JP7532706B1 - Manufacturing method of whey processed food - Google Patents

Abstract

The present invention provides a method for producing a whey processed food with a good texture, which comprises the following steps (1) to (3): (1) a step of hydrolyzing 10 to 20% by mass of lactose contained in a whey-containing liquid having a lactose content of 36 to 74% by mass calculated as solid content, (2) a step of heating and concentrating the whey-containing liquid after the hydrolysis treatment to prepare a whey concentrate having a solid content concentration of 55 to 90% by mass, and (3) a step of adding pulverized lactose to the whey concentrate adjusted to 60°C to 90°C, stirring, and cooling.

Description

The present invention relates to a method for producing a whey processed food. The present invention also relates to a whey processed food.

Raw milk is processed into various dairy products such as milk, cheese, yogurt, butter, and cream through processing technology, and is consumed by people. However, in the cheese manufacturing process, only about 10% of raw milk becomes cheese, and the remaining 90% is discharged as whey. As whey is a by-product of the cheese manufacturing process, it contains a large amount of various essential amino acids, proteins, vitamins, and sugars, and is also a nutritionally excellent food material. However, whey is not fully utilized in the food industry because it is easily deteriorated, has low preservation properties, and has a unique flavor. For this reason, whey used industrially is only 59% of the total whey discharged worldwide, and the remaining 41% is used as livestock feed or agricultural fertilizer, or is treated as industrial waste. For this reason, making effective use of whey and expanding its uses is an important issue, especially as a responsibility of companies that manufacture dairy products, in aiming to realize a sustainable society, such as making effective use of unused dairy resources and reducing waste to protect the environment.

One of the alterations of whey is that of lactose contained in whey. It is generally known that in foods and beverages with a high lactose concentration, lactose crystals are formed and grow to a large size, causing a rough feeling on the tongue and losing the smooth texture. This phenomenon occurs more significantly as the lactose concentration increases. The effect of lactose crystals on the texture of brown whey cheese, which is one of the whey processed foods with a high lactose concentration, has also been pointed out, and it is known that the ideal crystal size is 20-30 μm, and that when the crystal size exceeds 100 μm, the tongue feels rough (Non-Patent Document 1). For this reason, in order to effectively use whey containing a large amount of lactose as a food ingredient, it is necessary to prevent the lactose contained in whey from crystallizing and growing to a large size, and to maintain a good texture.

A method for suppressing the crystallization of lactose in whey is known in which whey is desalted by nanofiltration and then lactose is decomposed using a lactase (Patent Document 1). This method makes it possible to obtain lactose-decomposed, desalted whey that has a good flavor due to the desalting, has a low viscosity even when concentrated by decomposing lactose, and does not induce lactose crystallization during transportation of the concentrated liquid. In addition, although it is not a method for suppressing lactose crystallization, a method for suppressing mannitol crystallization using a non-crystalline carbohydrate as a crystal precipitation regulator is known (Patent Document 2).

JP 2004-129579 A JP 2007-215450 A

Siv Skeie, Roger K. Abrahamsen, “Chapter 45: Brown Whey Cheese”, Cheese 4th edition: Chemistry, Physics and Microbiology

The present invention aims to provide a whey processed food with a good texture in order to effectively utilize whey and expand the scope of its use. More specifically, the present invention aims to provide a whey processed food with a good texture that is smooth to the touch with little roughness on the tongue, has little adhesion to the teeth, and is easy to eat.

The present inventors have conducted intensive research to solve the above problems, and have found that in whey processed foods containing lactose at a high concentration of 15% by mass or more, reducing the lactose crystal content results in a smooth texture without any roughness, but increases adhesion to teeth. For this reason, further research was conducted to obtain a whey processed food with a good texture that combines smoothness with reduced adhesion to teeth. As a result, it was found that this can be achieved by reducing the lactose crystal content in whey processed foods to 3-5% and appropriately adjusting the ratio of coarse lactose crystals to fine lactose crystals in the lactose crystals.

The present invention has been completed based on these findings and further research, and includes the following embodiments.
(I) Method for producing whey processed food
(I-1) A method for producing a whey processed food comprising the following steps (1) to (3):
(1) a step of hydrolyzing 10 to 20% by mass of lactose contained in a whey-containing liquid having a lactose content of 36 to 74% by mass calculated on a solid content basis;
(2) a step of heating and concentrating the whey-containing liquid after the hydrolysis treatment to prepare a whey concentrate having a solid content concentration of 55 to 90% by mass; and (3) a step of adding pulverized lactose to the whey concentrate adjusted to 60°C to 90°C, stirring and then cooling;
The whey processed food has the following characteristics A to C:
A: Contains lactose at a ratio of 15% by mass or more;
B: The percentage of lactose crystals in the whey processed food is 3-5%.
C: The proportion of coarse lactose crystals in the lactose crystals contained in the whey processed food is 10% or less, and the proportion of fine lactose crystals is 70% or more;
The ratio of lactose crystals is a ratio calculated from the area of the peak at the corresponding position obtained for the test whey processed food, based on the area of the main peak of lactose monohydrate crystals (standard product) detected in the range of 2θ = 19.9 to 20.4 ° in the X-ray diffraction pattern measured by an X-ray diffractometer,
The proportion of coarse lactose crystals and fine lactose crystals in the lactose crystals is determined by observation with a phase contrast microscope and is the ratio of the total area of coarse lactose crystal particles and the ratio of the total area of fine lactose crystal particles to the total area of lactose crystal particles in the test whey processed food (100%).
(I-2) The production method according to (I-1), wherein the whey-containing liquid in the step (1) contains protein in an amount of 5 to 21% by mass in terms of solid content.
(I-3) The method according to (I-1) or (I-2), wherein the whey-containing liquid in the step (1) contains lipids in an amount of 9 to 60% by mass in terms of solid content.
(I-4) The production method according to any one of (I-1) to (I-3), wherein in the step (3), the amount of pulverized lactose added to the whey concentrate is 0.01% by mass or more.

(II) Whey processed food (II-1) A whey processed food having a solid content concentration of 55% by mass or more,
The whey processed food has a protein content of 5 to 21% by mass, a lactose content of 29 to 70% by mass, and a lipid content of 9 to 60% by mass, based on 100% by mass of the solid content of the whey processed food;
The whey protein content is 73 to 97% by mass out of 100% by mass of the total amount of protein;
A whey processed food having the following characteristics A to C:
A: Contains lactose at a ratio of 15% by mass or more;
B: The percentage of lactose crystals in the whey processed food is 3-5%.
C: The proportion of coarse lactose crystals in the lactose crystals contained in the whey processed food is 10% or less, and the proportion of fine lactose crystals is 70% or more;
The ratio of lactose crystals is a ratio calculated from the area of the peak at the corresponding position obtained for the test whey processed food, based on the area of the main peak of lactose monohydrate crystals (standard product) detected in the range of 2θ = 19.9 to 20.4 ° in the X-ray diffraction pattern measured by an X-ray diffractometer,
The proportion of coarse lactose crystals and fine lactose crystals in the lactose crystals is determined by observation with a phase contrast microscope and is the ratio of the total area of coarse lactose crystal particles and the ratio of the total area of fine lactose crystal particles to the total area of lactose crystal particles in the test whey processed food (100%).
(II-2) A whey processed food according to (II-1), in which the insoluble matter content of the whey processed food is 0.4 ml or less.
(II-3) A whey processed food according to (II-1) or (II-2), in which the α-lactalbumin content is 10 to 14% by mass and the β-lactoglobulin content is 31 to 42% by mass, based on 100% by mass of the total amount of protein.
(II-4) A whey processed food according to any one of (II-1) to (II-3), in which the amount of whey used in the production of 100 g of the whey processed food is 30 g or more, calculated as the amount of dried whey.

According to the present invention, it is possible to provide a method for producing a whey processed food that is smooth to the touch with little roughness on the tongue, has little adhesion to the teeth, and has a good texture, and to provide the whey processed food. According to the production method of the present invention, it is possible to effectively use whey as a food ingredient by solving the problem that whey has not been effectively utilized in the past, despite its excellent nutritional value.

The X-ray diffraction patterns of the whey processed foods A to E prepared in Experimental Example 1 are shown. The peaks detected in the range of 2θ = 5 to 40° are the peaks of lactose monohydrate crystals, and the largest main peak detected in the range of 2θ = 19.9 to 20.4° was used to calculate the proportion of lactose crystals. This shows an image of the cross-sectional tissue of a slice of whey processed food O (lactose decomposition rate 20%, seeded at 80°C) prepared in Experimental Example 1, observed with a phase contrast microscope (objective magnification x10).

(I) Whey Processed Food The whey processed food of the present invention (hereinafter also referred to as "the food") is a food produced using whey as a raw material.
Whey is a by-product of cheese production, with most of the fat and casein removed from mammalian milk. Whey includes whey concentrates (sweet whey, acid whey, etc.), whey concentrates, whey dried products (whey powder, etc.), and whey frozen products. Examples of mammals from which milk is derived include cows, buffaloes, goats, and sheep, but cows are preferred, especially dairy cows (Holstein and Jersey cows).

The present food product is produced using the above-mentioned whey as a raw material and is characterized by having the following properties:
(1) Lactose content: 15% by mass or more,
(2) Lactose crystal ratio: 3-5%
(3) The proportion of coarse lactose crystals in the lactose crystals in whey processed foods: 10% or less. The proportion of fine lactose crystals in the lactose crystals in whey processed foods: 70% or more.

These characteristics are explained below.
In the present invention, the term "solid content" refers to components excluding water.
In this specification, the term "solid content concentration" refers to the proportion of solids contained in a subject (e.g., a whey processed food), and is expressed as the proportion (mass %) of solids in the total amount when the total amount (wet mass) of the subject is taken as 100 mass %.

In addition, in this specification, the content of a component in a target object (e.g., a whey processed food) converted into solid content (also referred to as "solid content equivalent") means the ratio of the component contained in the target object converted into solid content. Specifically, when the total amount of solid content (dry mass) of the target object is taken as 100 mass%, it is expressed as the ratio (mass %) of the component to the total amount of solid content.

The mass and concentration of solids contained in the target object (solids concentration) can be determined by the normal pressure heating and drying method (sand mix method). Specifically, after determining a constant weight with sea sand and a glass rod placed in a weighing dish, the test sample and distilled water are added and dried in a dryer at 99°C for 4 hours. The moisture content of the test sample is then determined from the difference in mass of the test sample before and after drying. From the moisture content thus measured, the mass of solids contained in the test sample (before drying) can be determined, and the solids concentration can then be calculated.

(1) Lactose content The lactose content of the whey processed food may be 15% by mass or more. The lower limit is not limited, but examples thereof include 30% by mass, 35% by mass, 39% by mass, or 40% by mass. The upper limit is not limited, but examples thereof include about 60% by mass, 51% by mass, or 49% by mass. The lower and upper limits can be arbitrarily combined to set a range (hereinafter, the same applies in the description of this specification). The lactose content of the whey processed food can be appropriately set in the range of 15 to 60% by mass. Although not limited, examples thereof include a range of preferably 20 to 51% by mass, more preferably 30 to 51% by mass, even more preferably 35 to 51% by mass, and particularly preferably 39 to 49% by mass.

The lactose content can be 27% by mass or more in terms of solid content, that is, the lactose content in 100% by mass of the solid content of the whey processed food. The lower limit is 29% by mass or more, preferably 45% by mass, more preferably 47% by mass or more, and even more preferably 49% by mass or more. The upper limit is 70% by mass or less, preferably 68% by mass or less, and more preferably 67% by mass or less. Examples of such ranges include 27 to 70% by mass, 29 to 68% by mass, 29 to 67% by mass, 49 to 70% by mass, 49 to 68% by mass, and 49 to 67% by mass.

In the present invention, the lactose content can be measured using an enzyme electrode method. The specific measurement method will be described in detail in Experimental Example 2. The solids content equivalent of lactose in this food can be calculated from the lactose content in this food and the solids concentration of this food determined by the normal pressure heating and drying method (sand mixing method).

(2) Proportion of lactose crystals The proportion of lactose crystals in the present food is determined from the area of the peak at the position corresponding to the main peak of lactose monohydrate crystals (α type) (standard product) detected in the range of 2θ = 19.9 to 20.4° in the X-ray diffraction pattern measured with an X-ray diffractometer, obtained by the same method for the subject whey processed food. Details of the measurement and calculation methods will be explained in Experimental Example 1 below.

As a method for preparing the test sample (measurement sample) to be used for the measurement, for example, a hard solid whey processed food with a solid content concentration of 80% by mass or more can be prepared by slicing it to a thickness of 0.5 mm as in Experimental Example 1. On the other hand, for example, a semi-solid or soft solid whey processed food with a solid content concentration of less than 55 to 80% by mass can be prepared according to the Front loading method, which is one of the sample preparation methods used in powder X-ray diffraction measurement. Specifically, the test sample is filled into the sample filling section of a glass sample holder having a square columnar depression (sample filling section) with a depth of 0.5 mm and a bottom surface of 20 mm x 20 mm, and the surface is scraped off using the edge of another glass plate to make the surface of the test sample to be used for X-ray diffraction even (smooth and uniform), and then cooled at 5°C.

The percentage of lactose crystals in this food is preferably 3-5%, and can be set appropriately within this range.

(3) The proportion of coarse lactose crystals and fine lactose crystals in the lactose crystals in the whey processed food The proportion of coarse lactose crystals and fine lactose crystals in the lactose crystals in the food can be determined by phase contrast microscopy. Specifically, it is the proportion of the total area of coarse lactose crystal particles and the proportion of the total area of fine lactose crystal particles to the total area of 100% of the lactose crystal particles contained in the whey processed food, determined by phase contrast microscopy. The details of the measurement and calculation method will be explained in Experimental Example 1 below. The measurement preparation can be prepared by placing about 1 mg of the whey processed food on a slide glass and crushing the sample with a cover glass to spread it thinly (crushing method).

In the present invention, coarse lactose crystals refer to crystals having a circle-equivalent diameter of 30 μm or more calculated from the horizontal projected area of particles (lactose crystal particles) observed when whey processed foods are observed under a phase contrast microscope. Similarly, fine lactose crystals refer to crystals having a circle-equivalent diameter of 10 μm or less calculated from the horizontal projected area of particles (lactose crystal particles) observed when whey processed foods are observed under a phase contrast microscope. Details of the method for measuring the horizontal projected area of particles using a phase contrast microscope and the method for calculating the circle-equivalent diameter will also be explained in Experimental Example 1 described below.

The proportion of coarse lactose crystals in the total lactose crystals is 10% or less, calculated as the total area of the corresponding crystal particles. There is no particular limitation as long as it is 10% or less, but it is preferably 8% or less, more preferably 5% or less, particularly preferably 3% or less, and even more preferably 0%.

The proportion of fine lactose crystals in the total lactose crystals is 70% or more, calculated as the total area of the corresponding crystal particles. There is no particular limitation as long as it is 70% or more, but it is preferably 72% or more, more preferably 80% or more, particularly preferably 90% or more, and even more preferably 95% or more.

The food product may be a solid or semi-solid food product having the above-mentioned characteristics, and may be prepared by blending other ingredients as raw ingredients other than whey. As the raw material for lactose (lactose source), in addition to the above-mentioned whey, desalted whey, WPC, protein concentrated whey powder, and WPI can also be used. In addition, raw materials containing lactose, such as permeate powder, which is a by-product of protein concentrate, and food-grade lactose obtained by concentrating and refining whey or permeate, can also be used, regardless of their origin. Examples of other ingredients include raw milk, milk or dairy products (skim milk, concentrated milk, reduced milk, whole milk powder, skim milk powder, cream, butter, butter oil, milk proteins such as casein, etc.), goat's milk, reducing sugar, gelatin, stabilizers, etc.

In the present invention, a solid form refers to a form that does not deform under its own weight even when left to stand for at least 24 hours under conditions of 25°C and atmospheric pressure. A semi-solid form refers to a form that deforms under its own weight in the above-mentioned case. The whey processed food of the present invention may be any one having a solid content concentration of 55% by mass or more, and includes those in a paste form (semi-liquid, unformed form), a soft solid form, and a hard solid form. Although not limited thereto, examples of the solid content concentrations of the whey processed food in a paste form, a soft solid form, and a hard solid form are approximately 55 to less than 75% by mass, approximately 75 to less than 80% by mass, and approximately 80 to 90% by mass, respectively.

(4) Protein content in whey processed food : In the present food, the content of protein contained as a component other than lactose is not limited, but may be in the range of 2% by mass or more and less than 10% by mass, preferably 4 to 8% by mass, and more preferably 6 to 8% by mass.

The protein content, calculated as the solid content, i.e., the protein content in 100% by mass of the solid content of the whey processed food, can be in the range of 5 to 21% by mass. The lower limit is 5% by mass or more, preferably 6% by mass or more, and more preferably 7% by mass or more, and the upper limit is 21% by mass or less, preferably 13% by mass or less, and more preferably 11% by mass or less. Examples of such ranges include 7 to 21% by mass, 5 to 11% by mass, 7 to 11% by mass, and 8 to 9% by mass.

The total amount of protein contained in this food can be measured using the Kjeldahl method. Details are explained in the Examples section. The solids content of protein in this food can be calculated from the total protein content in this food and the solids concentration of this food determined by the normal pressure heating and drying method (sand mixing method) described above.

The proteins in the food product include whey protein and milk-derived proteins such as casein. The proportion of whey protein in the total protein content of the food product (100% by mass) is not limited, but may be in the range of 73 to 100% by mass, preferably 73 to 97% by mass. The remainder may be casein.

Whey protein is a protein component contained in whey, and representative components include α-lactalbumin (α-LA), β-lactoglobulin (β-LG), immunoglobulin, and lactoferrin. In the present invention, a part or all of a protein can be used as a whey protein. The proportions of α-LA and β-LG contained in 100% by mass of whey protein are not limited, but examples of the proportions include 12 to 28% by mass, preferably 13 to 15% by mass, for α-LA, and 37 to 74% by mass, preferably 42 to 44% by mass, for β-LG. Thus, the proportions of α-LA and β-LG contained in whey protein are almost determined depending on the type of milk. For example, in the case of whey protein derived from dairy cows, the proportions of α-LA and β-LG contained in the whey protein are about 49 to 90% by mass in total.
Although not limited thereto, the α-LA content and β-LG content in the present food product based on 100% by mass of the total protein amount can be, for example, 10 to 14% by mass and 31 to 42% by mass, respectively.

The solids content of the whey protein contained in the food product can be selected from the range of 5 to 21% by mass. The lower limit is 5% by mass or more, preferably more than 7.6% by mass, and more preferably 8% by mass or more, and the upper limit is 21% by mass or less, preferably 13% by mass or less, and more preferably 11% by mass or less. Examples of such ranges include 5 to 11% by mass, more than 7.6% by mass and 11% by mass or less, and 8 to 11% by mass.

Furthermore, although not limited thereto, the amount of α-LA contained in the food product in terms of solid content can be selected from the range of 0.7 to 2% by mass. The lower limit is 0.7% by mass or more, preferably more than 1.0% by mass, and more preferably 1.1% by mass or more, and the upper limit is 2% by mass or less, preferably 1.8% by mass or less, and more preferably 1.5% by mass or less. Examples of such ranges include 0.7 to 1.8% by mass, 0.7 to 1.5% by mass, 1.1 to 1.8% by mass, and 1.1 to 1.5% by mass.

Furthermore, although not limited thereto, the amount of β-LG contained in the food product in terms of solid content can be selected from the range of 2.2 to 5% by mass. The lower limit is 2.2% by mass or more, preferably more than 3.2% by mass, and more preferably 3.3% by mass or more, and the upper limit is 5% by mass or less, preferably 4.8% by mass or less, and more preferably 4.6% by mass or less. Examples of such ranges include 2.2 to 4.8% by mass, 2.2 to 4.6% by mass, 3.3 to 4.8% by mass, and 3.3 to 4.6% by mass.

The amounts of α-LA and β-LG contained in the present food can both be measured using SDS-PAGE. Details will be explained in the Examples section. It is preferable that the test sample to be subjected to SDS-PAGE is one prior to heating and concentration. The amount of α-LA or β-LG in the present food in terms of solid content can be calculated from the content of α-LA or β-LG in the present food and the solid content concentration of the present food determined by the normal pressure heating and drying method (sand mixing method) described above.
As described above, the content ratio of α-LA and β-LG in whey protein is almost fixed, so the amount of whey protein contained in the present food can be calculated from the total amount of α-LA and β-LG contained in the present food. For example, when the present food is produced using whey powder, the amount of whey protein contained in the present food can be calculated as 1.75 times the total amount of α-LA and β-LG.

The amount of casein in the food product in terms of solid content can be selected from the range of 0 to 5% by mass. The lower limit is 0% by mass or more, preferably more than 0.1% by mass, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more. The upper limit is 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less. Examples of such ranges include 0 to 5% by mass, 0 to 3% by mass, 0 to 2% by mass, 0.3 to 5% by mass, 0.3 to 3% by mass, and 0.3 to 2% by mass.

The amount of casein contained in the present food can be measured using the subtraction method (total protein - non-casein protein). Details will be explained in the Examples section. The casein solids content in the present food can be calculated from the total casein content in the present food and the solids concentration of the present food determined by the normal pressure heating and drying method (sand mixing method) described above. The types of casein include α _s-1 casein, α _s-2 casein, β-casein, κ-casein, and γ-casein.

(5) Lipid content in whey processed food The whey processed food of the present invention may also contain lipids as components other than lactose and protein, as long as the above-mentioned lactose content and lactose crystal properties are not impaired. The lipid content is not limited, but may be appropriately selected from the range of 5% by mass or more.

The lipid content may be 9 to 60% by mass in terms of solid content, i.e., lipid content in 100% by mass of solid content of the whey processed food. The lower limit is 9% by mass or more, preferably 25% by mass or more, more preferably 28% by mass or more, and even more preferably 39% by mass or more. The upper limit is 60% by mass or less, preferably 58% by mass or less, and more preferably 55% by mass or less. Examples of such ranges include 9 to 55% by mass, 25 to 55% by mass, 28 to 55% by mass, 39 to 60% by mass, and 39 to 55% by mass.
The lipid content in the present food can be measured by the Roese-Gottlieb method. The details will be explained in the Examples section. The lipid solid content in the present food can be calculated from the lipid content in the present food and the solid content concentration of the present food determined by the normal pressure heating and drying method (sand mixing method) described above.

(6) Content of insoluble matter in whey processed food The amount of insoluble matter contained in the present food is preferably 0.4 ml or less, more preferably 0.3 to 0.35 ml, and even more preferably 0.25 to 0.30 ml.
Details of the method for measuring the insoluble matter content will be described in the Examples section. In the present invention, the insoluble matter is a matter that is measured by the measurement method described below, and the insoluble matter content can be measured by the measurement method.

As described below, the present food is produced using whey as the main ingredient. Although not limited, it is preferable that the amount of whey used to produce 100 g of the present food is 30 g or more, calculated as the amount of dried whey.

The whey processed foods covered by the present invention include, but are not limited to, the brown whey cheese, yeast, and caramel described below. Although not limited thereto, these whey processed foods are known to be the following foods:

Brown whey cheese:
A food product with a solids concentration of 55-85% by mass and a lipid content of 4-30% by mass, obtained by adding milk and cream to whey and then heating and concentrating it. Note that brown whey cheese is also called brown cheese or brnost in some countries and regions, but all of these are the same whey processed food products.

Yetst:
This food product has a solid content of 55-85% by mass and a lipid content of 4-30% by mass, and is obtained by adding milk and cream to whey, followed by heating and concentrating the mixture, and all or part of the milk used is derived from goat's milk.

caramel:
This food is a soft candy-like structure made from dairy ingredients and flavored with a milky taste, and uses whey processed food as part of the dairy ingredients.

The food also includes products obtained by adding milk or milk fat to whey and by concentrating or drying the products, including those having the following characteristics:
(a) The milk fat content is 5% by mass or more (converted into solids content) of the total dry weight.
(b) the dry solids content is from 50% to 85% by weight of the total weight;
(c) It is molded or capable of being molded.

(II) Method for Producing Whey Processed Food The above-mentioned whey processed food can be produced by subjecting a whey-containing liquid containing proteins, lactose, and lipids, which is prepared using whey as a main raw material, to the following treatment.
(1) Lactose hydrolysis treatment,
(2) concentration process, and (3) seeding process.
The whey-containing liquid and the treatment will be described below.

In the present invention , "whey" refers to the water-soluble component (whey serum) remaining after removing fat, casein, fat-soluble vitamins, etc. from milk. However, whey may contain fat, casein, and/or fat-soluble vitamins that have not been completely removed. Examples of whey include cheese whey and rennet whey (also called sweet whey) obtained as by-products during the production of natural cheese and rennet casein, and casein whey, acid whey, and quark whey obtained during the production of fermented milk, quark, etc.

As the raw material for the whey-containing liquid, whey concentrate (sweet whey, acid whey, etc.), its concentrate, its dried product (whey powder, etc.), and its frozen product can be used. In addition, desalted whey, whey protein concentrate (WPC), protein concentrated whey powder, and whey protein purified product (WPI) can also be used. In general, WPC is a general term for products in which about 25% to about 80% by mass of the solid content is whey protein, and WPI is a general term for products in which about 80% by mass or more of the solid content is whey protein. As the raw material, whey concentrate and dried products (whey powder, etc.) are preferable, and whey dried products are more preferable. Although not limited, the amount of whey used to produce 100 g of this food is preferably 30 g or more when converted into the amount of whey dried product.

The whey-containing liquid preferably contains whey as a main ingredient and at least 36 to 74% by mass of lactose in terms of solid content. The amount of lactose in terms of solid content is preferably 46 to 70% by mass, more preferably 56 to 60% by mass.

The protein content in the whey-containing liquid is in the range of 5 to 21% by mass in terms of solid content, preferably 7 to 20% by mass, more preferably 9 to 10% by mass, in terms of solid content.
Although not limited, the ratio of lactose per 10 parts by mass of protein contained in the whey-containing liquid can be selected in the range of 30 to 68 parts by mass, preferably 63 to 67 parts by mass, and more preferably 63 to 66 parts by mass.

In addition to lactose and protein, the whey-containing liquid may also contain lipids. The lipid content in the whey-containing liquid is in the range of 9 to 60% by mass, calculated as solid content. The lipid content in solid content is preferably 20 to 40% by mass, and more preferably 25 to 30% by mass. Although not limited, the ratio of lipids to 10 parts by mass of protein content in the whey-containing liquid can be selected in the range of 9 to 79 parts by mass. It is preferably 12 to 31 parts by mass, and more preferably 17 to 31 parts by mass.

The water content in the whey-containing liquid is not limited, but may be in the range of 25 to 90% by mass, for example. It is preferably in the range of 25 to 50% by mass, and more preferably in the range of 25 to 40% by mass. The water content in a whey processed food can be determined by a normal pressure heat drying method. Examples of the raw material for water (water source) include, but are not limited to, the various raw materials used as the whey protein source, lactose source, and lipid source described above (for example, whey concentrate, its concentrate, raw milk, cow's milk, or dairy products).

(1) Lactose hydrolysis treatment Lactose hydrolysis treatment is a treatment for hydrolyzing lactose contained in a whey-containing liquid to reduce its molecular weight. The lactose hydrolysis treatment employed in the present invention is a treatment for hydrolyzing a part of the lactose contained in the whey-containing liquid, preferably 10 to 20% by mass of the total amount of lactose (100% by mass). In this way, as shown in Experimental Example 1, the lactose content and the ratio of lactose crystals in the produced whey processed food can be adjusted to a predetermined range, and as a result, a whey processed food with a good texture (feel in the mouth, reduced stickiness to the teeth) can be prepared.

To this extent, the method and conditions of the hydrolysis treatment are not particularly limited. Preferably, a lactase enzyme, such as lactase, is used to hydrolyze a portion of the lactose contained in the whey-containing liquid to glucose and galactose.

For example, a method of hydrolyzing 10-20% by mass of the total amount of lactose contained in a whey-containing liquid (100% by mass) using lactase can be set by appropriately adjusting the blending ratio, reaction temperature, enzyme treatment time, etc. according to the enzyme activity. Examples include, but are not limited to, a method of blending lactase with a whey-containing liquid and treating it at a temperature of about 50°C for about 10-20 minutes.

Whether or not 10-20% by mass of the total 100% by mass of lactose contained in the whey-containing liquid has been hydrolyzed can be evaluated by measuring the lactose concentration in the whey-containing liquid before and after hydrolysis and calculating the lactose hydrolysis rate from the following formula. The lactose concentration can be measured by the enzyme electrode method as described above.

[formula]
Lactose decomposition rate % =
100 - [(lactose concentration after hydrolysis/lactose concentration before hydrolysis) x 100]

(2) Concentration Treatment The concentration treatment is a treatment for preparing a whey concentrate by concentrating the whey-containing liquid after the hydrolysis treatment until the solid content becomes about 55 to 90% by mass. Although there are no particular limitations on the specific method or conditions as long as it is such a treatment, a preferred example is a method in which the whey-containing liquid is concentrated under reduced pressure while being stirred and heated until the solid content becomes about 55 to 90% by mass, or heated and concentrated under atmospheric pressure.

The heating conditions are not limited as long as the effects of the present invention are not hindered, but for example, in the case of reduced pressure concentration, the temperature can be in the range of 50 to 80°C. The range is preferably 60 to 70°C. The reduced pressure conditions are also not limited as long as the effects of the present invention are not hindered, but for example, the vacuum pressure (gauge pressure [relative pressure]) can be in the range of -20 kPa to -80 kPa. The range is preferably -40 kPa to -80 kPa. In the case of heating and concentration under atmospheric pressure, the temperature can be in the range of 100 to 130°C. The range is preferably 100 to 110°C.

(3) Seeding Treatment The seeding treatment is a treatment in which the whey concentrate prepared by the above treatment is adjusted to 60 to 90°C, ground lactose is added at this temperature, and the mixture is stirred to precipitate fine crystals.
The temperature condition can be set in the range of 60 to 90°C, preferably 60 to 85°C, and more preferably 70 to 80°C.

The ground lactose is usually α-hydrated crystalline lactose according to the Japanese Pharmacopoeia, which has been ground to 10 μm or less using a ball mill or hammer mill and then dry-heat sterilized or ozone sterilized at 130° C. for 1 to 2 hours. Ground lactose having a particle size D ₅₀ of 3 μm or less and D ₉₀ of 5 μm or less is preferred.

The amount of pulverized lactose added to the whey concentrate may be within a range that allows the food product to be produced that has the above-mentioned lactose crystal properties, and is not limited thereto, but the concentration of pulverized lactose in the whey concentrate can be set to 0.01% by mass or more. The preferred range is 0.02 to 0.5% by mass.

The stirring conditions and time are not limited as long as they are conditions and times that allow the production of the present food product having the lactose crystal properties described above, but examples of stirring conditions include rotation conditions in the range of 0 to 100 rpm using a twin-shaft kneader (manufactured by Irie Shokai Co., Ltd., with blades of diameter 60 mm, shaft distance 50 mm, length 120 mm, and twist angle of 60°, rotating in the same direction). Examples of stirring times include rotation conditions in the range of 15 to 30 minutes.

After the above-mentioned steps (1) to (3), the food product can be prepared by cooling to about 5°C.
Whether or not the whey processed food of the present invention has been obtained can be confirmed by measuring the lactose content and the ratio of lactose crystals in the whey processed food, as well as the ratio of coarse lactose crystals and fine lactose crystals in the lactose crystals, using the methods described above. If necessary, the protein content, lipid content, and insoluble matter content in the whey processed food can also be measured using the methods described above.

The food thus produced is a whey processed food containing 15% by mass or more of lactose, which is smooth to the touch, has little adhesion to the teeth, and has a good texture. Therefore, the production method of the present invention is useful as a method for producing such a whey processed food with a good texture.

As described above, in this specification, the terms "comprise" and "contain" include the meanings of "consisting of" and "consisting essentially of."

(Contribution to the Sustainable Development Goals (SDGs))
The present invention can be utilized as a means for achieving the Sustainable Development Goals (SDGs). By utilizing the present invention, it is possible to contribute to the achievement of the Sustainable Development Goals (SDGs) and targets.

Specifically, the Sustainable Development Goals (SDGs) are as follows (Transforming our world: the 2030 Agenda for Sustainable Development, Ministry of Foreign Affairs, Internet <URL: https://www.mofa.go.jp/mofaj/gaiko/oda/sdgs/pdf/000101402.pdf>):
Goal 1. End poverty in all its forms everywhere.
Goal 2. End hunger, achieve food security and improved nutrition and promote sustainable agriculture.
Goal 3. Ensure healthy lives and promote well-being for all at all ages.
Goal 4. Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all.
Goal 5. Achieve gender equality and empower all women and girls.
Goal 6. Ensure availability and sustainable management of water and sanitation for all.
Goal 7. Ensure access to affordable, reliable, sustainable and modern energy for all.
Goal 8. Promote inclusive and sustainable economic growth, full and productive employment and decent work for all.
Goal 9. Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation.
Goal 10. Reduce inequality within and among countries.
Goal 11. Make cities and human settlements inclusive, safe, resilient and sustainable.
Goal 12. Ensure sustainable consumption and production patterns.
Goal 13. Take urgent action to combat climate change and its impacts.
Goal 14. Conserve and sustainably use the oceans, seas and marine resources for sustainable development.
Goal 15. Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss.
Goal 16. Promote peaceful and inclusive societies for sustainable development, provide access to justice for all and build effective, accountable and inclusive institutions at all levels.
Goal 17. Strengthen the means of implementation and revitalize the global partnership for sustainable development.

The present invention can particularly contribute to the achievement of Goal 2 (end hunger, achieve food security and improved nutrition, and promote sustainable agriculture) and Goal 3 (ensure healthy lives and promote well-being for all at all ages). In other words, by providing whey, a nutritionally excellent food ingredient containing large amounts of various essential amino acids, proteins, vitamins, and sugars, as a whey processed food, it can contribute to supplying safe and sufficient food to all people, including young women, pregnant and lactating women, and the elderly.

Furthermore, the present invention can particularly contribute to the achievement of Goal 9 (Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation). In other words, by creating new added value for whey using this technology that suppresses the deterioration of whey, it is possible to promote technological development, research, and innovation such as industrial diversification and the creation of added value for products, thereby improving resource utilization efficiency and expanding and improving the efficiency of industrial processes, thereby promoting innovation in a sustainable and resilient manner.

Furthermore, the present invention can particularly contribute to the achievement of Goal 12 (ensuring sustainable consumption and production patterns). In other words, by effectively utilizing whey, which is often discarded during the cheese production process, as whey processed foods, cheese manufacturers can reduce food waste in production and supply chains. Furthermore, by reducing food waste by half, and carrying out sustainable development and development in harmony with nature, sustainable consumption and production patterns can be ensured.

Furthermore, the present invention can contribute to achieving the targets associated with each of the goals set out in "Transforming our world: the 2030 Agenda for Sustainable Development."

Hereinafter, the present invention will be described using experimental examples to aid in understanding the configuration and effects of the present invention. However, the present invention is not limited in any way by these experimental examples. The following experiments were carried out at room temperature (25±5°C) and atmospheric pressure conditions unless otherwise specified.

Experimental Example 1
Twenty-one types of whey processed foods A to U were produced, and the lactose content (mass%) and the percentage (%) of lactose crystals in each whey processed food were measured. In addition, the percentages of coarse lactose crystals and fine lactose crystals contained in the lactose crystals were measured for whey processed foods G to U. Furthermore, the texture (feel on the tongue, stickiness to teeth) of these whey processed foods A to U was evaluated.

(1) Raw materials The raw materials used in the production of whey processed foods are as follows:
Whey powder: Whey powder spray-dried (100% whey), lactose content 80%, protein content 12% (manufactured by Meiji Co., Ltd.);
Cream: Fat 47%, lactose 3% (Meiji Co., Ltd.),
Cream falls under the provision of the Ministerial Ordinance on the Compositional Standards of Milk and Dairy Products (Milk Ordinance), which states that it is "a substance obtained by removing all ingredients other than milk fat from raw milk, cow's milk or special cow's milk."
Lactase: Saphera (registered trademark) 2600L (manufactured by Novozymes Japan Co., Ltd.)
Milled lactose: (manufactured by Lacto Japan Co., Ltd.)
The standards used to measure the lactose content and the rate of lactose crystals are as follows:
Lactose monohydrate crystals (α-type): Lactose monohydrate (100% by mass), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Hereinafter referred to as "lactose crystals (standard product)."

(2) Test and Evaluation Methods The test and evaluation methods used in the following experimental examples are as follows.
(2-1) Measurement of lactose content (mass%) in whey processed foods
The lactose content in whey processed foods was measured using an enzyme electrode method.
2.5 g of whey processed food was adjusted to 100 mL with distilled water and used as a test sample in the measuring device under the following conditions. In addition, lactose crystals (standard) were previously diluted with distilled water to 0.25, 0.50, 1.0 and 1.5 g/100 mL, and used as standard solutions for the calibration curve. The calibration curve was created by using the measuring device under the following conditions. Based on this calibration curve, the lactose content in the test sample was determined from the measured values obtained for the test sample, and then the lactose content in the whey processed food was calculated.

[Measurement equipment and conditions]
Equipment: Enzyme electrode biosensor BF-7 (manufactured by Oji Scientific Instruments)
Buffer: BF buffer pH 7.0 (Oji Scientific Instruments)
Electrode: Lactose electrode (Oji Instruments)

(2-2) Percentage of lactose crystals in whey processed foods (%)
The whey processed food was sliced to a thickness of 0.5 mm and used as a test sample, and the amount of lactose crystals was determined using an X-ray diffraction measuring device (SmartLab X-ray DIFFRACTOMETER, manufactured by Rigaku).
Specifically, the test sample (one piece) was placed on a glass cell attached to the device so that the 0.5 mm thick side was on the top and bottom, and the X-ray diffraction image was measured using the X-ray diffraction measurement device. When the X-ray diffraction image of lactose crystals (standard product) was measured using the X-ray diffraction measurement device, multiple peaks derived from lactose crystals were detected in the range of 2θ = 19.9 to 20.4°, and the largest peak among them was set as the main peak. Next, the X-ray diffraction image obtained for the test sample was smoothed and the base portion was subtracted, and the area value of the peak corresponding to the main peak of lactose crystals (standard product) among the peaks detected in the range of 2θ = 19.9 to 20.4° was calculated.

Next, according to the formula below, the ratio of the area value of the above peak obtained for each whey processed food was calculated based on the area value of the main peak measured in the same manner for lactose crystals (standard product), and the percentage of lactose crystals contained in each whey processed food was calculated.

[formula]
Percentage of lactose crystals contained in whey processed foods (%)
= B/A x 100
A: Area value of the main peak at 2θ = 19.9 to 20.4° for lactose crystals (standard product) B: Area value of the peak corresponding to the main peak for whey processed food (test sample)

(2-3) Proportion of coarse lactose crystals and fine lactose crystals in lactose crystals in whey processed food About 1 mg of the whey processed food produced above was placed on a slide glass, and the sample was crushed with a cover glass (crushing method) to prepare a preparation, which was observed in 15 fields of view using a phase contrast microscope (objective magnification x 10, total magnification x 10). The images obtained in the observation of 15 fields of view were divided into background and particles (particles of lactose crystals) by binarization, and the total number of particles was counted. Next, the horizontal projection area of each particle (each lactose crystal) was measured, and the circle equivalent diameter of each was calculated. Particles with a circle equivalent diameter of 30 μm or more were classified as coarse lactose crystals, and particles with a circle equivalent diameter of 10 μm or less were classified as fine lactose crystals, and the number of coarse lactose crystals and the number of fine lactose crystals were calculated.

Next, the horizontal projection area of each particle (lactose crystal) included in the observation field was added up to determine the total area of all lactose crystal particles. This is also referred to as the "total lactose crystal area" in the present invention. Furthermore, the horizontal projection area of each particle that corresponds to coarse lactose crystals among all particles (lactose crystals) included in the observation field was added up to determine the total area of coarse lactose crystal particles. This is also referred to as the "total coarse lactose crystal area" in the present invention. Furthermore, the horizontal projection area of each particle that corresponds to fine lactose crystals among all particles (lactose crystals) included in the observation field was added up to determine the total area of fine lactose crystal particles. This is also referred to as the "total fine lactose crystal area" in the present invention.

The total area of lactose crystals was set as 100% (standard), and the percentage of the total area of coarse lactose crystals and the percentage of the total area of fine lactose crystals were calculated, which were then used as the percentage of coarse lactose crystals and the percentage of fine lactose crystals in lactose crystals, respectively.

(2-4) Protein content in whey processed food: Kjeldahl method About 1.5 g of the whey processed food produced above was precisely weighed, diluted or dissolved in hot water, transferred to a 100 ml measuring flask, cooled, and then adjusted to volume with water. 20 ml of this diluted solution was placed in a decomposition flask. To this, a decomposition accelerator (Keltab C) and 12 ml of sulfuric acid were gradually added and mixed, and then 8 ml of hydrogen peroxide was added and mixed. Next, the nitrogen was converted to ammonia by thermal decomposition in a decomposition apparatus. After the liquid in the decomposition flask became transparent and turned blue due to copper sulfate, it was cooled and diluted by gradually adding 50 ml of water. Then, it was distilled in a Kjeldahl distillation apparatus.
Specifically, an excess amount of sodium hydroxide was added to the above decomposition liquid ( _H2SO4 containing ( _{NH4)2SO4 )} to make it alkaline, and then _it was heated with steam to release ammonia _again , and the liberated ammonia was distilled with steam and collected in an aqueous boric acid solution. The resulting ammonia collection liquid was titrated with a standard sulfuric acid solution to determine the nitrogen content, and the protein mass was calculated by multiplying it by the nitrogen-to-protein conversion factor (6.38).

(2-5) Quantitative Analysis of α-LA and β-LG: SDS-PAGE Method Quantitative analysis of α-LA and β-LG can be carried out by the following SDS-PAGE method.

(i) Preparation of Reagents (a) Composition of Reducing Reagent: 50 mM Tris-HCl buffer (pH 6.8), 20% glycerin, 1% SDS, 50 mM DTT, 0.005% BPB

(b) Preparation of sample solution 100 μl of a test sample (whey processed food) adjusted to an estimated α-LA or β-LG value of approximately 75 mg/100 g was mixed with 900 μl of a reducing reagent to prepare a sample solution (adjusted to an estimated α-LA or β-LG value of approximately 7.5 mg/100 g).

(c) Preparation of standard solutions for calibration curves Standard solutions for calibration curves were prepared so that α-LA or β-LG had concentrations of 25, 50, 100, and 150 μg/ml. The standards used were as follows:
α-LA standard product: α-Lactalbumin from bovine milk-type1 lyophilized powder (manufactured by Sigma-Aldrich)
β-LG standard product: β-Lactoglobulin from bovine milk-type1 lyophilized powder (manufactured by Sigma-Aldrich)

(ii) Reduction and Electrophoresis A sample solution is collected in a microtube, heated at 100° C. for 5 minutes, and then cooled (reduction).
The standard solutions for the calibration curve are also subjected to the same reduction treatment.

Then, each solution is subjected to electrophoresis under the following conditions.
(Electrophoresis Conditions)
Gel: SPG520L (ATTO Corporation)
Buffer solution: EzRunC ⁺ (ATTO Corporation)
Sample solution injection volume: 10 μL
Current application: constant current of 40 mA (20 mA/gel) for approximately 70 minutes.

After applying the electric current, the gel was immersed in a staining solution (AE-1340 EzStain Aqua: ATTO Corporation) for 3 hours, then rinsed with distilled water, and immersed for 24 hours to destain it.
After destaining, the gel was placed on a highly transparent glass plate and scanned with a scanner. After background correction using image analysis software, bands were detected and the signal intensity was calculated.

Based on the calibration curve prepared using the standard calibration solution, the concentration of α-LA or β-LG in the test solution is calculated from the signal intensity of the α-LA or β-LG band obtained for the test solution, and the concentration in the test sample is converted.

(2-6) Quantitative determination of casein: subtraction method. Weigh out about 1.5 g of the whey processed food produced above, dilute or dissolve it in warm water, then place it in a 100 ml measuring flask to make the total volume about 80 ml. Keep this at 40°C, add 1 ml of 10% acetic acid, mix, and leave for about 10 minutes. Add 1 ml of 1N sodium acetate and mix again. Cool, adjust to volume with water, filter using dry filter paper (Toyo Filter Paper No. 6), take 20 ml of the filtrate, and place this in a decomposition flask. Thereafter, in the same manner as in (2-4), add a decomposition accelerator, sulfuric acid, and hydrogen peroxide, heat decompose in a decomposition apparatus, distill in a Kjeldahl distillation apparatus, and titrate the resulting ammonia collection liquid with a sulfuric acid standard solution to determine the nitrogen content and protein content. Using this protein content as the "non-casein protein content," calculate the casein content using the following formula.

[formula]
Casein content = total protein content - non-casein protein content

(2-7) Lipid content in whey processed food: Roese-Gottlieb method Approximately 1 g of the whey processed food produced above was dispersed in 2 ml of ammonia water, and then 10 ml of ethanol was added, followed by extraction with 25 ml of diethyl ether and 25 ml of petroleum ether. The second extraction was performed with 15 ml of diethyl ether and 15 ml of petroleum ether. The entire extract collected was dried to dryness, and the mass of the dried matter was measured, which was used as the lipid content in the test sample.

(2-8) Insoluble matter content in whey processed foods The insoluble matter content in whey processed foods was measured by adapting the method for measuring the solubility index of milk-derived proteins developed in the Standards for Grades of Dry Milks including Methods of Analysis (Bulletin 916) of the American Dairy Products Institute (ADPI).
Specifically, the whey processed food was dissolved in water heated to about 60°C to prepare an aqueous solution (test sample solution) with a whey processed food content of 1%. After the test sample solution was returned to room temperature, about 50 g of the test sample solution was placed in two tapered 50 ml graduated centrifuge tubes and centrifuged (720 xg, 5 min, 20°C). Immediately after centrifugation, the upper layer was removed with a Komagome pipette without disturbing the precipitate layer. Water (room temperature) was added up to the 50 ml mark, stirred with a micro spatula, and centrifuged again under the same conditions as above. The volume (mL) of the precipitate was read from the mark on the centrifuge tube, and the average value of the duplicates was taken as the insoluble matter content of the whey processed food (test sample).

(2-9) Texture evaluation of whey processed foods The whey processed foods were evaluated for "feel on the tongue" and "feel on the teeth" using an analytical sensory evaluation panel of four experts (training period: 5 to 15 years) trained in-house. Note that the whey processed foods I were stored for 1 hour under constant temperature and humidity conditions of a temperature of 10°C and a humidity of 50% before being subjected to the texture evaluation.

The whey processed foods were evaluated for "feel on the tongue" and "feel on the teeth" based on the following criteria.
(i) Texture: The presence or absence of roughness and smoothness felt on the tongue when eating. Evaluation was made on the following 5-point scale: 5 (best): No roughness at all, very smooth; 4 (good): Almost no roughness, very smooth; 3 (good): Some roughness, but smooth; 2 (bad): Roughness, not smooth; 1 (worst): Extremely rough, not smooth at all.

(ii) Feeling of adhesion to teeth: resistance felt due to adhesion to teeth when biting. 5 (best): Does not adhere to teeth at all, and there is no resistance to teeth. 4 (good): Almost no adhesion to teeth, and almost no resistance to teeth. 3 (good): Adheres to teeth somewhat, and there is some resistance to teeth. 2 (bad): Adheres to teeth, and there is a resistance to teeth. 1 (worst): Adheres to teeth significantly, and there is a strong resistance to teeth.

When conducting the texture evaluation, the entire panel worked together to reach a common understanding of the characteristics of each evaluation item. Each evaluation was carried out by each panel, and the results were then discussed by the entire panel, which then formed the final overall evaluation of the entire panel.

In addition, a comprehensive evaluation was made based on the results of both the texture on the tongue and the stickiness to the teeth, using the following criteria.
[comprehensive evaluation]
◎: Tongue feel is 5, tooth adhesion is 4 or more ○: Tongue feel and tooth adhesion are both 4
△: At least one of the feel on the tongue and the feeling on the teeth is rated 3 or less. ×: At least one of the feel on the tongue and the feeling on the teeth is rated 2 or less.

(3) Production and evaluation of whey processed foods A to F
(3-1) Manufacturing method of whey processed foods A to F
A whey-containing liquid was prepared by mixing the raw materials in the ratios shown in Table 1. The protein content in 100% whey-containing liquid was 7% (9% in terms of solid content), the lactose content was 42% (58% in terms of solid content), and the lipid content was 21% (29% in terms of solid content).

The obtained whey-containing liquid was either left as is (lactose decomposition rate 0%) or added with lactase and held at 50°C for 10 to 90 minutes to decompose 10 to 60% of the total lactose contained in the whey-containing liquid (100%) (see Table 2 for the lactose decomposition rates of the corresponding whey processed foods A to F). Each of these was concentrated under reduced pressure for 5 to 60 minutes at 70°C under vacuum (reduced pressure) pressure (gauge pressure [relative pressure] of the device: -20 kPa to -50 kPa, absolute pressure: approximately 80 kPa to 50 kPa) while stirring at 20 to 60 rpm, rotation radius 0.175 m, and 0.37 to 1.1 m/s in a continuous heating vacuum cooker device (manufactured by Mihama Co., Ltd.) until the solids concentration reached 80%. After concentrating to a solid content concentration of 80%, the concentrates were heated to 110-120°C under pressurized conditions (gauge pressure [relative pressure] of the apparatus: 10 kPa-20 kPa, absolute pressure: about 110 kPa-120 kPa) and treated until the concentrates (whey concentrates A-F) turned brown. Thereafter, whey concentrates A-E were cooled to 5°C or lower to obtain solid whey processed foods A-E with a solid content concentration of 84%.

For whey concentrate F (lactose decomposition rate: 0%), the product temperature was adjusted to 80°C, pulverized lactose was added at a ratio of 0.5%, and the mixture was stirred for 15 minutes under the same temperature conditions using a twin-screw kneader (manufactured by Irie Shokai Co., Ltd., with blades of diameter 60 mm, shaft distance 50 mm, length 120 mm, and twist angle of 60°, rotating in the same direction) (seeding treatment). After the seeding treatment, the mixture was cooled to below 10°C to obtain a solid whey processed food F with a solid content concentration of 84%.

(3-2) Evaluation of whey processed foods A to F The lactose content (%), the rate of lactose crystals (%), and the results of the texture evaluation for whey processed foods A to F, which differ in lactose decomposition rate and the presence or absence of seeding treatment, are shown in Table 2. The protein content (solid content equivalent) was 8%, the lipid content (solid content equivalent) was 24%, and the insoluble matter content was 0.25 to 0.35 mL in 100% by mass of solid content for these whey processed foods A to F. The results of measuring the X-ray diffraction patterns for whey processed foods A to E are shown in Figure 1 (X-ray diffraction patterns for whey processed foods A to E from the top).

As shown in the results of whey processed foods A to E in Table 2, when the percentage of lactose crystals contained in whey processed foods was reduced by lactose hydrolysis, the roughness felt on the tongue improved and the texture tended to become smoother. However, when the lactose hydrolysis rate was 10 to 20%, the texture improved to a certain extent by reducing the percentage of lactose crystals, but the roughness remained (whey processed foods B and C). When the percentage of lactose crystals was extremely low by setting the lactose hydrolysis rate to 30% or more, the texture was smooth, but the food was likely to stick to the teeth when biting (whey processed foods D and E). In addition, when whey processed food F was seeded without lactose hydrolysis, the percentage of lactose crystals doubled compared to whey processed food A not seeded, but the texture (roughness felt on the tongue) improved slightly, while no deterioration in the feeling of sticking to the teeth was observed. From this, it was found that the texture needs to be evaluated not only by the percentage (amount) of lactose crystals but also by the size of the lactose crystals.

Based on these results, it is expected that by combining lactose hydrolysis processing and seeding processing, it will be possible to prepare whey processed foods that have a smooth texture and good tooth adhesion (reduced tooth adhesion), in other words, whey processed foods that have both smoothness and reduced tooth adhesion.

(4) Production and Evaluation of Whey Processed Foods G to U Based on the evaluation results of the whey processed foods A to F, the combined effect of lactose decomposition and seeding treatment was verified. Here, the whey processed foods H to K, M to P, and R to U were produced by concentrating after the lactose decomposition treatment and then performing a seeding treatment, and the lactose content (%), the ratio of lactose crystals (%), the ratio of coarse lactose crystals and fine lactose crystals (%), and the texture of these whey processed foods were evaluated. In addition, for comparison, whey processed foods G, L, and Q were prepared by concentrating after lactose decomposition treatment and not performing a seeding treatment, similarly to the whey processed foods B to D prepared in (3), and were similarly evaluated.

(4-1) Method for producing whey processed foods G to U A whey-containing liquid was prepared by mixing the raw materials in the ratios shown in Table 1, and 10%, 20% or 30% of the total lactose contained in the whey-containing liquid (lactose decomposition rate: 10%, 20% or 30%) was decomposed by the method described in (3-1) above. The whey-containing liquid was then concentrated under reduced pressure to a solid content of 84% by the method described in (3-1) above. The whey concentrates B, C and D thus prepared (lactose decomposition rate: 10%, 20% and 30%) were cooled to 5°C or lower to obtain solid whey processed foods G, L and Q having a solid content of 84%. The whey concentrates B, C and D (lactose decomposition rate: 10%, 20% and 30%) were adjusted to temperatures of 60°C, 70°C, 80°C and 90°C, respectively, and pulverized lactose was added to each whey concentrate at a ratio of 0.5% under each temperature condition, and stirred for 15 minutes under the same temperature condition using a twin-shaft kneader (manufactured by Irie Shokai Co., Ltd., with a blade diameter of 60 mm, a shaft distance of 50 mm, a length of 120 mm and a twist angle of 60°, rotating in the same direction) (seeding treatment). After the seeding treatment, the mixture was cooled to 10°C or less to obtain whey processed foods H to K (lactose decomposition rate: 10%), whey processed foods M to P (lactose decomposition rate: 20%) and whey processed foods R to U (lactose decomposition rate: 30%) with a solid content concentration of 84%.

(4-2) Evaluation of whey processed foods G to U The lactose content (%), lactose crystal ratio (%), ratio of coarse crystals, ratio of fine crystals, and texture evaluation results for whey processed foods G to U, which differ in lactose decomposition rate, presence or absence of seeding treatment, and seeding treatment temperature, are shown in Table 3. The protein content (solid content equivalent) was 8%, the lipid content (solid content equivalent) was 24%, and the insoluble matter content was 0.3 to 0.35 mL in 100% by mass of solid content of these whey processed foods. Figure 2 shows an image of the structure of whey processed food O (lactose decomposition rate 20%, seeding treatment, 80°C) observed with a phase contrast microscope (objective magnification x10, total magnification x10).

From the texture evaluation results of whey processed food F shown in Table 2, it was expected that the seeding treatment would improve the stickiness to the teeth, but contrary to expectations, even when whey concentrate with a lactose decomposition rate of 30% or more was subjected to the seeding treatment, the stickiness to the teeth was not reduced (whey processed foods R to U). On the other hand, by subjecting whey concentrate with a lactose decomposition rate of 10 to 20% to the seeding treatment, the texture was improved more than expected, and the reduction in the stickiness to the teeth was also improved, and it was confirmed that a whey processed food having both a smooth texture and a reduced stickiness to the teeth could be obtained (whey processed foods H to K, whey processed foods M to P).
In particular, the results shown in Table 3 confirm that by adjusting the proportion of lactose crystals contained in a whey processed food to approximately 3-5%, and by using a seeding process (addition of pulverized lactose) to reduce the proportion of coarse lactose crystals to 10% or less and the proportion of fine lactose crystals to 70% or more, it is possible to prepare a whey processed food that has a good tooth-adhesive feel (reduced tooth adhesion) and an extremely smooth texture, thereby achieving both smoothness and reduced tooth-adhesive feel.

In addition, whey processed foods 1 to 15 were produced and evaluated in the same manner as whey processed foods G to U in (4) above, using a whey-containing liquid prepared by mixing the ingredients in a ratio in which the amount of cream in the recipe described in Table 1 was reduced to 1/4. The protein content in 100% of the whey-containing liquid was 7% (11% in terms of solids), the lactose content was 46% (74% in terms of solids), and the lipid content was 6% (9% in terms of solids).

As a result, the same results were obtained as for whey processed foods G to U listed in Table 3. In other words, even when the lipid content of the whey-containing liquid used as a raw material is reduced, it was confirmed that a whey processed food that has low tooth adhesion and an extremely smooth texture, achieving both smoothness and reduced tooth adhesion, can be prepared by adjusting the proportion of lactose crystals contained in the whey processed food to about 3 to 5% by lactose decomposition and seeding treatment, and by setting the proportion of coarse lactose crystals to 10% or less and the proportion of fine lactose crystals to 70% or more by seeding treatment (addition of pulverized lactose).

The present invention can be used as a means for achieving the Sustainable Development Goals (SDGs), and can contribute to the achievement of the Sustainable Development Goals (SDGs) and targets. The present invention can contribute to the achievement of Goals 2 and 3 of the Sustainable Development Goals. That is, by providing whey, which is a nutritionally excellent food material containing a large amount of various essential amino acids, proteins, vitamins, and sugars, as a whey processed food, it can contribute to supplying safe and sufficient food to all people, including young women, pregnant and lactating women, and the elderly. In addition, the present invention can contribute to the achievement of Goal 9 of the Sustainable Development Goals. That is, by creating new added value of whey using this technology that suppresses the deterioration of whey, it is possible to promote technological development, research, and innovation such as diversification of industry and creation of added value for products, thereby improving resource utilization efficiency and expanding and improving the efficiency of industrial processes, thereby promoting innovation in a sustainable and resilient manner. In addition, the present invention can contribute to the achievement of Goal 12 of the Sustainable Development Goals. In other words, by effectively utilizing whey, which is often discarded in the cheese manufacturing process, cheese manufacturers can reduce food waste in production and supply chains.Furthermore, by halving food waste, sustainable development and development in harmony with nature can be achieved, ensuring a sustainable production and consumption pattern.

Claims (9)

A method for producing a whey processed food comprising the following steps (1) to (3):
(1) a step of hydrolyzing 10 to 20% by mass of lactose contained in a whey-containing liquid having a lactose content of 36 to 74% by mass calculated on a solid content basis;
(2) a step of heating and concentrating the whey-containing liquid after the hydrolysis treatment to prepare a whey concentrate having a solid content concentration of 55 to 90% by mass; and (3) a step of adding pulverized lactose to the whey concentrate adjusted to 60°C to 90°C, stirring and then cooling;
The whey processed food has the following characteristics A to C:
A: Contains lactose at a ratio of 15% by mass or more;
B: The percentage of lactose crystals in the whey processed food is 3-5%.
C: The proportion of coarse lactose crystals in the lactose crystals contained in the whey processed food is 10% or less, and the proportion of fine lactose crystals is 70% or more;
The ratio of lactose crystals is a ratio calculated from the area of the peak at the corresponding position obtained for the test whey processed food, based on the area of the main peak of lactose monohydrate crystals (standard product) detected in the range of 2θ = 19.9 to 20.4 ° in the X-ray diffraction pattern measured by an X-ray diffractometer,
The proportion of coarse lactose crystals and fine lactose crystals in the lactose crystals is determined by observation with a phase contrast microscope and is the ratio of the total area of coarse lactose crystal particles and the ratio of the total area of fine lactose crystal particles to the total area of lactose crystal particles in the test whey processed food (100%). The method according to claim 1, wherein the whey-containing liquid in step (1) contains 5 to 21% by mass of protein in terms of solid content. The method according to claim 1 or 2, wherein the whey-containing liquid in step (1) contains lipids in an amount of 9 to 60% by mass calculated as solid content. The method according to claim 1 or 2, wherein in step (3), the amount of pulverized lactose added to the whey concentrate is 0.01% by mass or more. The method according to claim 3, wherein in step (3), the amount of pulverized lactose added to the whey concentrate is 0.01% by mass or more. A whey processed food having a solid content concentration of 55% by mass or more,
The whey processed food has a protein content of 5 to 21% by mass, a lactose content of 29 to 70% by mass, and a lipid content of 9 to 60% by mass, based on 100% by mass of the solid content of the whey processed food;
The whey protein content is 73 to 97% by mass out of 100% by mass of the total amount of protein;
A whey processed food having the following characteristics A to C:
A: Contains lactose at a ratio of 15% by mass or more;
B: The percentage of lactose crystals in the whey processed food is 3-5%.
C: The proportion of coarse lactose crystals in the lactose crystals contained in the whey processed food is 10% or less, and the proportion of fine lactose crystals is 70% or more;
The ratio of lactose crystals is a ratio calculated from the area of the peak at the corresponding position obtained for the test whey processed food, based on the area of the main peak of lactose monohydrate crystals (standard product) detected in the range of 2θ = 19.9 to 20.4 ° in the X-ray diffraction pattern measured by an X-ray diffractometer,
The proportion of coarse lactose crystals and fine lactose crystals in the lactose crystals is determined by observation with a phase contrast microscope and is the ratio of the total area of coarse lactose crystal particles and the ratio of the total area of fine lactose crystal particles to the total area of lactose crystal particles in the test whey processed food (100%). The whey processed food according to claim 6, wherein the insoluble matter content of the whey processed food is 0.4 ml or less. The whey processed food according to claim 6 or 7, in which the α-lactalbumin content is 10-14% by mass and the β-lactoglobulin content is 31-42% by mass, based on 100% by mass of the total protein. 8. The whey processed food according to claim 7 , wherein the amount of whey used in the production of 100 g of the whey processed food is 30 g or more, calculated as the amount of dried whey.

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