JP2018033415A - Method for manufacturing fermented milk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a fermented milk with an improved survival rate of lactic bacteria in cold storage without addition of a particular raw material.SOLUTION: A method for obtaining a fermented milk includes the steps of preparing a raw material milk (S1), homogenizing the raw material milk on an as needed basis (S2), sterilizing the raw material milk (S3), cooling the raw material milk down near the fermentation temperature (S4), inoculating a lactic bacteria starter into the raw material milk (S5), and fermenting the raw material milk (S7) to obtain a fermented milk. A method for manufacturing a fermented milk includes the steps of holding the fermented milk at 20 to 30°C for 5 minutes or more (S8), and then cooling the fermented milk down to a cold storage temperature (1 to 10°C) (S9). Preferably the lactic bacteria starter contains lactobacillus bulgaricus, more preferably contains thermophilus.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing fermented milk, and more particularly, to a method for producing fermented milk containing Bulgarian bacteria and Thermophilus bacteria.

  Yogurt is produced by adding lactic acid bacteria starter to raw milk and fermenting it. In the lactic acid bacteria starter, Bulgarian bacteria (Lactobacillus bulgaricus) and Thermophilus bacteria (Streptococcus thermophilus) are often used in combination, and in addition to these, bifidobacteria and the like may be added. In addition, when Bulgarian and Thermophilus are inoculated (added), Thermophilus produces formic acid necessary for the growth of Bulgaria, and Bulgaria produces amino acids and peptides that promote the growth of Thermophilus. These symbiotic actions allow lactic acid fermentation to proceed in a short time.

  Yogurt after fermentation is stored refrigerated, but generally there are lactic acid bacteria that are not highly resistant to low temperatures, as represented by Bulgarian bacteria, so the viable count of lactic acid bacteria decreases during refrigerated storage of yogurt. There is. On the other hand, during refrigerated storage of yogurt, it may be required that the viable count of lactic acid bacteria is difficult to decrease, and various methods for improving the survival rate of lactic acid bacteria have been studied.

  For example, Patent Document 1 describes that by adding oleic acid or a salt thereof or an ester thereof before or after fermentation with lactic acid bacteria, low-fat yogurt with a reduced number of viable bacteria can be produced even after storage. Yes. Patent Document 2 discloses that lactic acid bacteria are cultured in a medium to which guava leaf extract is added in the production stage of fermented foods, thereby improving the growth activity of lactic acid bacteria and maintaining the number of viable bacteria after commercialization. Have been described.

JP 2001-045968 A JP 2011-119305 A

  However, as in Patent Documents 1 and 2, the method of improving the survival rate of lactic acid bacteria by adding a specific raw material that is not used for the production of ordinary fermented milk is specific to the raw material that is actually added. If there is a flavor and physical properties, it is difficult to adjust the flavor and physical properties of the fermented milk, and there is a problem that the manufacturing cost increases by the amount of the raw material actually added.

  Therefore, the present invention provides a method for producing fermented milk that can produce fermented milk with improved survival rate of lactic acid bacteria such as Bulgaria bacteria during refrigerated storage without adding (adding) special raw materials. With the goal.

  The method for producing fermented milk according to the present invention comprises inoculating a raw milk with a lactic acid bacteria starter and fermenting the fermented milk obtained by fermentation at a predetermined fermentation temperature and a predetermined fermentation time at 20 to 30 ° C. for 5 minutes or more. Then, it is cooled to a predetermined refrigeration (storage) temperature.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of fermented milk which can manufacture fermented milk which improved the survival rate of lactic acid bacteria, such as a Bulgarian bacterium during refrigerated storage, can be provided, without adding a special raw material.

The figure which shows an example of the manufacturing method of fermented milk which concerns on embodiment The figure which shows another example of the manufacturing method of fermented milk which concerns on embodiment.

  Drawing 1 is a figure showing an example of a manufacturing method of fermented milk concerning an embodiment. The production method shown in FIG. 1 is a method in which a raw milk inoculated with a lactic acid bacteria starter is filled in a container, sealed, and fermented. Hard (set) type (solid) or plain type fermented milk (yogurt) Suitable for manufacturing.

  First, raw milk (yoghurt mix) is prepared (prepared) by mixing raw materials such as raw milk, skim milk, cream, and water using a tank with a stirring function and a jacket (step S1). In raw milk and skim milk, both of these may be used, or only one of these may be used. Here, skim milk is a form of skim milk itself obtained by separating a cream component (milk fat content) from raw milk, a form of skim milk concentrated by removing water from the skim milk itself, and skim milk itself. And the form of skim milk powder which has been concentrated and dried after removing water. And in skim milk, skim concentrated milk, and skim milk powder, all of these may be used and only some or any of these may be used. In addition, non-fat milk, non-fat concentrated milk and non-fat dry milk, in addition to normal non-fat milk, non-fat concentrated milk and non-fat dry milk, non-fat dry milk, de-salted non-fat concentrated milk and de-fat milk with reduced minerals such as sodium and potassium. You may use salt skim milk powder. In addition, in cream, for example, in order to provide smoothness to fermented milk, it is mix | blended with raw material milk, Compound cream etc. may be used other than fresh cream.

  Next, the raw material milk is homogenized using a homomixer, a homogenizer, or the like (step S2). In this step, the fat globules are finely pulverized and atomized in order to prevent or suppress the separation and levitation of milk fat contained in raw milk and cream, and are dispersed in the raw milk. However, this step may be omitted when raw milk or cream is not blended.

  Next, the raw material milk is heated to a predetermined sterilization temperature by using an indirect heating device, a direct heating device, an electric heating device, or the like, and held for a predetermined sterilization time to sterilize the raw material milk (step S3). Here, if necessary, the raw material milk is heated to a predetermined preheating temperature by using an indirect heating device, a tank, or the like, held for a predetermined preheating time, and then the raw material milk is sterilized. In this step, the pH of the raw milk may be adjusted as necessary before sterilizing the raw milk. And after sterilizing raw material milk, for example, raw material milk is cooled close to fermentation temperature (step S4).

  Next, the raw milk is inoculated with lactic acid bacteria starter and stirred (mixed) (step S5). As the lactic acid bacteria starter, those containing any lactic acid bacteria may be used, but those containing Bulgaria bacteria are preferably used, and those containing Bulgaria bacteria and Thermophilus bacteria are more preferably used. In addition to these lactic acid bacteria, for example, gazelli bacteria, casei bacteria, acidophilus bacteria, bifidobacteria, propionic acid bacteria and the like may be additionally used.

  Next, the raw milk is filled into a container, and the container is sealed with a lid or the like (step S6). Before filling the raw milk into the container, use a tank (batch type) or piping (in-line type) to add the auxiliary ingredients (sugar solution, pulp, vegetables, fruit juice, vegetable juice, sauce, preparation, etc.) You may add (mix) to fermented milk, and when filling raw material milk into a container, you may add an auxiliary material to fermented milk with each container. Thereafter, the raw material milk is fermented at a predetermined fermentation temperature and a predetermined fermentation time using a temperature-controlled room (step S7). Here, depending on the type of lactic acid bacteria starter, the fermentation temperature is, for example, 32-45 ° C, preferably 35-45 ° C, more preferably 37-43 ° C, and even more preferably 40-43 ° C. It is. And in fermentation time, it is 1-36 hours, for example, Preferably it is 1-24 hours, More preferably, it is 2-12 hours, More preferably, it is 2-8 hours, More preferably, it is 3-6 hours More preferably, it is 3 to 4 hours. Further, the acidity (lactic acidity) at the end of fermentation is, for example, 0.6%, preferably 0.65 in the case of raw milk (yogurt mix) having a nonfat milk solid content of 9 to 10% by weight. %, More preferably 0.67%, still more preferably 0.7%, and even more preferably 0.72%.

  After finishing the fermentation, the fermented milk is cooled to 20-30 ° C. using a temperature-controlled room or the like, and held at 20-30 ° C. for 5 minutes or more (step S8). In this step, if the holding temperature of the fermented milk is higher than 30 ° C., the fermentation further proceeds and the acidity becomes high. Therefore, the fermentation temperature is preferably cooled (rapidly cooled) from the fermentation temperature to 30 ° C. or less in a short time. Here, in the retention temperature of fermented milk, it is 20-30 degreeC, for example, Preferably it is 20-28 degreeC, More preferably, it is 20-26 degreeC, More preferably, it is 22-26 degreeC. And in retention time of fermented milk, it is 5 minutes or more, for example, Preferably it is 5 minutes-5 hours, More preferably, it is 10 minutes-5 hours, More preferably, they are 20 minutes-5 hours, More preferably Is 0.5 to 5 hours, more preferably 1 to 5 hours, still more preferably 1.5 to 4 hours, still more preferably 1.5 to 3.5 hours, and still more preferably 1 0.7 to 3.5 hours, and more preferably 1.7 to 3 hours. Then, fermented milk is cooled and stored in a short time to the refrigeration (storage) temperature using a refrigerator room or the like (step S9). Here, in the refrigeration (storage) temperature of fermented milk, it is 1-10 degreeC, for example, Preferably it is 1-8 degreeC, More preferably, it is 3-8 degreeC, It is 3-5 degreeC. In addition, a short time is 1 to 20 minutes, for example, Preferably it is 1 to 15 minutes, More preferably, it is 2 to 10 minutes, More preferably, it is 2 to 5 minutes.

  In addition, after the fermentation is finished, the temperature is lowered to any one of 10 to 25 ° C. lower than the optimum fermentation temperature of each fermented milk using a temperature-controlled room, etc. Any high temperature difference of 10 to 25 ° C. compared to an appropriate fermentation temperature is maintained for 1 minute or more (step S8). Here, in the temperature difference which cools compared with the optimal fermentation temperature of each fermented milk, it is 10-23 degreeC, for example, Preferably it is 10-20 degreeC, More preferably, it is 10-18 degreeC, Furthermore, Preferably it is 10-15 degreeC. And in retention time of fermented milk, it is 5 minutes or more, for example, Preferably it is 5 minutes-5 hours, More preferably, it is 10 minutes-5 hours, More preferably, they are 20 minutes-5 hours, More preferably Is 0.5 to 5 hours, more preferably 1 to 5 hours, still more preferably 1.5 to 4 hours, still more preferably 1.5 to 3.5 hours, and still more preferably 1 0.7 to 3.5 hours, and more preferably 1.7 to 3 hours.

  Drawing 2 is a figure showing other examples of a manufacturing method of fermented milk concerning an embodiment. The production method shown in FIG. 2 is a method in which raw milk inoculated with lactic acid bacteria starter is filled in a tank or the like, sealed and fermented. For the production of soft type (paste-like) or drink type (liquid) fermented milk Is suitable.

  First, raw materials are mixed to prepare raw material milk (step S1), the raw material milk is homogenized (step S2), and then the raw material milk is sterilized (step S3). And after sterilizing raw material milk, for example, after cooling raw material milk to the fermentation temperature vicinity (step S4), a lactic acid bacteria starter is inoculated and stirred (step S5). These steps S1 to S5 are the same as those described in FIG.

  Next, the raw material milk is fermented at a predetermined fermentation temperature and a predetermined fermentation time using a tank or the like (step S6 '). Here, the fermentation temperature, fermentation time, acidity at the end of fermentation, and the like are the same as those described in FIG.

  After the fermentation is completed, the fermented milk is cooled to 20-30 ° C. using an indirect heating device, a tank, etc., and held at 20-30 ° C. (step S7 ′). Here, the retention temperature of fermented milk, the retention time of fermented milk, etc. are the same as what was demonstrated in FIG. Thereafter, the fermented milk is rapidly cooled to the refrigeration temperature by using an indirect heating device or a tank (step S8 '). Here, the refrigeration temperature etc. of fermented milk are the same as what was demonstrated in FIG.

  Next, the fermented milk is filled in a container, and the container is sealed with a lid or the like (step S9 '). Before filling fermented milk into the container, use a tank (batch type) or piping (inline type) etc. to add auxiliary ingredients (sugar solution, pulp, vegetables, fruit juice, vegetable juice, sauce, preparation, etc.) You may add (mix) to fermented milk, and when filling fermented milk into a container, you may add an auxiliary material to fermented milk with each container.

  In a general method for producing fermented milk, when fermentation is completed, the fermented milk is cooled (rapidly cooled) to a refrigerated storage temperature in a short time (rapidly cooled) and stored. On the other hand, in the method for producing fermented milk according to the present invention, the fermented milk is cooled from the fermentation temperature (32 to 45 ° C.) to the intermediate temperature while the fermented milk is cooled to the refrigerated storage temperature after the fermentation is completed. A step (step S8 in FIG. 1 and step S7 ′ in FIG. 2) of cooling to (20 to 30 ° C.) and holding in this temperature range for 5 minutes or more is provided. By providing this step, in the fermented milk produced by the method for producing fermented milk according to the present invention, compared to fermented milk produced by a general method for producing fermented milk, Bulgaria during refrigerated storage (after refrigerated storage) The survival rate of lactic acid bacteria such as bacteria can be improved.

  In the prior art (technical common sense), it is known that at 10 ° C. or less, the activity of lactic acid bacteria decreases and the lactic acid bacteria are difficult to grow. However, the inventors of the present invention, like the method for producing fermented milk according to the present invention, after the fermentation is completed, the fermented milk is heated from the fermentation temperature (32 to 45 ° C.) to the intermediate temperature holding temperature (20 to 30 ° C.). The fermented milk is kept in a temperature range (20 to 30 ° C.) for a time (period) in which the activity of the lactic acid bacteria does not decrease too much, and an appropriate cooling stress (cold shock) is applied to the lactic acid bacteria. ), The low-temperature tolerance of lactic acid bacteria such as Bulgarian bacteria was expressed and improved. Moreover, when the inventors of the present invention rapidly cool from a fermentation temperature (32 to 45 ° C.) to a refrigerated (low temperature) storage temperature (1 to 10 ° C.) as in a general method for producing fermented milk, Bulgarian bacteria and the like It was found that the low-temperature resistance of lactic acid bacteria was not sufficiently expressed or improved. That is, like the manufacturing method of fermented milk which concerns on this invention, after finishing fermentation, fermented milk is cooled from fermentation temperature (32-45 degreeC) to intermediate temperature holding temperature (20-30 degreeC), fermented milk is made. In the temperature range of the medium temperature holding temperature (20-30 ° C.), when holding the lactic acid bacteria for a time (period) that does not decrease too much and giving an appropriate cooling stress to the lactic acid bacteria, It has been found that the survival rate of lactic acid bacteria can be improved.

  In addition, in the method for producing fermented milk according to the present invention, it is not necessary to add (add) special raw materials for the purpose of improving the survival rate of lactic acid bacteria such as Bulgarian bacteria. And the physical properties are not impaired, and the manufacturing cost does not increase (increase) by the amount of the raw material actually added.

  In addition, in the method for producing fermented milk according to the present invention, the survival rate of lactic acid bacteria such as Bulgaria bacteria can be improved, so the number of lactic acid bacteria (viable bacteria number) such as Bulgaria bacteria during refrigerated storage is a predetermined number or more. Can be maintained. In other words, in products such as fermented milk (special health foods, etc.) where the number of lactic acid bacteria such as Bulgarian bacteria is set at the standard value, the number of lactic acid bacteria such as Bulgarian bacteria during refrigerated storage is maintained at a predetermined value or more while maintaining the taste. The deadline can be effectively extended. At this time, in the fermented milk manufactured by the method for manufacturing fermented milk according to the present invention, the extension time of the expiration date (the number of days postponed) is, for example, 2 days, compared to the fermented milk manufactured by a general method for manufacturing fermented milk. It is above, Preferably it is 3 days or more, More preferably, it is 5 days or more, More preferably, it is 7 days or more, More preferably, it is 10 days or more, More preferably, it is 14 days or more.

  In addition, in the method for producing fermented milk according to the present invention, the survival rate of lactic acid bacteria such as Bulgaria bacteria can be improved, so the number of lactic acid bacteria (viable bacteria number) such as Bulgaria bacteria during refrigerated storage is a predetermined number or more. Can be maintained. That is, in products such as fermented milk (food for specified health use) that has established the standard number of lactic acid bacteria such as Bulgarian bacteria, the number of lactic acid bacteria such as Bulgarian bacteria during refrigerated storage is maintained at a predetermined value or more while maintaining the number of lactic acid bacteria. The inoculation amount (addition concentration) of the starter can be effectively reduced, and the manufacturing cost can also be effectively reduced. At this time, in the method for producing fermented milk according to the present invention, compared to a general method for producing fermented milk, the reduction rate (rate of decrease) of the lactic acid bacteria starter inoculation amount is, for example, 10% or more, preferably It is 20% or more, more preferably 30% or more, further preferably 50% or more, further preferably 70% or more, and further preferably 90% or more.

  In the fermented milk produced by the method for producing fermented milk according to the present invention, any of lactic acid bacteria such as Bulgaria bacteria during refrigerated storage (after refrigerated storage) compared to fermented milk produced by a general method for producing fermented milk The survival rate is preferably 1.1 times or more, more preferably 1.2 times or more, still more preferably 1.3 times or more, and still more preferably 1.times. 5 times or more, more preferably 1.8 times or more, and further preferably 2 times or more. Moreover, in the fermented milk manufactured with the manufacturing method of fermented milk which concerns on this invention, compared with fermented milk manufactured with the manufacturing method of general fermented milk, the survival of either lactic acid bacteria, such as a Bulgarian bacterium during refrigerated storage On the 17th day of refrigeration storage, the rate is preferably 1.1 times or more, more preferably 1.2 times or more, still more preferably 1.3 times or more, and further preferably 1.5 times or more. More preferably, it is 1.8 times or more, more preferably 2 times or more. Moreover, in the fermented milk manufactured with the manufacturing method of fermented milk which concerns on this invention, compared with fermented milk manufactured with the manufacturing method of general fermented milk, the survival of either lactic acid bacteria, such as a Bulgarian bacterium during refrigerated storage On the 25th day of refrigerated storage, the rate is preferably 1.1 times or more, more preferably 1.2 times or more, still more preferably 1.3 times or more, and further preferably 1.5 times or more. More preferably, it is 1.8 times or more, more preferably 2 times or more. Moreover, in the fermented milk manufactured with the manufacturing method of fermented milk which concerns on this invention, compared with fermented milk manufactured with the manufacturing method of general fermented milk, the survival of either lactic acid bacteria, such as a Bulgarian bacterium during refrigerated storage On the 35th day of refrigerated storage, the rate is preferably 1.1 times or more, more preferably 1.2 times or more, still more preferably 1.3 times or more, and further preferably 1.5 times or more. More preferably, it is 1.8 times or more, more preferably 2 times or more. The survival rate was calculated as the ratio (%) of the number of lactic acid bacteria after refrigerated storage with respect to the number of lactic acid bacteria on the date of manufacture.

  On the other hand, in the present invention, fermented milk obtained by inoculating raw milk with a lactic acid bacteria starter and fermented at a predetermined fermentation temperature and a predetermined fermentation time is kept at 20 to 30 ° C. for 5 minutes or more, It is also a method for maintaining the number of lactic acid bacteria (viable bacteria number) during refrigerated storage, characterized by cooling to the refrigerated (preserved) temperature. In addition, the present invention holds fermented milk obtained by inoculating raw milk with a lactic acid bacteria starter and fermenting at a predetermined fermentation temperature and a predetermined fermentation time at 20 to 30 ° C. for 5 minutes or more, and then It is also a method for improving the survival rate (survivability) of lactic acid bacteria during refrigerated storage, characterized by cooling to the refrigerated (preserved) temperature. At this time, operation conditions, processing conditions, and the like of the method for producing fermented milk according to the present invention can be appropriately employed. In addition, about fermented milk, the ratio (%) of the number of lactic acid bacteria after refrigerated preservation | save with respect to the number of lactic acid bacteria on the date of manufacture was defined as a survival rate.

  Examples in which the present invention is specifically implemented will be described below.

Example 1
In Example 1, after the fermentation was completed, the fermented milk was held at 25 ° C. (10 to 20 ° C.) for 2 hours (1 hour or more) and then cooled to a refrigerated storage temperature.

  First, raw milk: 500 g, skim milk powder: 49.8 g, fresh cream: 22 g, and water: 398.2 g were mixed to prepare raw milk (yogurt mix). The raw milk was heated (sterilized) at 95 ° C. for 5 minutes and then cooled to 43 ° C. Next, after inoculating 30 g (3% by weight of the total amount of raw milk) of lactic acid bacteria starter (bulk starter separated from Meiji Bulgaria Yogurt LB81 (trade name, Meiji Co., Ltd.)), a plastic cup container (capacity: 100 g) Raw material milk (including lactic acid bacteria starter) was filled and left in a fermentation chamber at 43 ° C. for fermentation. The fermentation was terminated when the lactic acid acidity reached 0.7%.

  After finishing the fermentation, the cup container was bathed in a cold water and cooled to 25 ° C., which is an intermediate temperature holding temperature, in a short time, and then held in a constant temperature room at 25 ° C. for 2 hours. Thereafter, the cup container was bathed in a cold water and cooled to 5 ° C., which is a refrigerated storage temperature, in a short time to produce a set (hard) type (and plain type) fermented milk (yogurt) according to Example 1. And the fermented milk after this manufacture was stored at 5 degreeC using the 5 degreeC refrigerator compartment.

(Comparative Example 1)
In Comparative Example 1, the fermented milk was cooled to the refrigerated storage temperature (at once) after the fermentation was completed.

  Fermented with the same raw material milk and production method as in Example 1. After finishing the fermentation, the cup container is bathed in a cold water and cooled to 5 ° C., which is a refrigerated storage temperature, in a short time, and the set (hard) type (and plain type) fermented milk (yogurt) according to Comparative Example 1 is obtained. Manufactured. And the fermented milk after this manufacture was stored at 5 degreeC using the 5 degreeC refrigerator compartment.

  For fermented milk according to Example 1 and fermented milk according to Comparative Example 1, the number of lactic acid bacteria on the date of manufacture (viable cell count) and the number of lactic acid bacteria after refrigerated storage (stored at 5 ° C.) for 17 days from the date of manufacture did. Moreover, the ratio (%) of the number of lactic acid bacteria after refrigerated storage with respect to the number of lactic acid bacteria on the date of manufacture was calculated as a survival rate.

  Table 1 shows the number of lactic acid bacteria and the survival rate of fermented milk according to Example 1 and Comparative Example 1. In addition, the measured value of the number of lactic acid bacteria shown in Table 1 is an average value of the measured values of three samples, respectively.

When the fermented milk according to Example 1 was stored at 5 ° C. for 17 days using a 5 ° C. refrigerator, the number of Bulgarian bacteria was from 18.7 × 10 ⁷ cfu / g to 5.0 × 10 ^7. After reducing to cfu / g and refrigerated storage for 17 days from the date of manufacture of fermented milk, the survival rate of the Bulgarian bacteria was 26.7%. The number of thermophilus bacteria increased from 25.0 × 10 ⁸ cfu / g to 39.0 × 10 ⁸ cfu / g, and after refrigerated storage for 17 days from the date of production of fermented milk, The survival rate of was 156.0%. Moreover, after refrigerated storage for 17 days from the date of manufacture of fermented milk, the acidity was 0.93%.

On the other hand, when the fermented milk according to Comparative Example 1 was stored at 5 ° C. for 17 days using a 5 ° C. refrigerator, the number of Bulgarian bacteria was from 16.7 × 10 ⁷ cfu / g to 2.2 ×. After decreasing to 10 ⁷ cfu / g and refrigerated for 17 days from the date of manufacture of fermented milk, the survival rate of the Bulgarian bacteria was 13.2%. In addition, the number of thermophilus bacteria increased from 22.7 × 10 ⁸ cfu / g to 42.0 × 10 ⁸ cfu / g, and after refrigerated storage for 17 days from the date of production of fermented milk, The survival rate of was 185.0%. Moreover, after refrigerated storage for 17 days from the date of manufacture of fermented milk, the acidity was 0.86%.

  From the above, when fermented milk is stored in a refrigerator (5 ° C.) for a predetermined period (17 days from the date of manufacture of fermented milk), the fermented milk according to Example 1 is compared with the fermented milk according to Comparative Example 1. As a result, the survival rate of Bulgaria bacteria increased about twice. In addition, in the fermented milk which concerns on Example 1, compared with the fermented milk which concerns on the comparative example 1, the survival rate of the thermophilus bacteria did not increase, but the survival rate of the thermophilus bacteria was a sufficient numerical value. It was.

(Example 2)
In Example 2, after the fermentation was completed, the fermented milk was held at 25 ° C. for 2 hours and then cooled to a refrigerated storage temperature.

  First, raw milk: 500 g, skim milk powder: 49.8 g, fresh cream: 22 g, and water: 398.2 g were mixed to prepare raw milk (yogurt mix). The raw milk was heated (sterilized) at 95 ° C. for 5 minutes and then cooled to 43 ° C. Next, after inoculating 30 g (3% by weight of the total amount of raw milk) of lactic acid bacteria starter (bulk starter separated from Meiji Tokachi Yogurt (trade name, Meiji Co., Ltd.)) into a plastic cup container (capacity: 100 g) Raw milk (including lactic acid bacteria starter) was filled and left to stand in a fermentation chamber at 43 ° C. for fermentation. The fermentation was terminated when the lactic acid acidity reached 0.7%.

  After finishing the fermentation, the cup container was bathed in a cold water and cooled to 25 ° C., which is an intermediate temperature holding temperature, in a short time, and then held in a constant temperature room at 25 ° C. for 2 hours. Thereafter, the cup container was bathed in a cold water and cooled to 5 ° C., which is a refrigerated storage temperature, in a short time to produce a set (hard) type fermented milk (yogurt) according to Example 2. And the fermented milk after this manufacture was stored at 5 degreeC using the 5 degreeC refrigerator compartment.

(Comparative Example 2)
In Comparative Example 2, after the fermentation was completed, the fermented milk was cooled to the refrigerated storage temperature (at once).

  Fermented with the same raw material milk and production method as in Example 2. After the fermentation was completed, the cup container was bathed in a cold water and cooled in a short time to the refrigerated storage temperature of 5 ° C. to produce a set (hard) type fermented milk (yogurt) according to Comparative Example 2. And the fermented milk after this manufacture was stored at 5 degreeC using the 5 degreeC refrigerator compartment.

  For the fermented milk according to Example 2 and the fermented milk according to Comparative Example 2, the number of lactic acid bacteria on the date of manufacture (viable cell count), and the number of lactic acid bacteria after refrigerated storage (stored at 5 ° C.) for 16 days from the date of manufacture, The number of lactic acid bacteria after refrigerated storage (stored at 5 ° C.) for 25 days from the date of manufacture and the number of lactic acid bacteria after refrigerated storage (stored at 5 ° C.) for 35 days from the date of manufacture were measured. Moreover, the ratio (%) of the number of lactic acid bacteria after refrigerated storage with respect to the number of lactic acid bacteria on the date of manufacture was calculated as a survival rate.

  Table 2 shows the number of lactic acid bacteria and the survival rate of fermented milk according to Example 2 and Comparative Example 2. In addition, the measured value of the number of lactic acid bacteria shown in Table 2 is an average value of the measured values of two samples, respectively.

When the fermented milk according to Example 2 was stored at 5 ° C. for 16 days using a 5 ° C. refrigerator, the number of Bulgarian bacteria was from 15.5 × 10 ⁷ cfu / g to 16.0 × 10 ^7. After increasing to cfu / g and refrigerated for 16 days from the date of manufacture of fermented milk, the survival rate of the Bulgarian bacteria was 103.2%. In addition, after refrigerated storage for 16 days from the date of production of fermented milk, the number of thermophilus bacteria decreased from 12.6 × 10 ⁸ cfu / g to 9.8 × 10 ⁸ cfu / g, and thermophilus bacteria The survival rate of was 77.8%.

And when the fermented milk which concerns on Example 2 was stored in 5 degreeC and 25 days using a 5 degreeC refrigerator compartment, the bacterial count of a Bulgarian bacterium is 11.5 * 10 < ⁷ > cfu / g, Fermented milk After refrigerated storage for 25 days from the date of manufacture, the survival rate of the Bulgarian bacteria was 74.2%. The number of thermophilus bacteria is 11.6 × 10 ⁸ cfu / g, and after refrigerated storage for 25 days from the date of manufacture of fermented milk, the survival rate of thermophilus bacteria is 92.1%. there were.

And when the fermented milk which concerns on Example 2 was stored in 5 degreeC and 35 days using a 5 degreeC refrigerator compartment, the bacteria count of a Bulgarian bacterium is 9.0x10 < ⁷ > cfu / g, Fermented milk After refrigerated storage for 35 days from the date of manufacture, the survival rate of the Bulgarian bacteria was 58.1%. The number of thermophilus bacteria is 9.2 × 10 ⁸ cfu / g. After refrigerated storage for 35 days from the date of production of fermented milk, the survival rate of thermophilus bacteria is 73.0%. there were.

On the other hand, when the fermented milk according to Comparative Example 2 was stored at 5 ° C. for 16 days using a 5 ° C. refrigerator, the number of Bulgarian bacteria was from 11.5 × 10 ⁷ cfu / g to 4.5 ×. After reducing to 10 ⁷ cfu / g and refrigerated storage for 16 days from the date of production of fermented milk, the survival rate of Bulgaria bacteria was 39.1%. The number of thermophilus bacteria increased from 11.8 × 10 ⁸ cfu / g to 12.0 × 10 ⁸ cfu / g, and after refrigerated storage for 16 days from the date of production of fermented milk, The survival rate of was 101.7%.

And when the fermented milk which concerns on the comparative example 2 was stored in 5 degreeC and 25 days using the 5 degreeC refrigerator compartment, the bacterial count of a Bulgarian bacterium is 4.0x10 < ⁷ > cfu / g, Fermented milk After refrigerated storage for 25 days from the date of manufacture, the survival rate of the Bulgarian bacteria was 34.8%. The number of thermophilus bacteria is 9.2 × 10 ⁸ cfu / g. After refrigerated storage for 25 days from the date of production of fermented milk, the survival rate of thermophilus bacteria is 78.0%. there were.

And when the fermented milk which concerns on the comparative example 2 was stored in 5 degreeC and 35 days using a 5 degreeC refrigerator compartment, the number of bacteria of a Bulgarian bacterium is 3.5x10 < ⁷ > cfu / g, Fermented milk After refrigerated storage for 35 days from the date of manufacture, the survival rate of the Bulgarian bacteria was 30.4%. The number of thermophilus bacteria is 8.0 × 10 ⁸ cfu / g. After refrigerated storage for 35 days from the date of production of fermented milk, the survival rate of thermophilus bacteria is 67.8%. there were.

  From the above, when the fermented milk is stored in a refrigerator (5 ° C.) for a predetermined period (16 days, 25 days and 35 days from the date of manufacture of the fermented milk), the fermented milk according to Example 2 is comparative example 2. As compared with fermented milk according to, the survival rate of each Bulgarian bacterium increased 2.6 times (16 days), 2.1 times (25 days) and 1.9 times (35 days). Moreover, in the fermented milk which concerns on Example 2, compared with the fermented milk which concerns on the comparative example 2, while the survival rate of each thermophilus microbe decreased to 0.8 time (16 days), 1.2 times (25 days) and 1.1 times (35 days). In addition, in the fermented milk which concerns on Example 2, compared with the fermented milk which concerns on the comparative example 2, the survival rate of the thermophilus bacteria did not necessarily increase, but the survival rate of each thermophilus bacteria is enough. It was a numerical value.

(Example 3)
In Example 3, after the fermentation was completed, the fermented milk was held at 25 ° C. for 2 hours and then cooled to a refrigerated storage temperature.

  First, raw milk: 500 g, skim milk powder: 49.8 g, fresh cream: 22 g, and water: 398.2 g were mixed to prepare raw milk (yogurt mix). The raw milk was heated (sterilized) at 95 ° C. for 5 minutes and then cooled to 43 ° C. Next, after inoculating 30 g (3% by weight of the total of raw milk) of lactic acid bacteria starter (bulk starter separated from Meiji Probio Yogurt R-1 (trade name, Meiji Co., Ltd.)), a plastic cup container (capacity: 100 g) was filled with raw material milk (including lactic acid bacteria starter) and allowed to stand in a fermentation chamber at 43 ° C. for fermentation. The fermentation was terminated when the lactic acid acidity reached 0.7%.

  After finishing the fermentation, the cup container was bathed in a cold water and cooled to 25 ° C., which is an intermediate temperature holding temperature, in a short time, and then held in a constant temperature room at 25 ° C. for 2 hours. Thereafter, the cup container was bathed in a cold water and cooled to 5 ° C., which is a refrigerated storage temperature, in a short time to produce a set (hard) type fermented milk (yogurt) according to Example 3. And the fermented milk after this manufacture was stored at 5 degreeC using the 5 degreeC refrigerator compartment.

(Comparative Example 3)
In Comparative Example 3, the fermented milk was cooled to the refrigerated storage temperature (at once) after the fermentation was completed.

  Fermented with the same raw material milk and production method as in Example 3. After the fermentation was completed, the cup container was bathed in a cold water and cooled in a short time to the refrigerated storage temperature of 5 ° C. to produce a set (hard) type fermented milk (yogurt) according to Comparative Example 3. And the fermented milk after this manufacture was stored at 5 degreeC using the 5 degreeC refrigerator compartment.

  For fermented milk according to Example 3 and fermented milk according to Comparative Example 3, the number of lactic acid bacteria on the date of manufacture (viable count), and the number of lactic acid bacteria after refrigerated storage (stored at 5 ° C.) for 16 days from the date of manufacture, The number of lactic acid bacteria after refrigerated storage (stored at 5 ° C.) for 25 days from the date of manufacture and the number of lactic acid bacteria after refrigerated storage (stored at 5 ° C.) for 35 days from the date of manufacture were measured. Moreover, the ratio (%) of the number of lactic acid bacteria after refrigerated storage with respect to the number of lactic acid bacteria on the date of manufacture was calculated as a survival rate.

  Table 3 shows the number of lactic acid bacteria and the survival rate of fermented milk according to Example 3 and Comparative Example 3. In addition, the measured value of the number of lactic acid bacteria shown in Table 3 is an average value of the measured values of two samples, respectively.

When the fermented milk according to Example 3 was stored at 5 ° C. for 16 days using a 5 ° C. refrigerator, the number of Bulgarian bacteria was 12.2 × 10 ⁷ cfu / g to 13.7 × 10 ^7. After increasing to cfu / g and refrigerated storage for 16 days from the date of manufacture of fermented milk, the survival rate of the Bulgarian bacteria was 112.3%. In addition, after refrigerated storage for 16 days from the date of production of fermented milk, the number of thermophilus bacteria decreased from 8.9 × 10 ⁸ cfu / g to 9.9 × 10 ⁸ cfu / g, and thermophilus bacteria The survival rate of was 111.2%.

And when the fermented milk which concerns on Example 3 was stored in 5 degreeC and 25 days using a 5 degreeC refrigerator compartment, the number of bacteria of Bulgaria bacteria is 7.9x10 < ⁷ > cfu / g, Fermented milk After refrigerated storage for 25 days from the date of manufacture, the survival rate of the Bulgarian bacteria was 64.8%. The number of thermophilus bacteria is 9.6 × 10 ⁸ cfu / g. After refrigerated storage for 25 days from the date of production of fermented milk, the survival rate of thermophilus bacteria is 107.9%. there were.

And when the fermented milk which concerns on Example 3 was stored in 5 degreeC and 35 days using a 5 degreeC refrigerator compartment, the bacterial count of a Bulgarian bacterium is 2.3x10 < ⁷ > cfu / g, Fermented milk After refrigerated storage for 35 days from the date of manufacture, the survival rate of the Bulgarian bacteria was 18.9%. The number of thermophilus bacteria is 5.8 × 10 ⁸ cfu / g, and after refrigerated storage for 35 days from the date of production of fermented milk, the survival rate of thermophilus bacteria is 65.2%. there were.

On the other hand, when the fermented milk according to Comparative Example 3 was stored at 5 ° C. for 16 days using a refrigerator at 5 ° C., the number of Bulgarian bacteria was from 14.7 × 10 ⁷ cfu / g to 0.3 ×. After decreasing to 10 ⁷ cfu / g and refrigerated for 16 days from the date of production of fermented milk, the survival rate of Bulgaria bacteria was 2.0%. The number of thermophilus bacteria increased from 10.2 × 10 ⁸ cfu / g to 8.2 × 10 ⁸ cfu / g, and after refrigerated storage for 16 days from the date of production of fermented milk, The survival rate was 80.4%.
It was.

And when the fermented milk which concerns on the comparative example 3 was stored in 5 degreeC and 25 days using the 5 degreeC refrigerator compartment, the number of bacteria of Bulgaria was less than 10 ⁷ cfu / g. The number of thermophilus bacteria is 8.9 × 10 ⁸ cfu / g, and after refrigerated storage for 25 days from the date of production of fermented milk, the survival rate of thermophilus bacteria is 87.3%. there were.

And when the fermented milk which concerns on the comparative example 3 was stored in 5 degreeC and 35 days using the 5 degreeC refrigerator compartment, the number of bacteria of Bulgaria was less than 10 ⁷ cfu / g. The number of thermophilus bacteria is 4.6 × 10 ⁸ cfu / g. After refrigerated storage for 35 days from the date of production of fermented milk, the survival rate of thermophilus bacteria is 45.1%. there were.

  From the above, when the fermented milk is stored in a refrigerator (5 ° C.) for a predetermined period (16 days, 25 days and 35 days from the date of manufacture of the fermented milk), the fermented milk according to Example 3 is comparative example 3 The survival rate of each Bulgarian bacterium increased more than 55 times compared with the fermented milk according to. Moreover, in the fermented milk which concerns on Example 3, compared with the fermented milk which concerns on the comparative example 3, the survival rate of each thermophilus bacteria is 1.3 times (16 days), 1.2 times (25 days) and Increased 1.4 times (35 days).

  From the results of Examples 1 to 3 and Comparative Examples 1 to 3, after the fermentation was completed, the fermented milk was cooled to 20 to 30 ° C., held for 1 hour or more, and then cooled to the refrigerated storage temperature. It was confirmed that the survival rate of Bulgarian bacteria and Thermophilus bacteria during refrigerated storage can be significantly improved regardless of the species of Bulgarian bacteria and Thermophilus bacteria contained in the lactic acid bacteria starter.

  INDUSTRIAL APPLICABILITY The present invention can be used in a method for producing fermented milk in which the number of surviving lactic acid bacteria such as Bulgaria bacteria during refrigerated storage is improved.

Claims (3)

  A fermented milk obtained by inoculating a raw milk with a lactic acid bacteria starter and fermenting the milk is kept at 20 to 30 ° C. for 5 minutes or more and then cooled to 1 to 10 ° C. .   The method for producing fermented milk according to claim 1, wherein the lactic acid bacteria starter contains Bulgaria bacteria.   The method for producing fermented milk according to claim 1 or 2, wherein the lactic acid bacteria starter contains Thermophilus bacteria.

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