Skim milk powder

Abstract

The purpose of the present invention is to provide an indicator substance of the fermentability of skim milk powder, a skim milk powder which has excellent fermentability and contains an optimal amount of the indicator substance, a use thereof, and an evaluation method of fermentability of skim milk powder using said indicator substance. It was found that skim milk powder with high homoserine concentration and / or creatinine concentration has a short fermentation time during yogurt production and excellent fermentability. A skim milk powder with excellent fermentability containing a high amount of said substance, and the use thereof, as well as an evaluation method of fermentability of skim milk powder are also provided.

Description

Skim milk powder

[0001] The present invention relates to highly fermentable skim milk powder.

[0002] In the production of yogurt, skim milk powder is used as a source of milk solids-not-fat (SNF). Skim milk powder is a powder obtained by sterilizing, concentrating, and spray-drying skim milk, which is obtained by separating cream from raw milk. The properties of dairy ingredients such as skim milk powder have various effects on the production efficiency and quality of yogurt. Therefore, various methods for yogurt production have been proposed, such as methods to shorten the fermentation time, improve the physical properties of yogurt, and increase the survival rate of lactic acid bacteria.

[0003] Japanese Patent Laid-Open Publication No. 11-028056 describes that blending a milk protein concentrate and delactose permeate into a milk raw material mix promotes fermentation and shortens the fermentation time, resulting in fermented milk with excellent hardness, viscosity, flavor, etc. (Patent Document 1) Furthermore, International Publication No. 2010 / 113680 describes that a medium made from a milk component having a free phosphate concentration of less than 0.25% by mass cannot stably maintain the number of lactic acid bacteria in a lactic acid bacteria culture, but that adding phosphate to the medium makes it possible to stably maintain the number of lactic acid bacteria in the resulting lactic acid bacteria culture (Patent Document 2).

[0004] Japanese Patent Application Laid-Open No. 11-028056 International Publication No. 2010 / 113680

[0005] Because the composition of skim milk powder varies depending on the season, region, and production conditions, it is difficult to consistently obtain skim milk powder with consistent properties. For example, some types of skim milk powder have poor fermentability, which can cause delayed fermentation during yogurt production. Delayed fermentation can lead to problems such as reduced yogurt production efficiency and quality deterioration. Therefore, by identifying a substance among the components of skim milk powder whose concentration correlates with fermentation time and using it as an indicator of the fermentability of skim milk powder, it becomes possible to develop and select skim milk powder with excellent fermentability, thereby preventing delayed fermentation during yogurt production. Therefore, the present invention aims to provide skim milk powder with excellent fermentability that contains an optimal amount of the indicator substance, its use, and a method for evaluating the fermentability of skim milk powder using the indicator substance.

[0006] In order to solve the above problems, the present inventors conducted detailed component analysis and fermentation tests on skim milk powder, and as a result, they found that skim milk powder with high homoserine and creatinine concentrations requires a short fermentation time during yogurt production, i.e., has excellent fermentability, and thus completed the present invention.

[0007] That is, the present invention is as follows. (1) Skim milk powder which, when prepared into 10% reconstituted skim milk powder, exhibits a homoserine concentration of 3.4 μM or more in the reconstituted skim milk powder. (2) Skim milk powder which, when prepared into 10% reconstituted skim milk powder, exhibits a creatinine concentration of 950 μM or more in the reconstituted skim milk powder. (3) Skim milk powder which, when prepared into 10% reconstituted skim milk powder, exhibits a homoserine concentration of 3.4 μM or more and a creatinine concentration of 950 μM or more in the reconstituted skim milk powder. (4) A method for producing yogurt using the skim milk powder described in any one of (1) to (3). (5) A method for evaluating the fermentability of skim milk powder, comprising preparing 10% reconstituted skim milk powder and quantifying the homoserine concentration and / or creatinine concentration in the reconstituted skim milk powder. (6) The evaluation method described in (5), wherein the quantification method is performed using mass spectrometry. (7) Whole milk powder, which, when prepared into 10% reconstituted whole milk powder, exhibits a homoserine concentration of 3.4 μM or more. (8) Whole milk powder, which, when prepared into 10% reconstituted whole milk powder, exhibits a creatinine concentration of 950 μM or more. (9) Whole milk powder, which, when prepared into 10% reconstituted whole milk powder, exhibits a homoserine concentration of 3.4 μM or more and a creatinine concentration of 950 μM or more. (10) A method for producing yogurt using the whole milk powder described in any one of (7) to (9). (11) A method for evaluating the fermentability of whole milk powder, which comprises preparing 10% reconstituted whole milk powder and quantifying the homoserine concentration and / or creatinine concentration in the reconstituted whole milk powder. (12) The evaluation method described in (11), wherein the quantification method is performed using mass spectrometry (MS). (13) Concentrated skim milk exhibits a homoserine concentration of 3.4 μM or more. (14) Skim concentrated milk having a creatinine concentration of 950 μM or more. (15) Skim concentrated milk having a homoserine concentration of 3.4 μM or more and a creatinine concentration of 950 μM or more. (16) A method for producing yogurt using the skim concentrated milk according to any one of (13) to (15). (17) A method for evaluating the fermentability of skim concentrated milk, comprising quantifying the homoserine concentration and / or creatinine concentration in the skim concentrated milk. (18) The evaluation method according to (17), wherein the quantification method is performed using mass spectrometry (MS).

[0008] According to the present invention, by using skim milk powder with a high concentration of homoserine and / or creatinine during yogurt production, it is possible to prevent delay in fermentation due to the properties of skim milk powder and to improve the efficiency of yogurt production by shortening the fermentation time. Furthermore, by quantifying the concentrations of homoserine and / or creatinine in skim milk powder, the fermentability of skim milk powder can be evaluated quickly and simply.

[0009] In the present invention, skim milk powder refers to skim milk (milk from which most of the milk fat has been removed; in the case of cow's milk, skim milk has a non-fat solid content of 8.0% or more and a milk fat content of less than 0.5%) that has been dried.

[0010] The skim milk powder of the present invention contains homoserine. Homoserine is an amino acid and is thought to become a precursor of cystathionine in vivo. In the present invention, homoserine is one of the indicators of the fermentability of skim milk powder. The homoserine concentration in the skim milk powder of the present invention can be quantified by preparing 10% reconstituted skim milk powder from the skim milk powder. The homoserine concentration in the 10% reconstituted skim milk powder is not particularly limited as long as it is within a range that does not cause fermentation delay, but the lower limit is preferably 3.4 μM, more preferably 3.7 μM, and even more preferably 4.0 μM. A concentration of 3.4 μM or higher tends to promote fermentation during yogurt production. Furthermore, the upper limit of the homoserine concentration in the 10% reconstituted skim milk powder is not particularly limited, but is preferably 7.0 μM, more preferably 6.0 μM, and even more preferably 5.5 μM. The range of homoserine concentration in the skim milk powder of the present invention can be set by arbitrarily combining these lower and upper limits. Here, "10% reconstituted skim milk powder" refers to skim milk powder dissolved in water at a concentration of 10% by weight.

[0011] The skim milk powder of the present invention contains creatinine. Creatinine is the anhydrous form of creatine, and in vivo, it is excreted in urine as a metabolic product of creatine in muscle cells. In the present invention, creatinine is one of the indicators of the fermentability of skim milk powder. The creatinine concentration in the skim milk powder of the present invention can be quantified by preparing 10% reconstituted skim milk powder from the skim milk powder. The creatinine concentration in the 10% reconstituted skim milk powder is not particularly limited as long as it is within a range that does not cause fermentation delay, but the lower limit is preferably 950 μM, more preferably 1000 μM, and even more preferably 1100 μM. If the concentration is 950 μM or higher, fermentation is likely to be promoted during yogurt production. Furthermore, the upper limit of the creatinine concentration in the 10% reconstituted skim milk powder is not particularly limited, but is preferably 1700 μM, more preferably 1600 μM, and even more preferably 1500 μM. The range of the creatinine concentration in the skim milk powder of the present invention can be set by arbitrarily combining these lower limit values ​​and upper limit values.

[0012] As an indicator of the fermentability of the skim milk powder of the present invention, either homoserine or creatinine may be used, but the fermentability of the skim milk powder can be evaluated more accurately by using both.

[0013] Furthermore, both homoserine and creatinine as indicators of fermentability in the present invention can also be applied to concentrated skim milk and whole milk powder. Concentrated skim milk is a liquid obtained by sterilizing and concentrating skim milk obtained by separating cream from raw milk, while whole milk powder is a powder obtained by removing water from raw milk, cow's milk, or special cow's milk.

[0014] The skim milk powder of the present invention can also be prepared by adding homoserine or creatinine to the skim milk powder.

[0015] The skim milk powder of the present invention exhibits excellent fermentability. Specifically, the time required to produce yogurt using the skim milk powder of the present invention is much shorter than the fermentation time required to produce yogurt using conventional skim milk powder. The method for measuring the fermentation time is not particularly limited as long as it is a common method. For example, when a predetermined amount of 10% reconstituted skim milk powder is inoculated with a predetermined amount of frozen bacteria consisting of L. bulgaricus and S. thermophilus as a fermented milk starter and fermented at 43°C, the fermentation time can be determined as the time required for the pH to reach 4.6. In the present invention, the lower limit of the fermentation time is not particularly limited, but is preferably 240 minutes, more preferably 270 minutes, and even more preferably 300 minutes.

[0016] In the present invention, the method for producing yogurt is not particularly limited as long as it is a common method, but may include, for example, a step of preparing a fermented milk mix using dairy ingredients such as skim milk powder, a step of heat-sterilizing the fermented milk mix, and a step of adding a fermented milk starter to the heat-sterilized fermented milk mix and fermenting it. The fermented milk mix is ​​a raw material preparation obtained by mixing dairy ingredients, and is prepared by adding (blending) water, sugar, sweeteners, stabilizers, flavorings, etc. to dairy ingredients such as skim milk powder and dissolving them under heating as necessary. The starter refers to a seed culture such as lactic acid bacteria or yeast that is inoculated to ferment the fermented milk mix. In the present invention, known starters can be used as appropriate, but it is preferable to use a lactic acid bacteria starter as the starter. Lactobacillus bulgaricus (L. bulgaricus) and Streptococcus thermophilus (S. thermophilus), etc. can be used as the lactic acid bacteria starter. The amount of starter to be added can be appropriately determined according to the method for determining the amount of starter to be added that is generally used in the production of fermented milk. The method for inoculating the starter is also not particularly limited, and any method commonly used in the production of fermented milk can be appropriately used. The fermentation conditions can be appropriately determined taking into consideration the type of fermented milk, the desired flavor, the type of starter to be used, and the like.

[0017] In the present invention, yogurt includes, for example, "fermented milk" or "lactic acid bacteria beverage" as defined in the Ministerial Ordinance on Milk, Dairy, etc. In the Ministerial Ordinance on Milk, etc., "fermented milk" is defined as "milk or milk containing an equivalent or greater amount of non-fat milk solids fermented with lactic acid bacteria or yeast to form a paste or liquid" or "a product of freezing these." Yogurt is broadly classified into "hard yogurt (solid fermented milk, set-type yogurt) that is fermented and solidified after being filled into a container," "soft yogurt (paste-like fermented milk) that is obtained by crushing the curd after fermentation and filling a container," and "drinkable yogurt (liquid fermented milk)" that is obtained by further crushing soft yogurt in a homogenizer to enhance its liquid properties. In addition, in the Ministerial Ordinance on Milk, etc., "lactic acid bacteria beverage" refers to "a beverage (excluding fermented milk) that is processed from, or uses as the main ingredient, milk, etc. that has been fermented with lactic acid bacteria or yeast."

[0018] The present invention also relates to a method for evaluating the fermentability of skim milk powder, characterized by quantifying the homoserine concentration and / or creatinine concentration in skim milk powder. Skim milk powder with higher homoserine and / or creatinine concentrations exhibits better fermentability. Here, mass spectrometry (hereinafter referred to as MS) is used as the method for quantifying the homoserine concentration in the present invention. High-performance liquid chromatography (HPLC) may be used as an alternative method, provided that the measured values ​​agree with those measured by the MS method. The MS method is used as the method for quantifying the creatinine concentration. HPLC may be used as an alternative method, provided that the measured values ​​agree with those measured by the MS method.

[0019] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0020] 80 g of 10% reconstituted skim milk powder was prepared for each of the 10 types of skim milk powder. A 0.15% frozen mixture of L. bulgaricus and S. thermophilus strains was inoculated into the mixture, which was then fermented at 43°C. The time required for the pH to reach 4.6 was measured, and this measurement time was used as the fermentation time. The homoserine and creatinine concentrations of these 10% reconstituted skim milk powders were also measured by mass spectrometry.

[0021] The fermentation time, homoserine concentration, and creatinine concentration of each skim milk powder are shown in Table 1. The homoserine concentration and creatinine concentration in the skim milk powder are values ​​calculated from the homoserine concentration and creatinine concentration in the 10% reconstituted skim milk powder solution.

[0022]

[0023] The results shown in Table 1 indicate that the higher the homoserine and creatinine concentrations in skim milk powder, the shorter the fermentation time of the skim milk powder. Specifically, when the homoserine concentration when preparing 10% reconstituted skim milk powder was within the range of 3.4 μM to 6.0 μM, the fermentation time was shorter than 320 minutes. When the creatinine concentration when preparing 10% reconstituted skim milk powder was within the range of 950 μM to 1647 μM, the fermentation time was shorter than 345 minutes, indicating a shorter fermentation time. In particular, when the homoserine concentration when preparing 10% reconstituted skim milk powder was within the range of 3.8 μM to 6.0 μM, or when the creatinine concentration when preparing 10% reconstituted skim milk powder was within the range of 1467 μM to 1647 μM, the fermentation time was shorter than 300 minutes, indicating a significantly shorter fermentation time of the skim milk powder. This indicates that skim milk powder with high homoserine and creatinine concentrations has excellent fermentability.

[0024] According to the present invention, it has been found that skim milk powder having a high concentration of homoserine and / or creatinine has a short fermentation time during yogurt production and is excellent in fermentability. Furthermore, the present invention makes it possible to prevent delay in fermentation due to the properties of skim milk powder and to improve the efficiency of yogurt production by shortening the fermentation time, and is therefore extremely useful industrially.

Claims

1. Skim milk powder which, when prepared as 10% reconstituted skim milk powder, exhibits a homoserine concentration of 3.4 μM or more in the reconstituted skim milk powder.

2. Skim milk powder which, when prepared as 10% reconstituted skim milk powder, exhibits a creatinine concentration of 950 μM or more in the reconstituted skim milk powder.

3. Skim milk powder which, when prepared as 10% reconstituted skim milk powder, exhibits a homoserine concentration of 3.4 μM or more and a creatinine concentration of 950 μM or more in the reconstituted skim milk powder.

4. A method for producing yogurt using the skim milk powder according to any one of claims 1 to 3.

5. A method for evaluating the fermentability of skim milk powder, which comprises preparing 10% reconstituted skim milk powder and quantifying the homoserine concentration and / or creatinine concentration in the reconstituted skim milk powder.

6. The evaluation method according to claim 5, wherein the quantitative analysis is performed using HPLC or MS.

7. Whole milk powder which, when prepared as 10% reconstituted whole milk powder, has a homoserine concentration of 3.4 μM or more.

8. Whole milk powder which, when prepared as 10% reconstituted whole milk powder, has a creatinine concentration of 950 μM or more.

9. Whole milk powder which, when prepared as 10% reconstituted whole milk powder, has a homoserine concentration of 3.4 μM or more and a creatinine concentration of 950 μM or more in the reconstituted whole milk powder.

10. A method for producing yogurt using the whole milk powder according to any one of claims 7 to 9.

11. A method for evaluating the fermentability of whole milk powder, comprising preparing 10% reconstituted whole milk powder and quantifying the homoserine concentration and / or creatinine concentration in the reconstituted whole milk powder.

12. The evaluation method according to claim 11, wherein the quantitative analysis is performed using mass spectrometry.

13. Concentrated skim milk having a homoserine concentration of 3.4 μM or more.

14. Concentrated skim milk with a creatinine concentration of 950 μM or more.

15. Concentrated skim milk having a homoserine concentration of 3.4 μM or more and a creatinine concentration of 950 μM or more.

16. A method for producing yogurt using the skim concentrated milk according to any one of claims 13 to 15.

17. A method for evaluating the fermentability of concentrated skim milk, comprising quantifying the homoserine concentration and / or creatinine concentration in concentrated skim milk.

18. The evaluation method according to claim 17, wherein the quantitative analysis is performed using mass spectrometry.