Method for producing heat-resistant liquid egg yolk hydrolyzate, intermediate raw material for processed foods containing the same, and processed foods

Abstract

To provide a method for producing a heat-resistant liquid egg yolk hydrolyzate in which coagulation or aggregation is hardly observed even when heat-treated at a temperature at which the liquid egg yolk coagulates and in which the egg yolk flavor is maintained, and to provide an intermediate raw material for processed foods containing the same, and processed foods. [Solution] A method for producing a heat-stable liquid egg yolk hydrolysate, in which liquid egg yolk is hydrolyzed to a specified degree with a protease extracted from Geobacillus stearothermophilus in the presence of a specified amount of polyhydric alcohol, and an intermediate raw material for processed foods containing this, and a processed food are also provided.

Description

[Technical field]

[0001] The present invention relates to a method for producing a heat-stable liquid egg yolk hydrolyzate in which almost no coagulation or aggregates are observed even when heat-treated at a temperature at which the liquid egg yolk coagulates and in which the egg yolk flavor is maintained, and to an intermediate raw material for processed foods and processed foods containing the same. More specifically, the present invention relates to a method for producing a heat-stable liquid egg yolk hydrolyzate in which the egg yolk flavor is maintained and which is hydrolyzed to a specific range by a protease extracted from Geobacillus stearothermophilus, a specific enzyme, in the presence of a polyhydric alcohol, and to an intermediate raw material for processed foods or processed foods containing the same. [Background technology]

[0002] As a method for improving the heat resistance of egg yolk, a method of hydrolyzing egg yolk with a protease is known. For example, Japanese Patent No. 3254026 (Patent Document 1) discloses a method for producing egg yolk with improved heat resistance and freezing resistance by partial hydrolysis with a protease derived from Bacillus bacteria or the like.

[0003] Patent Document 1 introduces various commercially available proteases derived from bacteria of the genus Bacillus. In the examples of the document, Protease S "Amano" (manufactured by Amano Pharmaceutical Co., Ltd.) is used. However, the heat-treated product of partial hydrolysis with the protease was endowed with heat resistance, but was accompanied by a bitter taste and it is difficult to say that the egg yolk flavor was maintained.

[0004] Patent Document 1 also describes a protease derived from Bacillus bacteria, geobacillus stearothermophilus, called Samoase (manufactured by Daiwa Kasei Co., Ltd.). However, a heat-treated product obtained by the manufacturing method described in the document did not solidify, but aggregates were observed, and it is difficult to say that sufficient heat resistance has been imparted to the product. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3254026 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a heat-stable liquid egg yolk hydrolyzate which is capable of maintaining the egg yolk flavor and in which almost no coagulation or aggregation is observed even when heat-treated at a temperature at which the egg yolk liquid coagulates. [Means for solving the problem]

[0007] The present inventors have conducted extensive research in order to achieve the above object. As a result, the inventors have unexpectedly found that if egg yolk liquid is hydrolyzed to a specific range in the presence of a polyhydric alcohol with a specific enzyme, a protease extracted from Geobacillus stearothermophilus, a heat-stable liquid egg yolk hydrolyzate can be obtained which, even when heated at a temperature at which the egg yolk liquid coagulates, hardly produces any coagulation or aggregates and which maintains the egg yolk flavor, thereby completing the present invention.

[0008] That is, the present invention provides (1) A method for producing a heat-stable liquid egg yolk hydrolyzate, comprising hydrolyzing 40% by mass or more of liquid egg yolk as a raw material with a protease, The protease is a protease extracted from Geobacillus stearothermophilus, The hydrolysis is carried out in the presence of a polyhydric alcohol, The polyhydric alcohol is 5 parts by mass or more per 100 parts by mass of the raw material liquid egg yolk, A method for producing a heat-stable liquid egg yolk hydrolyzate, wherein the degree of hydrolysis is 0.40 or more and 0.85 or less. (2) The method for producing a heat-resistant liquid egg yolk hydrolyzate according to (1), wherein the polyhydric alcohol is reduced starch syrup. (3) An intermediate raw material for processed foods that involves heat treatment at 70°C or higher, which contains the heat-resistant liquid egg yolk decomposition product obtained by the manufacturing method of (1) or (2). (4) Processed foods that contain intermediate raw materials for processed foods in (3) above and are heated to 70°C or higher. (5) Processed foods that involve heat treatment at 70°C or higher, which contain the heat-resistant liquid egg yolk hydrolyzate obtained by the manufacturing method of (1) or (2). It is. Effect of the Invention

[0009] According to the present invention, a heat-stable liquid egg yolk hydrolyzate can be obtained in which almost no coagulation or aggregates are observed even when the liquid egg yolk is heated at a temperature at which the liquid egg yolk coagulates, and in which the egg yolk flavor is maintained. This is expected to lead to expanded use of processed foods that involve heating in which it is desired to maintain the egg yolk in a non-coagulated state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. In the present invention, unless otherwise specified, "%" means "% by mass", "times" means "times by mass", and "parts" means "parts by mass".

[0011] <Features of the present invention> The present invention is characterized by providing a method for producing a heat-stable liquid egg yolk hydrolyzate, which not only imparts heat resistance to the liquid egg yolk hydrolyzate obtained by hydrolyzing liquid egg yolk, which would coagulate upon heating in an additive-free state prior to enzymatic hydrolysis, with a specific protease in the presence of a polyhydric alcohol, but also maintains the flavor of the egg yolk.

[0012] <Liquid egg yolk> In the present invention, liquid egg yolk refers to a liquid material containing polyhydric alcohol, an essential raw material of the present invention, before hydrolysis with protease, and containing 40% or more of raw material liquid egg yolk. As shown in Test Example 1 described later, liquid egg yolk that does not contain polyhydric alcohol and is diluted with water to contain 40% or more of raw material liquid egg yolk coagulates at a temperature at which raw egg yolk is reliably coagulated, and therefore in the present invention, liquid egg yolk containing 40% or more of raw material liquid egg yolk is targeted. In the present invention, in order to distinguish the liquid egg yolk from the liquid egg yolk before the addition of water, polyhydric alcohol, etc., the liquid egg yolk before the addition is referred to as raw material liquid egg yolk in the present invention.

[0013] <Liquid egg yolk raw material> The liquid egg yolk used in the present invention may be raw egg yolk, commercial liquid egg yolk generally available on the market, etc. Furthermore, refrigerated or frozen egg yolks, or those dried by spray drying or freeze drying and then reconstituted with water, or those to which salt, sugar, etc. have been added within the range that does not impair the effects of the present invention, may also be used.

[0014] <Polyhydric alcohol> The polyhydric alcohol contained in the liquid egg yolk of the present invention may be any organic compound having two or more alcoholic hydroxyl groups in one molecule that can be used as a food ingredient for processed foods.Specific examples include reduced starch syrup (also called dextrin alcohol) obtained by further reducing dextrin obtained by saccharifying starch, reduced starch syrup obtained by diluting the reduced starch syrup with water and adjusting the concentration to 70%, sorbitol, D-sorbitol solution obtained by diluting the sorbitol with water and adjusting the concentration to 70%, maltitol, xylitol, glycerin, etc., and the reduced starch syrup is particularly preferred because it easily produces a liquid egg yolk hydrolyzate that maintains the egg yolk flavor and has excellent heat resistance, which is the effect of the present invention, and is inexpensive and easy to handle in terms of productivity. In the present invention, when a polyhydric alcohol diluted with water, such as reduced starch syrup, is used, the actual concentration of the polyhydric alcohol is the amount excluding water.

[0015] <Polyhydric alcohol content> In the present invention, the content of polyhydric alcohol in the liquid egg yolk before hydrolysis with protease is 5 parts or more, preferably 7.5 parts or more, more preferably 10 parts or more, per 100 parts of raw liquid egg yolk. If the content of polyhydric alcohol is less than the above content, when the raw egg yolk is heated at a temperature at which it coagulates, the whole is not coagulated, but aggregates are observed, and sufficient heat resistance cannot be imparted. In the present invention, the upper limit of the content of polyhydric alcohol is not particularly limited, but it is preferable to set it to 35 parts or less, preferably 25 parts or less, more preferably 20 parts or less, per 100 parts of raw liquid egg yolk. By setting the content of polyhydric alcohol within the above upper limit, a heat-stable liquid egg yolk hydrolyzate with fewer additives can be obtained, and even if the content of polyhydric alcohol exceeds the above content, the heat resistance effect according to the content is not increased as expected, which is not economical.

[0016] <When to add polyhydric alcohol> In the present invention, the time of adding the polyhydric alcohol is not particularly limited as long as it is before the start of hydrolysis with the protease. Specifically, for example, the polyhydric alcohol is added to the raw material liquid egg yolk and mixed uniformly, then heated to a predetermined temperature for enzymatic decomposition, and then the enzyme is added to start hydrolysis. Alternatively, a method is exemplified in which the raw material liquid egg yolk is heated to a predetermined temperature for enzymatic decomposition, the polyhydric alcohol is added and mixed uniformly, and then the enzyme is added to start hydrolysis.

[0017] <Protease> In the present invention, liquid egg yolk containing a predetermined amount of polyhydric alcohol is hydrolyzed with a protease. There are various proteases of various origins, but in the present invention, it is essential to use a protease extracted from Geobacillus stearothermophilus. In the present invention, any protease extracted from Geobacillus stearothermophilus may be used, and a specific example thereof is "Thermoase PC10F" (trade name) manufactured by Amano Enzyme Co., Ltd.

[0018] <Degree of hydrolysis by protease> The present invention not only uses the specific protease, but also obtains a heat-resistant liquid egg yolk hydrolyzate that maintains the egg yolk flavor and does not show any coagulation or aggregates even when heated at a temperature at which the egg yolk liquid coagulates, which is the effect of the present invention, and also takes into consideration the productivity on an industrial scale, and the hydrolysis degree indicating the degree of hydrolysis is 0.40 to 0.85, preferably 0.40 to 0.80, more preferably 0.45 to 0.75. If the hydrolysis degree exceeds the above range, the obtained liquid egg yolk hydrolyzate can be given heat resistance, but it has a bitter taste and cannot maintain the egg yolk flavor. On the other hand, the lower limit of the hydrolysis degree is specified in consideration of the productivity on an industrial scale. That is, in order to stop hydrolysis by enzymes, it is necessary to inactivate the added enzyme. Enzyme inactivation is generally performed by raising the temperature to a temperature at which the enzyme is inactivated and performing an enzyme inactivation treatment. However, since hydrolysis by the enzyme proceeds during the temperature increase process for inactivating the enzyme, it is difficult to suppress the decomposition degree below the lower limit in industrial-scale production. Even if the decomposition degree can be suppressed below the lower limit, there are cases in which heat resistance cannot be imparted to the obtained liquid egg yolk decomposition product.

[0019] <Measurement of the degree of hydrolysis by protease> In the present invention, the degree of hydrolysis by the specific protease was measured by the following method. That is, 0.5 g of the heat-resistant liquid egg yolk hydrolyzate obtained by hydrolysis with the specific protease according to the production method of the present invention was collected in a 50 mL centrifuge tube, 9.5 mL of 2% (w / v) NaCl aqueous solution was added and stirred, and then 10 mL of 10% (w / v) trichloroacetic acid (TCA) solution was added and stirred well. After leaving it for 30 minutes, it was centrifuged at 3,500 rpm x 10 minutes and filtered with a 0.45 μm filter. The filtrate was measured at a wavelength of 280 nm using a spectrophotometer, and the absorbance was taken as the "degree of hydrolysis."

[0020] <Amount of protease added> In the present invention, the amount of the specific protease to be added is not particularly limited as long as it is an amount that can obtain the decomposition degree in the specific range, but in consideration of productivity, it is preferable to add 0.001 to 5.0 parts, more preferably 0.002 to 3.0 parts, per 100 parts of raw material liquid egg yolk. By setting the amount of protease to be added in the above range, it is easy to control the decomposition degree to a predetermined level, and productivity is excellent.

[0021] <Temperature and time of hydrolysis with protease> The treatment temperature and treatment time of hydrolysis using the specific protease of the present invention to obtain the decomposition degree in the specific range will depend on the amount of protease added, but specifically, for example, the treatment time is preferably 5 to 90 minutes, more preferably 10 to 75 minutes, and the treatment temperature is preferably 40 to 75° C., more preferably 45 to 70° C. By setting the treatment temperature and treatment time of hydrolysis within the above ranges, it is easy to control the decomposition degree to a predetermined level, similar to the amount of protease added, and productivity is excellent.

[0022] <Temperature and time for inactivation treatment to inactivate enzymes after hydrolysis with proteases> After hydrolysis to a degree of decomposition by the specific protease of the present invention within the specific range, the enzyme is inactivated according to a conventional method. The inactivation temperature and inactivation time at this time are not particularly limited as long as the specific protease is inactivated, although they depend on the amount of the specific protease added. Specifically, for example, the hydrolysis solution after hydrolysis is heated to the inactivation temperature, which is preferably 80 to 100°C, more preferably 85 to 98°C, and the inactivation time is preferably 1 to 45 minutes, more preferably 2 to 30 minutes.

[0023] <Treatment after enzyme inactivation, etc.> In the present invention, after the enzyme is inactivated, the product is cooled according to a conventional method. Although the cooling method is not particularly limited, taking into consideration the oxidation of oils, such as fats and oils and phospholipids, which are components of egg yolk, rapid cooling to room temperature (25° C.) within 30 minutes is preferable. The heat-stable liquid egg yolk hydrolyzate obtained by the production method of the present invention may be stored in a refrigerator or freezer for long-term storage.

[0024] <Other ingredients> The production method of the present invention requires liquid egg yolk, polyhydric alcohol, and protease extracted from Geobacillus stearothermophilus as essential raw materials, but other raw materials can be used as long as they do not impair the effects of the present invention, such as sugars such as sugar, salt, pH adjusters, chelating agents, antioxidants, etc.

[0025] <Processed food intermediate ingredients or processed foods> The heat-resistant liquid egg yolk hydrolyzate obtained by the production method of the present invention is a processed food that utilizes the full-bodied taste and emulsifying power of non-coagulated egg yolk, and is preferably blended into processed foods that are heated at 70°C or higher, such as cooking at 70°C or higher at which egg yolk coagulates, heat sterilization, etc., where the processed foods are heated at 70°C or higher. The processed foods that are heated at 70°C or higher are not particularly limited, but specific examples thereof include carbonara sauce, flower paste, custard cream, mayonnaise sauces that are sterilized, mayonnaise sauces for cooking or baking, and rice bowl dishes such as oyakodon and katsudon. The heat-resistant liquid egg yolk hydrolyzate obtained by the production method of the present invention may be used as an intermediate raw material in combination with raw materials other than the egg yolk portion of the processed food that is heated at 70°C or higher, and the intermediate raw material may be used in the processed food that is heated at 70°C or higher. The intermediate raw material is not particularly limited as long as it is combined with raw materials other than the egg yolk portion of the processed food, but specific examples thereof include a mixture with milk or fresh cream when the processed food that is heated at 70°C or higher is carbonara sauce.

[0026] The present invention will be specifically described below based on examples, comparative examples and test examples, but the present invention is not limited to these.

[0027] [Test Example 1] In Test Example 1, the effect on coagulation properties was investigated when the raw material liquid egg yolk was diluted with water to various concentrations. Commercial raw material liquid egg yolk (manufactured by Kewpie Egg Corporation) was diluted with water to the concentrations shown in Table 1. 1 ml of the resulting liquid egg yolk of each concentration was dispensed into Eppendorf tubes and heated in a 90°C water bath for 15 minutes, then removed from the tubes and the coagulation state was observed. The results are shown in Table 1.

[0028] The symbols in Table 1 are as follows. ○: The solidified state remains even when pressed with a finger. △: Before being pressed with a finger, the solidified state was observed, but when pressed with a finger, the solidified state was broken. ×: The liquid was in a cloudy state.

[0029] [Table 1]

[0030] From the results in Table 1, it was estimated that liquid egg yolk would coagulate if the concentration of the raw material liquid egg yolk was 40% or more. Therefore, the present invention was targeted at raw material liquid egg yolk of 40% or more, at which point liquid egg yolk would coagulate.

[0031] [Example 1]: Method for producing heat-resistant liquid egg yolk hydrolysate 200 kg of commercial raw material liquid egg yolk (Kewpie Egg Co., Ltd.), 30 kg of reduced starch syrup (Bussan Food Science Co., Ltd.: trade name SE 100, moisture 30%), and 70 kg of fresh water were uniformly mixed to prepare 300 kg of liquid egg yolk. Then, the 300 kg of liquid egg yolk was heated to 60°C, and 0.09 kg of Samoase PC10F (trade name) manufactured by Amano Enzyme Co., Ltd., which is a protease extracted from geobacillus stearothermophilus, was added, and enzymatic decomposition treatment was performed at 60°C for 50 minutes. After that, the temperature was raised to 90°C, and enzyme inactivation treatment was performed at the same temperature for 20 minutes, after which 1 kg was packed into a 3 kg plastic bag, and the packed material was cooled with 4°C chiller water (cooling water) so that the product temperature was room temperature (25°C) or lower within 30 minutes, and the heat-resistant liquid egg yolk decomposition product of the present invention was obtained. The obtained heat-stable liquid egg yolk hydrolyzate was stored in a freezer (-18°C) for long-term storage. The proportion of polyhydric alcohol excluding water in the reduced starch syrup was 10.5 parts and the proportion of the enzyme was 0.04 parts per 100 parts of egg yolk as the raw material liquid.

[0032] The heat-stable liquid egg yolk decomposition product (frozen product) packed in the obtained plastic bag was thawed to a product temperature of about 10°C, and the decomposition degree was measured by the measurement method described in paragraph 0020 and found to be 0.61. In addition, the thawed product was heated in a 90°C water bath for 10 minutes while still packed in a plastic bag, but no coagulation or aggregates were observed, and the egg yolk flavor was maintained when the heated product was eaten.

[0033] [Test Example 2] Except for Example 1, the raw material liquid egg yolk, polyhydric alcohol and fresh water in the prescribed amounts shown in Table 2 were uniformly mixed, then heated to 60°C, a prescribed amount of protease was added and enzymatic hydrolysis treatment was carried out at 60°C for a prescribed time. Then, 20 g of the enzymatically treated liquid was immediately filled and sealed in a 20 g nylon plastic bag and subjected to enzyme inactivation treatment in a water bath set at a prescribed temperature. Then, the product was cooled in ice water so that the product temperature was below room temperature (25°C) within 30 minutes, and a heat-stable liquid egg yolk hydrolyzate of the present invention was obtained. The obtained heat-stable liquid egg yolk hydrolyzate was stored in a freezer (-18°C) for long-term storage. In Examples 1 to 5 and Comparative Examples 1 and 2, the protease used was Samoase PC10F (product name) manufactured by Amano Enzyme Co., Ltd., in Comparative Example 3 was Food-Grade Refined Papain (product name) manufactured by Nagase ChemteX Corporation, and in Comparative Example 4 was Sumiteam BNP (product name) manufactured by Shin Nippon Chemical Industry Co., Ltd. The types and proportions of polyhydric alcohols, the proportions of the enzymes, enzyme treatment conditions, enzyme inactivation conditions, and decomposition degrees are as shown in Table 2. However, the percentage of polyhydric alcohol in Table 2 is the percentage of only the polyhydric alcohol portion excluding water, as all of the polyhydric alcohols used contained 30% water, and for the reduced starch syrup, SE 100 or SE 57, product names manufactured by Bussan Food Science Co., Ltd., were used. The decomposition degree is a value measured by the measurement method described in paragraph 0020 for a thawed product.

[0034] The heat resistance evaluation in Table 2 was performed by thawing the product to about 10° C., heating it in a water bath at 90° C. for 10 minutes, and visually observing and evaluating the state, as in Example 1. The evaluation criteria are shown below.

[0035] <Heat resistance evaluation criteria> ◎: No coagulation or aggregation was observed. ◯: No coagulation was observed, but very slight aggregates were observed, but not to the extent that they caused any problems. Δ: No coagulation, but slight aggregates were observed. ×: Coagulation occurred, or numerous aggregates were observed.

[0036] The flavor evaluation in Table 2 was carried out by a panel of experts who tasted and evaluated the products that did not solidify after heat treatment. The evaluation criteria are as follows:

[0037] <Flavor evaluation criteria> ◎: Almost no bitterness, and the egg yolk flavor was maintained. ◯: Slightly bitter, but not problematic, and egg yolk flavor was maintained. △: Slightly bitter, but the egg yolk flavor was maintained. ×: The bitterness was strong and the egg yolk flavor was not maintained.

[0038] [Table 2]

[0039] From Table 2, it can be seen that the liquid egg yolk hydrolyzed product obtained by using a protease extracted from Geobacillus stearothermophilus (Thermoase PC10F (trade name)) and mixing 5 parts or more of a polyhydric alcohol per 100 parts of the raw material liquid egg yolk and hydrolyzing the liquid egg yolk to a degree of decomposition by the enzyme of 0.40 to 0.85 shows almost no coagulation or aggregates even when heated at a temperature at which the egg yolk liquid coagulates, and furthermore maintains the egg yolk flavor. In particular, the liquid egg yolk hydrolyzed products obtained in Examples 1 to 4, which used 10 parts or more of a polyhydric alcohol per 100 parts of the raw material liquid egg yolk and had a degree of decomposition of 0.45 to 0.75, had excellent heat resistance and were also excellent in maintaining the egg yolk flavor.

[0040] [Example 6]: Intermediate raw material for the processed food, flower paste 65 g of rapeseed oil was gradually added to 35 g of the heat-stable liquid egg yolk hydrolyzate obtained in Example 1 while stirring to prepare an intermediate raw material (100 g) of an emulsified flour paste.

[0041] [Example 7]: Flour paste containing intermediate ingredients for processed foods A total of 500 g of the intermediate material of Example 6 (emulsion-like intermediate material of 35 g of heat-resistant liquid egg yolk hydrolyzate and 65 g of rapeseed oil), 20 g of starch, 10 g of soft flour, 72.5 g of granulated sugar, 30 g of skim milk powder, and 267.5 g of fresh water were mixed uniformly while being heated at 80° C. Then, while slowly stirring the whole, it was cooled to room temperature (25° C.) with cold water to produce a flour paste. The obtained flour paste was free of egg yolk aggregates and had a smooth paste-like texture.

[0042] [Example 8]: Carbonara, a processed food 100g of dried noodles were boiled for a specified time in 1000mL of boiling water with 12g (2 teaspoons) of salt dissolved therein. On the other hand, 75g of the heat-resistant liquid egg yolk hydrolyzate obtained in Example 1, 100g of fresh cream, and 12g (2 tablespoons) of powdered cheese were mixed uniformly in advance to prepare a mixture for the sauce. 12g (1 tablespoon) of olive oil and 50g of bacon cut into strips were placed in a frying pan and fried over medium heat until the bacon was browned, after which the boiled noodles and 50g of the boiling water were added and heated over medium heat until the mixture thickened. When the mixture thickened, the heat was reduced to low, the mixture for the sauce was added and mixed, and when the flavors were well blended, the frying pan was removed from the heat. The mixture was served on a plate and sprinkled with an appropriate amount of coarsely ground black pepper to prepare carbonara. The sauce of the resulting carbonara maintained its smoothness throughout the consumption.

Claims

1. A method for producing a heat-stable liquid egg yolk hydrolyzate, comprising hydrolyzing 40% by mass or more of liquid egg yolk as a raw material with a protease, The protease is a protease extracted from Geobacillus stearothermophilus, The hydrolysis is carried out in the presence of a polyhydric alcohol, The polyhydric alcohol is 5 parts by mass or more per 100 parts by mass of the raw material liquid egg yolk, The polyhydric alcohol is reduced starch syrup, The degree of decomposition by hydrolysis is 0.40 or more and 0.85 or less.

1. A method for producing a heat-stable liquid egg yolk hydrolyzate comprising the steps of:

2. A heat-resistant liquid egg yolk hydrolyzate obtained by the method according to claim 1 is blended. A method for producing intermediate raw materials for processed foods, which involves a heat treatment at 70°C or higher.

3. The intermediate raw material for processed foods according to claim 2 is blended. A method for producing processed foods, comprising the steps of:

4. A heat-resistant liquid egg yolk hydrolyzate obtained by the method according to claim 1 is blended. A method for producing processed foods, comprising the steps of:

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