Yogurt is one of the fermented foods that many people love because of its delicious taste and provides many nutrients that are good for health and beauty. In this article, we will learn about the industrial yogurt production process!

What is yogurt?

Yogurt is a dairy product created by bacteria fermenting milk. Yogurt is white, chewy, and has a sour taste due to the fermentation process of lactic sugar combined with the sweetness of milk. Yogurt contains many minerals such as: Calcium, zinc, lactic acid, vitamin A, vitamin C... Therefore, the nutritional content of this food is very high.

Yogurt with delicious flavor is formed during the natural fermentation process, so it brings many health benefits. The ingredients in yogurt help cool and cool the body on hot, humid days. In addition, yogurt also contains beneficial bacteria for the intestines and digestive system. Not only that, yogurt also has substances that help strengthen the immune system, support weight loss and help beautify the skin.

Yogurt classification?

Currently, there are many yogurt products on the market with many different types. Below are the basic types of yogurt you can refer to:

• Yogurt classification based on physical properties

Traditional yogurt: has a smooth texture. The traditional yogurt production process is formed right in the product packaging after being inoculated and fermented.

Stirred yogurt: does not have a smooth texture like traditional yogurt. The process is carried out in the following order: milk treatment > inoculation > fermentation > cooling and filling into packaging.

Drinkable yogurt: the process is similar to stirred yogurt, but after the fermentation stage, people use the stirring method to destroy the curd. Therefore, drinkable yogurt is in liquid form.

Frozen yogurt: has a form similar to ice cream. The fermentation process will be carried out and the product will be frozen.

Concentrated yogurt: After fermentation, stirring and cooling, the milk will be centrifuged to separate the cream and water. Therefore, this type of yogurt will be thicker than traditional yogurt.

• Classification of yogurt based on flavor

Natural: The original flavor of the product, created by the ingredients of yogurt when combined together.

Fruit: In some yogurt production processes, fruit can be used in pureed form to increase the sweetness of the product.

Flavoring: Many companies use flavoring or other additives to diversify the flavor of yogurt.

Industrial yogurt production process

Step 1: Import raw materials

Importing raw materials and checking the quality of milk is the first step in the yogurt production process. It is necessary to check and sterilize the containers of raw fresh milk before importing raw milk. When importing milk, the milk must be stirred well, the temperature measured, and samples taken to check the physical and chemical indicators, sensory indicators, and hygiene indicators.

Step 2: Mixing

Fresh cow's milk, skim milk powder, 25% fat milk powder, and hot water are mixed well to form a homogeneous mass. The content of skim milk powder and skim milk powder used is usually not higher than 3% compared to the amount of fresh milk. The requirement is that the milk powder must be dissolved in water, leaving no coarse particles, no burnt particles to avoid leaving color.

Stabilizers are added to stabilize the milk, forming a stable gel and the product does not separate during storage. The mixing step of the yogurt production process can be performed as follows: fresh milk (2 - 3ºC) → fully mixed → heated (5 - 10 minutes) → 50ºC milk → skim milk powder, 25% fat milk powder → mixed with sugar, stabilizer (15 minutes).

Step 3: Filter

The purpose is to remove impurities during the milking and transportation process, in addition to removing the remaining milk cream during the reconstitution of milk powder. The mixed solution is pumped through a tubular filter, then transferred to the balance tank.

Step 4: Balance tank

The balance tank helps to ensure that the mixing level is constant, helping the yogurt production process to be continuous, reducing fluctuations in product flow and avoiding air bubbles in the product.

Step 5: Heat treatment

Heat treatment is usually carried out in a plate or tube heat exchanger. The treatment mode is 90 - 95ºC for 3-5 minutes to destroy or inhibit to the maximum extent. In addition, this yogurt production process also pre-denatures the protein in the milk. As a result, during the lactic fermentation process, a curd is formed with a stable structure when storing yogurt.

Step 6: Homogenization 1

Homogenization to prevent separation of cream during incubation and fermentation, reduce the average diameter of fat globules into casein micelles, and avoid fat phase separation.

Yogurt production process on industrial chain

Step 7: Pasteurization 1

Kill unnecessary microorganisms in milk, making milk have a pure nutritional environment suitable for the growth of necessary microorganisms. Milk solution is pasteurized at 62ºC for 30 minutes. The process of raising the temperature of milk to 62ºC is carried out in the first compartment of the plate heat exchanger by exchanging heat with hot water. The average bar temperature is controlled according to the set value by the automatic temperature controller.

Step 8: Cooling 1

The pasteurized milk solution is cooled down to 4 - 8ºC in the plate heat exchanger through 3 stages:

Stage 1: Milk after pasteurization will be led into the second compartment of the plate heat exchanger. Here the milk is cooled by heat exchange with the milk liquid that is about to enter homogenization 1.

Stage 2: The milk is cooled in the third compartment of the plate heat exchanger.

Stage 3: The milk coming out of the third compartment will enter the fourth compartment of the plate heat exchanger to cool down to 4 - 8ºC

The milk liquid is kept at a temperature of 4 - 8ºC for 5 - 20 hours to stabilize the quality.

Step 9: Homogenization 2

The homogenization process 2 in the yogurt production process helps stabilize the ingredients, the homogeneous mixture creates favorable conditions for the following processes. The implementation method is similar to the homogenization process 1.

Step 10: Pasteurization 2

The milk liquid divided when leaving homogenization 2 will enter the first compartment of the heat exchanger to exchange heat with hot water and raise the temperature of the milk to 95ºC. Pasteurization temperature 2 is controlled according to the value to set by the automatic temperature controller. If the pasteurization temperature does not reach, the milk will be circulated back to the balance tank until the pasteurization temperature reaches. Milk at 95ºC is led into the temperature storage tube for 5-10 minutes.

Step 11: Cooling

The pasteurized milk is cooled down to 45ºC through the following 2 stages and then fermented.

Step 1: The pasteurized milk is led into compartment 2 of the plate heat exchanger. The milk is cooled by heat exchange with the milk.

Step 2: The milk is cooled in the third compartment and cold water in the fourth compartment of the plate heat exchanger.

Step 12: Fermentation

Conduct fermentation with standard strains from the laboratory. Inoculate the strains into pasteurized milk and incubate at the appropriate temperature. The strains will develop and cause the milk to coagulate.

Step 13: Cooling 2

Open the stirring paddle 2 – 3 minutes after stopping incubation, cool the milk to 15 – 20ºC for a few hours. The fermentation process gradually weakens and ends when the milk reaches 10ºC. After cooling, the milk is transferred to the filling tank to prepare for packaging.