Preparation method of fermented goat milk powder rich in high-activity lactic acid bacteria

Abstract

The invention discloses a preparation method of fermented goat milk powder rich in high-activity lactic acid bacteria. Comprising the following steps: homogenizing and sterilizing fresh goat milk, inoculating streptococcus thermophilus and lactobacillus bulgaricus in a specific proportion according to the weight of 2-3% of the fresh goat milk, fermenting at 40-45 DEG C until the acidity is 70-80 oT, crushing, concentrating under reduced pressure, adding lecithin, beta-dextrin and maltodextrin in a specific proportion, homogenizing, performing spray drying, and finally discharging powder to obtain the product. The strain protective agent adopted by the invention solves the problem of low survival rate of lactic acid bacteria in spray drying, the lactic acid bacteria concentration of the product reaches 107 cfu / g, the shelf life exceeds 12 months, and the product is simple in process, low in cost, environment-friendly and suitable for large-scale production, has high nutritional value and healthy efficacy, and meets the requirements of different people.

Description

Technical Field

[0001] The invention relates to the technical field of dairy product processing, and in particular to a method for preparing goat milk powder fermented with high-activity lactic acid bacteria. Background Art

[0002] Goat milk powder is widely regarded as a high-quality food because of its rich nutrition and easy absorption by the human body. It is especially suitable for specific groups such as diabetics, pregnant women, obese people and people with high blood lipids. Goat milk powder is rich in nutrients such as protein, amino acids, vitamins, inorganic salts, etc. It has the effects of improving immunity, protecting eyesight, replenishing blood and qi, strengthening the brain and protecting the liver. In addition, goat milk powder has a high calcium content, which helps to strengthen bones and reduce the risk of osteoporosis. As a low GI (glycemic index) food, goat milk powder has significant advantages in controlling blood sugar and blood lipids.

[0003] Yogurt is considered one of the best nutritional and health foods in the 21st century because it contains a large amount of active lactic acid bacteria. Lactic acid bacteria can regulate intestinal flora, enhance immunity, promote digestion and absorption, and have antibacterial and antiviral effects. However, the active lactic acid bacteria in yogurt are easily inactivated during storage and transportation, making it difficult to fully exert its health benefits.

[0004] Lactic acid bacteria fermented milk powder is a product that combines lactic acid bacteria with milk powder. It has the characteristics of long shelf life and convenient storage and consumption. The existing semi-fermentation method is to add fermented yogurt to concentrated milk in a certain proportion and spray dry it to obtain lactic acid bacteria milk powder. However, this method has the following problems:

[0005] 1. Low number of live bacteria: The number of live bacteria in lactic acid bacteria milk powder produced by semi-fermentation is usually less than 10 8 CFU / g, the number of viable bacteria after spray drying is about 10 6 CFU / g, which is much lower than the 10 7 CFU / g.

[0006] 2. It is difficult to maintain bacterial activity during the shelf life: Due to the lack of effective protection measures, lactic acid bacteria are easily inactivated during the shelf life, resulting in a decrease in the health efficacy of the product.

[0007] 3. Damage to lactic acid bacteria caused by high-temperature spray drying: In the traditional spray drying process, high temperature (such as inlet air temperature of 130-140°C and exhaust air temperature of 60-70°C) will cause a large number of lactic acid bacteria to die, affecting the number of live bacteria in the final product.

[0008] Therefore, how to improve the survival rate of lactic acid bacteria in milk powder and extend its shelf life has become a technical problem that needs to be urgently solved in the field of dairy processing.

[0009] In order to avoid the above technical problems, it is necessary to provide a method for preparing goat milk powder fermented with highly active lactic acid bacteria. Summary of the invention

[0010] The object of the present invention is to provide a goat milk powder fermented with high-activity lactic acid bacteria and a production method thereof, so as to solve the problems of low survival rate and short shelf life of lactic acid bacteria in the prior art. The present invention significantly improves the survival rate of lactic acid bacteria in the spray drying process and prolongs the shelf life of the product by optimizing the production process and combining a specific high-temperature protective agent.

[0011] The technical solution adopted to solve the above technical problems is the preparation method of the highly active lactic acid bacteria fermented goat milk powder, and the specific steps are as follows:

[0012] Step 1: Inoculate the starter

[0013] Inoculate the standardized fresh goat milk that has been processed by homogenization and sterilization with Streptococcus thermophilus and Lactobacillus bulgaricus at a ratio of 2% to 3% of the weight of the raw milk, wherein the inoculation ratio of Streptococcus thermophilus to Lactobacillus bulgaricus is 1:1 or 2:1;

[0014] Step 2: Fermentation

[0015] The inoculated fresh goat milk is kept warm and cultured at 40-45°C. When the acidity reaches 70-80°C, the culture is terminated to obtain fermented sour goat milk.

[0016] Step 3: Curd breaking

[0017] The fermented sour goat milk is subjected to curd breaking at 40-45°C and 15-20MPa pressure to improve the efficiency of the subsequent concentration step;

[0018] Step 4: Concentration

[0019] The vacuum concentration was carried out in a vacuum tank, and the vacuum degree was maintained at 17.33~15.67×10 3 Pa, the concentration temperature is 51-56°C, and concentrated fermented milk with a milk solid content of 40%-50% is obtained;

[0020] Step 5: Homogenize

[0021] Add lecithin, β-dextrin and maltodextrin as strain protectants to the concentrated fermented milk, with the specific addition amount being 1.50% β-dextrin, 0.13% (raw material solid mass ratio) lecithin and 5.00% (raw material solid mass ratio) maltodextrin by weight of the concentrated milk for homogenization. The homogenization pressure is 20-25 MPa and the temperature is 45-50°C;

[0022] Step 6: Spray Drying

[0023] The homogenized concentrated fermented milk mixture was spray dried using a spray drying equipment produced by ordinary milk powder. The process parameters of spray drying were: air inlet temperature 130-140°C, tower temperature 70-75°C, exhaust temperature 60-70°C. After spray drying, powder, jelly, sieving, packaging and inspection were carried out to finally obtain fermented goat milk powder containing high concentration of active lactic acid bacteria. The strain concentration reached 10 7 CFU / g, shelf life>12 months.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Highly active lactic acid bacteria

[0026] The present invention significantly improves the survival rate of lactic acid bacteria during the spray drying process by optimizing the fermentation process and adding a strain protective agent, and the number of live bacteria in the final product reaches 10 7 CFU / g, much higher than the existing technology of 10 6 CFU / g.

[0027] 2. Extended shelf life

[0028] Through the use of a high-temperature protective agent and process optimization, the fermented goat milk powder prepared by the present invention has a shelf life of more than 12 months, thereby solving the problem in the prior art that the activity of lactic acid bacteria is difficult to maintain.

[0029] 3. Simple process and low cost

[0030] The invention can realize industrialized production by adopting conventional dairy processing equipment, and has simple production process, environmental friendliness and low cost.

[0031] 4. Nutritious, healthy and widely applicable

[0032] The fermented goat milk powder prepared by the invention not only contains high-concentration active lactic acid bacteria, but also retains the beneficial metabolites of fermented milk, has the characteristics of nutrition, health, safety and convenience, and is suitable for consumption by all kinds of people. DETAILED DESCRIPTION

[0033] The content of the present invention will be described below in conjunction with embodiments. It should be understood that the embodiments described in the present invention are used to more clearly illustrate the present invention, rather than to limit the scope of the present invention.

[0034] Embodiment 1:

[0035] The highly active lactic acid bacteria fermented goat milk powder was prepared by the following steps

[0036] 1. Raw material preparation

[0037] Raw milk: Select fresh, pollution-free standardized goat milk with a milk solid content of 12% to 14%.

[0038] Starter: Streptococcus thermophilus and Lactobacillus bulgaricus, inoculated at a ratio of 1:1.

[0039] Strain protectants: lecithin, β-dextrin, maltodextrin.

[0040] 2. Process steps

[0041] 2.1 Inoculation of starter culture

[0042] Inoculation amount: 2% of the weight of the raw milk is inoculated with thermophilic Streptococcus and bulgaricus Lactobacillus, with an inoculation ratio of 1:1.

[0043] Operation method: Add the starter into the standardized fresh goat milk in proportion and stir evenly.

[0044] 2.2 Fermentation

[0045] Fermentation temperature: 40℃.

[0046] Fermentation time: Keep warm and terminate the culture when the acidity reaches 70oT.

[0047] Operation method: Put the inoculated fresh goat milk into the fermentation tank, keep it warm at 40℃, check the acidity regularly, and stop the fermentation when the acidity reaches 70oT.

[0048] 2.3 Curd breaking

[0049] Temperature: 40℃.

[0050] Pressure: 15MPa.

[0051] Operation method: Put the fermented sour goat milk into the curd breaking equipment and break the curd at 40℃ and 15MPa pressure to improve the efficiency of the subsequent concentration step.

[0052] 2.4 Concentration

[0053] Vacuum degree: 15.67×10 3 Pa.

[0054] Concentration temperature: 51°C.

[0055] Operation method: Put the fermented sour goat milk after curd breaking into a vacuum concentration tank and 3 Pa, and concentrated under reduced pressure at a concentration temperature of 51° C. to obtain concentrated fermented milk having a milk solid content of 40%.

[0056] 2.5 Homogenization

[0057] The amount of strain protective agent added: 1.50% of β-dextrin by weight of concentrated milk, 0.13% (raw material solid mass ratio) lecithin, 5.00% (raw material solid mass ratio) maltodextrin.

[0058] Homogenization pressure: 20MPa.

[0059] Homogenizing temperature: 45℃.

[0060] Operation method: Add 1.50% (raw material solid mass ratio) of β-dextrin, 0.13% (raw material solid mass ratio) of lecithin, and 5.00% (raw material solid mass ratio) of maltodextrin to the concentrated fermented milk in proportion, stir evenly and then homogenize at a homogenization pressure of 20 MPa and a temperature of 45°C.

[0061] 2.6 Spray Drying

[0062] Inlet air temperature: 130℃.

[0063] Tower temperature: 70℃.

[0064] Exhaust air temperature: 60℃.

[0065] Operation method: The homogenized concentrated fermented milk mixture is spray dried using a spray drying equipment for ordinary milk powder production, with an inlet air temperature of 130°C, a tower temperature of 70°C, and an exhaust air temperature of 60°C. After spray drying, powder, jelly, sieving, packaging and inspection are carried out to finally obtain fermented goat milk powder, in which the lactic acid bacteria concentration is 5×10 7 CFU / g.

[0066] Embodiment 2:

[0067] The highly active lactic acid bacteria fermented goat milk powder was prepared by the following steps

[0068] 1. Raw material preparation

[0069] Raw milk: Select fresh, pollution-free standardized goat milk with a milk solid content of 12% to 14%.

[0070] Starter: Streptococcus thermophilus and Lactobacillus bulgaricus, inoculated at a ratio of 2:1.

[0071] Strain protectants: lecithin, β-dextrin, maltodextrin.

[0072] 2. Process steps

[0073] 2.1 Inoculation of starter culture

[0074] Inoculation amount: 2% of the weight of the raw milk is inoculated with thermophilic Streptococcus and bulgaricus Lactobacillus, with an inoculation ratio of 2:1.

[0075] Operation method: Add the starter into the standardized fresh goat milk in proportion and stir evenly.

[0076] 2.2 Fermentation

[0077] Fermentation temperature: 45℃.

[0078] Fermentation time: Keep warm and terminate the culture when the acidity reaches 70oT.

[0079] Operation method: Put the inoculated fresh goat milk into the fermentation tank, keep it warm at 45℃, check the acidity regularly, and stop the fermentation when the acidity reaches 70oT.

[0080] 2.3 Curd breaking

[0081] Temperature: 40℃.

[0082] Pressure: 20MPa.

[0083] Operation method: Put the fermented sour goat milk into the curd breaking equipment and break the curd at 40℃ and 20MPa pressure to improve the efficiency of the subsequent concentration step.

[0084] 2.4 Concentration

[0085] Vacuum degree: 17.33×10 3 Pa.

[0086] Concentration temperature: 51°C.

[0087] Operation method: Put the fermented sour goat milk after curd breaking into a vacuum concentration tank and 3 Pa, and concentrated under reduced pressure at a concentration temperature of 51° C. to obtain concentrated fermented milk having a milk solid content of 40%.

[0088] 2.5 Homogenization

[0089] The amount of strain protective agent added: 1.50% of β-dextrin by weight of concentrated milk, 0.13% (raw material solid mass ratio) lecithin, 5.00% (raw material solid mass ratio) maltodextrin.

[0090] Homogenization pressure: 20MPa.

[0091] Homogenizing temperature: 45℃.

[0092] Operation method: Add 1.50% (raw material solid mass ratio) of β-dextrin, 0.13% (raw material solid mass ratio) of lecithin, and 5.00% (raw material solid mass ratio) of maltodextrin to the concentrated fermented milk in proportion, stir evenly and then homogenize at a homogenization pressure of 20 MPa and a temperature of 45°C.

[0093] 2.6 Spray Drying

[0094] Inlet air temperature: 140℃.

[0095] Tower temperature: 70℃.

[0096] Exhaust air temperature: 70℃.

[0097] Operation method: The homogenized concentrated fermented milk mixture is spray dried using a spray drying equipment for ordinary milk powder production, with an inlet air temperature of 140°C, a tower temperature of 70°C, and an exhaust air temperature of 70°C. After spray drying, powder, jelly, sieving, packaging and inspection are carried out to finally obtain fermented goat milk powder, in which the lactic acid bacteria concentration is 5×10 7 CFU / g.

[0098] Comparative Example 1:

[0099] The goat milk powder was prepared in the same manner as in Example 1 except that lecithin, β-dextrin and maltodextrin were not added to obtain fermented goat milk powder. The lactic acid bacteria concentration was 3×10 6 CFU / g, it is difficult to maintain bacterial activity during the shelf life.

[0100] Comparative Example 2:

[0101] Goat milk powder was prepared in the same manner as in Example 2 except that 1.50% by weight of β-dextrin, 0.13% (raw material solid mass ratio) of lecithin, and 5.00% (raw material solid mass ratio) of maltodextrin were not added to obtain fermented goat milk powder. The lactic acid bacteria concentration was 5×10 6 CFU / g, it is difficult to maintain bacterial activity during the shelf life.

[0102] Through the detailed description of Example 1 and Example 2, the present invention provides a method for preparing a highly active lactic acid bacteria fermented goat milk powder. This method significantly improves the survival rate of lactic acid bacteria and the shelf life of the product by optimizing the fermentation process, adding a strain protective agent, and accurately controlling the spray drying parameters. The fermented goat milk powder prepared by the present invention not only has a high concentration of active lactic acid bacteria, but also retains the beneficial metabolites of fermented milk. It is nutritious, healthy, safe and convenient, and suitable for consumption by all kinds of people. According to Comparative Examples 1-2, it can be seen that when 1.50% of the weight of concentrated milk β-dextrin, 0.13% (raw material solid mass ratio) lecithin, and 5.00% (raw material solid mass ratio) maltodextrin are added to the concentrated fermented milk according to the present invention, the lactic acid bacteria concentration in the obtained fermented goat milk powder can reach 10 7 CFU / g, which is higher than the lactic acid bacteria concentration in the comparative example, thus proving that the amount added in the present invention is the best technical solution.

[0103] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0104] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0106] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing goat milk powder fermented with high-activity lactic acid bacteria, characterized in that: The following steps are involved: Step 1: Inoculate the starter: After the standardized fresh goat milk is homogenized and sterilized, inoculate thermophilic streptococci and bulgaricus at 2% to 3% of the weight of the raw milk; Step 2, fermentation: keep warm and culture at 40-45°C, and terminate the culture when the acidity reaches 70-80oT to obtain fermented sour goat milk; Step 3, curd breaking: curd breaking the fermented sour goat milk at 40-45°C and 15-20MPa; Step 4: Concentrate: Reduce pressure and concentrate in a vacuum tank, and keep the vacuum degree at 17.33~15.67×10 3 Pa, the concentration temperature is 51-56°C, and concentrated fermented milk with a milk solid content of 40-50% is obtained; Step 5, homogenization: adding a high temperature protective agent to the concentrated fermented milk for homogenization to obtain a concentrated fermented milk mixture, the homogenization pressure is 20-25 MPa, and the temperature is 45-50° C.; Step six, spray drying: spray drying the homogenized concentrated fermented milk mixture, with an inlet air temperature of 130-140°C, a tower temperature of 70-75°C, and an exhaust air temperature of 60-70°C. After spray drying, powder, jelly, sieving, packaging, and inspection are performed to finally obtain fermented goat milk powder containing a high concentration of active lactic acid bacteria.

2. The preparation method according to claim 1, characterized in that: In the step 1, the inoculation ratio of thermophilic streptococcus and bulgaricus lactobacillus is 1:1 or 2:

1.

3. The method for preparing goat milk powder fermented with high-activity lactic acid bacteria according to claim 1, characterized in that: The pressure in the curd breaking step is 15 MPa or 20 MPa.

4. The method for preparing goat milk powder fermented with high-activity lactic acid bacteria according to claim 1, characterized in that: The vacuum degree in the concentration step is 15.67×10 3 Pa or 17.33×10 3 Pa.

5. The method for preparing goat milk powder fermented with high-activity lactic acid bacteria according to claim 1, characterized in that: The homogenization pressure in the homogenization step is 20 MPa or 25 MPa.

6. The method for preparing goat milk powder fermented with high-activity lactic acid bacteria according to claim 1, characterized in that: In the spray drying step, the inlet air temperature is 130°C or 140°C, the tower temperature is 70°C or 75°C, and the exhaust air temperature is 60°C or 70°C.

7. The method for preparing goat milk powder fermented with high-activity lactic acid bacteria according to claim 1, characterized in that: The strain protective agent in step five is lecithin, β-dextrin and maltodextrin.

8. The method for preparing goat milk powder fermented with high-activity lactic acid bacteria according to claim 7, characterized in that: 1.50% (by weight of the raw material solid content) of β-dextrin, 0.13% (by weight of the raw material solid content) of lecithin, and 5.00% (by weight of the raw material solid content) of maltodextrin were homogenized.

9. A highly active lactic acid bacteria fermented goat milk powder prepared by the method according to any one of claims 1 to 8, characterized in that: Contains high concentration of active lactic acid bacteria, the concentration of bacteria is 10 7 cfu / g, shelf life>12 months.