1. Theoretical basis

It can be seen from the structural formula that the hydrogen (Na+) on CMC is very easy to dissociate in aqueous solution (generally exists in the form of sodium salt), so CMC exists in the form of anion in aqueous solution, that is, it has a negative charge and is amphoteric. When the pH of the protein is lower than the isoelectric point, its ability to bind the -COO- group of the proton is much greater than the ability of the -NH3+ group to donate the proton, so it has a positive charge. In milk, 80% of the protein is casein, and The isoelectric point of casein is about 4.6, and the pH of general acidic milk drinks is 3.8-4.2, so under acidic conditions, CMC and milk protein can be complexed by charge attraction, forming a relatively stable structure, and can be absorbed in protein A protective film is formed around it, and this performance of CMC is called the microcapsule embedding binding characteristic.

2. Suggested formula of acidic milk drink

(1) Basic formula of blended acidic milk drink (according to 1000Kg):

Fresh milk (whole milk powder) 350 (33) Kg
White sugar 50Kg
Compound sweetener (50 times) 0.9Kg
CMC 3.5～6Kg
Monoglyceride 0.35Kg
Sodium citrate 0.8Kg
Citric acid 3Kg
Lactic acid (80%) 1.5Kg

Note:

1) Milk powder can be replaced by partially hydrolyzed protein, control protein ≥ 1%.
2) The final acidity of the product is controlled at around 50-60°T.
3) Soluble solids 7.5% to 12%.

(2) Lactic acid bacteria beverage formula (according to 1000Kg):
Fermented milk 350～600Kg
White sugar 60Kg
Compound sweetener (50 times) 1Kg
CMC 3.2～8Kg
Monoglyceride 0.35Kg
Sodium citrate 1Kg
Moderate amount of citric acid
Note: Use citric acid solution to adjust the acidity of the milk, and the final acidity of the product is controlled at about 60-70°T.

3. Key points of CMC selection

FH9 and FH9 Extra High (FVH9) are generally selected for blended yogurt drinks. FH9 has a thick taste, and the addition amount is 0.35% to 0.5%, while FH9 Extra High is more refreshing and has a good effect of increasing the adjustment, and the addition amount is 0.33% to 0.45%.

Lactic acid bacteria beverages generally choose FL100, FM9 and FH9 super high (produced by special process). FL100 is generally made into products with thick taste and long shelf life. The addition amount is 0.6% to 0.8%. FM9 is the most widely used product. The consistency is moderate, and the product can achieve a longer shelf life. The added amount is 0.45% to 0.6%. The product of FH9 super high-grade lactic acid bacteria drink is thick but not greasy, and the added amount can be small, and the cost is low. It is suitable for making thick lactic acid bacteria drink. , the addition amount is 0.45% to 0.6%.

4. How to use CMC

Dissolution of CMC: The concentration is generally dissolved in an aqueous solution of 0.5%-2%. It is best to dissolve with a high-speed mixer. After the CMC is dissolved for about 15-20 minutes, pass through a colloid mill and cool down to 20-40°C for later use.

5. Points for attention in the process of acidic milk beverage

The quality of raw milk (including reconstituted milk): antibiotic milk, mastitis milk, colostrum, and final milk are not suitable for making acidic milk drinks. The protein components of these four types of milk have undergone great changes. Resistance, acid resistance, and salt resistance are also poor, and affect the taste of milk.

In addition, these four kinds of milk contain a large amount of four kinds of enzymes (lipase, protease, phosphatase, catalase), these enzymes have more than 10% residue even at ultra-high temperature of 140 ℃, these enzymes will be revived during milk storage . During the storage period, the milk will appear smelly, bitter, flatulent, etc., which will directly affect the shelf life of the product. Generally, 75% alcohol equivalent test, boiling test, pH and titration acidity of the milk can be used for selective detection. Raw milk, the 75% alcohol test and boiling test of normal milk are negative, the pH is between 6.4 and 6.8, and the acidity is ≤18°T. When the acidity is ≥22°T, protein coagulation occurs when boiling, and when the pH is less than 6.4, it is mostly colostrum or Sourdough milk, when the pH>6.8 is mostly mastitis milk or low-acidity milk.

(1) Points for attention in the process of blended acidic milk drinks
Preparation of yogurt: Preparation of reconstituted milk: Slowly add milk powder into stirred hot water at 50-60°C (control the water consumption to be more than 10 times the amount of milk powder) and fully dissolve for 15-20 minutes (it is best to grind it with colloid) Once), cool down to 40°C for later use.

Prepare the CMC solution according to the usage method of CMC, add it to the prepared milk, stir well, and then roughly measure with water (deduct the amount of water occupied by the acid solution).

Slowly, continuously, and evenly add the acid solution to the milk, and pay attention to controlling the acid addition time between 1.5 and 2 minutes. If the acid addition time is too long, the protein stays at the isoelectric point for too long, resulting in serious protein denaturation. If it is too short, the acid dispersion time is too short, the local acidity of the milk is too high, and the protein denaturation is serious. In addition, it should be noted that the temperature of the milk and acid should not be too high when adding acid, and it is best to control it at 20-25°C between.

Generally, the natural temperature of the milk can be used for homogenization, and the pressure is controlled at 18-25Mpa.

Sterilization temperature: Post-sterilization products generally use 85-90°C for 25-30 minutes, and other products generally use ultra-high temperature sterilization at 137-140°C for 3-5 seconds.

(2) Points for attention in the process of lactic acid bacteria beverage
Measure the protein content of milk, add milk powder to make the protein of the milk between 2.9% and 4.5%, raise the temperature to 70-75°C, adjust the pressure of the homogenizer to 18-20Mpa for homogenization, and then use 90-95°C, 15- Pasteurize for 30 minutes, cool to 42-43°C, inoculate the prepared strains at 2%-3%, stir for 10-15 minutes, turn off the stirring, and keep a constant temperature of 41-43°C for fermentation. When the acidity of the milk reaches 85-100°T, the fermentation is stopped, and it is quickly cooled to 15-20°C by the cold plate and then poured into the vat for later use.

If the protein content in the milk is low, there will be too much whey in the fermented milk, and protein flocs will easily appear. Pasteurization at 90-95°C is conducive to the moderate denaturation of the protein and improves the quality of the fermented milk. If the fermentation temperature is too low or If the amount of inoculum is too small, the fermentation time will be too long, and the bacteria will grow too much, which will affect the taste and shelf life of the product. If the temperature is too high or the amount of inoculum is too large, the fermentation will be too fast, the whey will be precipitated more or protein lumps will be produced, which will affect the stability of the product. In addition, one-time strains can also be selected when selecting strains, but strains with weak post-acidity should be selected as much as possible.

Cool down the CMC liquid to 15-25°C and mix it with the milk evenly, and use water to make up the volume (deduct the amount of water occupied by the acid liquid), and then add the acid liquid to the milk liquid slowly, continuously and evenly (preferably acid by spraying). Stir well and set aside.

Generally, the natural temperature of the milk can be used for homogenization, and the pressure is controlled at 15-20Mpa.

Sterilization temperature: post-sterilization products generally use 85-90°C for 25-30 minutes, and other products generally use ultra-high temperature sterilization at 110-121°C for 4-5 seconds or 95-105°C for 30 seconds.