Method for producing calcium / dehydrated onions

Abstract

The present invention aims to solve the problem of producing onions that retain their texture well even when heated and are suitable for heating in a microwave oven. [Solution] The present invention relates to a method for producing calcium / dehydrated onions, comprising subjecting onions cut to a size that can pass through a sieve with a mesh opening of 20 mm to dehydration and calcium treatment to obtain calcium / dehydrated onions. The present invention also relates to a method for producing food products, comprising incorporating the calcium / dehydrated onions produced by the above method, and a method for producing pressurized heat-sterilized packaged food products, comprising placing the food product containing the calcium / dehydrated onions produced by the above method into a container, sealing it, and pressurizing heat sterilization.

Description

Technical Field

[0001] The present invention relates to a method for producing onions that are easy to maintain their texture even when heated and are suitable for heating in a microwave oven, a method for producing foods using the onions, and a method for producing container-packed foods that are subjected to pressure heating sterilization using the onions.

Background Art

[0002] A variety of preserved food products such as curry and stew containing vegetables such as onions as ingredients are on the market. In order to enhance their preservation properties, these preserved food products are generally subjected to pressure heating sterilization (retort sterilization). The preserved food products may be heated in a microwave oven by consumers when eaten.

[0003] When heating foods containing vegetables, the problem that the vegetables are overly softened and lose their shape has been conventionally recognized. As a means for solving this problem, for example, in Patent Document 1, when subjecting vegetables to heat treatment or freezing treatment, the vegetables are impregnated in advance with at least any one of brine, sugar solution, and sugar alcohol solution, and then impregnated with an aqueous calcium salt solution and / or an aqueous magnesium salt solution, and a method for preventing softening of vegetables is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Vegetables treated with calcium are difficult to soften by heating and are easy to maintain their texture.

[0006] On the other hand, the inventors of the present invention have discovered a new problem: onions whose softening has been suppressed by calcium treatment are prone to popping noises when heated in a microwave oven, especially when their dimensions are relatively small (for example, small enough to pass through a sieve with a mesh size of 20 mm).

[0007] Therefore, the problem to be solved by the present invention is to produce onions that retain their texture well even when heated and are suitable for heating in a microwave oven. [Means for solving the problem]

[0008] The inventors have discovered that calcium / dehydrated onions, produced by subjecting onions cut to a size that can pass through a sieve with a mesh size of 20 mm to dehydration and calcium treatment, retain their texture well even after heat treatment such as pressurized heat sterilization, and are suitable for heating in a microwave oven. Based on this, they have completed the following embodiments disclosed herein.

[0009] [1] Onions cut to a size that can pass through a sieve with a mesh size of 20 mm are subjected to dehydration and calcium treatment to obtain calcium / dehydrated onions. A method for producing calcium / dehydrated onions, including [the specified ingredient].

[0010] [2] The method according to [1], wherein the dehydration treatment comprises immersing the onion in a saline solution containing salt at a concentration of less than 8% by mass.

[0011] [3] The method according to [1] or [2], wherein the calcium treatment comprises immersing the onion in an aqueous calcium salt solution containing calcium at a concentration of less than 0.27% by mass in terms of calcium lactate.

[0012] [4] Subjecting the onions to the dehydration treatment to obtain dehydrated onions, and The dehydrated onions are subjected to the calcium treatment to obtain calcium / dehydrated onions. A method of any of [1] to [3], including the above.

[0013] A method for producing a food product, comprising incorporating the calcium / dehydrated onion produced by any of the methods described in [5][1] to [4].

[0014] [6] The method according to [5], wherein the food comprises 2% by mass or more of the calcium / dehydrated onion based on the total amount.

[0015] A method for producing a pressurized and heat-sterilized packaged food product, comprising placing the food product containing the calcium / dehydrated onion produced by any of the methods in [7][1] to [4] into a container, sealing it, and pressurizing and heat-sterilizing it. [Effects of the Invention]

[0016] The calcium / dehydrated onions, food products, and pressure-heat-sterilized containerized food products produced by the method of the present invention retain their onion texture even after heating and are suitable for microwave heating. [Modes for carrying out the invention]

[0017] <Onion> In this disclosure, unless otherwise specified, "onion" refers to the bulb (a collection of scale leaves) of an onion that is normally consumed. Raw onions cut to a predetermined size can be used as raw material for the method according to the first aspect of this disclosure described below.

[0018] <First aspect: Method for producing calcium / dehydrated onions> The first aspect of this disclosure is: Onions cut to a size that can pass through a sieve with a mesh size of 20 mm are subjected to dehydration and calcium treatment to obtain calcium / dehydrated onions. A method for producing calcium / dehydrated onions, Regarding.

[0019] The inventors have found that onions treated only with calcium have their cell walls strengthened and are likely to retain their texture when heated, but when the onions are of a size that can pass through a sieve with a mesh size of 20 mm, they are likely to burst during microwave heating. The inventors have also found that onions of the above-mentioned size treated only with dehydration treatment are unlikely to produce a cracking sound during microwave heating, but soften too much during heating and have an unfavorable texture. In the method according to the first aspect of the present disclosure, by subjecting onions cut to a size that can pass through a sieve with a mesh size of 20 mm to both dehydration treatment and calcium treatment, it is possible to produce calcium / dehydration-treated onions that have the advantageous effect of being likely to retain their texture even when heated by pressure heating treatment or the like, and being unlikely to produce a cracking sound when heated by a microwave oven.

[0020] The onions used as raw materials are raw onions cut to a size that can pass through a sieve with a mesh size of 20 mm. Raw onions are preferred as the onions used as raw materials. Onions of this size are suitable as ingredients for curry sauce, stew sauce, and the like. The above-mentioned size of the onions used as raw materials is more preferably a size that can pass through a sieve with a mesh size of 20 mm and cannot pass through a sieve with a mesh size of 4 mm, and even more preferably a size that can pass through a sieve with a mesh size of 10 mm and cannot pass through a sieve with a mesh size of 4 mm. In the present disclosure, an S.I.K standard sieve (manufactured by Iida Seisakusho Co., Ltd.) can be used as the sieve.

[0021] In the method according to the first aspect of the present disclosure, the onions cut to a predetermined size are subjected to dehydration treatment and calcium treatment, but the order of dehydration treatment and calcium treatment is not particularly limited, and either can be performed first, and one or both of dehydration treatment and calcium treatment can be performed multiple times, but preferably, dehydration treatment is performed first, followed by calcium treatment.

[0022] The dehydration process preferably involves immersing the onions in a saline solution to dehydrate them by transferring water from the inside of the onions to the saline solution due to the osmotic pressure difference. The salt concentration of the saline solution used in the dehydration process is preferably less than 8% by mass, more preferably 7% by mass or less, and particularly preferably 4% by mass or more and 7% by mass or less. Combining a dehydration process using a saline solution with a salt concentration in this range with a calcium treatment is particularly advantageous in producing calcium / dehydrated onions that maintain texture during heating and are suitable for microwave heating. The saline solution may be any solution in which salt is dissolved in water, and may further contain other components. The amount of saline solution used in the dehydration process may be in excess of the onions; for example, 0.7 parts by mass or more of saline solution can be used per 1 part by mass of onion. The time for immersing the onions in the saline solution is not particularly limited, but can be, for example, 5 minutes or more, preferably 10 minutes or more, more preferably 15 minutes or more, more preferably 5 minutes or more and 30 minutes or less, more preferably 10 minutes or more and 25 minutes or less, and particularly preferably 15 minutes or more and 20 minutes or less. The temperature when immersing the onions in the saline solution is not particularly limited, but can be, for example, 10°C or more and 75°C or less, more preferably 15°C or more and 30°C or less.

[0023] The calcium treatment preferably includes immersing the onion in an aqueous calcium salt solution to impregnate the onion with calcium ions. The impregnated calcium ions are presumed to strengthen the cell wall of the onion. The concentration of the calcium salt in the aqueous calcium salt solution used for the calcium treatment, in terms of the calcium lactate equivalent concentration, is preferably less than 0.27% by mass, more preferably 0.18% by mass or less, still more preferably 0.15% by mass or less, and more preferably, it contains calcium at a concentration of 0.05% by mass or more and less than 0.27% by mass, more preferably 0.05% by mass or more and 0.18% by mass or less, particularly preferably 0.05% by mass or more and 0.15% by mass or less. Combining the calcium treatment using an aqueous calcium salt solution with a calcium salt concentration within this range with a dehydration treatment is particularly advantageous for producing calcium / dehydrated treated onions in which the texture retention during heating and the suitability for microwave heating are compatible. The calcium salt may be any water-soluble calcium salt acceptable as a food, and examples include calcium lactate, calcium chloride or calcium acetate. Particularly, calcium lactate or calcium chloride is preferred. A combination of multiple types of calcium salts can also be used. The aqueous calcium salt solution may be a solution in which the calcium salt is dissolved in water and may further contain other components. The aqueous calcium salt solution used in the calcium treatment may be in an excessive amount relative to the onion. For example, 1.1 parts by mass or more of the aqueous calcium salt solution can be used per 1 part by mass of the onion. The time for immersing the onion in the aqueous calcium salt solution is not particularly limited, but it can be, for example, 5 minutes or more, preferably 8 minutes or more, more preferably 5 minutes or more and 30 minutes or less, and still more preferably 8 minutes or more and 25 minutes or less. The temperature when immersing the onion in the aqueous calcium salt solution is not particularly limited, but it can be, for example, 15°C or more and 75°C or less.

[0024] The method according to the first aspect of the present disclosure preferably subjects the cut raw onion to a dehydration treatment to obtain a dehydrated treated onion, and subjects the dehydrated treated onion to a calcium treatment to obtain a calcium / dehydrated treated onion. This includes the following. The specific details of the dehydration and calcium treatment are as described above.

[0025] The configuration in which the dehydration treatment and calcium treatment are carried out in this order is particularly preferred. Step 1) The cut raw onions are immersed in a saline solution containing salt at a predetermined concentration to obtain dehydrated onions, and, Step 2) Add calcium salt and water or an aqueous calcium salt solution to the saline solution containing the dehydrated onions to make an aqueous calcium salt solution containing calcium at a predetermined concentration, and then immerse the dehydrated onions in it to obtain calcium / dehydrated onions. The method according to the first aspect of this disclosure, including steps 1) and 2), is particularly preferred because it produces less wastewater. The predetermined concentrations of sodium chloride and calcium salt in steps 1) and 2) are the concentrations described for dehydration and calcium treatment, respectively.

[0026] <Food manufacturing methods> A second aspect of this disclosure is: A method for producing a food product, comprising incorporating calcium / dehydrated onions produced by the method of the first aspect of this disclosure, Regarding.

[0027] Food products containing calcium / dehydrated onions, manufactured by the method of the second aspect of this disclosure, retain the texture of the onions even when heated and are suitable for heating in a microwave oven.

[0028] The type of food is not particularly limited, but is preferably a liquid or paste-like food such as curry sauce, stew sauce, pasta sauce, gumbo sauce, or gapao rice. Liquid or paste-like foods also include liquid or paste-like foods that have viscosity.

[0029] Food products produced by the method of the second aspect of this disclosure preferably contain 2% by mass or more, more preferably 2% by mass or more and 20% by mass or less, of the calcium / dehydrated onion based on the total amount. Food products containing the calcium / dehydrated onion in this range are particularly preferred because they have high texture retention when heated and suitability for microwave heating.

[0030] A method according to a second aspect of this disclosure includes producing a food product by combining calcium / dehydrated onions with other ingredients. The other ingredients are not particularly limited and include, for example, water, oils and fats, spices, sugars, starches, meat, fish, vegetables, etc.

[0031] If the method of the first aspect of this disclosure includes steps 1) and 2), it is preferable that the method of the second aspect of this disclosure is a method of producing food by adding water or other ingredients to the calcium salt aqueous solution containing calcium / dehydrated onions formed in step 2), without separating the calcium / dehydrated onions from the calcium salt aqueous solution, in order to suppress the generation of wastewater.

[0032] <Method for manufacturing containerized food products that have been sterilized by pressurized heating> A third aspect of this disclosure is: A method for producing a pressurized and heat-sterilized packaged food, comprising placing a food containing calcium / dehydrated onions produced by the method of the first aspect of this disclosure into a container, sealing it, and pressurizing and heat-sterilizing it, Regarding.

[0033] The packaged food manufactured by the method of the third aspect of this disclosure is storable for a long period of time, retains the texture of the onions, and is suitable for microwave heating. The packaged food is suitable for microwave heating both while still in the container and after being removed from the container and placed on a plate or the like.

[0034] The container can be any airtight container that is resistant to pressurized heat sterilization, and can be in the form of a pouch, pack, etc. Materials that can be used for pressurized heat resistant containers include paper, cans, coated paper, resins such as PET, metals such as aluminum, and glass. The container may also have a mechanism for releasing steam when heated in a microwave oven. Preferably, the pressurized heat resistant container is made of a resin film. The resin film is preferably a multilayer film having a layered structure such as PET (polyethylene terephthalate) / NY (nylon) / AL (aluminum foil) / CPP (unoriented polypropylene), aluminum-deposited PET / NY / CPP, PET / NY / CPP, PET / NY / NY / CPP, PET / EVAL(trademark) / NY / CPP, or transparent-deposited PET / NY / CPP.

[0035] The food contained in the container in the method of the third aspect of this disclosure does not need to be finished at the time of containerization, but includes food that is finished after heating by pressurized heat sterilization. The type of food is not particularly limited, but preferably it is a liquid or paste-like food such as curry sauce or stew sauce. Liquid or paste-like foods also include liquid or paste-like foods that have viscosity. The method of the third aspect of this disclosure includes containing calcium / dehydrated onions in combination with other ingredients in a container. Other ingredients are not particularly limited and include, for example, water, oils and fats, spices, sugars, starches, meat, fish, vegetables, etc.

[0036] The conditions for pressurized heat sterilization are not particularly limited, but examples include pressurized heat sterilization with a maximum temperature of 110°C to 140°C and a heating time of 5 to 50 minutes.

[0037] The packaged food produced by the method of the third aspect of this disclosure contains, preferably 2% by mass or more, more preferably 2% by mass or more and 20% by mass or less, of the calcium / dehydrated onion based on the total amount of the contents of the container. Packaged food containing the calcium / dehydrated onion in this range is preferred because it has a good onion texture and is particularly suitable for microwave heating.

[0038] If the method of the first aspect of this disclosure is a method comprising steps 1) and 2), it is preferable that the method of the third aspect of this disclosure is a method for producing packaged food by mixing water and other ingredients with the calcium salt aqueous solution containing calcium / dehydrated onions formed in step 2), without separating the calcium / dehydrated onions from the calcium salt aqueous solution, placing the mixture in a container, sealing it, and sterilizing it by pressurized heating, as this suppresses the generation of wastewater. [Examples]

[0039] 1. Examination of raw material onions 1.1. Experiment 1-1 Raw onions cut into 8mm x 8mm pieces were heated in hot water at 65°C for 10 seconds. 33g of the heated onions were sealed in a retort pouch with 117g of water. The retort pouch was sterilized by pressurized heating at 122°C for 20 minutes.

[0040] 1.2. Experiment 1-2 33g of raw onion, cut into 8mm x 8mm pieces, was placed in a retort pouch with 117g of water and sealed. The retort pouch was sterilized by pressurized heating at 122°C for 20 minutes.

[0041] 1.3. Evaluation of texture The retort pouches from Experiments 1-1 and 1-2, which had been sterilized under pressure and heat, were opened, and the onions were removed. Five evaluators then assessed the texture at room temperature. All five evaluators rated both the onions from Experiment 1-1 and Experiment 1-2 as being too soft and having an undesirable texture.

[0042] 1.4. Evaluation of microwave heating suitability I prepared the curry sauce using commercially available curry roux. The samples were prepared by adding 17g of onion, removed from the retort pouches of Experiments 1-1 and 1-2 after pressure-heat sterilization, to 83g of the aforementioned curry sauce. 100g of the sample was placed in a container and heated in a microwave oven at 600W for 4 minutes. The microwave heating suitability was evaluated by two evaluators according to the following criteria.

[0043] ○: No sound is made during microwave heating, or the sound is very quiet and not bothersome. △: There is a sound when the microwave is heating, but the volume is not loud enough to be a concern. ×: A loud noise occurs while the microwave is heating, causing anxiety.

[0044] Both evaluators rated the microwave heating suitability of the onions from Experiment 1-1 and Experiment 1-2 as "good" (✓).

[0045] 2. Examination of dehydration treatment conditions 2.1. Raw material: Onion Raw onions cut to a size of 8mm x 8mm were used as raw materials. In this specification, the size of the onion cuts, Mmm x Nmm, refers to the distance between the multiple first cut surfaces and the distance between the multiple second cut surfaces when the onion bulb halves are placed on the top surface of a board with the cut surface facing downwards, and the bulb halves are cut with a knife along multiple first cut surfaces that are evenly spaced and parallel to a first surface perpendicular to the top surface of the board, and multiple second cut surfaces that are evenly spaced and parallel to a second surface that is perpendicular to both the first surface and the top surface of the board.

[0046] 2.2. Dehydration Process 320g of chopped raw onions were dehydrated by immersing them for 15 minutes in either water without salt (salt concentration 0% by mass) or 250g of saline solution with a concentration of 3%, 4%, 5%, or 8% by mass.

[0047] 2.3. Calcium treatment After 15 minutes, calcium lactate solution was added to the mixture of onions and water or saline solution so that the final concentration of calcium lactate in the aqueous solution was 0.27% by mass. The mixture was then held for 10 minutes to perform calcium treatment.

[0048] 2.4. Pressurized heat sterilization treatment After calcium treatment, the onions were separated from the surrounding aqueous solution. 33g of the separated onions and 117g of an aqueous solution containing 1.3% by mass of sodium chloride and 0.125% by mass of calcium lactate were placed in a retort pouch and sealed. The retort pouch was sterilized by pressurized heating at 122°C for 20 minutes.

[0049] 2.5. Evaluation of texture Each retort pouch, which had been sterilized under pressure and heat, was opened, and the onions were removed. Five evaluators then assessed the texture at room temperature. Each evaluator evaluated the texture according to the following criteria, and the average value was calculated.

[0050] 5: It retains its texture and is crisp. 4: It retains its texture and has a good bite. 3: It has texture, but feels soft. 2: Soft enough to feel the fibers when chewed. 1: Can be crushed with the tongue

[0051] 2.6. Evaluation of suitability for microwave heating I prepared the curry sauce using commercially available curry roux.

[0052] The sample consisted of 17g of onion, removed from each retort pouch that had undergone pressure-heat sterilization, and added to 83g of the aforementioned curry sauce. 100g of the sample was placed in a container and heated in a microwave oven at 600W for 4 minutes. Two evaluators assessed the microwave heating suitability according to the following criteria. A score of ○ or △ was considered a pass, and a score of × was considered a fail.

[0053] ○: No sound is made during microwave heating, or the sound is very quiet and not bothersome. △: There is a sound when the microwave is heating, but the volume is not loud enough to be a concern. ×: A loud noise occurs while the microwave is heating, causing anxiety.

[0054] 2.7.Results The table below shows the texture and microwave heating suitability of onions processed under the above conditions, which differ in dehydration conditions.

[0055] [Table 1]

[0056] 3. Examination of calcium treatment conditions 3.1. Raw material: Onion The raw ingredients used were raw onions cut into 8mm x 8mm pieces.

[0057] 3.2. Dehydration Process 320g of chopped raw onions were immersed in 250g of a 4% by mass saline solution for 15 minutes to dehydrate them.

[0058] 3.3. Calcium treatment After 15 minutes, calcium lactate-free water or calcium lactate aqueous solution was added to the mixture of onions and saline solution, so that the final concentrations of calcium lactate in the aqueous solution were 0.09% by mass, 0.135% by mass, and 0.270% by mass. The mixture was then held for 10 minutes to perform calcium treatment.

[0059] 3.4. Pressurized heat sterilization treatment After calcium treatment, the onions were separated from the surrounding aqueous solution. 33g of the separated onions and 117g of an aqueous solution containing 1.3% by mass of sodium chloride and 0.125% by mass of calcium lactate were sealed in a retort pouch. The retort pouch was sterilized by pressurized heating at 122°C for 20 minutes.

[0060] 3.5. Evaluation of texture The texture of onions removed from retort pouches that had undergone pressure and heat sterilization was evaluated by five evaluators following the procedure described in section 2.5.

[0061] 3.6. Evaluation of microwave heating suitability Two evaluators assessed the microwave heating suitability of onions removed from retort pouches that had undergone pressure-heat sterilization, following the procedure described in 2.6.

[0062] 3.7.Results The table below shows the texture and microwave heating suitability of onions treated under the above conditions, which differ in calcium treatment conditions.

[0063] [Table 2]

[0064] 4. Considering the size of the onions 4.1. Raw material: Onion Raw onions cut into 8mm x 8mm, 8mm x 15mm, 15mm x 15mm, or 30mm x 30mm pieces were used as the raw material.

[0065] 4.2. Dehydration Process 320g of chopped raw onions were immersed in 250g of a 4% by mass saline solution for 15 minutes to dehydrate them.

[0066] 4.3. Calcium treatment After 15 minutes, calcium lactate solution was added to the mixture of onions and saline solution so that the final concentration of calcium lactate in the aqueous solution was 0.270% by mass. The mixture was then held for 10 minutes to perform calcium treatment.

[0067] 4.4. Pressurized heat sterilization treatment After calcium treatment, the onions were separated from the surrounding aqueous solution. 33g of the separated onions and 117g of an aqueous solution containing 1.3% by mass of sodium chloride and 0.125% by mass of calcium lactate were sealed in a retort pouch. The retort pouch was sterilized by pressurized heating at 122°C for 20 minutes.

[0068] 4.5. Evaluation of texture The texture of onions removed from retort pouches that had undergone pressure and heat sterilization was evaluated by five evaluators following the procedure described in section 2.5.

[0069] 4.6. Evaluation of suitability for microwave heating Two evaluators assessed the microwave heating suitability of onions removed from retort pouches that had undergone pressure-heat sterilization, following the procedure described in 2.6.

[0070] 4.7.Results The table below shows the texture and microwave heating suitability of onions processed under pressure using raw onions of different sizes.

[0071] [Table 3]

Claims

1. Onions cut to a size that can pass through a sieve with a mesh size of 20 mm are subjected to dehydration and calcium treatment to obtain calcium / dehydrated onions. A method for producing calcium / dehydrated onions, including [the specified ingredient].

2. The method according to claim 1, wherein the dehydration treatment includes immersing the onion in a saline solution containing salt at a concentration of less than 8% by mass.

3. The method according to claim 1 or 2, wherein the calcium treatment comprises immersing the onion in an aqueous calcium salt solution containing calcium at a concentration of less than 0.27% by mass in terms of calcium lactate.

4. The onions are subjected to the dehydration treatment to obtain dehydrated onions, and The dehydrated onions are subjected to the calcium treatment to obtain calcium / dehydrated onions. The method according to claim 1 or 2, including the method described in claim 1 or 2.

5. A method for producing a food product, comprising incorporating the calcium / dehydrated onion produced by the method described in claim 1 or 2.

6. The method according to claim 5, wherein the food contains 2% by mass or more of the calcium / dehydrated onion based on the total amount.

7. A method for producing a pressurized and heat-sterilized packaged food product, comprising placing the food product containing the calcium / dehydrated onion produced by the method of claim 1 or 2 into a container, sealing it, and subjecting it to pressurized and heat-sterilized treatment.

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