Process of preparing fermented milk beverage keeping high viable cell count at ambient temperature

Abstract

The invention provides a process of preparing fermented milk beverage keeping high viable cell count at ambient temperature. The process includes the steps of adding regular yoghurt lactobacillus into milk for fermentation, fermenting until pH value to 3.8-4.8, diluting, mixing and sterilizing with conventional method, adding concentrated culture, concentrated frozen culture or freeze dried culture containing Lactobacillus rhamnosus ATCC 53103 into mixed milk beverage at aseptic condition. According to various pH value of finished product, it can be stored at ambient temperature for 1-6 months, and the viable cell count will not be less than 10.sup.5 cfu/ml milk beverage. The indexes of storage period and viable cell count are much higher than fermented milk beverage produced by conventional process. Thereby the defect that fermented milk beverage has short shelf life and low viable cell count at ambient temperature is overcome efficiently.

Claims

1. A process of preparing fermented milk beverage keeping high viable cell count at ambient temperature, comprising: adding regular yoghurt lactobacillus into milk for fermentation; fermenting said milk until pH value to 3.8-4.8; diluting and mixing the fermented milk with additives and water; sterilizing the diluted and mixed fermented milk; and adding Lactobacillus rhamnosus ATCC 53103 into the sterilized fermented milk beverage at aseptic condition to produce a final product, wherein said regular yoghurt lactobacillus is selected from the group consisting of a single strain of Lactobacillus bulgaricus, a single strain of Streptococcus thermophilus, mixed strains of Lactobacillus bulgaricus, mixed strains of Streptococcus thermophilus, and mixed strains of Lactobacillus bulgaricus and Streptococcus thermophilus, and wherein said final product can be stored for 1-6 months under room temperature with a viable cell count of Lactobacillus rhamnosus ATCC 53103 of at least 10.sup.5 cfu/ml milk beverage.

2. The process according to claim 1, wherein said milk beverage is made from fresh milk or reconstituted milk, or fresh milk or reconstituted milk into which concentrated whey protein is added, the protein concentration of the milk beverage is 0.1-5%.

3. The process according to claim 2, wherein the protein concentration of the milk beverage is 0.3-2.5%.

4. The process according to claim 2, wherein said Lactobacillus rhamnosus ATCC 53103 is added in the form of concentrated liquid culture, concentrated frozen culture or freeze-dried culture.

5. The process according to claim 1, wherein the fermentation temperature of regular yoghurt lactobacillus is 35-45 C., and the fermentation time is 2.5-10 hours.

6. The process according to claim 1, wherein said diluting and mixing means the fermented milk is mixed to prepare milk beverages containing 0.7-2.5% milk protein, and the fermented milk is diluted to 1.5-10 times.

7. The process according to claim 1, wherein the pH value of finished product of said mixed milk beverage is finally controlled within the range of 3.5-4.7.

8. The process according to claim 7, wherein said Lactobacillus rhamnosus ATCC 53103 is added in the form of concentrated liquid culture, concentrated frozen culture or freeze-dried culture.

9. The process according to claim 1, wherein the addition amount of said Lactobacillus rhamnosus ATCC 53103 is 10.sup.5-10.sup.7 cfu/ml milk beverage.

10. The process according to claim 1, wherein said Lactobacillus rhamnosus ATCC 53103 is added in the form of concentrated liquid culture, concentrated frozen culture or freeze-dried culture.

11. A fermented milk beverage prepared by a process comprising the steps of: adding regular yoghurt lactobacillus into milk for fermentation; fermenting said milk until pH value to 3.8-4.8; diluting and mixing the fermented milk with additives and water; sterilizing the diluted and mixed fermented milk; and adding Lactobacillus rhamnosus ATCC 53103 into the sterilized fermented milk beverage at aseptic condition to produce a final product, wherein said regular yoghurt lactobacillus is selected from the group consisting of a single strain of Lactobacillus bulgaricus, a single strain of Streptococcus thermophilus, mixed strains of Lactobacillus bulgaricus, mixed strains of Streptococcus thermophilus, and mixed strains of Lactobacillus bulgaricus and Streptococcus thermophilus, and wherein said final product keeps a viable cell count of Lactobacillus rhamnosus ATCC 53103 of at least 10.sup.5 cfu/ml milk beverage for 1-6 months when stored at room temperature.

Description

DESCRIPTION OF EMBODIMENTS

(1) The following examples are used to illustrate the invention, but not to limit the scope of the invention.

Example 1 Fermented Milk Beverage Prepared with the Addition of Lactobacillus rhamnosus after Regular Yoghurt Lactobacillus Fermentation and Sterilization and its Storage Test

(2) Add 8% whole milk powder and 3% concentrated whey protein (WPC-80, protein content 80%) into water, thereby obtain reconstituted whole milk. Take 1000 ml reconstituted whole milk and heat at 115 C. for 15 minutes, then cool down. Inoculate with regular yoghurt bacteria BF-203 (available from BEIING FUMENGTE BIOTECHNOLOGY COMPANY LTD, composed of Streptococcus thermophilus and Lactobacillus bulgaricus), ferment until pH value to 4.5, cool down to below 25 C.

(3) Use 400 ml of water at 70 C. to dissolve acidic milk beverage stabilizer SY-806 (available from BEIING FUMENGTE BIOTECHNOLOGY COMPANY LTD.) 6 g and Ace-K (available from ZHANGJIAGANG HAOBO CHEMISTRY COMPANY) 0.5 g, stir for 20 minutes and cool down to below 25 C. After hydration for 30 minutes, take 100 ml above-mentioned reconstituted fermented milk into above-mentioned stabilizer solution, adjust pH value of the mixture solution to 4.4 with 10% citric acid, fix the volume with water to 1000 ml, and stir for 5 minutes. Preheat to 70 C., homogenize with the pressure of 20 MPa, then sterilize it at 115 C. for 15 minutes.

(4) Cool it down again to below 37 C., inoculate above-mentioned milk beverage with freeze dried culture powder of Lactobacillus rhamnosus ATCC 53103 with the quantity of 510.sup.5 cfu/ml milk beverage. Store the said beverage at 12-25 C. and measure the pH value and viable cell count at different storage period. The results are listed in table 1. The results show that after storage at 12-25 C. for 8 weeks, viable cell count is at least 10.sup.6 cfu/ml milk beverage, and the pH value of product is above 3.7.

(5) TABLE-US-00001 TABLE 1 Viability of lactobacillus and the pH value variation of the milk beverage at different storage period storage time Viable cell count(10.sup.7 (week) pH value cfu/ml milk beverage) 0 4.4 0.05 1 3.85 22 2 3.76 27 3 3.72 15 4 3.75 11 5 3.70 8.2 6 3.73 7.6 7 3.73 3.5 8 3.79 0.9

Example 2 Fermented Milk Beverage Prepared with the Addition of Lactobacillus rhamnosus after Regular Yoghurt Lactobacillus Fermentation and Sterilization and its Storage Test

(6) According to the same process of Example 1, 14% whole milk powder is used to prepare reconstituted whole milk. Inoculate with regular yoghurt lactobacillus BF-306 (available from BEIING FUMENGTE BIOTECHNOLOGY COMPANY LTD, composed of Streptococcus thermophilus and Lactobacillus bulgaricus), ferment until pH value to 3.8.

(7) Dilute above-mentioned reconstituted fermented milk for 5 times, prepare a milk beverage with 0.7% protein concentration. Adjust pH value of the mixture solution to 4.4 with 10% citric acid. According to the process of Example 1, homogenize and sterilize, then inoculate above-mentioned milk beverage with concentrated culture of Lactobacillus rhamnosus ATCC 53103 with quantity of 1.510.sup.7 cfu/ml milk beverage. Store the said beverage at 12-25 C. and measure the pH value and viable cell count at different period. The results are listed in table 2. The results show that after storage at 12-25 C. for 6 months, viable cell count of Lactobacillus rhamnosus is at least 10.sup.7 cfu/ml milk beverage, and the pH value of product is above 4.2.

(8) TABLE-US-00002 TABLE 2 Viability of lactobacillus and the pH value variation of the milk beverage at different storage period storage time Viable cell count(10.sup.7 (month) pH value cfu/ml milk beverage) 0 4.4 1.5 1 4.17 28 2 4.20 32 3 4.19 25 4 4.23 7.1 5 4.25 6.5 6 4.30 2.4

Example 3 Fermented Milk Beverage Prepared with the Addition of Lactobacillus rhamnosus after Regular Yoghurt Lactobacillus Fermentation and Sterilization and its Storage Test

(9) According to the same process of Example 1, adding 3.5% whole milk powder into fresh milk containing 11.5% milk solid to prepare whole milk with 15% solid concentration. Inoculate with regular yoghurt lactobacillus BF-301 (available from BEIING FUMENGTE BIOTECHNOLOGY COMPANY LTD, composed of Streptococcus thermophilus and Lactobacillus bulgaricus), ferment until pH value to 4.0.

(10) Dilute above mentioned reconstituted fermented milk for 5.5 times, prepare a milk beverage with 0.7% protein concentration. Adjust pH value of the mixture solution to 4.3 with 10% citric acid. According to the process of Example 1, homogenize, mix and sterilize, then inoculate above-mentioned milk beverage with Lactobacillus rhamnosus ATCC 53103 with quantity of 210.sup.6 cfu/ml milk beverage. Store the said beverage at 37 C. for 15 days and measure the pH value and viable cell count. The results are listed in table 3. The results show that after storage at 37 C. for 15 days, viable cell count is at least 10.sup.7 cfu/ml milk beverage, and the pH value of product is above 3.9.

(11) TABLE-US-00003 TABLE 3 Viability of lactobacillus and pH value variation of the milk beverage stored at 37 C. for 15 days storage time Viable cell count(10.sup.7 (day) pH value cfu/ml milk beverage) 0 4.31 0.15 1 4.17 26 4 3.94 17 7 3.98 21 10 3.93 3 15 3.93 1.1

Example 4 Fermented Milk Beverage Prepared with the Addition of Lactobacillus rhamnosus after Regular Yoghurt Lactobacillus Fermentation and Sterilization and its Storage Test

(12) According to the same process of Example 1, 15% whole milk powder is used to prepare reconstituted whole milk. Inoculate with regular yoghurt lactobacillus BF-208 (available from BEIING FUMENGTE BIOTECHNOLOGY COMPANY LTD, composed of Streptococcus thermophilus), ferment until the pH value to 4.5.

(13) For preparing a milk beverage with 1.8% protein in finished product, dilute above-mentioned reconstituted fermented milk for 2 times. Mix and sterilize, then inoculae above-mentioned milk beverage with Lactobacillus rhamnosus ATCC 53103 with quantity of 510.sup.6 cfu/ml milk beverage. Store the said beverage at 12-25 C. and measure the pH value and viable cell count at different period. The results are listed in table 4. The results show that after storage at 12-25 C. for 6 months, viable cell count is at least 10.sup.7 cfu/ml milk beverage, and the pH value of product is above 4.3.

(14) TABLE-US-00004 TABLE 4 Viability of lactobacillus and the pH value variation of the milk beverage at different storage period storage time Viable cell count(10.sup.7 (month) pH value cfu/ml milk beverage) 0 4.5 0.5 1 4.33 27 2 4.35 29 3 4.40 32 4 4.37 22 5 4.41 15 6 4.33 7.6