Yogurt

Yogurt, also known as sour milk, is a popular fermented milk. The so-called fermented milk is a milk beverage with special flavor, which takes raw milk, fresh milk or dairy products as the main raw materials, adds lactic acid bacteria or yeast, and becomes condensed or liquid after fermentation.

The manufacturing method and drinking method of yogurt vary from country to country. The sour taste of yogurt in China and Japan is generally mild. In recent years, in Japan and western European countries, the pulp-mashed yogurt has developed rapidly.

the ingredients of yogurt must meet certain specifications before drinking. It contains fat-free milk solids above 8%, lactic acid bacteria above 1 million/ml, and coliforms must be negative, so as to ensure the content of beneficial bacteria (lactic acid bacteria) and prevent the invasion of harmful fungi.

production method 1. raw material requirements: (1) raw milk: first, fresh and high-quality milk should be selected, which must not contain antibiotics and other harmful fungi (flora), and the solid content of fat-free milk should be above 8.5%. The milk fat of full-fat yogurt is below .5%. In order to increase milk solids, 1 ~ 3% skimmed milk powder is often added, which can inhibit whey separation and improve flavor. However, if skimmed milk powder is added more than 3%, it is easy to produce milk powder odor, so it is best to add concentrated goat milk or condensed milk, which has better flavor.

(2) Sweetener: sugar, glucose or honey can be used, and the addition amount is generally 8-1%. If the acidity of the product is to be improved, the addition amount can be appropriately increased.

(3) Hardener: It is best to increase the milk solid component in order to harden yogurt curd. In addition, .5 ~ .1% agar, .5% gelatin or .3% starch can also be added, which can also improve the strength and is very economical. Agar is also the best tissue state.

(4) spices and pulp: lemon, vanilla, orange and other essences, chocolate and curry can be used. In the pulp yogurt, the pulp or natural juice is put at the bottom of the container first, so that it can be evenly dispersed in the yogurt, and the dosage of pulp is 5 ~ 8%.

2. Preparation and sterilization: (1) First, mix whole milk, skimmed milk, skimmed milk powder and sugar according to the formula, heat to 5-6℃, and then filter. However, if milk powder is used as raw material, it must be dissolved and heated into milk first, and then mixed with other liquid raw materials.

(2) Chop agar first, add water to dissolve it into 3% solution, and then add it to the mixture.

(3) When preparing, it must be fully and evenly stirred to prevent separation of milk fat during fermentation, and generally it can be heated to 5 ~ 6℃ to achieve homogenization.

(4) sterilize after homogenizing the liquid. Sterilization temperature is 9℃ for 3 minutes. You can also use ultra-high temperature instant sterilization at 11℃ for 1 minute or 135℃ for 2 seconds.

(5) Immediately after sterilization, the milk should be quickly cooled to about 4℃.

3. Fermentation and cold storage: (1) At present, most strains in the food industry use the mixed starter of Lactococcus lactis and Lactobacillus bulgaricus, and the addition amount is 2-3%, and they are mixed evenly after addition. The fermentation temperature is 41 ~ 44℃, preferably 43℃. The fermentation time is 3-4 hours. However, due to different strains, the fermentation time should be flexibly controlled. The most important factor in making fermented milk (sour fermentation) is to cultivate a good starter. The quality requirement of starter is that it does not contain any miscellaneous bacteria except lactic acid bacteria, and the activity of lactic acid bacteria is high; Good color and texture, no peculiar smell. The culture of starter culture is carried out in a special laboratory, and the operation is not difficult. Generally, it is divided into three generations, that is, test-tube strain, triangular bottle strain and production starter.

the first step: the test-tube strain is to add 5ml of 5% litmus solution (the granular litmus sold in the market is dissolved in water and filtered to make 5% litmus solution) to 1ml of raw milk, which is litmus milk. Then subpackage into 1 ~ 15ml of each test tube and use a pressure cooker (1kg/cm? 2) Sterilization for 15 minutes or intermittent sterilization at 1℃ for 3 minutes once a day. Sterilized litmus milk is cultured in an incubator at 37℃ for 3 days. If there is no flora, it means that the culture medium is qualified. Prepare necessary instruments in advance, disinfect them with carbolic acid, connect the purchased strains or fermentation broth into test tubes in sterile rooms (boxes), and cultivate them in an incubator at 37℃ for 1 day. If there is no abnormality, they can be used as test tube strains and stored at 5℃ for 2 ~ 3 weeks.

Step 2: In order to expand the strain amount, the triangular flask strain is made: the culture medium is the same as the test-tube strain, with milk or skim milk (powder) but without litmus solution. Put 15 ml of culture medium into a 2 ml triangular bottle, and sterilize it just like the test-tube strain. Because the sugar in milk is heated, the reaction is slightly brown. After sterilization and cooling, put 1.5 ml of test-tube strain fermentation liquid, shake it evenly, cultivate it at 37℃ for 24 hours, and the acidity can reach .8 ~ 1.%, and then store it below 5℃ for 2 ~ 3 weeks.

Step 3: Make a starter for culture and production, so that the inoculation amount can be further expanded. Its culture medium is the same as triangular flask strain, and its sterilization temperature is 9℃ for 6 minutes or 1℃ for 3 minutes. Immediately after sterilization, it was cooled to 3℃, then inoculated with triangular flask strain fermentation liquid, and the inoculation amount was about 1%. After stirring, it was cultured at 35 ~ 4℃. After 24 hours, the acidity can reach about 1%, and the number of lactic acid bacteria increases (1? 8/ ml or more), stored at ~ 5℃ for later use. The starter for production is usually used on the same day. First, the curd is stirred, filtered by sterilized filter cloth and then added to the original milk.

(2) cold storage: when the emulsion reaches a certain acidity (.7 ~ .8%), it is immediately moved to a cold storage (or refrigerator) and kept at ~ 5℃ until it is safely cooled down. Yogurt without refrigeration is not good enough. In order to improve the flavor of yogurt, it is better to refrigerate yogurt for 1 ~ 2 weeks.

(3) preservative: in order to preserve yogurt for a long time and have a sour taste of yamanashi, we should use sorbic acid juice with the dosage below .3g/kg (strictly control the dosage) to achieve the purpose of preservation and flavor enhancement.

4. production method of pulp yogurt: firstly, cut the fruit (such as orange, grass mold, apple, apricot, peach, pineapple, etc.) into blocks of appropriate size, add sugar solution and raw milk, mix and prepare, heat and sterilize, cool to 42 ~ 43℃, add mixed starter 2 ~ 3%, and then ferment in a fermentor, after the acidity reaches .9%. The cooled pulp yogurt should be aged in an aging tank for 12 hours at about 1℃, which can improve the flavor and quality. If the aging temperature is too high, the acidity will rise quickly. If it is too low, the viscosity will decrease. Only after proper aging, the viscosity is about 2 times higher than that when it is cooled. The components of pulp yogurt are sucrose 1-12% and pulp 5-8%. It is especially important to note that the aged yogurt is put into the pulp, so it must be smashed evenly so that the pulp is evenly dispersed in the yogurt.

product features 1. After raw milk and dairy products are fermented into fermented milk, the nutritional value is improved a lot. Has the effects of cleaning intestinal tract and preventing and treating gastroenteritis.

2. protein in fermented milk is easy to digest and absorb, and lactic acid in fermented milk can reduce the secretion of gastric acid, reduce the burden on the stomach and help digestion.

3. Yogurt can inhibit other abnormal fermentation in the intestine and kill harmful flora in the intestine.

4. Calcium salts in fermented milk are also easier to digest and absorb than those in raw milk.

Nutritional value of yogurt

Yogurt is made from fresh milk fermented by lactic acid bacteria. Yogurt has the following nutritional values:

(1) Increase the absorption of nutrients: Yogurt not only preserves all the nutrients of the original fresh milk, but also makes protein form fine coagulated milk, which can increase the digestion and absorption rate. At the same time, the calcium absorption rate in yogurt is higher than that in fresh milk.

(2) Vitamin C content is high: some lactic acid bacteria can synthesize vitamin C, so the vitamin C content in yogurt is high.

(3) Lactic acid content is high: Lactic acid bacteria can decompose lactose in milk to form lactic acid, so it is more suitable for those who are prone to diarrhea after drinking fresh milk without lactase. Some people who lack stomach acid can improve their appetite and digestion by eating yogurt.

(4) It has a certain health care function: Lactic acid bacteria can not only produce organic acids in yogurt, but also produce antibacterial substances, which can inhibit the reproduction of spoilage bacteria in the intestine and reduce the toxin produced by spoilage bacteria in the intestine, thus playing a good health care role. And has a certain effect of delaying aging.

The health care function of yogurt is as follows: ① The product of yogurt with Bifidobacterium in the intestine is acetic acid, which can lower the pH of the intestine, inhibit harmful bacteria and achieve the purpose of preventing diseases; ② The high choline content in yogurt can reduce cholesterol and prevent cardiovascular diseases; ③ Using yogurt with Bifidobacterium to treat infantile diarrhea without side effects; (4) After operation, cancer patients drinking yogurt containing Bifidobacterium can make the microorganisms in the intestine normal, which is beneficial to the smooth progress of chemotherapy.

Yogurt is made by adding a certain amount of fermenting bacteria, such as lactic acid bacteria, to high-quality fresh milk. Yogurt not only retains all the original nutrients of milk, but also has pure texture, fragrant smell, sweet and sour taste, and is popular in Xian Yi, young and old.

According to the determination, yogurt is richer in nutrients than ordinary milk, and it is more easily absorbed by human body, and it is also a safe food with "self-protection function". Its self-protection function mainly depends on the existence of lactic acid bacteria. After milk is fermented by lactic acid bacteria, 2%-3% of lactose contained in it is decomposed into glucose and galactose, and then converted into lactic acid and other products. Lactic acid itself can be used as a nutrient source of human body and can provide heat to human body; Lactic acid can make milk protein form fine curd, and it is easy to combine with calcium in milk to produce calcium lactate, which is convenient for human body to absorb and utilize. Galactose is the monosaccharide most easily absorbed by human body, which can be converted into polypeptide, amino acid and fatty acid after being absorbed by human body, thus improving the utilization ratio of milk protein and milk fat. Drinking yogurt for a long time can significantly improve the absorption and utilization rate of phosphorus, calcium and iron, so it plays an important role in preventing rickets in infants and osteoporosis in the elderly. Milk will also synthesize a variety of vitamins, such as folic acid, during fermentation, so yogurt is a good nutritious food for pregnant women and children.

After years of research by scientists, people now have a more perfect scientific explanation for the health care function of yogurt, which mainly includes the following points:

1. Relieve the discomfort of milk:

Some people will have gastrointestinal discomfort symptoms such as abdominal pain, abdominal distension and diarrhea after drinking fresh milk, which is because lactase in this part of the human body is insufficient or lacking. After drinking milk, lactose in milk can not be digested and absorbed, but often. One third of the lactose in fermented milk is converted into lactic acid and other substances, which reduces the lactose content and can greatly alleviate the lactose intolerance of these people, thus increasing the number of people who eat milk.

2. Antibacterial and intestinal balancing:

Bacteria in human intestines are called intestinal flora, which can be divided into beneficial bacteria and harmful bacteria. Under normal circumstances, beneficial bacteria are dominant to make the intestinal flora in a balanced state, and harmful bacteria are morbid when they are dominant. Lactic acid in yogurt can not only reduce the PH value of intestinal contents, make the intestinal tract in a weak acidic environment, but also produce antibacterial substances, inhibit the reproduction and growth of spoilage bacteria in the intestinal tract (antagonistic to pathogenic bacteria, such as typhoid Bacillus, paratyphoid Bacillus, Salmonella, Escherichia coli, etc.), thus reducing the generation of harmful substances, maintaining the balance of intestinal flora, and having a health care effect on the human body. There is a 7-year-old man in Henan who has had his stomach removed by 2/3 and weighs only 7 kilograms. After drinking Prince's yogurt for two months, his appetite improved and his weight increased by more than 1 kilograms. He has been drinking yogurt for more than three years.

3. Reduce cholesterol and blood ammonia:

Yogurt contains not only low cholesterol, but also a substance that can inhibit the synthesis of cholesterol in the liver, so eating yogurt regularly can reduce the cholesterol content in the blood. It is reported that the cholesterol content in serum can be degraded by 5%-1% after one week for each person to eat 2 ml of yogurt, which may be due to the fact that lactic acid bacteria can inhibit the activity of hydroxymethylglutaric acid coenzyme A reductase; In addition, the whey acid produced in fermentation can also play a role in lowering cholesterol.

4. Improve constipation:

Drinking sour milk frequently, lactic acid bacteria proliferate in the intestine, which increases the water content in feces, and organic acids such as lactic acid and acetic acid produced during metabolism can stimulate the intestine, which can accelerate intestinal peristalsis and is very beneficial to improve senile constipation caused by functional decline in the elderly.

5. Immunity:

Studies show that there are three kinds of enzymes in the intestine: β-glucuronidase, azo reductase and nitro reductase, any of which can transform a series of substances into carcinogens. If the activities of these three enzymes can be reduced, the chances of tumor cell formation will be greatly reduced. Scientists have made many experiments on people, rats, pigs, etc., all of which prove that the activities of these three enzymes will be greatly reduced after drinking yogurt. Macrophages in the body can inhibit the growth of tumor cells. Experts' research has proved that eating lactic acid bacteria can activate macrophages in animals, thus playing a certain immune role.

1. What is cheese?

Cheese (one of which is also called cheese) is a fermented milk product. Its properties are similar to those of common yogurt. Both of them are made by fermentation process, and they also contain lactic acid bacteria that can protect health. However, the concentration of cheese is higher than that of yogurt, which is similar to solid food, and its nutritional value is therefore richer. Each kilogram of cheese products are concentrated from 1 kilograms of milk, which is rich in nutrients such as protein, calcium, fat, phosphorus and vitamins, and is a pure natural food. In terms of technology, cheese is fermented milk; As far as nutrition is concerned, cheese is concentrated milk.

The origin of cheese is generally believed to be invented by nomadic people. They used to store fresh milk in cowhide rucksacks, but it often turned sour after a few days. Later, they found that the sour milk would be lumpy and turned into delicious cheese after a few days in a cool and humid climate, so this method of preserving milk was circulated. Cheese has always been one of the main foods of these nomadic people.

Although cheese is relatively storable, it is always in the process of fermentation, so it will go bad if it takes too long. Although this change is slow, cheese will become inedible one day.

Now, the types and eating methods of cheese are more and more abundant. In addition to making western-style dishes, cheese can be cut into small pieces and eaten directly with red wine. It can also be eaten together with steamed bread, bread, biscuits and hamburgers, or mixed with salads and noodles. With the increasing foreign exchanges, more and more young people have a clearer understanding of the nutritional value of cheese. Maybe you've eaten cheeseburgers from McDonald's and pizza hut. One of the important ingredients in these foods is cheese.

At present, the cheese on the market is mainly flaky, such as bright full-fat cheese and low-fat cheese, which is produced by bright dairy, a famous dairy manufacturer in China, using high-quality fresh milk in Australia, and is especially suitable for rushing in the morning.