention, while carrying out the second salting process under a relatively low ambient temperature of 10°C, is able to fully bring out the umami, flavor, and texture of the cod roe, and the texture, umami, and flavor of the resulting packaged grilled cod roe are in no way inferior to grilled cod roe cooked at home.

[0077] 4. Experiment 2: Total bacterial count and coliform count of homemade grilled cod roe For Comparative Example 3, which replicated homemade grilled cod roe, the total number of viable bacteria and coliform bacteria were measured separately in the inside of the roe sac and the egg membrane before grilling, immediately after opening the package, after 48 hours of storage at 25°C after opening, and after 72 hours of storage at 25°C after opening. The results are shown in Table 4.

[0078] [Table 4]

[0079] Comparative Example 3, which is equivalent to a reproduction of grilled cod roe prepared at home, produced Control Product 3. Immediately after opening the package, the total bacterial count inside the cod roe sac was 60 CFU / g, the coliform count was 20 CFU / g, the total bacterial count in the cod roe membrane was less than 10 CFU / g, and the coliform count was negative. Since the coliform count was positive, this result does not meet the standards for frozen foods (total bacterial count of 100,000 CFU / g or less, coliform negative) described in each article of the aforementioned "Standards and Specifications for Foods, Food Additives, etc." (Ministry of Health and Welfare Notification No. 370 of 1959). In other words, grilled cod roe prepared at home is not suitable for shipment as a frozen food, although it may be acceptable if consumed on the spot.

[0080] Next, after opening the package of control product 3 and storing it at 25°C for 48 hours, the total bacterial count and coliform count of the roasted cod roe of control product 3 were measured. The total bacterial count inside the cod roe sac was 16,000 CFU / g, and the coliform count was 1,400 CFU / g. Furthermore, although the total bacterial count in the egg membrane immediately after opening the package was less than 10 CFU / g and the coliform count was negative, surprisingly, after 48 hours of storage at 25°C after opening the package, the total bacterial count increased to 18,000 CFU / g and the coliform count increased to 980 CFU / g. This means that commercially available salted cod roe, which shows the total bacterial count and coliform count in the "Before Roasting" column of Table 4, could not sufficiently reduce the total bacterial count and coliform count by the roasting process alone. Furthermore, after storing the grilled cod roe of control product 3 at 25°C for 72 hours, the total bacterial count and coliform count were measured. The total bacterial count inside the cod roe sac had increased to 48,000 CFU / g, and the coliform count to 8,800 CFU / g. The total bacterial count in the cod roe membrane had increased to 56,000 CFU / g, and the coliform count to 7,200 CFU / g. In other words, it was shown that grilled cod roe prepared at home is completely unsuitable as an ingredient for rice balls, which are expected to be consumed after being stored at room temperature for 48 or 72 hours.

[0081] 5. Experiment 3: Evaluation of texture, umami, and flavor After thawing Sample 1, prepared in Example 1, and returning it to room temperature, it was tasted by 10 healthy male and female panelists who evaluated its texture, umami, and flavor. Similarly, the texture, umami, and flavor of Control Product 1 (pasteurized), equivalent to existing packaged grilled cod roe prepared in Comparative Example 1, were also evaluated by the panelists. The evaluation used Control Product 3, equivalent to grilled cod roe prepared using typical household cooking methods, as the baseline. The evaluation was conducted on a 5-point scale: "Excellent = 5", "Good = 4", "Equivalent = 3", "Poor = 2", and "Very Poor = 1", and the average value was calculated. The results are shown in Tables 5 and 6.

[0082] [Table 5]

[0083] [Table 6]

[0084] The results are shown in Table 5. Sample 1, the packaged grilled cod roe of the present invention, received a superior evaluation in terms of texture, umami, and flavor compared to control product 3, which was obtained by replicating a cooking method used in a typical household, with the rating exceeding "equivalent = 3". This means that the packaged grilled cod roe of the present invention possesses not only the flavor and umami characteristic of grilled cod roe, but also a contrast in texture where the surface is grilled and slightly firm, while the inside of the cod roe remains raw, as well as a popping texture reminiscent of fish roe bursting in the air.

[0085] In contrast, as shown in Table 6, Control Product 1, an existing packaged grilled cod roe manufactured through a pasteurization process, received a rating below "equivalent = 3" in terms of texture, umami, and flavor compared to Control Product 3, which was obtained by replicating a cooking method used in a typical household. In particular, the decline in the rating for texture was significant, with an average score of 1.2 points, close to "very bad = 1". This result clearly shows that packaged grilled cod roe manufactured through conventional pasteurization processes loses the unique texture, umami, and flavor of grilled cod roe.

[0086] Furthermore, as is clear from comparing the evaluation of Sample 1 with the evaluation of Control Product 1, Sample 1, the packaged grilled cod roe of the present invention, surpassed Control Product 1, an existing packaged grilled cod roe manufactured through a low-temperature pasteurization process, in terms of texture, umami, and flavor. It was evaluated as superior to Control Product 1 in terms of texture, umami, and flavor.

[0087] As shown in Table 3, Control Product 1 maintained approximately the same levels of total bacterial count and coliform bacteria as Sample 1 even after opening the pack and storing it at 25°C for 48 hours or 25°C for 72 hours. By undergoing a pasteurization process after packaging, the total bacterial count and coliform bacteria were reduced to a level sufficient for market distribution, with a total bacterial count of 10,000 CFU / g or less and coliform bacteria negative even after 48 or 72 hours of storage at 25°C. Thus, Sample 1, the packaged grilled cod roe according to the present invention, is a packaged grilled cod roe in which the total bacterial count and coliform bacteria were reduced to a level sufficient for market distribution. Furthermore, compared to Control Product 1, a conventional packaged grilled cod roe in which the total bacterial count and coliform bacteria were reduced to a level sufficient for market distribution through pasteurization after packaging, Sample 1 is superior not only in texture and umami but also in flavor.

[0088] 6. Experiment 4: Comparison of the appearance of grilled cod roe cross-sections In addition to the texture, taste, and flavor perceived when food is placed in the mouth, the visual appearance of food, which is observed before consumption, also greatly influences consumer purchasing intent and satisfaction. In light of this, the appearances of Sample 1, Control 1, and Control 3 were observed and compared using the naked eye. For the observation, grilled cod roe from Sample 1, Control 1, and Control 3 were sliced ​​into rings approximately 2 cm apart, and the cross-sections of these slices were observed, with photographs taken of the cross-sections.

[0089] The photographs taken are shown in Figures 2 to 4. Figure 2 is Sample 1, which is packaged grilled cod roe according to the present invention; Figure 3 is Control Product 1, which is existing packaged grilled cod roe that has undergone a pasteurization process; and Figure 4 is a cross-sectional photograph of Control Product 3, which is a reproduction of grilled cod roe prepared in a typical home kitchen.

[0090] As is clear from Figure 4, when observing the cross-section of grilled cod roe prepared in a typical home, i.e., control product 3, only the roe near the egg membrane turns white, while no whitening is observed in the roe inside the cluster. This indicates that only the roe near the egg membrane undergoes thermal denaturation during grilling, which corresponds to the slightly hardened surface due to grilling, while the inside remains raw and the roe has the characteristic popping texture of grilled cod roe.

[0091] In contrast, as shown in Figure 3, when observing the cross-section of an existing packaged grilled cod roe that had undergone pasteurization, i.e., control product 1, it was observed that not only the fish eggs near the egg membrane but also the fish eggs inside the roe clusters had turned white. This is thought to be because the pasteurization process, which involves immersion in warm water for a relatively long time, caused thermal denaturation of the fish eggs inside the roe clusters. Visual observation of the cross-section also revealed that the grilled cod roe of control product 1 had already lost the characteristic texture of grilled cod roe, where the surface is grilled and somewhat hard, while the inside of the clusters retains a raw texture, which is consistent with the results of the sensory evaluation in Experiment 3.

[0092] On the other hand, as shown in Figure 2, when observing the cross-section of the packaged grilled cod roe of the present invention, i.e., sample 1, the fish eggs near the egg membrane appeared white, but no clear whitening was observed in the fish eggs inside the roe cluster. The appearance of this cross-section is similar to that of control product 3 (Figure 4), which corresponds to grilled cod roe cooked in a typical home kitchen, confirming that the packaged grilled cod roe of the present invention has a slightly hardened surface due to grilling, while retaining the raw texture inside and the popping texture of the fish eggs, which is characteristic of grilled cod roe. Thus, sample 1, the packaged grilled cod roe of the present invention, is superior to the pasteurized control product 1 in terms of appearance as well.

[0093] 7. Experiment 5: Measurement of Moisture Content To provide a physical basis for the differences in texture between grilled cod roe, we focused on the difference in moisture content between the egg membrane and the inside of the egg sac. We measured the moisture content of the egg membrane and the inside of the egg sac for Sample 1, Control 1, and Control 3, and determined the difference.

[0094] <Measurement sample> In this experiment, to avoid data variability due to individual differences in the shape of grilled cod roe, the grilled cod roe was sliced ​​into rings approximately 2 cm wide from the center in the longitudinal direction. These slices were then separated into the egg membrane and the inside of the roe clusters, and approximately 5 g of each was used as one sample for moisture content measurement. Furthermore, the egg membrane and the inside of the roe clusters of Sample 1 (packaged grilled cod roe according to the present invention), Control Product 1 (existing packaged grilled cod roe that has undergone a pasteurization process), and Control Product 3 (a reproduction of grilled cod roe prepared in a typical home) were used for moisture content measurement. Moisture content measurements were performed on four samples each for Sample 1 and Control Product 1, and on one sample for Control Product 3.

[0095] <Method for measuring moisture content> The moisture content of each sample was measured using a commercially available infrared moisture meter (model "FD-660," manufactured by Kett Scientific Co., Ltd.) by the dry weight method. Specifically, approximately 5 g of the sample was heated at a heating temperature of 120°C for 50 minutes using the above infrared moisture meter, and the moisture content (mass %) was calculated from the mass difference before and after heating based on the following formula.

[0096]

number

[0097] Table 7 shows the water content of the ovary and the membrane of each sample, as well as the difference between them.

[0098] [Table 7]

[0099] As shown in Table 7, the moisture content inside the egg sac of control product 3, which corresponds to grilled cod roe prepared in a typical home kitchen, was 71.0% by mass, and the moisture content of the egg membrane was 69.2% by mass, a difference of 1.8% by mass. This result, in which the moisture content of the egg membrane is lower than that of the inside of the egg sac, and the difference is 1.8% by mass, is thought to reflect the characteristics of grilled cod roe prepared in a typical home kitchen, where the surface of the cod roe is grilled and somewhat hard, while the inside of the egg sac remains raw and the roe has a popping texture. Thus, the reason for this difference in moisture content between the egg membrane and the inside of the egg sac is presumed to be that, during the grilling process, the area near the surface of the cod roe is heated more strongly than the inside of the egg sac, causing it to lose moisture more easily.

[0100] On the other hand, the moisture content inside the egg sac of packaged grilled cod roe that had undergone pasteurization, i.e., control product 1, was an average of 70.9% by mass, and the moisture content of the egg membrane was also an average of 70.4% by mass. The difference in moisture content between the egg membrane and the inside of the egg sac was 0.5% by mass on average across four samples. This difference in moisture content is significantly smaller, about 1 / 3 to 1 / 4 of the 1.8% by mass difference observed in control product 3, which corresponds to grilled cod roe prepared in a typical home kitchen. This indicates that the moisture content of the egg membrane of the cod roe has become almost the same as that of the inside of the egg sac. This result suggests that in packaged grilled cod roe that has undergone pasteurization, not only the surface but also the inside of the egg sac is heated, resulting in a nearly uniform state of fish roe tissue in both the egg membrane and the inside of the egg sac. This is thought to reflect the loss of the unique texture of grilled cod roe.

[0101] In contrast, in Sample 1, which is packaged grilled cod roe according to the present invention, the moisture content inside the roe cluster was 70.2% by mass on average, and the moisture content in the egg membrane was 68.5% by mass on average. The difference in moisture content between the egg membrane and the inside of the roe cluster was 1.7% by mass on average across the four samples, which was almost the same as that of Control Product 3. This result indicates that the grilled cod roe of the present invention has a texture comparable to grilled cod roe prepared in ordinary households (the surface is grilled and slightly firm, while the inside is still raw and the fish eggs have a popping texture), and corresponds to the results of the sensory evaluation in Experiment 3.

[0102] 8. Experiment 6: Effects of curing solution temperature and maturation temperature on total viable bacteria count and coliform bacteria count. 8.1 Effect of curing solution temperature on total bacterial count and coliform bacteria count of cod roe after curing process Except for setting the temperature of the brine solution at the start of the first brine treatment process (process 5Aα) to 10°C or 30°C, the procedure was carried out in the same manner as in Example 1 up to the second brine treatment process (process 5Aβ). The total number of viable bacteria and coliform bacteria of the cod roe immediately after the second brine treatment process were measured separately in the inside of the roe sac and in the egg membrane. The results are shown in Table 8. Note that in Table 8, the results for when the brine solution temperature at the start of the first brine treatment process was 20°C are a re-presentation of the data from Table 1.

[0103] [Table 8]

[0104] As shown in Table 8, regardless of whether the brine temperature at the start of salting was 10°C, 20°C, or 30°C, the total bacterial count and coliform count of the cod roe after the salting process were suppressed to very low levels. This indicates that the total bacterial count and coliform count immediately after the salting process can be suppressed to an extremely low level regardless of whether the brine temperature at the start of salting is between 10°C and 30°C. This result is thought to be because, even if the brine temperature changes from 10°C to 30°C, the brine temperature converges to the ambient temperature of 20°C during the 24-hour first salting process at an ambient temperature of 20°C.

[0105] 8.2 The effect of ambient temperature during maturation on the total bacterial count and coliform count of cod roe after the maturation process. The salting and maturation processes were carried out in the same manner as in Example 1, except that the temperature of the salting solution at the start of the first salting process (process 5Aα) was set to 10°C, 20°C, or 30°C, and the ambient temperature during maturation was set to 5°C, 10°C, or 15°C. The total number of viable bacteria and coliform bacteria of the cod roe immediately after the maturation process were measured separately in the inside of the roe sac and in the egg membrane. The results are shown in Table 9. Note that in Table 9, the sample with a salting solution temperature of 20°C at the start of the first salting process and a maturation temperature of 10°C is the same sample as in Experiment 1, so the data from Table 2 is repeated.

[0106] [Table 9]

[0107] As shown in Table 9, under all manufacturing conditions, the total bacterial count and coliform count in the egg membrane and inside the roe sac after the maturation process were suppressed to very low levels. In other words, it was shown that a maturation temperature within the range of at least 5°C to 15°C can be suitably used for the production of packaged grilled cod roe according to the present invention. Furthermore, as will be described later, the total bacterial count and coliform count in the egg membrane and inside the roe sac are at a level that can be sufficiently sterilized by surface baking with superheated steam.

[0108] 8.3 Effects of salting liquid temperature and aging liquid temperature on total bacterial count and coliform bacteria count in packaged grilled cod roe In Experiment 6, the tarako (cod roe) was processed in the same manner as in Example 1, except that the temperature of the brine at the start of the first brine process (process 5Aα) was set to 10°C, 20°C, or 30°C, and the ambient temperature during maturation was set to 5°C, 10°C, or 15°C. The manufacturing process after the maturation process was then carried out in the same manner as in Example 1 to produce samples A to I, which correspond to the packaged grilled tarako of the present invention. The total number of viable bacteria and coliform bacteria were measured separately in the inside of the roe sac and in the egg membrane of the produced samples A to I immediately after opening the packs and after being stored at 25°C for 48 hours after opening. The results are shown in Table 10. Note that in Table 10, sample E, which was produced with a brine temperature of 20°C at the start of the first brine process and a maturation temperature of 10°C, is the same as sample 1 produced in Experiment 1, so the data from Table 3 is repeated.

[0109] [Table 10]

[0110] As shown in Table 10, the obtained samples A to I, both inside the egg sac and in the egg membrane, had a total bacterial count of less than 10 CFU / g immediately after opening, and were negative for coliform bacteria. This meets the standards for frozen foods described in each article of the aforementioned "Standards for Foods, Additives, etc." (Ministry of Health and Welfare Notification No. 370 of 1959). In other words, all packaged grilled cod roe, manufactured with a brine temperature of 10°C, 20°C, and 30°C at the start of salting, and a maturation temperature of 5°C, 10°C, and 15°C, are completely free of hygienic problems when shipped as frozen food.

[0111] Furthermore, even after storing samples A-I at 25°C for 48 hours after opening, while the total bacterial count tended to increase as the initial brine temperature or maturation temperature rose, the total bacterial count remained low, and coliform bacteria were suppressed to a negative level. This indicates that all of samples A-I, produced with initial brine temperatures of 10°C, 20°C, and 30°C, and maturation temperatures of 5°C, 10°C, and 15°C, maintained a level of suppression in total bacterial count and coliform bacteria that allowed them to be safely consumed without any problems, even after being shipped as ingredients for rice balls, and after the rice balls made using these ingredients were shipped to convenience stores, displayed, and purchased by consumers.

[0112] 8.4 The effect of salting liquid temperature and aging liquid temperature on the texture, umami, and flavor of packaged grilled cod roe Sensory evaluation of samples A to I was conducted in the same manner as in Experiment 3. Specifically, ten healthy male and female panelists tasted the packaged grilled cod roe of the present invention immediately after opening the package and evaluated its texture, umami, and flavor. The evaluation was based on control product 3, which was obtained by replicating a typical household cooking method, and was given on a five-point scale: "Excellent = 5", "Good = 4", "Equivalent = 3", "Poor = 2", and "Very Poor = 1". The average value was used as the result. The results are shown in Table 11. The results for control product 1 and sample 1 were copied from Tables 5 and 6.

[0113] [Table 11]

[0114] The results are shown in Table 11. Samples A to I, which are packaged grilled cod roe according to the present invention, received excellent evaluations in terms of texture, umami, and flavor, being equivalent to or nearly equivalent to control product 3, which was obtained by replicating a cooking method used in a typical household. These results mean that, in all cases within the scope of the study, the packaged grilled cod roe of the present invention possesses sufficient umami, the characteristic savory flavor of grilled cod roe, and a texture that is slightly firm on the surface due to grilling, while retaining the raw feel of the inside and the popping sensation of the fish roe. Furthermore, the evaluations of texture, umami, and flavor of samples A to I all surpassed those of control product 1, indicating that samples A to I are superior to control product 1 in terms of texture, umami, and flavor.

[0115] Furthermore, Table 11 shows that as the ambient temperature during maturation increased from 5°C to 10°C to 15°C, the evaluation tended to improve, particularly in terms of umami and flavor. From this result, it can be seen that an ambient temperature of 10°C to 15°C during maturation is more preferable from the standpoint of enhancing the umami and flavor of grilled cod roe. It should be noted that the above trend is consistent with the established knowledge in the field that higher ambient temperatures during maturation bring out more umami and flavor in cod roe. In particular, samples B, C, E, and F, which were produced with a brine temperature of 10°C or 20°C at the start of salting and an ambient temperature of 10°C or 15°C during maturation, received significantly higher evaluations than control product 3, which was obtained by replicating a cooking method used in a typical household. From this result, it can be seen that a combination of a brine temperature of 10°C to 20°C at the start of maturation and an ambient temperature of 10°C to 15°C during maturation is more preferable from the standpoint of enhancing the umami and flavor of grilled cod roe. Although the reason why the grilled cod roe produced using the above combination received a significantly higher evaluation than control product 3 is unclear, it is presumed that the method for producing packaged grilled cod roe according to the present invention allows for the enhancement of the texture, flavor, and umami of the cod roe while suppressing the total number of viable bacteria and coliform bacteria to an extremely low level. As a result, off-flavors derived from bacteria or bacterial metabolites are reduced, allowing consumers to more strongly perceive the original flavor and umami of the cod roe. The evaluation results of each panelist for each of the samples A to I (except for sample E, which is the same as sample 1) are shown in Tables 12 to 19.

[0116] [Table 12]

[0117] [Table 13]

[0118] [Table 14]

[0119] [Table 15]

[0120] [Table 16]

[0121] [Table 17]

[0122] [Table 18]

[0123] [Table 19]

[0124] 9. Experiment 7: Investigation of firing temperature Samples J-M, which represent an example of packaged grilled cod roe according to the present invention, were produced in the same manner as in Example 1, with the superheated steam temperature blown into the roasting machine set to 240°C, 250°C, 260°C, and 270°C, except for the superheated steam temperature. After the maturation process, the total number of viable bacteria and coliform bacteria in the entire cod roe were measured immediately after opening the package and after being stored at 25°C for 48 hours after opening the package. In addition, the experimenter tasted the grilled cod roe immediately after opening the package and evaluated its texture. The results are shown in Table 20.

[0125] [Table 20]

[0126] As shown in Table 20, regardless of the superheated steam temperature used for baking, the packaged grilled cod roe products, which were baked using superheated steam, then packaged while maintaining a relatively high temperature after baking, cooled, and frozen, all had low levels of total viable bacteria and coliform bacteria, sufficient for shipment as frozen food. Furthermore, the total viable bacteria and coliform bacteria levels after opening the package and storing at 25°C for 48 hours were also suppressed to low levels in all samples. This means that regardless of the superheated steam temperature used for baking, the packaged grilled cod roe produced had its total viable bacteria and coliform bacteria levels reduced to a level that poses no problem when used as a filling for rice balls. Therefore, it was shown that if surface baking is performed at a superheated steam temperature of at least 240°C or higher, grilled cod roe products that pose no hygiene problems can be obtained.

[0127] On the other hand, looking at the texture evaluation results shown in Table 20, while each product baked at a superheated steam temperature of 260°C or lower showed a "good" result, the product baked at a superheated steam temperature of 270°C had a hard texture. These results mean that, in the method for producing packaged baked cod roe of the present invention, when surface baking is performed using superheated steam at a temperature of 240°C to 260°C, it is possible to produce packaged baked cod roe products with a suitable texture.

[0128] Furthermore, when the baking time was changed to 2 minutes or 3 minutes, while maintaining the same procedure as in the above experiment, the same results as described above were obtained in both cases. From this, it can be seen that when the time the cod roe to be baked is present in the space from which superheated steam is blown is between 2 minutes and 3 minutes, the packaged baked cod roe of the present invention is obtained that has the same texture and flavor as home-baked cod roe, and in which the total number of viable bacteria and coliform bacteria are suppressed to an extremely low level.

[0129] 10. Experiment 8: Examination of the presence or absence of bacteriostatic agents. Samples N to R, which are packaged grilled cod roe, were prepared in the same manner as in Example 1, except that a commercially available bacteriostatic agent (product name "SM-P", manufactured by Ueno Food Techno Co., Ltd.) was added to the salting solution at an amount of 0.4, 0.6, 0.7, 0.9, 1.0, or 1.5% by mass relative to the cod roe. After the maturation process, the total number of viable bacteria and coliform bacteria in the entire cod roe were measured immediately after opening the package and after being stored at 25°C for 48 hours after opening. In addition, immediately after opening the package, the experimenter tasted the grilled cod roe and evaluated whether the taste of the bacteriostatic agent could be detected. The results of these experiments are shown in Table 21.

[0130] [Table 21]

[0131] As shown in Table 21, regardless of the concentration of the bacteriostatic agent used, the total bacterial count in the entire cod roe after the maturation process was suppressed to a low level, and in addition, the coliform count was negative. This is equivalent to the results shown in Table 2 of Experiment 1, which measured the cod roe after the salting process when the salting solution did not contain a bacteriostatic agent. Furthermore, samples N to R, which are packaged grilled cod roe produced by surface-baking these matured cod roe with superheated steam, followed by packaging, cooling, and freezing, all showed low levels of total bacterial count and coliform count immediately after opening, similar to sample 1 shown in Table 3 of Experiment 1, which did not contain a bacteriostatic agent. Moreover, the total bacterial count and coliform count after storing the product at 25°C for 48 hours after opening the package were also suppressed to low levels in all samples. This means that the packaged grilled cod roe of the present invention, produced using a bacteriostatic agent, has reduced the total bacterial count and coliform count to a level that poses no problem when used as a filling for rice balls.

[0132] On the other hand, looking at the sensory evaluation results shown in Table 21, while each product with an added bacteriostatic agent of 0.9% by mass or less showed "no effect," packaged grilled cod roe produced using a brine solution containing 1.0% by mass of bacteriostatic agent was found to have a "taste of bacteriostatic agent." Furthermore, packaged grilled cod roe produced using a brine solution containing 1.5% by mass of bacteriostatic agent had a "strong taste of bacteriostatic agent." These results mean that, in the method for producing packaged grilled cod roe of the present invention, when a bacteriostatic agent is added to the brine solution at a concentration of 0.9% by mass or less relative to the cod roe, it is possible to suppress variations in bacterial count during the manufacturing process without affecting the taste of the packaged grilled cod roe product.

[0133] 11. Experiment 9: Examination of salting and maturation conditions in the presence of bacteriostatic agents. Samples a to i, which are examples of packaged grilled cod roe according to the present invention, were prepared in the same manner as in Experiment 6, except that a commercially available bacteriostatic agent (product name "SM-P", manufactured by Ueno Food Techno Co., Ltd.) was added to the salt solution at a concentration of 0.7% by mass relative to the cod roe. The total number of viable bacteria and coliform bacteria of the prepared samples a to i were measured immediately after opening the packs and after being stored at 25°C for 48 hours after opening the packs. The results are shown in Table 22.

[0134] [Table 22]

[0135] As shown in Table 22, the obtained samples a-i all showed a total bacterial count of less than 10 CFU / g in both the inside of the egg sac and the egg membrane immediately after opening the pack, and were negative for coliform bacteria. This meets the standards for frozen foods described in each article of the aforementioned "Standards and Specifications for Foods, Food Additives, etc." (Ministry of Health and Welfare Notification No. 370 of 1959), and all of the packaged grilled cod roe poses no hygiene problems whatsoever when shipped as frozen food.

[0136] Furthermore, even after storing samples a-i at 25°C for 48 or 72 hours after opening the pack, while the bacterial count tended to increase as the temperature of the brine at the start of salting or the maturation temperature rose, the total viable cell count remained very low, and coliform bacteria were suppressed to a negative level. This means that all of samples a-i were shipped as ingredients for rice balls, and a processor removed them from the pack and used them, for example, as ingredients for rice balls. These rice balls could then be consumed without any hygienic problems for up to 72 hours from the time the pack was opened, at a temperature of around 25°C.

[0137] Next, sensory evaluations of the manufactured samples a-i were conducted in the same manner as in Experiment 3. Specifically, ten healthy male and female panelists tasted the packaged grilled cod roe of the present invention and evaluated its texture, umami, and flavor. The evaluation was based on control product 3, which was obtained by replicating a cooking method used in a typical household, and was given on a five-point scale: "Excellent = 5", "Good = 4", "Equivalent = 3", "Poor = 2", and "Very Poor = 1". The average value was used as the evaluation value. In addition, a new packaged grilled cod roe was manufactured using the method described in Comparative Example 1, and this was used as control product 1. Panelists tasted it in the same manner as samples a-i and evaluated its texture, umami, and flavor. The results are shown in Table 23. Control product 3 was also newly prepared using the method described in Comparative Example 3.

[0138] [Table 23]

[0139] As shown in Table 23, samples a-i, which are packaged grilled cod roe, received excellent evaluations in terms of texture, umami, and flavor, being equivalent to or nearly equivalent to control product 3, which was obtained by replicating a cooking method used in a typical home. These results mean that the packaged grilled cod roe of the present invention, even when salted using a brine solution to which a bacteriostatic agent was added at 0.7% by mass relative to the cod roe, possesses the same umami, the characteristic savory flavor of grilled cod roe, and a contrast in texture—a slightly firm surface due to grilling, while the inside retains a raw texture—as well as the popping texture of the fish roe. Furthermore, the evaluations of umami, texture, and flavor for samples a-i all surpassed those of control product 1, and were evaluated as superior to control product 1, which was pasteurized.

[0140] Furthermore, Table 23 shows that as the ambient temperature during maturation increased from 5°C to 10°C to 15°C, the evaluation tended to improve, particularly in terms of umami and flavor. This trend is similar to that observed in Table 11 for samples produced without the use of bacteriostatic agents in the curing solution. This is also consistent with the established knowledge in the field that higher maturation temperatures bring out more umami and flavor in cod roe. In particular, samples b, c, e, f, h, and i, produced at an ambient temperature of 10°C or 15°C during maturation, received significantly higher evaluations than control sample 3, which was obtained by replicating a cooking method used in a typical home. From these results, it can be seen that an ambient temperature of 10°C to 15°C during maturation is more preferable from the standpoint of enhancing the umami and flavor of grilled cod roe. This is consistent with the results observed in Table 11 for samples produced without the use of bacteriostatic agents in the curing solution. Although the reason why the above sample received a significantly higher evaluation than control product 3 is unclear, it is presumed that the method for producing packaged grilled cod roe according to the present invention allows for the sufficient enhancement of the texture, flavor, and umami of the cod roe while suppressing the total number of viable bacteria and coliform bacteria to a low level. As a result, off-flavors derived from bacteria or bacterial metabolites are reduced, allowing consumers to more strongly perceive the original flavor and umami of the cod roe. The evaluation results of each panelist for the newly prepared control product 1 and samples a to i are shown in Tables 24 to 33.

[0141] [Table 24]

[0142] [Table 25]

[0143] [Table 26]

[0144] [Table 27]

[0145] [Table 28]

[0146] [Table 29]

[0147] [Table 30]

[0148] [Table 31]

[0149] [Table 32]

[0150] [Table 33] [Industrial applicability]

[0151] As described above, the packaged grilled cod roe of the present invention has a sufficiently reduced total bacterial count and coliform count to the extent that it can be distributed to the market as a product. However, it has a superior texture and flavor compared to conventional packaged grilled cod roe that has been pasteurized to reduce bacterial counts, and preferably has a superior aroma. Furthermore, it preferably possesses the appearance, texture, flavor, and preferably aroma of grilled cod roe that is cooked at home, such as commercially available salted cod roe whose surface has been heated and grilled. In other words, the packaged grilled cod roe of the present invention has a homemade feel, and for example, a rice ball made with it as an ingredient gives the eater a sense of satisfaction that makes it seem as if it were a homemade rice ball. Thus, the packaged grilled cod roe of the present invention and its manufacturing method contribute to improving people's lives through food, and have great industrial applicability.

Claims

[Claim 1] Grilled cod roe, which is made by grilling salted and aged cod roe, is packaged in a pack. The total bacterial count measured immediately after opening the pack and removing the product from the pack is 10,000 CFU / g or less, and the coliform bacteria test is negative. The difference in moisture content between the egg membrane and the inside of the roe sac of the grilled cod roe, measured immediately after removal from the pack, is 1.0% by mass or more and 2.5% by mass or less, After being removed from the package and stored at 25°C for 48 hours, the total bacterial count of the grilled cod roe measured is 10,000 CFU / g or less, and the coliform bacteria test is negative. A packaged grilled cod roe product featuring these characteristics.

Images