SG182379A1 - Method for producing fermented milk, and dairy product - Google Patents
Method for producing fermented milk, and dairy product Download PDFInfo
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- SG182379A1 SG182379A1 SG2012049805A SG2012049805A SG182379A1 SG 182379 A1 SG182379 A1 SG 182379A1 SG 2012049805 A SG2012049805 A SG 2012049805A SG 2012049805 A SG2012049805 A SG 2012049805A SG 182379 A1 SG182379 A1 SG 182379A1
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- SG
- Singapore
- Prior art keywords
- fermented milk
- fermentation
- dairy product
- lactic acid
- acid bacteria
- Prior art date
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 28
- 235000021001 fermented dairy product Nutrition 0.000 title description 60
- 235000014048 cultured milk product Nutrition 0.000 title description 14
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims abstract description 174
- 235000015140 cultured milk Nutrition 0.000 claims abstract description 147
- 238000000855 fermentation Methods 0.000 claims abstract description 127
- 230000004151 fermentation Effects 0.000 claims abstract description 122
- 239000004310 lactic acid Substances 0.000 claims abstract description 87
- 235000014655 lactic acid Nutrition 0.000 claims abstract description 87
- 235000013365 dairy product Nutrition 0.000 claims abstract description 47
- 241000894006 Bacteria Species 0.000 claims description 76
- 235000013618 yogurt Nutrition 0.000 claims description 49
- 239000002994 raw material Substances 0.000 claims description 31
- 235000008924 yoghurt drink Nutrition 0.000 claims description 23
- 235000013960 Lactobacillus bulgaricus Nutrition 0.000 claims description 9
- 235000013361 beverage Nutrition 0.000 claims description 9
- 229940004208 lactobacillus bulgaricus Drugs 0.000 claims description 9
- 241000194020 Streptococcus thermophilus Species 0.000 claims description 8
- 230000014759 maintenance of location Effects 0.000 claims description 3
- 241000186672 Lactobacillus delbrueckii subsp. bulgaricus Species 0.000 claims 1
- 238000003860 storage Methods 0.000 abstract description 20
- 230000008859 change Effects 0.000 abstract description 13
- 238000010438 heat treatment Methods 0.000 abstract description 11
- 239000007858 starting material Substances 0.000 abstract description 8
- 239000000654 additive Substances 0.000 abstract description 5
- 230000000996 additive effect Effects 0.000 abstract description 5
- 239000000796 flavoring agent Substances 0.000 abstract description 4
- 241001478240 Coccus Species 0.000 abstract description 2
- 235000019634 flavors Nutrition 0.000 abstract 2
- 241000193830 Bacillus <bacterium> Species 0.000 abstract 1
- 230000002123 temporal effect Effects 0.000 abstract 1
- 239000000047 product Substances 0.000 description 36
- 230000000052 comparative effect Effects 0.000 description 17
- 238000000034 method Methods 0.000 description 15
- 235000013336 milk Nutrition 0.000 description 13
- 239000008267 milk Substances 0.000 description 13
- 210000004080 milk Anatomy 0.000 description 13
- 238000002360 preparation method Methods 0.000 description 13
- 239000007788 liquid Substances 0.000 description 12
- 239000007787 solid Substances 0.000 description 12
- 238000011156 evaluation Methods 0.000 description 11
- 239000000203 mixture Substances 0.000 description 11
- 238000002156 mixing Methods 0.000 description 10
- 239000000843 powder Substances 0.000 description 10
- 235000020183 skimmed milk Nutrition 0.000 description 10
- 235000013861 fat-free Nutrition 0.000 description 9
- 244000199885 Lactobacillus bulgaricus Species 0.000 description 8
- 230000001953 sensory effect Effects 0.000 description 8
- 235000003599 food sweetener Nutrition 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 239000003765 sweetening agent Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 6
- 230000001954 sterilising effect Effects 0.000 description 6
- 238000004659 sterilization and disinfection Methods 0.000 description 6
- 239000008399 tap water Substances 0.000 description 6
- 235000020679 tap water Nutrition 0.000 description 6
- 229920001661 Chitosan Polymers 0.000 description 5
- 235000013399 edible fruits Nutrition 0.000 description 5
- 238000009928 pasteurization Methods 0.000 description 5
- 235000008939 whole milk Nutrition 0.000 description 5
- 206010013911 Dysgeusia Diseases 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 230000001771 impaired effect Effects 0.000 description 4
- 239000013067 intermediate product Substances 0.000 description 4
- 244000005700 microbiome Species 0.000 description 4
- 240000004808 Saccharomyces cerevisiae Species 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000005862 Whey Substances 0.000 description 3
- 102000007544 Whey Proteins Human genes 0.000 description 3
- 108010046377 Whey Proteins Proteins 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000001814 pectin Substances 0.000 description 3
- 229920001277 pectin Polymers 0.000 description 3
- 235000010987 pectin Nutrition 0.000 description 3
- KJFMBFZCATUALV-UHFFFAOYSA-N phenolphthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2C(=O)O1 KJFMBFZCATUALV-UHFFFAOYSA-N 0.000 description 3
- 235000020185 raw untreated milk Nutrition 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 235000013373 food additive Nutrition 0.000 description 2
- 239000002778 food additive Substances 0.000 description 2
- 235000012041 food component Nutrition 0.000 description 2
- 235000013355 food flavoring agent Nutrition 0.000 description 2
- 239000005417 food ingredient Substances 0.000 description 2
- 235000015203 fruit juice Nutrition 0.000 description 2
- 235000019534 high fructose corn syrup Nutrition 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 235000015067 sauces Nutrition 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229920001817 Agar Polymers 0.000 description 1
- 241000186000 Bifidobacterium Species 0.000 description 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 1
- 108010010803 Gelatin Proteins 0.000 description 1
- 244000068988 Glycine max Species 0.000 description 1
- 235000010469 Glycine max Nutrition 0.000 description 1
- 241001147746 Lactobacillus delbrueckii subsp. lactis Species 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000008272 agar Substances 0.000 description 1
- 235000020244 animal milk Nutrition 0.000 description 1
- 230000001580 bacterial effect Effects 0.000 description 1
- 235000014121 butter Nutrition 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 235000013351 cheese Nutrition 0.000 description 1
- 230000001332 colony forming effect Effects 0.000 description 1
- 235000020186 condensed milk Nutrition 0.000 description 1
- 235000020247 cow milk Nutrition 0.000 description 1
- 239000006071 cream Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000012470 diluted sample Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 235000003086 food stabiliser Nutrition 0.000 description 1
- 239000008273 gelatin Substances 0.000 description 1
- 229920000159 gelatin Polymers 0.000 description 1
- 235000019322 gelatine Nutrition 0.000 description 1
- 235000011852 gelatine desserts Nutrition 0.000 description 1
- 150000004676 glycans Chemical class 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 235000019629 palatability Nutrition 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 235000011837 pasties Nutrition 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 239000011782 vitamin Substances 0.000 description 1
- 229940088594 vitamin Drugs 0.000 description 1
- 229930003231 vitamin Natural products 0.000 description 1
- 235000013343 vitamin Nutrition 0.000 description 1
- 150000003722 vitamin derivatives Chemical class 0.000 description 1
- 235000020125 yoghurt-based beverage Nutrition 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
- A23C9/00—Milk preparations; Milk powder or milk powder preparations
- A23C9/12—Fermented milk preparations; Treatment using microorganisms or enzymes
- A23C9/123—Fermented milk preparations; Treatment using microorganisms or enzymes using only microorganisms of the genus lactobacteriaceae; Yoghurt
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Dairy Products (AREA)
Abstract
Provided is a method for producing a fermented milk in which a temporal increase in acidity and decrease in pH are prevented and thus which can sustain an appropriate flavor (for example, sourness) and keep good qualities over a long period of time without requiring any troublesome operation such as post-fermentation heating or addition of an additive. By adding a lactic acid bacillus and a lactic acid coccus to a starting material of a fermented milk and then conducting fermentation at 44-55°C, the fermentation temperature being higher than the optimum temperature in the conventional fermentation processes, the acidity of a dairy product containing the fermented milk can be maintained at an appropriate level during refrigerated storage, compared with a case wherein fermentation is conducted at the conventional optimum temperature. Thus, a change in the flavor of a fermented milk, which is caused by the excessively strong acidity of the fermented milk, can be prevented.
Description
METHOD FOR PRODUCING FERMENTED MILK, AND DAIRY PRODUCT
[0001] The present invention relates to a method for producing fermented milk which can improve taste and quality of fermented milk simply and efficiently, and more particularly, to a method for producing fermented milk which can suppress changes in acidity and pH during refrigerated storage of a fermented milk-containing dairy product such as pre-fermentation type drinkable yogurt, soft stirred type yogurt, and the like.
[0002] According to "Ministerial Ordinance Regarding
Compositional Standards, etc. of Milk and Dairy Products", fermented milk is defined as a product obtained by subjectingmilk or processed milk containing solid non-fat in an amount not less than that of milk to fermentation with a lactic acid bacterium or yeast to form a paste or a liquid, or a frozen product thereof. The fermented milk isbroadlyclassifiedinto: (a) hard yogurt (i.e. solid fermented milk or set type yogurt) obtained mainly by filling its material into a container, and then fermenting and solidifying the material in the container; (b) soft stirred type yogurt (i.e. pasty fermented milk) obtained by fermentation in a large tank or the like, the subsequent curd pulverization, and optional mixing with fruit pulp,
sauce or the like, followed by filling the obtained mixture into a container; and (c) drinkable yogurt (i.e. liquid fermented milk) obtained by fine crushing of hard yogurt or soft stirred type yogurt with a homogenizer or the like to enhance properties as a liquid, optionalmixingwith fruit pulp, sauce or the like, and the subsequent filling into a container.
[0003] According to the compositional standards of fermented milk defined in Japan, the ratio of solid non-fat (i.e. milk solid non-fat) in fermented milk should be 8% or more, and the number of lactic acid bacteria or yeast per ml should be 10,000,000 or more. Further, according to the international standards of yogurt definedby the Food and Agriculture Organizationof theUnitedNations (FAQ) /World Health Organization (WHO), a coagulated dairy product obtained by subjecting milk or a dairy product to lactic acid fermentation through actions of Lactobacillus bulgaricus and
Streptococcus thermophilus is defined as "yogurt".
[0004] The fermented milk such as yogurt contains viable cells of lactic acid bacteria. Hence, when the fermented milk is stored for a long period of time, there arises a problem in that an increase in acidity and a decrease in pH with time occur owing to lactic acid and the like to be generated by the lactic acid bacteria, and changes in taste and quality occur as compared to those immediately afterproduction. Inordertoalleviatetheproblem, variousmethods have been proposed up to now.
[0005] As an example of such methods, there is a proposal concerning a method for producing yogurt containing viable lactic acidbacteriumcells, comprisinga stepof adding lacticacidbacteria to a yogurt material composition to control a fermentation degree of milk in the composition to a desired degree, a step of leaving the resultant to stand at a low temperature, a step of heating the lactic acid bacteria under such temperature and time conditions that the temperature is equal to or higher than the limit temperature on high temperature side for growth arrest and that complete killing is not achieved, and a step of cooling the resultant (see Patent
Reference 1 described below). In this method for producing yogurt, when the lactic acid bacteria are Lactobacillus bulgaricus, the limit temperature on high temperature side for growth arrest is 50 to 55°C, and the conditions for complete killing are, for example, 63°C for 30 minutes.
As another example of such methods, there is a proposal concerning fermented milk containing chitosan which can suppress an increase in acidity (see Patent Reference 2 described below).
List of Patent References
[0006] [Patent Reference 1] JP 850-6745 A [Patent Reference 2] JP H03-292853 A
Problems to be solved by the invention
[0007] The method of Patent Reference 1 includes a step of treating the lactic acid bacteria under particular heating conditions with regard to temperature and time after a step for fermentation. This method has the following problems. The adjustment of heating conditions is complicated. Also, thermal energy for heating is required excessively. Furthermore, the taste of yogurt may deteriorate under the conditions that the heating temperature is high.
In the method of Patent Reference 2, chitosan is used as an additive for fermented milk. In the conventional art, chitosan is not contained in fermented milk generally. The method of Patent
Reference 2 has the following problems. The addition of chitosan degrades marketability. Also, the taste of fermented milk may be changed by the taste of chitosan.
[0008] The object of thepresent inventionis toprovide amethod for producing fermented milk which does not require any complicated operations such as heating, use of an additive after fermentation, and the like, and which can suppress an increase in acidity and a decrease in pH with time, keep appropriate taste (e.g. sourness) over a long period of time, and maintain satisfactory quality.
Means for Solving the Problems
[0009] The inventors of the present invention have made intensive studies in order to solve the aforementioned problems, and have found that by adding rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria to a raw material of fermented milk and carrying out fermentation at a higher temperature (e.g. 44 to 49°C) than the conventional optimum temperature (i.e. approximately 38 to 43°C) for a fermentation step, an increase in acidity and a decrease in pH in a fermented milk-containing product during refrigerated storage can be suppressed with substantially no increase in fermentation time as compared to the case of carrying out fermentation at the conventional optimum temperature. The inventorshave also found that inthecaseof carryingout fermentation at the fermentation temperature of the present invention (e.g. 44 to 46°C), there is substantially no change in viable cell counts (i.e. the number of viable cells) of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria as compared to the case of carrying out fermentation at the conventional optimum temperature, and thus a commercial value in the market as a fermented milk-containing dairy product is not impaired. The inventors have also found that in the case of carrying out fermentation at the fermentation temperature of the present invention (e.g. 44 to 50°C), the taste and properties (i.e. quality) of a fermented milk-containing dairy product are maintained at equivalent levels as compared to the case of carrying out fermentation at the conventional optimum temperature, and thus a commercial value in the market is not impaired. Thus, the present invention has been completed.
[0010] That is, the present invention provides the following items (1) to (8). (1) A methed for producing fermented milk, comprising a fermentation step of adding rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria to a raw material of fermented milk and carrying out fermentation at a fermentation temperature of from 44 to 55°C to yield fermented milk. (2) The method for producing fermented milk according to the above-mentioned item (1), in which the fermentation temperature is 44 to 49°C. (3) The method for producing fermented milk according to the above-mentioned item (1) or (2), in which a retention time of the fermentation temperature is 2 to 24 hours. (4) The method for producing fermented milk according to any one of the above-mentioned items (1) to (3), in which the rod-shaped lactic acid bacteria are Lactobacillus bulgaricus and the coccus-shaped lactic acid bacteria are Streptococcus thermophilus. (5) A dairy product, including the fermented milk produced by the method for producing fermented milk according to any one of the above-mentioned items (1) to (4). (6) The dairy product according to the above-mentioned item {5}, in which the dairy product is one selected from a drinkable yogurt (i.e. a yogurt drink) , a soft stirred type yogurt, a lactic acid bacteria beverage (i.e. a lactic fermented milk drink), and a set type yogurt. (7) The dairy product according to the above-mentioned item (5)
or (6), in which when the dairy product is stored at a temperature of 10°C for 25days fromthe completion of preparing the dairy product, the amount of increase in acidity (%) of the dairy product is 0.25% or less. (8) The dairy product according to any one of the above-mentioned items (5) to (7), in which when the dairy product is stored at a temperature of 10°C for 25 days from the completion of preparing the dairy product, the amount of decrease in pH of the dairy product is 0.28 or less.
[0011] The term of "raw material of fermented milk" to be used in the present inventionmeans a liquid containingamilk constituent such as raw milk, whole milk, skim milk, whey, and the like. The examples of the raw milk include animal milk such as cow's milk.
Examples of the components which may constitute the raw material of fermented milk include raw milk, whole milk, skim milk, whey, and other processed products thereof (e.g. whole milk powder, condensed whole milk, skim milk powder, condensed skim milk, condensed milk, whey powder, cream, butter, cheese, and the like).
In the case that a solid raw material such as whole milk powder is used, a liquid raw material of fermented milk may be prepared by adding a liquid such as water.
It should be noted that the raw material of fermented milk may be one generally called "yogurt mix" or the like, andmay contain, in addition to the milk constituent, for example, a food ingredient or a food additive such as sugar, a saccharide, a sweetener, a flavoring agent, fruit juice, fruit pulp, a vitamin, a mineral, or the like. Further, a stabilizer such as pectin, a soybean polysaccharide, carboxymethylcellulose {CMC), agar, gelatin or the like may be contained in the raw material of fermented milk as necessary.
[0012] The term of "fermented milk" in the present invention means (a) post-fermentation type yogurt such as set type yogurt {e.g. plain yogurt, hard yogurt, and the like}, or (b) one which is an intermediate product after the completion (i.e. end) of the fermentationstepandbeforetheadditionofanauxiliaryrawmaterial tobe added after the fermentation step, and which is an intermediate product during the production {in other words, a product in the course of production other than a finished product) of a soft stirred type yogurt, a drinkable yogurt, or a lactic acid bacteria beverage.
Also, "fermented milk" in the present invention contains a milk censtituent, and does not have a limitation on the ratio of solid non-fat and the viable cell count. That is, the "fermented mitk" in the present invention is not limited Lo one containing 8% by weight or more of solid non-fat (narrowly-defined "fermented milk" defined by Ministerial Ordinance Regarding Compositional
Standards, etc. ofMilkandDairy Products in Japan), andencompasses, for example, one containing at least 3% and less than 8% by weight of solid non-fat (narrowly-defined "dairy product" defined by
Ministerial Ordinance Regarding Compositional Standards, etc. of
Milk and Dairy Products in Japan) and one containing less than 3%
by weight of solid non-fat. Further, the "fermented milk" in the present invention is not limited to one in which the number of lactic acid bacteria per ml is 10,000,000 or more {narrowly-defined "fermented milk" defined by Ministerial Ordinance Regarding
Compositional Standards, etc. of Milk and Dairy Products in Japan}, and encompasses one in which the number of lactic acid bacteria per ml is less than 10,000,000.
The examples of "fermented dairy product" include pre-fermentation type yogurt such as soft stirred type yogurt, drinkable yogurt, and the like, and a lactic acid bacteria beverage, which are prepared by mixing an auxiliary raw material such as a sugar solution and the like with fermentedmilk (e.g. an intermediate product during theproductionof soft stirred type yogurt ordrinkable yogurt) obtained by the method of the present invention. The auxiliaryrawmaterialmaycontain the food ingredient, food additive, stabilizer, or the like to be blended as necessary, which are exemplified in the explanation of the "raw material for fermented milk" described above.
Each of "dairy product" and "fermented dairy product™ as used herein is not limited to one containing 3% by weight or more of solid non-fat (narrowly-defined "dairy products" defined by
Ministerial Ordinance Regarding Compositional Standards, etc. of
Milk and Dairy Products in Japan), and encompass one containing less than 3% by weight of solid non-fat. "Dairy product" as used herein is a finished product (i.e.
a final product) and encompasses a set type yogurt, a soft stirred type yogurt, a drinkable yogurt, anda lactic acidbacteriabeverage.
The term of "finished product" means a product ready to be eaten or drunk by a consumer. The term of "finished product" means fermented milk in the case of post-fermentation type yogurt (i.e. set type yogurt), and means a fermented dairy product in the case of soft stirred type yogurt, drinkable yogurt, and a lactic acid bacteria beverage.
[0013] The term of "acidity" as used herein means a value measuredby "5Method formeasuringacidityofmilkanddairyproducts™ described on page 56 in "Laws and Ordinances Regarding Milk" (Association of Dairy Companies for Hygiene, which is "Nyugyo Dantail
Eisei Renraku Kycgikai" in Japanese; March 2004}.
The details of this method are as follows. 10 ml of water free of carbon oxide gas is added to 10 ml of a sample to dilute the sample, and 0.5 ml of a phenolphthalein solution is added to the diluted sample as an indicator. The resultant is titrated with a 0.1 mol/L sodium hydroxide solution until the faint pink color persists for 30 seconds. Based on the titration amount, the percentage amount of lactic acid per 100 gof the sample is determined andusedas thevalueofacidity. 1mlofthe0.lmol/Lsodiumhydroxide solution corresponds to 9 mg of lactic acid. The indicator is preparedby dissolving 1 g of phenolphthalein in 50% ethanol solution and adjusting the volume to 100 ml.
[0014] According to the present invention, by adding rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria to a raw material of fermented milk and carrying out fermentation at a higher temperature (e.g. 44 to 47°C) than the conventional optimum temperature (about 38 to 43°C) for a fermentation step, an increase in acidity with time in a fermented milk-containing product (i.e. a fermented milk or a fermented dairy product) during refrigerated storage can be suppressed to keep the acidity at an appropriate level as compared to the case of carrying out fermentation at the conventional optimum temperature. Thus, the deterioration in taste of fermented milk due to the excessively strong sourness of the fermented milk can be avoided. In addition, for example, the best-before date of about 14 days in the case of adding rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria to a raw material for fermented milk and carrying out fermentation at the conventional optimum temperature can be extended to about 20 to 30 days by carrying out fermentation at the fermentation temperature of the present invention.
[0015] Further, according to the present invention, in spite of adding rod-shaped lactic acid bacteria and coccus-shaped lactic acld bacteria to a raw material for fermented milk and carrying out fermentation at a higher temperature (e.g. 44 to 46°C) than the conventional optimum temperature (about 38 to 43°C) for a fermentation step, there is substantially no change in viable cell counts of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria as compared to the case of carrying out fermentation at the conventional optimum temperature, and viable cell counts of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria required for fermented milk can be ensured. Thus, a commercial value in the market as a fermented milk-containing dairy product is not impaired.
In addition, in the case of carrying out fermentation at the fermentation temperature of the present invention (e.g. 44 to 50°C), the taste and properties (i.e. quality) of a fermented milk-containing dairy product as a finished product are maintained at equivalent levels as compared to the case of carrying out fermentation at the conventional optimum temperature, and thus a commercial value in the market as a finished product is not impaired.
[0016] That is, according to the present invention, it is possible to provide the method for producing a fermented milk which does not require any complicated operation such as heating, use of an additive, and the like after a fermentation step and which can suppress an increase in acidity and a decrease in pH with time, keep appropriate taste over a long period of time, and maintain satisfactory quality.
Embodiments for Carrying Out the Invention
[0017] A method for producing a fermented milk according to the present invention includes a fermentation step including adding rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria to a raw material of the fermented milk and carrying out fermentation at a fermentation temperature of from 44 to 55°C to yield the fermented milk.
In the present invention, the fermentation temperature is set to a higher value (i.e. 44 to 55°C) than the conventional optimum temperature {about 38 to 43°C). Hence, it is possible to suppress an increase in acidity and a decrease in pH in a fermented milk or a fermented dairy product containing the fermented milk. In the present invention, it seems that the vitality (i.e. activity) or cell count of microorganisms such as lactic acid bacteria, bifidobacteria and the like, or various components contained in a raw material of the fermented milk are affected by carrying out fermentation at the high temperature (i.e. 44 to 55°C), and as a result, for example, an increase in acidity during refrigerated storage can be suppressed.
The fermentation temperature in the present invention is a temperature that the lactic acid bacteria in fermented milk are not killed, and is 44 to 55°C, preferably 44 to 50°C, more preferably 44 to 49°C, even more preferably 44 to 48°C, even more preferably 44 to 47°C, even more preferably 45 to 47°C, even more preferably 45 to 46.5°C, most preferably 45 to 46°C.
Further, in the present invention, the difference between the fermentation temperature cf the present invention and the upper limit value (i.e. 43°C) of the conventional optimum temperature range (i.e. 38 to 43°C) is preferably 1 to 15°C, more preferably 2 to 12°C, even more preferably 2 to 10°C, even more preferably 2 to 8°C, even more preferably 2 to 7°C, even more preferably 2 to 6°C, even more preferably 2 to 5°C, most preferably 2 to 4°C.
In the present invention, the retention time of the fermentation temperature is preferably 2 to 24 hours, more preferably 3 to 12 hours, even more preferably 3.5 to 8 hours, most preferably 4 to 6 hours from the viewpoint of providing a fermented milk satisfactory in taste and properties efficiently.
[0018] Through the adoption of the fermentation conditions as described above, microorganisms in fermented milk (e.g. rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria) are not killed to ensure the viable cell counts required for fermented milk similarly to the case of carrying out fermentation at the conventional optimum temperature, and the taste and properties {i.e. quality) of a fermented milk or a fermented dairy product can be maintained at equivalent levels as compared to the case of carrying out fermentation at the conventional optimum temperature. It should be noted that in the case of the commercial-scale (in other words, mass) production of fermented milk, it is difficult to control the fermentation temperature under exactly the same condition, andhence it is recommended to set a fermentation condition on the assumption of upward and downward changes by about 1 to 2°C from a temperature to be set actually.
[0019] Next, lactic acid bacteria for being added and mixed as a starter in a raw material of fermented milk are described.
Examples of the rod-shaped lactic acid bacteria to be used in the present invention include Lactobacillus bulgaricus and
Lactobacillus lactis.
Examples of the coccus-shaped lactic acid bacteria to be used in the present invention include Streptococcus thermophilus. :
In the present invention, in addition to the rod-shaped lactic acid bacteria and the coccus-shaped lactic acid bacteria, other microorganisms may also be used. Examples of the other microorganisms include yeast.
A preferred combination of the rod-shaped lactic acid bacteria and the coccus~shaped lactic acid bacteria to be used in the present invention is ,for example, the combination of Lactobacillus bulgaricus as the rod-shaped lactic acid bacteria and Streptococcus thermophilus as the coccus-shaped lactic acid bacteria. This combination is preferably used in the present invention, because this combination gives distinctive richness and freshness to yogurt tomake the consumers to have high preference, and the yogurt obtained by using the combination is approved as "yogurt" in the international standards. That is, from the viewpoint of sufficiently exhibiting the effect of the present invention, it is desired to use at least
Lactobacillus bulgaricus as the rod-shaped lactic acid bacteria and use at least Streptococcus thermophilus as the coccus-shaped lactic acid bacteria. It should be noted that in the present invention, it is not necessary to use amutant strain having specific properties as the rod-shaped lactic acid bacteria or coccus-shaped lactic acid bacteria, and a bacterial strain for general use may be used.
[0020] The fermented milk to be obtained in the present inventionmaybe used for the production of a fermented dairy product.
In this case, examples of the fermented dairy product include drinkable yogurt, soft stirred type yogurt, anda lacticacidbacteria beverage.
In the present invention, among forms of a fermentedmilk (i.e. set type yogurt) and a fermented milk product (i.e. a drinkable yogurt, a soft stirred type vogurt, and a lactic acid bacteria beverage) as finishedproducts, ingeneral, thedegreeof aninfluence by a sensory change in sourness (i.e. taste) due to an increase in acidity and a decrease in pH during refrigerated storage is the largest in liquid form such as drinkable yogurt (i.e. pre—-fermentation type) and the lactic acid bacterium beverage, is the second largest in paste form such as soft stirred type yogurt (i.e. pre-fermentation type), and is relatively small in solid form such as set type yogurt (i.e. post-fermentation type). That is, although the effectof thepresent inventioncanbe certainlyobtained regardless of the forms of the finished products, the effect of the present invention is more remarkable in the case of the pre-fermentation type such as drinkable yogurt and soft stirred type yogurt which are liable to be affected by a change in sourness.
Further, the effect of the present invention is most remarkable in the case of drinkable yogurt which is particularly liable to be affected by the surrounding environment because of its liquid form. Furthermore, the effect of the present invention can be expected to be obtained similarly in a yogurt-based beverage containing lactic acid bacteria (e.g. viable cells) such as a lactic acid bacteria beverage, which is not classified as fermented milk in Ministerial Ordinance Regarding Compositional Standards, etc. of Milk and Dairy Products in Japan but has a form close to drinkable yogurt.
[0021] The method for producing fermented milk according to the present invention may include a pasteurization step and the like before the fermentation step. Examples of the pasteurization step include a ultra high temperature (abbreviated as "UHT") : pasteurization method including a heating treatment under the condition of, for example, 120 to 150°C for 1 second to 60 seconds, and a high temperature short time (abbreviated as "“HTST") pasteurization method including a heating treatment under the condition of, for example, 80 to 100°C for 10 seconds to 30 minutes.
[0022] The method for producing fermented milk according to the present invention may include a cooling step, a curd crushing step, an auxiliary raw material addition step, and the like after the fermentation step.
In the cooling step, for example, the fermentedmilk is cooled from the fermentation temperature to a predetermined low temperature (e.g. 10°Cor less asaconditioninlabelingof "KeepRefrigerated”).
In the curd crushing step, for example, the fermented milk is subjected to stirring, pressurization, and the like to achieve the reduction in particle size (i.e. micronization) and dispersion of fermented milk curd. It should be noted that the curd crushing stepalsoencompasses the casewhere the fermentedmilk is homogenized to liquefy fermented milk curd, for example.
In the auxiliary raw material addition step, for example, a component (i.e. auxiliary raw material) other than fermented milk, such as a sugar solution, fruit juice, fruit pulp, or a fruit preparation 1s mixed with fermented milk, and the obtained mixture is stirred. It should be noted that the auxiliary raw material addition step also encompasses the case where the auxiliary raw material is mixed with fermented milk in a tank or the like, and the obtained mixture is stirred to be stabilized.
[0023] The method for producing fermented milk according to thepresent inventionmay include other steps suchas thecurdcrushing step and the auxiliary raw material addition step as necessary in addition to steps to be generally included, i.e. the pasteurization step, the fermentation step, and the cooling step.
Anyone of the curd crushing step and the auxiliary rawmaterial addition step may be included alone, or both of the steps may be included in the method of the present invention. Further, in the case where both of the steps are included, in general, the auxiliary rawmaterial addition step is included after the curd crushing step.
[0024] When the fermented milk or the dairy product containing the fermented milk to be obtained in the present invention (hereinafter, referred to as "fermented milk or the like of the present invention") is stored at a temperature of 10°C for 25 days from the end of the preparation of a finished product (inmore detail, in the case where the finished product is a fermented milk, the end of the fermentation step of the fermented milk, and in the case where the finished product is a dairy product other than fermented milk, the end of the preparation step of the dairy product), the amount of increase in acidity (8%) for 25 days (in other words, a value obtained by subtracting a value of acidity after 0 days from a value of acidity after 25 days) is preferably 0.25% or less, more preferably 0.23% or less, even more preferably 0.20% or less, particularly preferably 0.18% or less. The lower limit of the value is not particularly limited, is preferably as small as possible, and is generally 0.10%. }
Further, when the fermented milk or the like of the present invention is stored at a temperature of 10°C for 25 days from the end of the preparation of a finished product, the acidity (%) after the lapse of 25 days is preferably 0.98% or less, more preferably 0.96% or less, even more preferably 0.93% or less, particularly preferably 0.91% or less. The lower limit of the value is not particularly limited, and is generally 0.80%.
[0025] When the fermented milk or the like of the present invention is stored at a temperature of 10°C for 12 days from the end of the preparation of a finished product, the amount of increase inacidity (3) for12daysispreferably 0.18% or less, more preferably 0.17% or less, even more preferably 0.15% or less, particularly preferably 0.13% or less. The lower limit of the value is not particularly limited, is preferably as small as possible, and is generally 0.10%.
Further, when the fermented milk or the like of the present invention is stored at a temperature of 10°C for 12 days from the end of the preparation of a finished product, the acidity (8%) after the lapse of 12 days is preferably 0.91% or less, more preferably 0.90% or less, evenmorepreferably 0.88% or less, evenmorepreferably 0.86% or less. The lower limit of the value is not particularly limited, and is generally 0.80%.
[0026] When the fermented milk or the like of the present invention is stored at a temperature of 10°C for 25 days from the end of the preparation of a finished produc, the amount of decrease in pH for 25 days (in other words, a value obtained by subtracting a value of pH after 25 days from a value of pH after 0 days) is preferably 0.28 or less, more preferably 0.25 or less, even more preferably 0.20 or less, particularly preferably 0.15 or less. The lower limit of the value is not particularly limited, is preferably as small as possible, and is generally 0.05.
When the fermented milk or the like of the present invention 1s stored at a temperature of 10°C for 25 days from the end of the preparation of a finished product, pH after the lapse of 25 days is preferably 3.90 or more, more preferably 3.95 or more, even more preferably 4.00 or more, particularly preferably 4.05 or more. The upper limit of the value isnot particularly limited, and is generally 4.20,
[0027] When the fermented milk or the like of the present invention 1s stored at a temperature of 10°C for 12 days from the end of the preparation of a finished product, the amount of decrease in pH for 12 days is preferably 0.20 or less, more preferably 0.18 or less, even more preferably 0.15 or less, particularly preferably 0.100r less. Thelowerlimitofthevalueisnotparticularlylimited, is preferably as small as possible, and is generally 0.05.
When the fermented milk or the like of the present invention is stored at a temperature of 10°C for 12 days from the end of the preparation of a finished product, pH after the lapse of 12 days is preferably 3.95 or more, more preferably 4.00 or more, even more preferably 4.05 or more, even more preferably 4.10 or more. The upper limit of the value isnot particularly limited, andis generally 4.20,
[0028] In the present invention, when the acidity or pH falls within the preferred range described above, the best-before date of a fermented milk-containing product (i.e. a fermented milk or a fermented dairy product) as a finished product can be sufficiently : extended.
Meanwhile, in the fermented milk or fermented dairy product, in general, in order to suppress sourness to provide mild taste, a sweetener or the like is added to enhance sweetness and to strike a balance between sourness and sweetness for increasing preference (i.e. palatability). In this regard, in the present invention, sourness derived from the fermented milk or fermented dairy product + can be suppressed, because an increase in acidity and a decrease in pH are suppressed. Hence, the amount of the sweetener or the like to be added can be reduced. In this case, fermented milk or a fermenteddairyproduct, whichhas light sournesswhilemaintaining richness and freshness inherent in the fermented milk or fermented dairy product, can be provided.
Examples {0029} Hereinafter, the present invention is explained by way of Examples. However, it shouldbe noted that the present invention is not limited to the following Examples. For example, the present invention is applicable to set type yogurt as well.
[0030] [Example 1; Case of carrying out fermentation at a high temperature of 45°C (laboratory-scale experiment) ]
Arawmaterial of fermentedmilk (i.e. yogurt mix) was prepared by mixing 705 g of skim milk powder with 4,195 g of tap water. The raw material of fermented milk was subjected to heat sterilization at 95°C for 10 minutes and then cooled to 45°C. Next, 100 g of a mixed starter of Lactobacillus bulgaricus and Streptococcus thermophilus each isolated from "Meiji Bulgaria Yogurt" (trade name; manufactured byMeiji Dairies Corporation) were inoculated therein.
The resultant was subjected to fermentation in a tank at 45°C. The fermentation step was terminated at the fermentation time of 5 hours when the acidity reached 1.20% through the generation of lactic acid. Theresultantwasthencooledtol1l0°Corlesstoyield fermented milk. It should be noted that the fermentation time of 5 hours was the same as that of Comparative Example 1 described below in which fermentation was carried out at the conventional optimum "temperature.
[0031] The resultant fermented milk was homogenized through first pressurization at about 10 MPa and second pressurization at about 5 MPa to yield liquid fermented milk. The liquid fermented milk was then mixed with a sugar solution (i.e. aqueous solution obtained by blending 5.5 mass$% (in other words, % by weight) of sugar, 16 mass?® of high-fructose corn syrup, and 0.6mass% of pectin) at a mass ratio of 6:4 to yield a fermented dairy product (i.e. drinkable yogurt) as a finished product. The resultant fermented dairy product was stored at 10°C, and changes with time in acidity, pH, viscosity, and viable cell counts of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria in the fermented dairy product were examined with a starting point of the fermented dairy product being in a fresh state immediately after preparation.
It should be noted that the viable cell count of each of rod-shaped lactic acid bacteria and viable coccus-shaped lactic acid bacteria is a numerical value obtained by measuring the number of colonies per ml (i.e. colony forming unit) of a fermented dairy product.
[0032] [Example 2; Case of carrying out fermentation at a high temperature of 47°C (laboratory-scale experiment) ]
Arawmaterial of fermentedmilk (i.e. yogurt mix) was prepared by mixing 705 g of skim milk powder with 4,195 g of tap water. The raw material of fermented milk was subjected to heat sterilization at 95°C for 10 minutes and then cooled to 47°C. Next, 100 g of a mixed starter were inoculated therein in the same manner as that in Example 1. The resultant was subjected to fermentation in a tank at 47°C. The fermentation step was terminated at the fermentation timeof 5.5hourswhentheacidityreachedl.20% throughthegeneration of lactic acid. The resultant was then cooled to 10°C or less to yield fermentedmilk. It shouldbe noted that the fermentation time of 5.5hours was substantially the same as that of Comparative Example 1 described below in which fermentation was carried out at the conventional optimum temperature.
[0033] The resultant fermented milk was subjected to the same procedure as that in Example 1 to yield a fermented dairy product (i.e. drinkable yogurt) as a finished product. With regard to the resultant fermented dairy product, changes with time in acidity,
PH, viscosity, and viable cell counts of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria in the fermented dairy product were examined in the same manner as those in Example 1. f0034] [Comparative Example 1; Case of carrying out fermentation at the conventional optimum temperature of 43°C (laboratory-scale experiment) ]
Arawmaterial of fermentedmilk (i.e. yogurtmix) was prepared by mixing 705 g of skim milk powder with 4,195 g of tap water. The raw material of fermented milk was subjected to heat sterilization at 95°C for 10 minutes and then cooled to 43°C. Next, 100 g of a mixed starter were inoculated therein in the same manner as that in Example 1. The resultant was subjected to fermentation in a tank at 43°C. The fermentation step was terminated at the fermentation time of 5 hours when the acidity reached 1.20% through the generation of lactic acid. The resultant was then cooled to 10°C or less to yield fermented milk.
[0035] The resultant fermented milk was subjected to the same procedure as that in Example 1 to yield a fermented dairy product (i.e. drinkable yogurt) as a finished product. With regard to the resultant fermented dairy product, changes with time in acidity, pH, viable cell counts of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria, and viscosity in the fermented dairy product were examined in the same manner as those in Example 1.
[0036] Tables 1 to 4 show changes with time in acidity, pH, and viable cell counts of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria, respectively, in the fermented dairy products of Example 1, Example 2, and Comparative Example 1.
[0037] {Table 1]
Change with time in acidity in fermented dairy product (laboratory scale) " Number of days elapsed (days)
Acidity ( o [5s 12 [a7 [25 mais [om [om [owe [om | os
Erammie 2
[0038] [Table 2]
Change with time in pH in fermented dairy product (laboratory scale)
Number of days elapsed (days) [| 0 [5s Jaz [a7 | 25 mamie [waa [ae eas [sos aos mew: Jam [ew [en [na em
[0039] [Table 3]
Change with time in viable cell count of rod-shaped lactic acid bacteria in fermented dairy product (laboratory scale)
Viable cell count of Number of days elapsed (days) rod-shaped lactic acid bacteria (s10’ cewrmy | © | 5 [32 | 37 | 2s [semi [ve [so [eo [es [ao mewicz [70 | es [eo [5s [es
[0040] [Table 4]
Change with time in viable cell count of coccus-shaped lactic acid bacteria in fermented dairy product (laboratory scale)
Viable cell count of Number of days elapsed (days) coccus-shaped lactic acid bacteria (10 cewmy | © | = [12 [17 | 2s [meme [we [ww | w [m maiz [0 | 0 | m [ew |e]
[0041] As shown in Tables 1 and 2, an increase in acidity and a decrease in pH during refrigerated (i.e. 10°C or less) storage were suppressed in Example 1 in which fermentation was carried out at a high temperature (i.e. 45°C) as well as in Example 2 in which fermentation was carried out at a high temperature (i.e. 47°C) as compared to Comparative Example 1 in which fermentation was carried out at the conventional optimum temperature (i.e. 43°C).
[0042] Tables 1 and 2 reveal that an increase in acidity and a decrease in pH were suppressed in the storage for 25 days (about 4 weeks) in Examples 1 and 2 as compared to those in the storage for 12 to 17 days in Comparative Example 1. This indicates that the best-before date of the fermentedmilk or fermented dairy product can be extended by the present invention.
Meanwhile, in the fermented milk or fermented dairy product, in general, in order to suppress sourness to provide mild taste, a sweetener or the like is added to enhance sweetness and to strike a balance between sourness and sweetness for increasing preference.
According to the present invention, sourness derived from the fermented milk or fermented dairy product can be suppressed through the suppression of an increase in acidity and a decrease in pH.
Hence, the amount of the sweetener or the like to be added can be reduced in the present invention. In this case, fermented milk or a fermenteddairyproduct, whichhas light sournesswhilemaintaining richness and freshness inherent in the fermented milk or fermented dairy product, can be provided.
[0043] On the other hand, as shown in Tables 3 and 4, there was nosignificant difference inchangeswith time in counts of rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria between
Example 1 in which fermentation was carried out at a high temperature (i.e. 45°C) and Comparative Example 1 in which fermentation was carried out at a conventional optimum temperature (i.e. 43°C), as well as between Example 2 in which fermentation was carried out at a high temperature (i.e. 47°C) and Comparative Example 1. In addition, it was able to be confirmed that in each of Examples 1 and 2, the viable cell count per ml of lactic acid bacteria was 10,000,000 (i.e. 1x10’) cfu or more, sufficiently satisfying the standard of fermented milk in Japan. Further, although not shown in the Tables, the viscosity as an indicator of the properties (i.e. quality) of the fermented dairy product were examined. As a result, there was no significant difference in change with time in viscosity between Example 1 in which fermentation was carried out at a high temperature (i.e. 45°C) and Comparative Example 1 in which fermentationwas carriedout at the conventional cptimum temperature (i.e. 43°C), as well as between Example 2 in which fermentation was carried out at a high temperature (i.e. 47°C) and Comparative
Examplel. Inotherwords, itwasabletobeconfirmedthatnoincrease in viscosity during refrigerated (i.e. 10°C or less) storage occurred.
[0044] The results of Example 1, Example 2, and Comparative
Example 1 reveal that by carrying out fermentation at a higher temperature (i.e. 45 to 47°C) than a fermentation temperature which : has been said to be the conventional optimum temperature during the preparation of fermented milk or a fermented dairy product, the standard and commercial value of a fermented milk-containing dairy product can be sufficiently satisfied, and the generation of an acid during refrigerated storage can be suppressed, while keeping a fermentation time equivalent to the conventional one.
[0045] [Example 3; Case of carrying out fermentation at a high temperature of 45 to 47°C (real-scale experiment) ]
Arawmaterial of fermentedmilk (i.e. yogurt mix) was prepared by mixing 1.4 tons of skim milk powder with 8.4 tons of tap water.
Therawmaterial of fermentedmilkwas subjectedtoheat sterilization at 95°C for 10 minutes and then cooled to about 45°C. Next, 0.2 ton of amixed starter of Lactobacillus bulgaricus and Streptococcus thermophilus each isolated from "Meiji Bulgaria Yogurt" was inoculated therein. Fermentation was started in a tank at about 45°C. The fermentation step was terminated at the fermentation time of 4 hours when the acidity reached 1.10% through the generation of lactic acid. The resultant was then cooled to 10°C or less to yield fermented milk. It shouldbe noted that the fermentation time of 4 hours was the same as that of Comparative Example 2 described below in which fermentation was carried out at the conventional optimum temperature. At the time when 4 hours elapsed as the fermentation time, the fermentation temperature reached about 47°C through the progression of the fermentation. Further, the fermentation temperature was not entirely uniform in the tank, and an outer portion and an inner (i.e. central) portion had different - temperatures. The temperatures of about 45°C and about 47°C described above are measured at the cutermost point in the tank.
The innermost point (i.e. central point) has a higher temperature than that of the outermost point by about 2.0°C.
[0046] The resultant fermented milk was homogenized through first pressurization at about 10 MPa and second pressurization at about 5 MPa to yield liquid fermented milk. The liquid fermented milk was then mixed with a sugar solution (i.e. aqueous solution obtained by blending 5.5 mass% of sugar, 16 mass% of high-fructose corn syrup, and 0.6 mass$% of pectin) at a mass ratio of 6:4 to yield a fermented dairy product (i.e. drinkable yogurt) as a finished product. The resultant fermented dairy product was stored at 10°C and 5°C, and changes with time in the amount of increase in acidity in the fermented dairy product were examined with a starting point of the fermented dairy product being in a fresh state immediately after preparation.
[0047] [Example 4; Case of carrying out fermentation at a high temperature of 47 to 49°C (real-scale experiment) ]
Arawmaterial of fermentedmilk (i.e. yogurt mix) was prepared by mixing 1.4 tons of skim milk powder with 8.4 tons of tap water.
The rawmaterial of fermentedmilkwas subjected toheat sterilization at 95°C for 10 minutes and then cooled to about 47°C. Next, 0.2 ton of a mixed starter was inoculated therein in the same manner as that in Example 3. Fermentation was started in a tank at about 45°C. The fermentation stepwas terminated at the fermentation time of 4.7 hours when the acidity reached 1.10% through the generation of lactic acid. The resultant was then cooled to 10°C or less to yield fermentedmilk. It shouldbe noted that the fermentation time of 4.7 hours was somewhat longer than that of Comparative Example 2 described below in which fermentation was carried out at the conventional optimumtemperature. Atthetimewhen4.7hourselapsed as the fermentation time, the fermentation temperature reached about 49°C through the progression of the fermentation. Further, the fermentation temperature was not entirely uniform in the tank, and an outer portion and an inner {i.e. central) portion had different temperatures. It should be noted that the measurement points and the difference in temperatures in the tank were the same as those in Example 3.
[0048] The resultant fermented milk was subjected to the same procedure as that in Example 3 to yield a fermented dairy product (i.e. drinkable yogurt} as a finished product. With regard to the resultant fermented dairy product, changes with time in the amount of increase in acidity in the fermented dairy product were examined in the same manner as that in Example 3.
[0049] [Comparative Example 2; Case of carrying out fermentation at the conventional optimum temperature of 43 to 44°C {(real-scale experiment) ] :
Arawmaterial of fermentedmilk (i.e. yogurt mix) was prepared by mixing 1.4 tons of skim milk powder with 8.4 tons of tap water.
The rawmaterial of fermentedmilkwas subjected toheat sterilization at 95°C for 10 minutes and then cooled to about 43°C. Next, 0.2 ton of a mixed starter was inoculated therein in the same manner as that in Example 3. Fermentation was started in a tank at about 43°C. The fermentation step was terminated at the fermentation time of 4 hours when the acidity reached 1.10% through the generation of lactic acid. The resultant was then cooled to 10°C or less to yield fermented milk. At the time when 4 hours elapsed as the fermentation time, the fermentation temperature reached about 44°C through the progression of the fermentation. Further, the fermentation temperature was not entirely uniform in the tank, and an outer portion and an inner (i.e. central) portion had different temperatures. It should be noted that the measurement points and the difference in temperatures in the tank were the same as those in Example 3.
[0050] The resultant fermented milk was subjected to the same procedure as that in Example 3 to yield a fermented dairy product (i.e. drinkable yogurt) as a finished product. With regard to the resultant fermented dairy product, changes with time in the amount of increase in acidity in the fermented dairy product were examined in the same manner as that in Example 3.
[0051] Table 5 (storage temperature: 10°C) and Table 6 (storage temperature: 5°C) show changes with time in the amount of increase in acidity in the fermented dairy products of Example 3, Example
4, and Comparative Example 2.
[0052] [Table 5]
Change with time in the amount of increase in acidity in fermented dairy product (real scale; storage temperature: 10°C)
Amount of increase in Number of days elapsed (days) mmies | 0 [os [a3 [03a [ote [0c eemics | 0 [oe [oes [os [oo [0.08
[0053] [Table 6]
Change with time in the amount of increase in acidity in fermented dairy product (real scale; storage temperature: 5°C)
Amount of increase Number of days elapsed (days) messy [To 7 Tw J [a [3 memics | 0 0.05 [0.07 [009 [om [on marie «| 0 [0.01 [0.03 [0:04 [0:05 [0.06 {00541 As shown in Tables 5 and 6, an increase in acidity was suppressed in the storage for 36 days (i.e. 1 month or more) in
Examples 3 and 4 as compared to the storage for 7 to 12 days in
Comparative Example 2. This indicates that the best-before date of the fermented milk or fermented dairy product can be extended by the present invention. Meanwhile, according to the present invention, sourness derived from the fermented milk or fermented dairyproduct canbe suppressed through the suppressionof an increase in acidity. Hence, the amount of the sweetener or the like to be added can be reduced. In this case, fermented milk or a fermented dairy product, which has light sourness while maintaining richness and freshness inherent in the fermented milk or fermented dairy product, can be provided.
[0055] The fermenteddairyproductsof Example 3 andComparative
Example 2 were each subjected to sensory evaluation by twelve : specialized panelists. In this sensory evaluation, degrees of sourness, sweetness, aftertaste, and texture (i.e smoothness) were selected as evaluation items, and evaluation scores were expressed with five grades of "2, 1, 0, -1, and -2." With regard to these grades, larger numerical values in the evaluation scores mean "stronger" in sourness and sweetness, andmean "better" inaftertaste and texture. A smaller numerical value is better for sourness, and a larger numerical value is better for sweetness, aftertaste, and texture. Table 7 shows changes with time in average values of the evaluation scores given by twelve specialized panelists in this sensory evaluation.
[0056] [Table 7}
Change with time in sensory evaluation in fermented dairy product {real scale; storage temperature: 10°C)
Sensory |Number of days elapsed (days) evaluation items | 7 | 18 [27 | 36
Exanple 3 Strength of | 0-0 | -0.5 |-0.5 | -0.5 ample 3 Strength of | 0-5 | 1.0 | 0.5 | 0.5 ample 3 Goodness of | 0-0 | 0.0 [0.5 [0.0
[0057] As shown in Table 7, Example 3 is evaluated to have weaker sourness, stronger sweetness, equivalent aftertaste, and better texture as compared to Comparative Example 2. This indicates that according to the present invention, it is possible to enhance sweetness while suppressing sourness of fermentedmilkor a fermented dairy product, and to improve the texture while maintaining the aftertaste unchanged. From this sensory evaluation, it was confirmed that according to the present invention, it was possible to provide fermented milk or a fermented dairy product, which has light sourness while maintaining richness and freshness inherent in the fermented milk or fermented dairy product, as a stored product after refrigerated storage as well as a fresh product immediately after production. The result obtained in the sensory evaluation was similar to the result in Examples described above.
[0058] According to the present invention, changes in acidity and pH during refrigerated storage can be suppressed while maintaining a commercial value as a fermented milk-containing dairy product without adding any new step such as heating or use of an additive after a fermentation step. Thus, even when a fermented milk as an intermediate product during production (e.g. fermented milk as a raw material for drinkable yogurt), or a finished product such as fermented milk (e.g. set type yogurt) or a fermented dairy product (e.g. drinkable yogurt) is stored for a long period of time,
changes with time in taste and quality can be suppressed as compared to taste and quality of a fresh product immediately after the production.
Hence, the best-before date can be extended.
In addition, the amount to be used of a flavoring agent, a sweetener, or the like, which has been added in order to artificially adjust the taste and quality of fermentedmilk or a fermented dairy product, can be reduced.
Claims (8)
1. A method for producing fermented milk, comprising a fermentation step of adding rod-shaped lactic acid bacteria and coccus-shaped lactic acid bacteria to a raw material of fermented milk and carrying out fermentation at a fermentation temperature of from 44 to 55°C to yield fermented milk.
2. The method for producing fermented milk according to claim 1, wherein the fermentation temperature is 44 to 49°C.
3. The method for producing fermented milk according to claim 1 or 2, wherein a retention time of the fermentation temperature is 2 to 24 hours.
4, The method for producing fermented milk according to any one of claims 1 to 3, wherein the rod-shaped lactic acid bacteria are Lactobacillus bulgaricus and the coccus-shaped lactic acid bacteria are Streptococcus thermophilus.
5. A dairy product, comprising the fermented milk produced by the method for producing fermented milk according to any one of claims 1 to 3.
6. The dairy product according to claim 5, wherein the dairy product is one selected from a drinkable yogurt, a soft stirred type yogurt, a lactic acid bacteria beverage, and a set type yogurt.
7. The dairy product according to claim 5 or 6, wherein when the dairy product is stored at a temperature of 10°C for 25 days from the completion of preparing the dairy product, the amount of increase in acidity (%) of the dairy product is 0.25% or less.
8. The dairy product according to any one of claims 5 to 7, wherein when the dairy product is stored at a temperature of 10°C for 25 days from the completion of preparing the dairy product, the amount of decrease in pH of the dairy product is 0.28 or less.
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| PCT/JP2011/050001 WO2011083776A1 (en) | 2010-01-06 | 2011-01-04 | Method for producing fermented milk, and dairy product |
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| JP6509737B2 (en) * | 2013-11-08 | 2019-05-08 | 株式会社明治 | Fermented milk with suppressed acidity rise and method for producing the same |
| CN107172883A (en) * | 2014-01-22 | 2017-09-15 | 株式会社明治 | The preparation method of citrulling |
| MX2017010557A (en) * | 2015-02-17 | 2017-12-07 | Yakult Honsha Kk | Method for producing fermented milk food. |
| JP2019058132A (en) * | 2017-09-27 | 2019-04-18 | 株式会社明治 | Fermented milk and manufacturing method of fermented milk |
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| JPS506745A (en) * | 1973-05-26 | 1975-01-23 | ||
| CH649196A5 (en) * | 1981-12-16 | 1985-05-15 | Nestle Sa | PROCESS FOR THE MANUFACTURE OF YOGURT. |
| JPS60256341A (en) * | 1984-05-31 | 1985-12-18 | Sennosuke Tokumaru | Preparation of yogurt |
| IL95682A (en) * | 1989-09-15 | 1995-07-31 | Pfw Bv | Yoghurt flavor and its manufacture |
| JP2884000B2 (en) * | 1990-04-12 | 1999-04-19 | 雪印乳業株式会社 | Fermented milk with suppressed increase in acidity during storage and method for producing the same |
| JP3184572B2 (en) * | 1991-08-12 | 2001-07-09 | グリコ乳業株式会社 | Medium for the isolation and culture of a lactic acid bacterium belonging to Lactobacillus, a method for training the lactic acid bacterium into a milk medium, and a method for producing fermented milk or a lactic acid bacterium beverage using the same |
| JP3101143B2 (en) * | 1994-03-02 | 2000-10-23 | 雪印乳業株式会社 | A method for producing fermented milk with reduced acidity during storage. |
| JP2832159B2 (en) * | 1995-03-13 | 1998-12-02 | 雪印乳業株式会社 | Determination of fermentation end time or acidity of lactic acid bacteria |
| JP3013157B2 (en) * | 1996-09-27 | 2000-02-28 | カルピス株式会社 | Lactic acid bacteria fermented milk material with suppressed increase in lactic acidity |
| JP3645986B2 (en) * | 1997-03-26 | 2005-05-11 | 雪印乳業株式会社 | Method for producing liquid fermented milk |
| JP3755855B2 (en) * | 1997-05-13 | 2006-03-15 | 日本ミルクコミュニティ株式会社 | Fermented milk and its production method |
| JPH1132724A (en) * | 1997-07-18 | 1999-02-09 | Snow Brand Milk Prod Co Ltd | Production of food or drink high in survival rate of bacillus bifidus |
| JP4331309B2 (en) * | 1999-03-23 | 2009-09-16 | 雪印乳業株式会社 | Cryogenic lactic acid strain |
| ES2242541B1 (en) * | 2004-04-30 | 2006-12-16 | Consejo Superior De Investigaciones Cientificas | FERMENTED PRODUCT WITHOUT LACTOSE FROM DRIED FRUITS OF NON-VEGETABLE FRUITS AND / OR HORCHATA. |
| JP4465297B2 (en) * | 2005-04-13 | 2010-05-19 | 明治乳業株式会社 | Fermented milk production method and fermented milk |
| FR2886313B1 (en) * | 2005-05-31 | 2007-08-17 | Gervais Danone Sa | MUTANT STRAINS OF LACTIC ACID BACTERIA HAVING NON - PHOSPHORYLABLE LACTOSE PERMEASE. |
| JP2007028920A (en) * | 2005-07-22 | 2007-02-08 | Japan Research & Development Association For New Functional Foods | Fermented milk and method for producing the same |
| JP5005897B2 (en) * | 2005-08-30 | 2012-08-22 | 株式会社明治 | Fermented milk production method and fermented milk |
| WO2009151602A1 (en) * | 2008-06-13 | 2009-12-17 | General Mills, Inc. | Method for continuous production of fermented dairy products |
| JP5116731B2 (en) * | 2009-06-29 | 2013-01-09 | 株式会社明治 | Method for producing fermented milk |
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| CN105123922A (en) | 2015-12-09 |
| JPWO2011083776A1 (en) | 2013-05-13 |
| WO2011083776A1 (en) | 2011-07-14 |
| JP2016026501A (en) | 2016-02-18 |
| JP6192697B2 (en) | 2017-09-06 |
| JP5822729B2 (en) | 2015-11-24 |
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