Natural cheese having heat-resistant shape retention property

Abstract

The present disclosure provides a natural cheese that has heat-resistant shape retention property and a soft texture. This natural cheese has: a heat-resistant shape retention property; an unmodified whey protein nitrogen content of at least 3.00 mg / g in terms of dry matter; a moisture content of 50 to 64 mass%; and a needle penetration hardness of no greater than 500 mN after being baked for 4 minutes at 200℃ and then allowed to cool for three minutes under a condition of 20℃.

Description

Heat-resistant and shape-retaining natural cheese

[0001] There is provided a natural cheese having heat-resistant shape-retaining properties and a soft texture.

[0002] Cheeses can be broadly classified into natural cheeses and processed cheeses. Natural cheeses are those obtained by coagulating milk raw materials such as raw milk with lactic acid bacteria or rennet and removing a part of the whey (non-aged type), or those obtained by aging this (aged type). On the other hand, processed cheese is obtained by adding an emulsifier or the like to natural cheese, heating and melting it (heat emulsification), and remolding it by allowing it to cool or be cooled.

[0003] Unlike processed cheese obtained by heat emulsifying natural cheese, natural cheese has a natural flavor of milk and a unique texture, and its demand is expanding in recent gourmet booms. Natural cheese can be eaten as it is, but it can also be used for cooking, and by using it for cooking, a cheesy flavor can be imparted to the dish. In addition, since natural cheese has the property of "melting (meltability)" or "melting and stretching (thread-dragging property)" by heating, using this property, it is also widely used for heat cooking purposes such as toppings for heated dishes such as pizza and gratin.

[0004] On the other hand, when using cheese as an ingredient for confectionery, bread making, fried foods such as fried and tempura, stir-fried foods, and grilled foods, meltability and thread-dragging property are not required, and it is required to have heat-resistant shape-retaining properties that are difficult to melt even when heated and can maintain the original shape at a certain temperature. Such cheeses with enhanced heat-resistant shape-retaining properties are generally mostly processed cheeses and cheese foods, and among natural cheeses, cheeses of the type that are baked and eaten, such as halloumi cheese native to Cyprus, are known. Note that cheese food is made by crushing and mixing one or more types of natural cheese or processed cheese, heating and melting it, and emulsifying it, and the weight of the cheese content in the product is 51% or more.

[0005] Halloumi cheese, as described above, is produced by heating raw milk in whey at a high temperature of approximately 90°C without using lactic acid bacteria to obtain heat resistance and shape retention, and it has a distinctive sweet and strong milk flavor. However, while halloumi cheese has high heat resistance and shape retention, it is characterized by a hard texture and a crunchy bite.

[0006] One proposed method for imparting heat-resistant shape retention to natural cheese involves adding transglutaminase to the cheese guard obtained by draining the whey after curdling and then aging the cheese (Patent Document 1). However, this method requires an aging process, and a long aging period of more than one month is necessary to obtain 40% or more of moist heat-resistant shape retention. As a result, it has the disadvantage of reducing the sweet and strong milky flavor characteristic of halloumi cheese, which is a natural cheese that possesses heat-resistant shape retention.

[0007] Furthermore, as a method for imparting heat and water resistance to natural cheese, a method has been proposed in which a milk protein concentrate powder, prepared by heating, concentrating, and drying desalted skim milk to adjust the milk protein content to 40% or more, is dissolved in water, raw milk, or skim milk to a milk protein concentration of 6-20% by weight, milk fat is added to this, homogenization is performed, and then a lactic acid bacteria starter or acidifying agent and rennet are added, and the temperature is raised to 40°C or higher under pH 4.0-5.0 conditions to form curd (Patent Document 2). However, in order to impart heat and water resistance to natural cheese using this method, it is necessary to adjust and strictly control the milk protein concentration of the raw milk, as well as the pH and temperature during curd formation, within the aforementioned ranges.

[0008] International Publication No. WO2016 / 043177, Japanese Patent Publication No. 2002-95410

[0009] One of the challenges is to provide a natural cheese that is heat-resistant, retains its shape, and has a soft texture.

[0010] The inventions described below are provided. Item 1. A heat-resistant, shape-retaining natural cheese having an undenatured whey protein nitrogen content of 3.0 mg / g or more on a dry basis, a moisture content of 50-64% by mass, and a penetrating hardness of 500 mN or less after baking at 200°C for 4 minutes and then cooling at 20°C for 3 minutes. Item 2. Heat-resistant, shape-retaining natural cheese with a hardness of 500 mN or less as shown by the following formula: [Formula] Hardness (mN) = (Moisture content × A) + (Undenatured whey protein nitrogen content × B) + C A: -31.60482832 B: -159.3399422 C: 2767.088996 Hardness (mN): Hardness corresponding to the peak load (penetration hardness) when natural cheese, after heat treatment (heated at 200°C for 4 minutes, then cooled at 20°C for 3 minutes), is inserted 10 mm into a 3 mm diameter plunger at a speed of 15 cm / min, Moisture content: Percentage of moisture (mass%) contained in natural cheese (100% by mass) before heat treatment, Undenatured whey protein nitrogen content: Whey protein nitrogen content of natural cheese before heat treatment (on a dry basis) (mg / g). Item 3. A heat-resistant, shape-retaining natural cheese according to item 1 or 2, having a pH of 6.3 to 6.9. Item 4. A heat-resistant, shape-retaining natural cheese according to any one of items 1 to 3, which is a natural cheese for cooking. Item 5. A natural cheese according to any one of items 1 to 4, having a heat resistance of 80% or more. Item 6. A food product for cooking, containing a heat-resistant, shape-retaining natural cheese according to any one of items 1 to 5.

[0011] A natural cheese is offered that combines heat resistance and shape retention with a soft texture even after heating.

[0012] This figure shows the relationship between the nitrogen content of undenatured whey protein (on a dry basis) (mg / g) and the indentation hardness (mN) after heat treatment for the natural cheeses of Examples 1 and 2 and Comparative Examples 1 and 2.

[0013] (I) Heat-resistant, shape-retaining natural cheese In Japan's Food Sanitation Act (Ministry of Health, Labour and Welfare), natural cheese is defined in the "Ministerial Ordinance Concerning Standards for Ingredients of Milk and Dairy Products (commonly known as the Milk and Dairy Products Ordinance)" as curd obtained by coagulating almost all or some of the proteins of milk, buttermilk, skim milk, cream, or mixtures thereof (collectively referred to as "raw milk") with enzymes or other coagulants, from which some of the whey has been removed (unaged natural cheese), or by aging these (aged natural cheese). The natural cheese of this disclosure may be either an unaged natural cheese or an aged natural cheese. Preferably, it is an unaged natural cheese.

[0014] The natural cheese of this disclosure has the following characteristics (1) to (4). In addition to the characteristics (1) to (4), the "natural cheese" of this disclosure may also have the following characteristic (5). (1) Undenatured whey protein nitrogen content is 3.0 mg / g or more on a dry basis. (2) Moisture content is 55 to 64% by mass. (3) Penetration hardness after baking at 200°C for 4 minutes and then cooling at 20°C for 3 minutes is 500 mN or less. (4) Heat-resistant and retains shape. (5) pH is 6.3 to 6.9.

[0015] Furthermore, the natural cheeses disclosed herein include natural cheeses whose hardness, as calculated by the following formula 1, is 500 mN or less. [Formula 1] Hardness (mN) = (Moisture content × A) + (Nitrogen content of undenatured whey protein [on a dry basis] × B) + C A: -31.60482832 B: -159.3399422 C: 2767.088996.

[0016] (1) Nitrogen content of undenatured whey protein The heat-resistant, shape-retaining natural cheese of this disclosure has a nitrogen content of undenatured whey protein of 3.0 mg / g or more on a dry basis. Preferably, it is 3.2 mg / g or more.

[0017] The nitrogen content of undenatured whey protein in natural cheese can be determined by salting out the natural cheese sample, filtering it, and then performing a quantitative analysis of the protein in the filtrate (Kjeldahl method). For further details, please refer to the examples described below.

[0018] The dry weight equivalent (mg / g) can be obtained by recalculating the nitrogen content of undenatured whey protein obtained by the above method as mg per gram of dry weight of natural cheese. The dry weight of natural cheese can be calculated by subtracting the moisture content, which is calculated by the sand-mixing method described later, from the weight of natural cheese.

[0019] (2) Moisture Content The heat-resistant, shape-retaining natural cheese of this disclosure has a moisture content of 50 to 64% by mass. Preferably, it is 55 to 64% by mass, and more preferably 56 to 64% by mass. The moisture content in the natural cheese can be determined by the sand-mixing method. Details can be found in the examples described later.

[0020] (3) Penetration hardness The heat-resistant, shape-retaining natural cheese of this disclosure has a penetration hardness of 500 mN or less after being baked at 200°C for 4 minutes and then cooled at 20°C for 3 minutes. Preferably, it is 100 to 500 mN, more preferably 200 to 500 mN, and particularly preferably 250 to 500 mN. This penetration hardness can be measured using a Shimadzu EZ-SX small benchtop tester (with a 3 mm diameter plunger and a speed of 15 cm / min for 10 mm penetration) after heating a cube-shaped natural cheese with three sides of 13 mm at 200°C for 4 minutes under dry heat conditions (non-moist heat conditions) and then cooling at 20°C for 3 minutes (in this specification, these series of processes may be collectively referred to as "heat treatment"). Details of the heat treatment method for the natural cheese and the subsequent method and conditions for measuring the penetration hardness will be described in the section on Experimental Example 1. As shown in Experimental Example 1 described later, the heat-resistant, shape-retaining natural cheese of this disclosure has a hardness of 500 mN or less after heat treatment, and therefore is not too hard when bitten, and has a soft texture.

[0021] (4) Heat-resistant and shape-retaining properties In the heat-resistant and shape-retaining natural cheese of this disclosure, "having heat-resistant and shape-retaining properties" means shape retention against heating under dry heat conditions (non-moist heat conditions) (shape retention during dry heat heating), which can be measured by the following method. Details will be explained in the Examples section. Aluminum foil is placed on an aluminum tray, and the natural cheese to be tested, cut into a cube shape, is placed on top of it. Then, it is heated at 200°C for 4 minutes under dry heat conditions (non-moist heat conditions), and then allowed to cool for 3 minutes under room temperature (20°C) conditions. Specifically, as shown in the Examples section, the natural cheese is cut into a cube shape with a side length of 13 mm, this cut natural cheese is heated under the above conditions, and after heating and cooling under the above conditions, the height of the natural cheese is measured, and the heat-resistant and shape-retaining properties are calculated based on the height of the natural cheese before heating (13 mm) and the following formula 2. Here, "height of the natural cheese" means the length of the natural cheese in the direction of gravity (vertical direction). The same applies to "height" below.

[0022] [Formula 2] Heat resistance and shape retention (%) = [Height of cheese after heat treatment (mm) / Height of cheese before heat treatment (13 mm)] × 100

[0023] If the calculated heat-resistant shape retention (%) is 80% or higher, the natural cheese under test can be evaluated as having "heat-resistant shape retention." Preferably, the heat-resistant shape retention (%) is 81% or higher, more preferably 82%, and more preferably 83% or higher.

[0024] (5) pH The heat-resistant, shape-retaining natural cheese of this disclosure preferably has a neutral pH of 6.3 to 6.9. More preferably, it has a pH of 6.4 to 6.8. The pH of the natural cheese can be measured by inserting a pH meter into the center while the cheese is kept at a temperature of 12°C. Alternatively, a commercially available pH meter can be used for measurement.

[0025] The heat-resistant, shape-retaining natural cheese of this disclosure can be manufactured in accordance with conventional natural cheese manufacturing methods, provided that it has the above characteristics (1) to (4), more preferably (1) to (5).

[0026] Generally, unaged natural cheese is produced by the following steps 1-3, and aged natural cheese is produced by the following steps 1-4. Step 1: Sterilizing the raw milk. Step 2: Coagulating the sterilized milk obtained in the above step to prepare curd. Step 3: Discharging the whey from the curd to prepare cheese curd. Step 4: Aging the cheese curd. These steps are explained below.

[0027] (Step 1) Sterilization Step The "raw milk" used in Step 1 can be any milk raw material used as a raw material for the manufacture of natural cheese. Typically, it is unpasteurized milk, and for example, milk from animals such as cows, sheep, buffaloes, and goats can be used. Preferably, it is cow-derived milk, and more preferably, milk from dairy cows. The composition of the raw milk may be adjusted as needed. For example, it is possible to adjust the milk fat content by separating skim milk and cream from unpasteurized milk using a cream separator and blending these skim milk and cream in various mixing ratios. It is also possible to adjust the content of minerals, vitamins, lactose, milk protein, milk fat, etc. by separating them using a known separation membrane and blending these components in mixing ratios. Furthermore, it is possible to adjust the milk fat content and non-fat milk solids content by mixing buttermilk, skim milk, cream, etc. with unpasteurized milk.

[0028] The milk fat content of raw milk can be expressed as the percentage of milk fat in the total solids of the raw milk. For example, if the percentage of milk fat in the total solids of the raw milk is low, it becomes a so-called low-fat type of natural cheese, and if the percentage of milk fat in the total solids of the raw milk is high, it becomes a so-called high-fat type of natural cheese. There are no particular restrictions on the percentage of milk fat in the total solids of the raw milk, but for example, it can be 0-80% by mass, 0-70% by mass, 0.5-65% by mass, 0.5-60% by mass, 1-55% by mass, 2-55% by mass, 5-55% by mass, 10-55% by mass, 15-55% by mass, 20-55% by mass, 25-55% by mass, 30-55% by mass, or 35-55% by mass.

[0029] In the case of non-fat natural cheese, the percentage of milk fat in the total solids of the raw milk is 0% by mass. In the case of low-fat natural cheese, the lower limit of the percentage of milk fat in the total solids of the raw milk is 0.5% by mass, preferably 1% by mass, more preferably 2% by mass, and even more preferably 5% by mass, and the upper limit is 20% by mass, preferably 15% by mass, more preferably 10% by mass, and even more preferably 5% by mass. At this time, the lower limit and upper limit of the percentage of milk fat in the total solids of the raw milk can be set by appropriately combining them.

[0030] For natural cheese with a normal fat content, the lower limit of the percentage of milk fat in the total solids of the raw milk is 20% by mass, preferably 25% by mass, more preferably 30% by mass, and even more preferably 35% by mass, and the upper limit is 80% by mass, preferably 70% by mass, more preferably 65% ​​by mass, even more preferably 60% by mass, and even more preferably 55% by mass. At this time, the lower limit and upper limit of the percentage of milk fat in the total solids of the raw milk can be set by appropriately combining them.

[0031] In step 1, high-temperature short-time pasteurization (HTST), which involves heating the raw milk at a temperature of 72-75°C for about 15-20 seconds, can be used for pasteurization. By pasteurizing at a temperature below 80°C, excessive denaturation of milk proteins due to heating can be suppressed. HTST treatment can be carried out using a conventional HTST pasteurizer. Alternatively, a pasteurization treatment having a thermal history substantially similar to that of HTST treatment can be used. This pasteurization treatment can be treated as the same treatment as the HTST treatment in this invention. By performing HTST treatment, it is possible to inactivate enzymes present in the raw milk and reduce the number of viable bacteria while suppressing excessive thermal denaturation of milk proteins.

[0032] It is preferable to cool the pasteurized milk (pasteurized milk) before using it in step 2 and adjust its temperature to be in the range of 30 to 45°C (temperature control treatment). By temperature control treatment of pasteurized milk, it becomes possible to efficiently coagulate the milk through the action of rennet enzymes and promote subsequent whey discharge (syneresis). The temperature control temperature is preferably 32 to 45°C, more preferably 38 to 42°C.

[0033] (Step 2) Curd Preparation Step 2 is a step in which the pasteurized milk prepared in Step 1 is coagulated to prepare curd. Coagulation of pasteurized milk (curd preparation) can be carried out using a rennet. The amount of rennet used should be an amount sufficient to achieve the objective of coagulating the pasteurized milk, and can be set appropriately within that range.

[0034] Rennet is an enzyme that acts on the milk protein κ-casein to coagulate milk, and its main component is chymosin, a proteolytic enzyme. As the rennet, any conventional enzyme that has the effect of coagulating milk can be used. Rennets currently in use include those derived from animals (e.g., cattle, sheep, and goats) obtained by extraction, rennets derived from plants (e.g., Korean thistle and fig), rennets derived from microorganisms (yeast, basidiomycetes, filamentous fungi, bacteria) produced by fermentation, and genetically modified rennets, and these can be used without limitation. Preferably, rennet is derived from animals, and more preferably from cattle.

[0035] Calcium chloride can also be used in conjunction with rennet. Calcium chloride is used as an ingredient to promote milk coagulation (rennet). When raw milk is pasteurized, some of the dissolved calcium phosphate becomes insoluble, which would otherwise delay the rennetting process. Therefore, calcium chloride is added to promote rennetting. When κ-casein on the surface of casein micelles is broken down by the rennet and hydrophilic glycomacropeptides (GMP) are removed from the surface, the hydrophobicity of the casein micelle surface increases, and its sensitivity to calcium ions increases. The presence of calcium ions derived from calcium chloride makes it easier for casein micelles to associate with each other, thereby promoting the progression of rennet. Calcium chloride can also be used in the form of its hydrate (calcium chloride dihydrate). While there are no restrictions on the amount of calcium chloride added to pasteurized milk, it can be appropriately selected from, for example, 0.001 to 0.1% by mass per 100% by mass of pasteurized milk.

[0036] In general natural cheese production methods, lactic acid bacteria are added to the raw milk, and the lactic acid bacteria ferment it, lowering the pH and causing the milk to coagulate. In this case, the lowering of pH may affect the flavor of the cheese (especially the milk flavor). Therefore, although the use of lactic acid bacteria is not excluded, it is preferable not to use them in order to minimize the impact on the flavor of the cheese.

[0037] (Step 3) Cheese Curd Preparation Step 3 is a step in which cheese curd is prepared by draining whey from the curd prepared in Step 2. Cheese curd refers to what is obtained by draining all or part of the whey that is separated and produced when pasteurized milk coagulates. Whey is water (liquid) containing whey protein and lactose. "Draining whey" means draining and removing the whey from a state in which the coagulated product produced by the coagulation of milk and the whey coexist.

[0038] As a method for draining the whey, methods commonly used in the production of natural cheese (forced draining method, natural draining method, pasta filler method) can be used. One example, though not limited, is a method in which the coagulated product obtained by coagulating milk is cut, the whey contained inside the coagulated product is drained, and then the coagulated product is further packed into a container and compressed by its own weight or by pressing to drain and remove the whey from the coagulated product (forced draining method).

[0039] For typical natural cheeses, the degree to which whey is drained from the coagulated product is such that the moisture content in the cheese curd after whey draining is approximately 30 to 80% by mass. In the case of the heat-resistant, shape-retaining natural cheese targeted by the present invention, there are no limitations, but a good example is when the moisture content in the cheese curd after whey draining is approximately 50 to 70% by mass. Preferably, it is desirable to adjust the moisture content in the cheese curd to this range so that the moisture content of the final natural cheese is in the range of 50 to 64% by mass, more preferably 55 to 64% by mass. The moisture content in the cheese curd (natural cheese) can be measured using the sand-mixing method. Details of this method will be explained in the Examples section.

[0040] The cheese curd preparation process is not limited, but is preferably carried out at a temperature range of 28 to 35°C, preferably 28 to 32°C.

[0041] If necessary, the cheese curd may be heat-treated after step 3. The heat treatment of the cheese curd can be any method and conditions that do not interfere with the nitrogen content of undenatured whey protein in the final natural cheese (3.0 mg / g or more on a dry basis), for example, by heat treatment in the presence of water or steam (moist heat treatment). Such heat treatment methods include heat treatment by placing the cheese curd in hot water (boiling treatment) and heat treatment by using high-temperature steam (steam treatment). This heat treatment is usually carried out under atmospheric pressure conditions without pressurization (non-pressurized conditions). The heat treatment conditions are not limited, but as shown in the examples section below, an example is to boil the cheese curd in hot water at 90°C for 15 minutes or less under non-pressurized conditions. In addition to boiling at 90°C for 15 minutes or less, other heat treatments with a similar thermal history can also be used. Here, thermal history is a measure indicating the amount of heat applied to the cheese curd obtained in step 2. Therefore, the thermal history is not limited to a specific heating temperature and heating time such as 90°C for 15 minutes or less, but any thermal history that can impart an amount of heating equivalent to that obtained in the said thermal history to the cheese curd is acceptable.

[0042] After step 3, if necessary, the cheese card can be salted. When performing the heat treatment, the timing of salting the cheese card may be after step 3 and before the heat treatment, or after the heat treatment. That is, the cheese card obtained in step 3 before the heat treatment may be subjected to a salting treatment, or the cheese card heat-treated after step 3 may be subjected to a salting treatment. As the method of salting the cheese card, known methods such as a brine immersion method of immersing the cheese card in brine water and a dry salt application method of directly applying salt to the surface of the cheese card can be used. Preferably, it is the brine immersion method. As the brine water used for salting, an aqueous solution containing sodium chloride (table salt) can be mentioned. Although not limited, for example, brine with a salt concentration of 5 to 21% by mass, preferably 10 to 21% by mass, about 15 to 21% by mass can be exemplified. From the viewpoint of salting efficiency, the higher the salt concentration and the closer it is to the saturation concentration (the closer it is to saturated brine), the better. Also, according to the preference of the natural cheese to be prepared, in addition to seasonings such as salt, spices and herbs for flavoring can also be blended. Although the temperature of the brine water to be immersed is not limited, a range of 3 to 25 °C, preferably 3 to 15 °C, more preferably 3 to 10 °C can be exemplified.

[0043] The salted cheese card is preferably left standing under low temperature conditions of about 2 to 6 °C once after being taken out from the brine water in the case of, for example, the brine immersion method (refrigeration treatment). The standing time is not particularly limited, but for example, about 5 to 20 hours, preferably about 5 to 18 hours, more preferably about 5 to 12 hours can be mentioned.

[0044] The cheese card of the present disclosure is prepared without kneading. That is, the cheese card of the present disclosure does not include pasta filata cheese produced by a process of kneading or spreading while heating the cheese card until its physical properties become smooth.

[0045] By the above-described steps 1 to 3, an immature formed heat-resistant shape-retaining natural cheese can be prepared. Such a manufacturing method can be used as a manufacturing method for an immature formed natural cheese also called a fresh type.

[0046] In addition to the above steps 1 to 3, a step of aging the cheese card (hereinafter also referred to as "step 4" or "aging step") can also be carried out. As described in the experimental examples to be described later, by the manufacturing method of steps 1 to 3, a natural cheese having heat-resistant shape retention property, preferably a natural cheese having a soft texture in addition to the heat-resistant shape retention property, can be obtained without carrying out the aging step. Therefore, in order to obtain the effects of the present invention, the aging step is not necessarily required.

[0047] The aging step can be carried out using known methods and conditions employed in the manufacturing method of ordinary aged natural cheese. Examples of the known methods and conditions include, for example, a method of holding the cheese card under the conditions of a temperature of 4 to 20°C and a humidity of 50 to 80%. The period for aging the cheese card is not particularly limited as long as the heat-resistant shape retention property, which is the first effect of the present invention, is not impaired, and preferably, in addition to the heat-resistant shape retention property, a soft texture is not impaired. For example, as the aging period, it is 1 day or more, preferably 2 days or more, more preferably 1 week or more, still more preferably 2 weeks or more, and still more preferably 1 month or more.

[0048] Further, as long as it does not significantly affect the heat-resistant shape retention property, in consideration of the product design and the like, arbitrary food raw materials and / or food additives can be added as necessary.

[0049] Since the natural cheese targeted by the present disclosure has heat-resistant shape retention property, it is also suitable for use as a cheese material to be placed on the surface of heat-cooked foods such as pizza and gratin and heated. Here, heat cooking is not particularly limited as long as it is cooking that raises the temperature of the object, and is suitable for use in heat-cooked foods such as baking, frying, and frying. The heat treatment is not limited to the above heat treatment, and may be cooking that raises the temperature of the object in the presence of water or steam. For example, cooking such as boiling, simmering, steaming, and cooking can also be exemplified. Thus, it is also possible to use it as a cheese material for heating and cooking in heated cooked foods with a large amount of moisture, such as dumplings, curry, stew, pot-au-feu, steamed rice, and soup.

[0050] In this specification, the terms "contains" and "contains" include the meanings of "consisting of" and "substantially consisting of." Furthermore, in this specification, the expression "〇 to △" (where 〇 and △ are numerical values ​​in the relationship 〇 < △) means 〇 or greater and △ or less.

[0051] The present invention will be described below using experimental examples to aid in understanding its structure and effects. However, the present invention is not limited in any way by these experimental examples. Unless otherwise specified, the following experiments were conducted at room temperature (25 ± 5°C) and under atmospheric pressure conditions (non-pressurized and non-reduced pressure conditions). Unless otherwise specified, "%" below means "mass percent" and "parts" means "parts by mass".

[0052] <Materials> The materials used in the following experimental example are as follows: Raw milk: Raw milk from dairy cows (unprocessed milk that has not undergone any heat sterilization or other treatments: protein 3.4%, fat 4.0%, carbohydrates 4.5%, non-fat solids 8.8%, total solids 12.9%), Rennet: Calfrennet, manufactured by RENCO, Calcium chloride: Calcium chloride dihydrate.

[0053] Experimental Example 1: Production and Evaluation of Natural Cheese 1. Production of Natural Cheese (Examples 1-2, Comparative Examples 1-2) Raw milk (approximately 10 kg) was used as the raw material, and it was pasteurized at 72°C for 20 seconds (HTST: High Temperature Short Time Pasteurization) and cooled to 4°C. This pasteurization process was carried out by passing the raw milk between heated plates using a plate heat exchanger (a sealed corrugated plate heat exchanger connecting a preheating section, a heating section, and a cooling section) (manufactured by Powerpoint International). Next, the temperature of the pasteurized milk, which had been cooled to 4°C, was raised to 36°C, and calcium chloride was added at a ratio of 100 ppm of the total volume, and rennet at a ratio of 50 ppm of the total volume. After stirring and mixing at a speed of 40 rpm, it was left to stand at 36°C for 30 minutes to coagulate. The resulting curd was cut into cubes with sides of 10 mm using a 10 mm wide wire cutter, and then stirred for 20 to 60 minutes (Examples 1 and 2: 60 minutes, Comparative Example 1: 40 minutes, Comparative Example 2: 20 minutes). Next, the entire amount of liquid (whey) produced by stirring was separated and removed to prepare cheese curd. The prepared cheese curd was transferred to a mold (size: diameter 80 mm x height 60 mm) and deposited for 180 minutes while maintaining a temperature of 30°C.

[0054] Next, the molded cheese curds (Examples 1 and 2, Comparative Examples 1 and 2) were subjected to the following steps, according to the examples and comparative examples, to prepare natural cheese.

[0055] (1) Example 1 The molded cheese curds were packaged and stored in a refrigerator at 4°C.

[0056] (2) Example 2 The molded cheese curds were placed in a mold and immersed in 90°C hot water for 15 minutes (boiling treatment). Next, the boiled cheese curds were immersed in a 20% salt solution (4°C) (brine water) for 5 minutes to add salt. After that, the salted cheese was removed from the brine water, packaged, and stored in a refrigerator at 4°C.

[0057] (3) Comparative Example 1 The molded cheese curds were placed in a mold and immersed in 90°C hot water for 30 minutes (boiling treatment). Next, the boiled cheese curds were immersed in a 20% salt solution (4°C) (brine water) for 5 minutes to add salt. After that, the salted cheese was removed from the brine water, packaged, and stored in a refrigerator at 4°C.

[0058] (4) Comparative Example 2 The molded cheese curds were placed in a mold and immersed in 90°C hot water for 60 minutes (boiling treatment). Next, the boiled cheese curds were immersed in a 20% salt solution (4°C) (brine water) for 5 minutes to add salt. After that, the salted cheese was removed from the brine water, packaged, and stored in a refrigerator at 4°C.

[0059] 2. Evaluation of Natural Cheeses (Examples 1 and 2, Comparative Examples 1 and 2) The flavor and appearance of each of the prepared natural cheeses (Examples 1 and 2, Comparative Examples 1 and 2) were all good.

[0060] 2-1. Evaluation Methods For each of these natural cheeses, pH, moisture content, and undenatured whey protein nitrogen content were measured using the following methods. In addition, heat resistance and hardness after heat treatment were evaluated using the following methods.

[0061] (A) pH measurement: The obtained cheese was heated to 12°C, and the pH was measured by directly inserting a pH meter into the center of the cheese. A Seven2Go Pro (Mettler Toledo) pH meter was used.

[0062] (B) Measurement Method for Moisture Content (Sand Mixing Method) 1. Place the natural cheese, which is the test sample, into an aluminum cup (containing silica sand and a glass rod) whose mass (cup weight a) has been measured, and measure the total amount (weight b before drying). 2. Place the cup containing the test sample on a hot plate and stir the test sample with a glass rod to evaporate the moisture. 3. After the moisture has evaporated, place the cup containing the test sample in an air oven (set the internal temperature to 102°C) and dry for 2 hours. 4. Transfer the cup containing the test sample to a desiccator and allow it to cool in the desiccator for 30 minutes, after which measure the mass of the cup containing the test sample after drying (weight c after drying). 5. Calculate the moisture content of the test sample (natural cheese) using the following formula 3.

[0063] [Equation 3] Moisture content (mass %) = 100 - {[(Weight after drying c - Weight in cups a) / (Weight before drying b - Weight in cups a)] × 100}

[0064] (C) Nitrogen content of undenatured whey protein was measured using the Kjeldahl method. Specifically, 5.0 g of the sample was weighed into a 100 ml glass beaker, and 60 ml of 0.05 M trisodium citrate dihydrate, heated to 50°C, was added. The mixture was homogenized using a homogenizer (Ultra Trax) at 8000 rpm for 3 minutes, and 33 g of the resulting sample solution was mixed with 12 g of sodium chloride. The mixture was heated in a 37°C water bath for a total of 16 minutes with stirring every 2 minutes, and then left to stand in a 37°C incubator for 12 hours (salting-out treatment). After that, the mixture was filtered through filter paper (TOYO No. 6) to obtain the filtrate. 4 ml of this filtrate was accurately weighed, and 5 ml of sulfuric acid and 2 ml of hydrogen peroxide were added. The temperature was then gradually increased in the following order: 210°C for 5 minutes → 280°C for 5 minutes → 350°C for 5 minutes → 420°C for 60 minutes. Subsequently, the solution was allowed to cool for 15 minutes at 20°C, 10 ml of distilled water was added and mixed, and the titration volume of hydrochloric acid in the resulting solution was measured using the Kjeldahl method with a Kjeldahl automated distillation, titration, and calculation system (Super Kjel 1600, manufactured by Actac Co., Ltd.). As a control, the titration volume of hydrochloric acid measured with ion-exchanged water alone, without adding the sample, was used as a blank. Based on the titration volume obtained by the Kjeldahl method, the nitrogen content of undenatured whey protein was calculated using Equation 4 below.

[0065] [Equation 4] Nitrogen content of undenatured whey protein (mg / g) = 14.01 × N × F × (number of ml titrations - blank) / sample (g) N: normality of sulfuric acid, F: factor of sulfuric acid

[0066] The undenatured whey protein nitrogen content calculated using Equation 4 above was recalculated as mg per gram of dry weight of natural cheese using Equation 5 to obtain the dry weight equivalent value (mg / g) of the undenatured whey protein nitrogen content. [Equation 5] Dry weight equivalent value of undenatured whey protein nitrogen content (mg / g) = Undenatured whey protein nitrogen content (mg / g) ÷ [(100 - moisture content) / 100] Moisture content: Moisture content of natural cheese (mass %).

[0067] (D) Evaluation of hardness The hardness after heating was measured by the following method. For the test, as with the evaluation of heat resistance and shape retention, samples (test specimens) cut into a cubic shape with the lengths of all three sides being exactly 13 mm were used (n=3). These were placed on aluminum foil and heated in an oven at 200°C for 4 minutes. After being removed from the oven, the samples (test specimens) were allowed to cool for 3 minutes at room temperature (20°C). Hardness was measured using a small benchtop testing machine (EZ-SX, manufactured by Shimadzu Corporation), and the peak load when a 3 mm diameter plunger was inserted 10 mm at a speed of 15 cm / min was used as the penetration hardness.

[0068] (E) Evaluation of heat resistance and shape retention The heat resistance and shape retention were measured and quantified using the following method, and evaluated based on the numerical value. For the tests, samples (test specimens) were cut from each natural cheese (Examples 1 and 2, Comparative Examples 1 and 2) into cubes (13 mm × 13 mm × 13 mm) so that the lengths of all three sides were exactly 13 mm, and measurements were taken using three samples (n=3) for each example and comparative example.

[0069] Set the oven (SANYO DRYING OVEN SDW27) to 200°C, line an aluminum tray with aluminum foil, place the samples (n=3) on the aluminum foil, and heat at 200°C for 4 minutes. The samples (n=3) are arranged in a single row in the center of the aluminum tray, with three samples spaced equally apart (this is done for each example and comparative example). After heating, remove the aluminum tray and samples from the oven and allow them to cool at room temperature (20°C) for 3 minutes. After cooling, measure the height of the samples (height of the heated samples) with calipers. Using the height of the sample before heating (13 mm) as a reference, quantify the heat resistance and shape retention using the following formula 6. If the value calculated using this formula is 85% or higher, it is evaluated as having "good heat resistance and shape retention".

[0070] [Formula 6] Heat resistance and shape retention (%) = [Height of sample after heat treatment (mm) / Height of sample before heating (13 mm)] × 100

[0071] 2-2. Evaluation Results Table 1 shows the results of the evaluation of pH, moisture content, undenatured whey protein nitrogen content, heat resistance and shape retention, and indentation hardness after heat treatment for each natural cheese (Examples 1 and 2, Comparative Examples 1 and 2). The results in Table 1 are the average values ​​obtained for three samples (n=3) of each test sample. Figure 1 also shows the relationship between undenatured whey protein nitrogen content (dry equivalent) (mg / g) and indentation hardness (mN) after heat treatment.

[0072]

[0073] These results show that by setting the moisture content in natural cheese (and cheese curd) to 50-64% by mass, preferably 55-64% by mass, more preferably 56-64% by mass, and even more preferably 56-60% by mass, and setting the undenatured whey protein nitrogen content to 3.00 mg / g or more on a dry basis, it is possible to obtain a natural cheese with a soft texture that has heat resistance and shape retention, while having a puncture hardness of 500 mN or less, particularly 400 mN or less, after heat treatment.

[0074] Experimental Example 2 Based on the results of Example 1 of Multiple Regression Analysis, multiple regression analysis was performed using two factors, the moisture content (mass%) of the natural cheese and the nitrogen content of undenatured whey protein (on a dry basis), to predict the hardness (indentation hardness) (mN) of the natural cheese after heat treatment. From the results, the following equation 7 was derived.

[0075] [Equation 7] Hardness after heat treatment (mN) = [Moisture content × A] + [Undenatured whey protein nitrogen content × B] + C A: -31.6048 B: -159.3399 C: 2767.0889 Hardness after heat treatment (mN): Hardness corresponding to the peak load (penetration hardness) when the natural cheese after heat treatment is inserted 10 mm into a 3 mm diameter plunger at a speed of 15 cm / min, Moisture content: Percentage of moisture (mass%) contained in the natural cheese (100% by mass) before heat treatment (see Equation 3), Undenatured whey protein nitrogen content: Whey protein nitrogen content of the natural cheese before heat treatment (on a dry basis) (mg / g) (see Equation 5)

[0076] Table 2 shows that the coefficients of Equation 7 (A: X value 1, B: X value 2, C: intercept) have been calculated correctly.

[0077] Calculation Example 1: The hardness (mN) of a natural cheese with a moisture content of 65% by mass and a whey protein nitrogen content (on a dry basis) of 1 mg / g after heat treatment is predicted to be as follows: Hardness (mN) after heat treatment = 65 × (-31.6048) + 1 × (-159.3399) + 2767.0889 = 553.4352 mN. This natural cheese has a hardness of 553.4 mN after heating, which exceeds the standard value of 500 mN. Therefore, it is considered to have a firm hardness after heating.

[0078] Calculation Example 2 The hardness (mN) of a natural cheese with a moisture content of 54% by mass and a whey protein nitrogen content (on a dry basis) of 2 mg / g after heat treatment is predicted to be as follows: Hardness (mN) after heat treatment = 54 × (-31.6048) + 2 × (-159.3399) + 2767.0889 = 741.7484 mN. This natural cheese has a hardness of 741.7484 mN after heat treatment, which is significantly higher than the standard value of 500 mN. Therefore, it is considered to have an even harder texture than the aforementioned natural cheese. From this, it can be predicted that the lower the moisture content, the harder the cheese tends to become after heat treatment.

[0079] Calculation Example 3: The hardness (mN) of a natural cheese with a moisture content of 59.5% by mass and a whey protein nitrogen content (on a dry basis) of 3 mg / g is predicted to be as follows after heat treatment: Hardness (mN) after heat treatment = 59.5 × (-31.6048) + 3 × (-159.3399) + 2767.0889 = 408.5819 mN. This natural cheese has a hardness of 408.5819 mN after heat treatment, which is below the standard value of 500 mN. Therefore, it is considered to have a soft texture after heat treatment.

[0080] Furthermore, the following can be said from these analysis results: (1) The hardness of natural cheese after heat treatment can be controlled by adjusting the moisture content (mass%) and whey protein nitrogen content (mg / g) of natural cheese. (2) By satisfying specific ranges for moisture content and whey protein nitrogen content, it is possible to manufacture and provide natural cheese that has heat resistance and shape retention while having a soft texture. (3) By using formula 7, the hardness of natural cheese after heat treatment can be predicted before manufacturing, which is useful for product design and quality control of natural cheese.

Claims

1. A heat-resistant, shape-retaining natural cheese having an undenatured whey protein nitrogen content of 3.0 mg / g or more on a dry weight basis, a moisture content of 50-64% by mass, and a hardness of 500 mN or less after baking at 200°C for 4 minutes followed by cooling at 20°C for 3 minutes.

2. Heat-resistant, shape-retaining natural cheese having a hardness of 500 mN or less as shown by the following formula: [Formula] Hardness (mN) = (Moisture content × A) + (Undenatured whey protein nitrogen content × B) + C A: -31.60482832 B: -159.3399422 C: 2767.088996 Hardness (mN): Hardness corresponding to the peak load (penetration hardness) when natural cheese, after heat treatment (heated at 200°C for 4 minutes and then cooled at 20°C for 3 minutes), is inserted 10 mm into a 3 mm diameter plunger at a speed of 15 cm / min, Moisture content: Percentage of moisture (mass%) contained in natural cheese (100% by mass) before heat treatment, Undenatured whey protein nitrogen content: Whey protein nitrogen content of natural cheese before heat treatment (on a dry basis) (mg / g).

3. A heat-resistant, shape-retaining natural cheese according to claim 1, wherein the pH is 6.3 to 6.

9.

4. A heat-resistant, shape-retaining natural cheese as described in claim 1 or 2, which is a natural cheese for cooking.

5. A food for cooking that includes the heat-resistant, shape-retaining natural cheese described in claim 1 or 2.

6. A food for cooking that includes the heat-resistant, shape-retaining natural cheese described in claim 3.

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