JP4759643B2 - Fermented milk production method and fermented milk - Google Patents

Description

  The present invention is a fermented milk having a smooth texture and a mellow flavor with reduced acidity and cream cheese-like body compared to conventional fermented milk, and having a structure that does not collapse in the distribution stage The fermented milk obtained by this manufacturing method and its manufacturing method is provided.

  Fermented milk is made by fermenting milk or milk containing non-fat milk solids equal to or higher than this with lactic acid bacteria or yeast, and making it pasty or liquid, or by freezing it, roughly divided into two types it can. One is a pre-fermentation type and the other is a post-fermentation type. The former is a crushed fermented milk that has been fermented and cooled in a tank before it is packed in a container, and then packed into a single food container for distribution. In the latter case, a fermented milk material mix (hereinafter referred to as a mix) with a certain amount of starter added is packed into a distribution container such as a paper container, and then fermented in a fermentation room until a predetermined degree of lactic acidity is reached. After solidifying, it is cooled. Pre-fermentation is often used for the production of fruit yogurt with pulp and drink yogurt, and post-fermentation is often used for the production of so-called hard type or plain type yogurt.

  In both types of fermentation, the fermentation process is performed by adding a starter to the sterilized mix at a predetermined temperature until fermentation reaches a predetermined acidity, and cooling to stop the fermentation. In this case, the fermentation temperature and fermentation time not only affect the production efficiency of the product but also greatly affect the flavor and quality of the product. is there. For example, to give a mild flavor to the product, the fermentation temperature is lowered.

  The problem here is that, for example, if the fermentation temperature is lowered in order to give the product a mellow flavor, the fermentation time until reaching a predetermined acidity will be greatly extended, and the hardness of the tissue will be The problem is that the production efficiency and the product quality before and after the distribution, such as only having a low hardness that will collapse in the distribution process. Therefore, it has been difficult to obtain fermented milk that has a mellow flavor and does not collapse during the distribution process without extending the fermentation time.

  As a means for solving the above problem, the present inventors have already performed normal fermentation time without extending the fermentation time by reducing the dissolved oxygen concentration in the fermented milk mix to 5 ppm or less even when fermentation is performed at a lower temperature than usual. It was found that a new fermented milk that has the necessary acidity, has a smooth texture and a mellow flavor, and has a firm structure that does not collapse in the distribution stage can be obtained. Has played a solution. (Patent Document 1)

  The method of Patent Document 1 realizes a new fermented milk having both a smooth texture and a mellow flavor that has not been heretofore, and also having a firm structure, and is very useful. However, since there is a restriction that the fermentation process is performed at a temperature lower than usual, whether or not similar fermented milk can be obtained by other methods with less restrictions has been left as a problem.

  As in the present application, there is a preceding example in which deoxygenation treatment is performed on fermented milk to which peroxidase (hereinafter referred to as POD) is added as fermented milk obtained by combining deoxygenation treatment. (Patent Document 2) In the present invention, when POD is added to a fermented milk mix for the purpose of suppressing whey separation, POD softens the structure of the fermented milk. Content that fermented milk having a structure equivalent to that of normal fermented milk without POD was obtained by preventing the tissue from being softened when fermented under a reduced oxygen concentration. It has something.

  That is, Patent Document 2 carries out fermentation after setting the dissolved oxygen concentration in the fermented milk mix containing POD to 10 ppm or less by nitrogen substitution or the like for the purpose of preventing the hardness reduction of the fermented milk tissue caused by the addition of POD. The method of obtaining fermented milk having a fermented milk tissue of normal hardness is disclosed, and has a smooth texture and a mellow flavor of the product of the present invention, and a structure of a hardness that does not collapse in the distribution process It was not disclosed how to obtain fermented milk. In addition, as for the description about the fermentation temperature, only a temperature suitable for the growth of lactic acid bacteria is mentioned, and there is no mention about the relationship between the fermentation temperature and the deoxygenation treatment that has a great influence on the physical properties of the fermented milk disclosed in Patent Document 1. I did not give any suggestion.

International Publication WO2004 / 049812 Japanese Patent Laid-Open No. 10-099019

  The present invention removes the restriction on the production process of performing fermentation under a temperature condition lower than usual in order to obtain a fermented milk having a smooth texture and a mellow flavor, and is fermented under various conditions, particularly normal temperature conditions. It was accomplished for the purpose of providing a method for obtaining fermented milk that has a smooth texture and a mild flavor even when it is applied, and has a structure with a hardness that does not collapse during the distribution process.

  As a result of intensive studies to solve the above problems, the present inventors have tried using the fermented milk starter added to the mix at the start of fermentation with a greatly reduced amount of the dissolved oxygen in the mix. When fermentation is performed near normal temperature with reduced concentration, the target lactic acid acidity is reached within normal fermentation time or shorter than normal fermentation time, even though the amount of starter used is significantly low It has been found that fermented milk having good physical properties having a smooth texture and a mellow flavor similar to those obtained in Patent Document 1 and having a structure with a hardness that does not collapse in the distribution process is obtained after fermentation is completed. It was.

  At this time, if it is added without reducing the amount of starter used and fermented at normal temperature with the dissolved oxygen concentration lowered, only normal fermented milk can be obtained and fermented milk with mellow physical properties. It was confirmed again that it is not possible to obtain.

  Furthermore, in addition to reducing the amount of starter added, the amount of the previous starter was reduced when it was used as a starter of normal addition amount after reducing the activity related to the fermentation power of the starter by applying some load to the starter. Similarly to the case, even when fermentation is performed near the normal temperature in a state where the dissolved oxygen concentration in the fermented milk mix is reduced, the target lactic acid acidity is reached near the normal time, and the fermentation is completed. It was found that fermented milk having good physical properties similar to those obtained was obtained.

  In addition, after adding a starter to the raw material mix, after performing a treatment or treatment that reduces the fermentative power of lactic acid bacteria in the fermented milk mix, the fermentation is performed near normal temperature with the dissolved oxygen concentration reduced in the mix However, it was found that the desired lactic acid acidity was reached in the vicinity of normal time and fermentation was completed, and fermented milk having good physical properties similar to those obtained in Patent Document 1 was obtained.

  As a result of considering matters common to the results of the above three cases, the present inventors are in a state in which the lactic acid bacteria in the fermented milk mix are adjusted and / or adjusted so that the induction period of fermentation becomes longer. In this state, the fermentation was performed by reducing the dissolved oxygen concentration in the mix, and when the dissolved oxygen concentration was reduced, in any case at least around the normal fermentation time without extending the fermentation time. I realized that the fermentation was over.

That is, the present invention is a method for producing a hard type or plain type yogurt,
(1) (a) Refrigerated storage, freezing treatment or freeze-drying treatment without adjusting immediately after adjusting the starter, or
(B) a step of reducing the fermentation power of the starter and extending the induction period of fermentation by storing it in a refrigerator after adding the starter to the mix;
and,
(2) before adding the starter and / or after adding the starter, the step of reducing the dissolved oxygen concentration in the mix in which the dissolved oxygen concentration exceeds 5 ppm to 5 ppm or less,
Starter, Lactobacillus bulgaricus (L. bulgaricus), Ri Streptococcus thermophilus (S. thermophilus) and Der least one member selected from Lactobacillus group consisting Bacillus lactis (L. lactis),
The fermentation temperature is 41 ° C to 47 ° C.
It relates to the manufacturing method.
Furthermore, this invention relates to the said manufacturing method whose said (1) (a) is a 7-21 day preservation | save at 5 degreeC after adjusting a starter.
In addition, the present invention provides (1) (a) wherein the starter added to the mix has a fermenting power of 100% when the lactic acid acidity exhibited by the product when the above (1) and (2) are not performed. It is related with the said manufacturing method which is reducing so that acidity may be set to 85 to 50%.
Further, in the present invention, (1) and (b) indicate the fermenting power of the fermented milk mix after adding the starter in the mix, and the lactic acid acidity indicated by the product when the above (1) and (2) are not performed. It is related with the said manufacturing method which is making it reduce so that the lactic acid acidity when setting it as% may be 85% to 50%.
Or the invention, hard type or plain type yogurt is a hardness measured by the card meter 100g load at a measurement temperature of 5 to 10 ° C. or more 40 g, and intrusion angle of yogurt knife 40 degrees or less It is related with the said manufacturing method.

  As described above, in the present invention, the lactic acid bacteria in the fermented milk mix are given a “condition for extending the induction period of fermentation” by some method, and then the “dissolved oxygen concentration in the fermented milk mix is set to 5 ppm or less. When the `` reducing method '' is combined, the fermentation reaches the target degree of lactic acid acid in a normal fermentation time or in a time shorter than the normal fermentation time without actually extending the fermentation induction period, and as a result, Fermented milk with a smooth texture and a mild flavor with reduced acidity and cream cheese-like body compared to conventional fermented milk, and a firm structure that does not collapse in the distribution stage is obtained. Is disclosed. This method has an advantage that, for example, fermented milk having the above-mentioned physical properties that can only be obtained when fermentation is performed at a low temperature can be produced at a normal fermentation temperature. That is, the method of the present invention has an effect that it is possible to provide fermented milk having excellent physical properties by a method capable of selecting production conditions having a relatively high degree of freedom in accordance with factory facilities and production processes.

FIG. 1 is a diagram showing a method of reading an intrusion angle and hardness from a chart paper measured using a card meter. FIG. 2 is a diagram showing the examination results of the relationship between the dissolved oxygen concentration in the mix and the fermentability of the lactic acid bacteria starter. FIG. 3 is a view showing the examination result of the relationship between the addition rate of lactic acid bacteria starter (A + B) and fermentability. FIG. 4 is a diagram showing the results of studying fermentability when using a lactic acid bacteria starter (C + B) and a lactic acid bacteria starter (D + B).

  Hereinafter, the present invention will be described in detail. Lactic acid bacteria starter inoculated into the mix according to the present invention is generally used for the production of fermented milk in addition to L. bulgaricus, Streptococcus thermophilus, L. lactis. In the present invention, Lactobacillus bulgari standardized as a yogurt starter in the Codex standard can be used. A starter based on a mixed starter of cas (L. bulgaricus) and Streptococcus thermophilus (S. thermophilus) can be preferably used. Based on this yogurt starter, after considering the fermentation temperature and fermentation conditions of the target fermented milk, add other lactic acid bacteria such as Lactobacillus gasseri and Bifidobacterium Also good.

In the case of the present application, the addition amount of the starter in the case where the fermentation is performed up to a state where the fermentation temperature is 43 ° C. and the lactic acid acidity is 0.7% after 3 hours of fermentation is set as the normal addition amount. When the fermenting power of the starter indicated by is used as normal fermenting power, it is necessary to use the starter previously selected as follows.
1) Reduce the amount of starter added from 50% to 25% of the normal amount and add it to the raw mix. 50% is a threshold for the maximum amount of use, and the product of the present invention can be obtained in general. Further, 25% is a threshold for the minimum usage amount, and in some cases, fermented milk is insufficient as a product of the present invention in terms of firmness. Therefore, the preferable amount of starter added is usually 45% to 30%, more preferably 40% to 35% of the amount used.
2) A normal addition amount is added to the raw material mix using a fermenter whose fermenting power of the starter is reduced from 85% to 50% of the normal fermenting power in advance. The 85% in this case is fermented to the extent that the lactic acid acidity of 0.6% is 0.6 / 0.7 = 85% under the same conditions when the lactic acid acidity of 0.7% indicated by a normal starter is 100%. Indicates that a starter with reduced power is used.
Although the evaluation of 3) or the starter becomes complicated, a method of appropriately combining the methods 1) and 2) is also possible.

The following method can be performed as a specific method for reducing the fermentation power of the starter. For example, after preparing a starter, the fermentability can be reduced by refrigerated storage for about one week without immediately using it (Table 3). Alternatively, a starter with reduced fermentative power can be obtained by a treatment such as a freezing treatment or a freeze-drying treatment. Further, as a similar treatment, a fermented milk mix after adding a starter can be refrigerated and the fermenting power reduced in a fermented milk mix state.
Even when the fermenting power is reduced by any of the above methods, the fermenting power of a starter or the like can be confirmed by comparison with the previous normal fermentation conditions using the degree of lactic acid as an index.

  Among the methods for extending the induction period of fermentation, the method of extending the induction period by subtracting the starter addition from the normal addition is the simplest, making it easy to check the quality and manage the process. Since it has the advantage that the amount used can be greatly reduced, it can be said that the method can be carried out more suitably.

The raw material mix used in the present invention is a stabilizer that warms and dissolves raw materials commonly used in the production of fermented milk, such as milk, skim milk, skim milk powder, cream, and other raw materials such as sugar, sugar, fragrance, and water. Can be obtained by adding and mixing gelatin solution, agar solution, pectin, etc. that have been heated and dissolved in advance.

  In the case of the present invention, it is possible to obtain a firm structure that does not cause problems during transportation without the addition of a stabilizer or the like. In general, it is more preferable not to add a stabilizer such as gelatin because it greatly affects the product characteristics of the product. In other words, the method of the present invention is a method that can be used more suitably in the case of seeking commerciality as plain yogurt or commerciality such as 100% raw milk.

  The raw material mix obtained above is homogenized, sterilized, and then cooled to a predetermined temperature (fermentation temperature). Next, inoculate with a lactic acid bacteria starter that has been pre-reduced or reduced in activity, and in the case of pre-fermentation after stirring, fill in the tank and start the fermentation. Start fermentation.

  As a method for reducing the dissolved oxygen concentration in the mix, a method by gas replacement treatment with an inert gas, a membrane separation method using a deoxygenation membrane, or the like can be used. Among the above, the method by inert gas replacement can be performed even after the starter is added, and there are relatively few restrictions on the process. Hereinafter, although the method by inert gas substitution is described, the substitution treatment may be performed from the stage of preparing the raw material mix to the start of fermentation after inoculation with the lactic acid bacteria starter, and the substitution time in the production process is arbitrary. However, since it is important that the dissolved oxygen concentration is maintained at the start of fermentation, it is desirable that the inert gas replacement of the mix be performed immediately before and after inoculation with the lactic acid bacteria starter. However, when fermenting power is intentionally reduced as a fermented milk mix, it is necessary to preserve the fermented milk mix, so it is desirable to perform an inert gas replacement process before adjusting to the fermentation temperature after the process.

  As for the dissolved oxygen concentration of the mix at the start of the fermentation, a better result is obtained as the concentration is lower in the previous studies. However, the concentration giving a practically useful result is 5 ppm or less, preferably 3 ppm or less when the temperature of the mix is about 40 ° C. as shown in FIG. These results are almost the same when the temperature of the mix is around 45 ° C.

  Nitrogen gas, argon gas, helium gas, or the like can be used as an inert gas when replacing inert gas as a method for reducing the dissolved oxygen concentration. Among them, nitrogen gas is not commonly used in foods. It can be used more suitably as an active gas. As a method for replacing dissolved oxygen with an inert gas, a known method such as a method of directly bubbling these inert gases into the mix, a method using a static mixer, or a gas mixed into the mixer together with the mix is used. be able to.

  When a membrane separation method is performed as a method for reducing the dissolved oxygen concentration, a hollow fiber membrane (such as Mitsubishi Rayon MHF304KM) can be used as a deoxygenation membrane. The method of use may be used with reference to the method of use of the membrane, and is more suitably used when applied to the mix before the starter is added to reduce the dissolved oxygen concentration.

  In the case of the method of the present invention, even when fermentation is performed using a normal fermentation temperature, a smooth food that has been thought to be obtained only by fermentation at a low temperature without using any stabilizer. A fermented milk having a good physical property value which has a feeling and further satisfies both mellowness and firmness can be obtained. Specifically, good fermented milk can be obtained even when the fermentation temperature is 41 ° C to 47 ° C, preferably 42 ° C to 45 ° C, more preferably 43 ° C to 44 ° C.

  In the case of the method of the present invention, the mechanism that can be obtained even when fermented milk having good physical properties that has been realized only by low-temperature fermentation conventionally is fermented at normal temperature is unknown. However, the state of the fermented milk mix to which the starter has been added is adjusted and / or adjusted so that the induction period of fermentation is longer than that of normal fermentation, and then, before the starter is added and / or after the starter is added. When the fermentation is carried out by reducing the dissolved oxygen concentration to 5 ppm or less, preferably 3 ppm or less by substitution with an inert gas, etc., the target lactic acid acidity is reached in a time comparable to or shorter than that of normal fermentation. It is clear that this phenomenon contributes to the realization of good physical properties.

  Conventionally, it has been recognized that fermentation at a low temperature is essential even when a production method for reducing dissolved oxygen in fermented milk is performed when it is desired to give a fermented milk product a finer and milder flavor than a normal product. However, at the start of fermentation, the present inventors adjusted and / or adjusted so that the induction period of fermentation becomes longer by some method, and combined with a method for reducing dissolved oxygen in the mix, the normal fermentation temperature It was found that even when fermented in, fermented milk having a smooth texture and a mellow flavor with reduced acidity and a hardness structure that does not collapse in the distribution stage can be obtained. is there.

  As a method of adjusting and / or adjusting so that the induction period of fermentation becomes longer, a method of reducing the starter addition amount to 1/2 or less of the normal use amount, etc. was presented, but other methods not presented here Needless to say, any method can be used in the present invention as long as the induction period of fermentation is prolonged.

  The mellowness and tissue hardness of the fermented milk of the present invention can be expressed by the following values measured according to the measurement manual of Neo Card Meter M302 (I Techno Engineering: Former Iio Electric). That is, the “mellowness” of fermented milk in the method of the present invention can be evaluated by measuring the penetration angle of a yogurt knife when a weight of 100 g is applied at 5 ° C. to 10 ° C. Specifically, based on the measurement curve represented by the bold line shown in FIG. 1, the tangent line (tangent line 1) passing through the origin and toward the break point, and the tangent line (tangent line 2) passing through the break point and along the penetration direction of the yogurt knife. Then, the angle (angle A) with the intersection of two tangents as the base point is measured, and this is defined as the penetration angle. When this angle is close to 90 °, it can be evaluated as fermented milk having a rough texture, and as the angle is smaller, it can be evaluated as fermented milk having a smooth and smooth texture.

  “Hardness” in the method of the present invention is defined as “hardness” which is the length B of the straight line connecting the intersection of tangent line 1 and tangent line 2 in FIG.

  Hereinafter, the contents of the present invention will be described in more detail with reference to test examples, but the present invention is not limited to these test examples.

(Test Example 1) Relationship between dissolved oxygen concentration in the mix at the start of fermentation and increase in lactic acid acidity
A mix prepared by mixing 78.2 kg of milk, 2.6 kg of skim milk powder, and 17.2 kg of water was prepared, sterilized by heating at 95 ° C. for 5 minutes, then cooled to around 40 ° C., and lactic acid bacteria starter (A And B) was inoculated at 2% by weight. Nitrogen gas was mixed and dispersed in this mix through a pipe, and the dissolved oxygen concentration was adjusted to 7, 6, 5, 4, 3, 2 ppm.
Next, the mix adjusted to each dissolved oxygen concentration is filled into a 100 ml container, and is left to stand in a fermentation room at around 40 ° C., and when the lactic acid acidity reaches around 0.7%, it is placed in a refrigerator at 10 ° C. or less. The cooling and fermentation were stopped. For comparison, a fermented product without adjusting the dissolved oxygen concentration was used. In this case, the dissolved oxygen concentration of the mix at the stage of inoculating the lactic acid bacteria starter (without nitrogen substitution treatment) was 8 ppm.
The lactic acid acidity was calculated by titrating with 0.1 N NaOH and using phenolphthalein as an indicator.

  The results of changes in lactic acid acidity during fermentation in Test Example 1 are shown in FIG. It can be seen from FIG. 2 that the lower the dissolved oxygen concentration in the pre-fermentation mix, the faster the lactic acid acidity rises, and as a result, the time to reach the target lactic acid acidity is shortened. The shortening effect is noticeable when the dissolved oxygen concentration is 5 ppm or less, and when it is 3 ppm or less, the difference from the case where the dissolved oxygen in the mix is not reduced (8 ppm) becomes clearer. Therefore, it can be judged that the dissolved oxygen concentration in the fermentation mix effective for shortening the fermentation time is 5 ppm or less, preferably 3 ppm or less.

(Test Example 2) Examination of relationship between addition amount of starter and progress of fermentation After preparing a mix in which 78.2 kg of milk, 2.6 kg of skim milk powder, and 17.2 kg of water were prepared, the mixture was sterilized by heating at 95 ° C. for 5 minutes. The mixture was cooled to around 43 ° C. and inoculated with lactic acid bacteria starter (lactic acid bacteria A and lactic acid bacteria B) 2.0 (data not shown), 1.5, 1.0, 0.8, and 0.5% by weight. Nitrogen gas was mixed and dispersed in this mix through a pipe to adjust the dissolved oxygen concentration to 5 ppm or less. Fill this in a 100 ml container, leave it in a fermentation chamber at 43 ° C, leave it in a refrigerator at 10 ° C or lower when the lactic acid acidity reaches around 0.7%, and cool and stop fermentation to produce fermented milk did. Moreover, according to patent document 1 as a control, dissolved oxygen concentration was adjusted to 5 ppm or less, and what inoculated 2.0 weight% of lactic acid bacteria starters (lactic acid bacteria A and lactic acid bacteria B) was also prepared. Fill this into a 100 ml container, leave it in a 37 ° C fermentation room, and place it in a refrigerator at 10 ° C or lower when the lactic acid acidity reaches around 0.7%, and cool and stop fermentation to produce fermented milk did.

  Table 1 shows comparison data of physical property values of fermented milk produced by reducing the starter addition amount obtained above and fermented milk produced according to Patent Document 1. Further, FIG. 3 shows the relationship between the change in lactic acid acidity and the fermentation time in this case.

  From the results of Test Example 2, the physical properties of fermented milk fermented at 43 ° C. after inoculating 1.0, 0.8, 0.5 wt% of lactic acid bacteria starter, deoxygenating dissolved oxygen to 5 ppm or less are as follows: It was confirmed that the fermented milk had the same value as the patented product, had a smooth texture even when not fermented at a low temperature, and had a hardness capable of maintaining the structure in the distribution stage.

  Table 2 shows the results of sensory evaluation of the fermented milk of the present invention method and the fermented milk of the prior patent application method by a three-point identification test using a special panel.

  As a result of sensory evaluation, there is no difference in sensory evaluation between the product of the present invention and the prior patented product, fermented milk obtained not only at low temperature fermentation temperature zone but also at normal fermentation temperature in terms of sensory evaluation as well as physical properties Nevertheless, it was confirmed that fermented milk equivalent to the fermented milk obtained in Patent Document 1 can be obtained.

(Test Example 3) Examination using a lactic acid bacteria starter with reduced fermenting power Instead of reducing the amount of starter added, fermented milk was produced in the same manner as in Test Example 2 using a starter with reduced fermenting power and the presence or absence of the effect. Study was carried out. In this case, after the mix used in Test Example 2 was sterilized by heating and cooled to around 43 ° C., the fermenting power was reduced to 76%, and the lactic acid bacteria starter (mixed culture of lactic acid bacteria A and lactic acid bacteria B was refrigerated to reduce the fermenting power. 2.0% by weight inoculation). Thereafter, deoxygenation treatment was performed by nitrogen substitution, the dissolved oxygen concentration was adjusted to 5 ppm or less, and fermentation was performed at 43 ° C. In addition, according to Patent Document 1, as a control, a dissolved oxygen concentration was adjusted to 5 ppm or less, and a lactic acid bacteria starter (lactic acid bacteria A and lactic acid bacteria B) having a normal fermentation ability was inoculated with 2.0% by weight. 2. Fermentation was carried out in the same manner.

  The comparison data of the physical property values for the fermented milk obtained above and the fermented milk of Patent Document 1 are shown in Table 1, and the sensory evaluation results are shown in Table 2.

  As a result, fermented milk fermented at 43 ° C after inoculating 2.0% by weight of lactic acid bacteria starter (lactic acid bacteria A and lactic acid bacteria B) whose fermentability was reduced to 76%, deoxygenated to 5 ppm or less of dissolved oxygen The physical property values of these were the same as the fermented milk of Patent Document 1, and the sensory evaluation results were also confirmed to be equivalent to the fermented milk of Patent Document 1. Moreover, also when fermenting power as fermented milk mix was reduced, the result similar to Test Example 3 was given (data not shown).

  For the above reference, Table 3 shows the evaluation results of the starter activity value when the activity was lowered by refrigerated storage of the starter.

(Test Example 4) Examination of fermentation temperature (41 ° C., 47 ° C., 49 ° C.) The mix used in Test Example 2 was sterilized by heating and then cooled to 41 ° C., 47 ° C., and around 49 ° C., respectively, and then lactic acid bacteria starter (Lactic acid bacteria A and Inoculated with 0.8% by weight of a mixed culture of lactic acid bacteria B). After the dissolved oxygen concentration is reduced to 3 ppm or less by nitrogen substitution treatment, it is left to stand in a fermentation chamber at each temperature, and when the lactic acid acidity reaches around 0.7%, it is placed in a refrigerator at 10 ° C. or lower for cooling and fermentation. Stopped to produce fermented milk. In addition, according to Patent Document 1, as a control, a dissolved oxygen concentration was adjusted to 3 ppm or less, and a normal vital lactic acid bacteria starter (mixed culture of lactic acid bacteria A and lactic acid bacteria B) was inoculated with 2.0% by weight. . Fill this into a 100 ml container, leave it in a 37 ° C fermentation room, and place it in a refrigerator at 10 ° C or lower when the lactic acid acidity reaches around 0.7%, and cool and stop fermentation to produce fermented milk did.

  Table 1 shows comparison data of physical property values of the fermented milk produced by the method of the present invention and the fermented milk produced by the method of Patent Document 1.

  As a result of measuring physical properties, the physical property values of fermented milk fermented at 41 ° C. and 47 ° C. showed values equivalent to those of fermented milk produced by the method of Patent Document 1. However, the fermented milk fermented at 49 ° C. became a very hard tissue, and the mellowness was lost, resulting in a fermented milk with a texture that was crisp. The fermentation at around 48 ° C., which was examined separately, had a problem with reproducibility (data not shown).

  In addition, Table 2 shows the results of sensory evaluation of the above fermented milk fermented at 41 ° C. by a three-point identification test using a specialized panel.

  From the above results, according to the method of the present invention, it was confirmed that the same fermented milk as in Patent Document 1 can be obtained even when a fermentation temperature of 41 ° C. to 47 ° C. is used.

(Test Example 5) Examination using a starter different from Test Examples 1, 2, and 3 A mix prepared by mixing 78.2 kg of milk, 2.6 kg of skim milk powder, and 17.2 kg of water was prepared and heated at 95 ° C. for 5 minutes. After sterilization, the mixture was cooled to around 43 ° C. and inoculated with 1.2% by weight of lactic acid bacteria starter (lactic acid bacteria C and lactic acid bacteria B). The mixed culture of lactic acid bacteria C and lactic acid bacteria B has a slower fermentation rate than the mixed culture of lactic acid bacteria A and lactic acid bacteria B. Therefore, in order to reach a predetermined lactic acid acidity in the same fermentation time, 1.5 cm in normal fermentation is required. Doubler (3%) starter addition is required. Nitrogen gas was mixed and dispersed in this mix through a pipe to adjust the dissolved oxygen concentration to 5 ppm or less. Fill this in a 100 ml container, leave it in a fermentation chamber at 43 ° C, leave it in a refrigerator at 10 ° C or lower when the lactic acid acidity reaches around 0.7%, and cool and stop fermentation to produce fermented milk did. Further, as a control, in accordance with Patent Document 1, the dissolved oxygen concentration was adjusted to 5 ppm or less, and a lactic acid bacteria starter (lactic acid bacteria A and lactic acid bacteria B) was inoculated with 2.0% by weight. Fill this into a 100 ml container, leave it in a 37 ° C fermentation room, and place it in a refrigerator at 10 ° C or lower when the lactic acid acidity reaches around 0.7%, and cool and stop fermentation to produce fermented milk did.
In addition, the same production was performed by inoculating a starter addition concentration of 0.8% by weight using a combination of lactic acid bacteria D and lactic acid bacteria B.

  Table 1 shows comparison data of physical property values of the fermented milk of the present invention and the fermented milk of Patent Document 1 manufactured as described above.

As a result of measuring physical properties, the hardness of the method of the present invention is 47 g and the penetration angle is 37 degrees, and the hardness according to the prior patent method is 55 g and the penetration angle is 31 degrees. Thus, it was confirmed that it had the same hardness as that of the previous patented product and had a hardness that could maintain the structure in the distribution stage. Also, it was confirmed that the actual flavor was as precise and smooth as the patented product.
Similar results were obtained when other lactic acid bacteria starters (lactic acid bacteria D and lactic acid bacteria B) were used (Table 1). FIG. 4 shows the relationship between the change in lactic acid acidity and the fermentation time when the above two types of starters are used.

Claims (5)

A method for producing a hard type or plain type yogurt,
(1) (a) Refrigerated storage, freezing treatment or freeze-drying treatment without adjusting immediately after adjusting the starter, or
(B) a step of reducing the fermentation power of the starter and extending the induction period of fermentation by storing it in a refrigerator after adding the starter to the mix;
and,
(2) before adding the starter and / or after adding the starter, the step of reducing the dissolved oxygen concentration in the mix in which the dissolved oxygen concentration exceeds 5 ppm to 5 ppm or less,
Starter, Lactobacillus bulgaricus (L. bulgaricus), Ri Streptococcus thermophilus (S. thermophilus) and Der least one member selected from Lactobacillus group consisting Bacillus lactis (L. lactis),
The fermentation temperature is 41 ° C to 47 ° C.
The manufacturing method.   The manufacturing method according to claim 1, wherein (1) and (a) are stored for 7 to 21 days at 5 ° C. after adjusting the starter.   The fermenting power of the starter (1) (a) added to the mix is from 85% lactic acid acidity when the lactic acid acidity indicated by the product when not performing (1) and (2) is 100%. The manufacturing method according to claim 1, wherein the manufacturing method is to reduce the amount to 50%.   (1) (b), when adding the starter to the mix, the fermenting power of the fermented milk mix when the lactic acid acidity indicated by the product when not performing (1) and (2) is 100% The production method according to claim 1, wherein the lactic acid acidity is reduced from 85% to 50%. The hard type or plain type yogurt has a hardness measured by a card meter with a load of 100 g at a measurement temperature of 5 to 10 ° C. of 40 g or more, and a penetration angle of the yogurt knife is 40 degrees or less. 5. The production method according to any one of 4 above.

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