Main raw material: milk

Main effects: promoting gastric juice secretion, stimulating appetite, and promoting and strengthening digestion.

Overview: Yogurt is a kind of dairy product made from fresh milk, adding beneficial bacteria (starter) to pasteurized milk, fermenting, cooling and filling. At present, most yogurt products on the market are solidified, stirred and fruity with various juices and jams. Yogurt not only retains all the advantages of milk, but also exerts its advantages and avoids its weaknesses in some aspects, making it more suitable for human nutrition and health care products. Experts call it "2 1 century food", which is a kind of "nutritional product with unique functions" and can adjust the balance of microorganisms in the body.

manufacturing method

I. Production technology

The production process of yogurt can be summarized as batching, preheating, homogenization, sterilization, cooling, inoculation, (filling: for solidified yogurt), fermentation, cooling, (stirring: for stirred yogurt), packaging and post-ripening. Modified starch is added in the batching stage, and its application effect is closely related to process control:

1. Ingredients: select the required raw materials according to the material balance table, such as fresh milk, sugar, stabilizer, etc. The modified starch can be added alone or after dry mixing with other edible gums. Considering that starch and edible gum are mostly macromolecular substances with high hydrophilicity, it is best to mix them with proper amount of sugar and dissolve them in hot milk (55℃-65℃, depending on the description of modified starch) under high-speed stirring to improve their dispersibility.

2. Preheating: The purpose of preheating is to improve the efficiency of the next process-homogenization, and the preheating temperature should not be higher than the gelatinization temperature of starch (to avoid the particle structure being destroyed in the homogenization process after starch gelatinization).

3. Homogenization: Homogenization refers to the mechanical treatment of milk fat globules so that they are evenly dispersed in milk in the form of smaller fat globules. In the homogenization stage, materials are subjected to three forces: shear, collision and cavitation. Modified starch starch has strong mechanical shear resistance after cross-linking, which can maintain the complete particle structure and is beneficial to maintain the viscosity and posture of yogurt.

4. Sterilization: Pasteurization is generally adopted, and the sterilization process at 95℃ and 300S is generally adopted in dairy plants. At this stage, the modified starch is fully expanded and gelatinized, forming viscosity.

5. Cooling, inoculation and fermentation: Modified starch is a high molecular substance. Compared with the original starch, it still retains some properties of the original starch, that is, the properties of polysaccharide. In the pH environment of yogurt, starch will not be degraded by bacteria, so the stability of the system can be maintained. When the pH value of the fermentation system drops to the isoelectric point of casein, casein denatures and solidifies, and the skeleton of the three-dimensional network system of casein micelle connected with water becomes curd-like. At this time, gelatinized starch can fill the skeleton, bind free water and maintain the stability of the system.

6. Cooling, stirring and post-ripening: The purpose of stirring yogurt cooling is to quickly inhibit the growth of microorganisms and the activity of enzymes, mainly to prevent excessive acid production during fermentation and dehydration during stirring. There are many sources of modified starch raw materials, and the degree of denaturation is different. Different modified starches have different functions in yogurt production. Therefore, according to the different requirements of yogurt quality, corresponding modified starch can be provided.

The specific manufacturing method is as follows:

The instruments and materials for making yogurt include sterilization equipment, fermentor or fermentation chamber, heating tank, ultraviolet lamp, glass bottle or porcelain bottle or special paper basin, fresh milk, sugar, lactic acid bacteria (Bulgaria bacillus and Streptococcus thermophilus) and so on.

Production steps:

1. Disinfection and sterilization of glass bottles. The glass bottles are sterilized in the sterilizer for half an hour, the steamer takes 45 minutes, the inoculation room needs ultraviolet sterilization for 50 minutes, and the inoculation tools need to be sterilized in the autoclave for 30 minutes.

2. Milk sterilization. Put fresh milk in a heating tank, add 10- 12% white sugar, and sterilize at 85-90℃ for 30 minutes or by other methods. No matter which method is adopted, it is best not to destroy the original nutrients of milk, and then cool it after sterilization. Before or during sterilization, it is best to remove the upper grease to defat the milk.

Vaccinate. Sub-package the sterilized milk with the temperature below 43℃ into sterilized glass bottles, inoculate it into the inoculation room according to the inoculation amount of 2%-4% of the milk, and stir evenly. Pay attention to canning without gaps, and seal immediately after connection to ensure anaerobic conditions of lactic acid fermentation. Then it is sent to the cold storage at 0-5℃ for refrigeration and ripening for 8- 10 hour, and then it can be put on the market for sale. After-cooked yogurt has a special aromatic smell because it contains esters. On the one hand, the function of refrigeration can prevent the increase of acidity and the pollution of miscellaneous bacteria, on the other hand, it can make the texture compact and recover whey, thus greatly improving the stability of yogurt quality. In the whole process, attention should be paid to aseptic operation. Workers should wear sterile overalls, sterile gloves and masks, and clean their hands. They must be vaccinated without masks to prevent all kinds of bacterial pollution.

4. Quality standards. The appearance of high-quality yogurt is milky white or yellowish, the surface is smooth, the curd is firm, the tissue is delicate, the texture is uniform, a small amount of whey is allowed to precipitate, there is no bubble, the sour and sweet taste is moderate, and there is no pungent smell or other peculiar smell. If there are bubbles in yogurt, or the bottle cap bulges, or there is an odor such as spicy taste, it means that fresh milk has been contaminated by miscellaneous bacteria during fermentation and cannot be eaten. If the seed (koji) produced has the above situation, it must not be used for production to prevent unnecessary losses. If it is overtime at an appropriate temperature, there is little milk coagulation, whey precipitation, or even no milk coagulation, and a large number of suspended substances appear, which indicates that the strain has been seriously degraded or contaminated by miscellaneous bacteria and should be stopped. If the strain declines, the declining strain can be cultured on inclined culture medium, purified and rejuvenated, and then propagated to obtain excellent production strain.

Second, the self-made method

Method 1: Room temperature above 30℃ in summer is enough. Only the coagulation time is longer, and the higher the room temperature, the shorter the coagulation time.

The method is to clean coarse glass bottles or porcelain bottles (cans can't be used because the bottle mouth is too big and easy to be polluted by miscellaneous bacteria), put milk on it, cover the bottle mouth with clean double-layer plastic film and tie it tightly with string. The rope should be loosened, because a lot of steam will be generated in the bottle during heating. If it is tied too tightly, the membrane will rupture and pollution will easily occur.

Boil the glass bottle and milk in the pot for 30 minutes. Soak in water until there is no milk surface. Don't cover the pot. Then cool 2%-4% fresh pure yogurt sold in the market and take it out until the back of your hand doesn't touch your hand. Tie the plastic film immediately after adding the bought yogurt to ensure the oxygen-free environment in the bottle. At room temperature 10 hour later, fresh milk solidifies like tofu brain and yogurt is served.

Put the yogurt bottle in the refrigerator at 0-5℃ for 2-4 hours, and you can eat it. White sugar can be added during sterilization or when eating, depending on personal taste.

You can make a small bottle alone when cooking. If the curd is good, you can keep it as a strain, but you can't use it many times. Because aseptic operation can't be guaranteed at home, you can put the strains in the refrigerator. If the film on the bottle mouth bulges and gas is generated inside, it means that it has entered the gas-producing bacteria, which can only be eaten and cannot be preserved as a strain.

Method 2:

1. Pour the milk into a small pot, heat it to about 70 degrees with a small fire, it will be in a boiling state, and then air it on the fire until it is warm.

2. All tools (bottles, fresh-keeping boxes) are scalded with boiling water, disinfected and cooled.

3. Pour the milk powder into a fresh-keeping box or bottle. If the temperature is too high, the temperature should be lowered, which can be slightly (or lowered). Pour in yogurt.

4. Stir the milk and yogurt evenly.

5. The quality of milk, the number of strains, the activity and other effects are different. After freezing, it is stored in the refrigerator for one night, and the taste is the best.

Reserve method

One method (1) is to add 70kg sucrose and 10kg glucose to 100kg skim milk (milk fat content is lower than 3%), then homogenize under the pressure of 20MPa, then heat to 98℃, keep the temperature for 2.5min, and sterilize. After sterilization, it was quickly cooled to 30℃, then 0.25kgIST starter was added and stirred evenly, and fermented at this temperature. When the pH value reaches 4.2, the fermentation is stopped, which is the curd yogurt.

When the yogurt prepared by the above method is cooled to 15℃, food-grade citric acid is added to adjust the pH value to 4. 1, then the mixture is stirred, and 29kg of orange pectin solution and 3.5kg of orange essence are added. The preparation method of citrus pectin solution is as follows: 2.2 kg of citrus pectin is added to 27 kg of water and stirred evenly. It is best to homogenize the above mixture with colloid mill at 20MPa and then heat it to 565,438 0℃. In the whole process, pay attention to the temperature difference between the heating medium and the material should not be higher than 5℃. When the temperature reaches 5 1℃, check the temperature quickly and accurately. And let it cool to 32℃, pay attention to the temperature difference between the cooling medium and the material should not be higher than 5℃. When the material is cooled to 32℃, it is homogenized again under the pressure of 20MPa, and then heated to 90℃ for 30s. Pay attention to continuous stirring during heating and heat preservation. In addition, during heating sterilization, the temperature difference between the heating medium and the material should not exceed 5℃. Finally, the sterilized materials are cooled to 22℃ and packaged under aseptic conditions at this temperature to obtain the final product. At this time, the number of bacteria was detected, and the result was 90 /mL. If this product is stored at room temperature, there will be no whey precipitation and flavor deterioration after 6 months.

(2) In the second method, all the operations in 1 are repeated, but the control parameters need to be slightly changed, that is, when the material is heated to 90℃ and sterilized for 30s, the cooling temperature is changed from 22℃ to 30℃, and packaging is carried out at this temperature. The product was stored at 65438 05℃ for 6 months, and there were still no quality accidents such as whey precipitation and flavor deterioration.

(3) The third method repeats the operation of the first method, but sugar and fruit essence are not added in the formula. After aseptic packaging, the bacterial count of the product prepared according to the above formula is 92 /mL. After storage for 6 months, there is no separation and precipitation of whey, and its flavor is like fresh products.

(4) Method 4 repeats the production operation of method 1, but changes the following process parameters. One is to change orange essence into raspberry essence (also called raspberry). Secondly, when the temperature rises to 565,438+0℃, the temperature difference between the heating medium and the cooling medium and the material is 8℃, which decreases from 565,438+0℃ to 32℃. The products made according to this process and formula have no whey precipitation and precipitation, and the flavor has not changed after being stored at room temperature for 6 months.

(5) The production process of the fifth method remains unchanged, but after the last homogenization, the materials are put into glass bottles and then sterilized at 90℃ for 30s. Finally, cooling to room temperature to obtain the product. The product prepared by this method is stored at room temperature for 6 months, and the flavor of the product remains unchanged, and there are no quality accidents such as whey precipitation and precipitation.

Applicable people of yogurt

Most of the sugar in milk is lactose, but the lack of lactase in digestive juice of some adults affects the digestion, absorption and utilization of lactose, which leads to stomach discomfort and even diarrhea after drinking milk, which is called "lactose intolerance". This is why many people don't drink milk. At this time, you can choose yogurt instead of milk, and don't worry about lactose. Yogurt contains lactic acid bacteria; Lactose in milk can be converted into lactic acid by lactic acid bacteria fermentation, and lactose intolerant people will not have diarrhea symptoms when drinking yogurt, which just solves the problems that some people may have when drinking milk. However, it is worth noting that many yogurt drinks (instead of yogurt) are made of milk, water and sour agents, and these products may also contain lactose, which may also cause "lactose intolerance" symptoms.

In terms of diet, yogurt is suitable for the elderly, the sick, women and children. It is suitable for people with weakness, deficiency of qi and blood, malnutrition, dry skin, constipation due to intestinal dryness, hypercholesterolemia, arteriosclerosis, coronary heart disease, fatty liver, digestive tract cancer, etc. Antibiotic users and the elderly and infirm should always drink yogurt; In addition, yogurt can also be eaten as a beauty food. Although yogurt nourishes yin and tonifies deficiency, people with hyperacidity should not eat more. [ 10]

1, hypertensive patients

Some nutritionists have found that yogurt contains a "milk factor", which can lower the serum cholesterol in the human body. Calcium lactate in yogurt is easily absorbed by human body. Some people have done experiments, drinking 720 grams of yogurt every day can significantly reduce serum cholesterol after one week.

2. Cancer patients

Lactobacillus bifidus in yogurt produces acetic acid, lactic acid and formic acid during fermentation, which can inhibit nitrate-reducing bacteria and block the formation of carcinogenic nitrosamines, thus playing a role in preventing cancer. Some countries with developed dairy industry in Europe believe that "a cup of yogurt a day keeps women from worrying about breast cancer".

3. Old and frail patients

Lactic acid bacteria in yogurt can decompose lactose in milk to form lactic acid, make intestines acidic, inhibit spoilage bacteria that grow and reproduce in neutral or alkaline environment, and synthesize nutrients such as vitamin B, folic acid, vitamin E, etc., which are rich in protein and vitamin A itself, and are very beneficial to the elderly and infirm.

4. Enhance physical fitness.

Yogurt contains a lot of protein and carbonated water. Muscles in the human body need a lot of protein and carbonated water 30 to 50 minutes after exercise, which is very beneficial to children, teenagers and middle-aged people.

5, the use of antibiotics

Antibiotics control pathogenic bacteria and inhibit non-pathogenic bacteria, which can lead to loss of appetite, nausea and vomiting, dizziness and so on. And even lead to another infectious disease. Yogurt contains active Mycobacterium longum, which can restore the imbalance of gastrointestinal flora.

6. Osteoporosis

Yogurt contains calcium lactate which is easily absorbed by people. This will increase patients' calcium, which is beneficial to the prevention and treatment of osteoporosis.

In order to identify varieties, there are many kinds of "milk yogurt" made of milk or milk powder, sugar, lactic acid or citric acid, malic acid, spices and preservatives, which do not have the health care function of yogurt, so we should carefully identify them when buying.

7. Diabetic patients

Low-fat fermented dairy products such as yogurt are not only low in fat, but also rich in probiotics and vitamin K, which may play a preventive role in diabetes.

Misunderstanding of yogurt

1. Drink yogurt drinks without losing weight.

Yogurt is made of high-quality milk fermented by lactic acid bacteria, which belongs to the category of milk in essence. Yogurt drink is just a drink, not milk. Drinking yogurt helps to lose weight, while drinking yogurt drinks will only backfire. Generally speaking, yogurt drinks are drinks with high sugar content. Therefore, drinking yogurt drinks to lose weight will cause you to consume too many calories.

2. Low-fat yogurt is slimmer

Yogurt can help you lose weight, but if you want to achieve better slimming effect, you should choose low-fat yogurt. Excessive fat intake is also a major cause of obesity, and the calcium contained in low-fat yogurt can help you burn fat faster without excessive fat intake, which is very beneficial to healthy weight loss.

3. Drink yogurt to lose weight.

Don't think that yogurt can lose weight, drink too much. No matter what food it is, enough is enough. Drinking too much yogurt will lead to hyperacidity, affect the secretion of gastric mucosa and digestive enzymes, and reduce appetite. Those who have hyperacidity, often feel weak spleen and stomach, and abdominal distension should not drink more. For healthy people, about 250 grams a day is more appropriate.

Drinking yogurt alone won't help you lose weight.

Yogurt is really a slimming product. Not only delicious, but also can accelerate fat burning. However, it is unscientific to lose weight only by drinking yogurt, which will not only reduce metabolism when restoring diet, but also lead to unbalanced nutrient intake, which is not conducive to health and slimming.

5. Yogurt fasting method does not lose weight.

Yogurt fasting is one of the most popular ways to lose weight, but it is not popular or good. A healthy diet is the king of losing weight. In the case of insufficient calorie intake, the body will enter the self-protection mode, and the calorie intake will become fat and be stored, so that you can't lose weight.

6. I like to drink yogurt at midnight.

Eating too much at night and exercising too little will lead to insufficient calorie consumption, which will lead to obesity in the long run. Therefore, eating less at night is a very effective secret to lose weight. But in order to prevent energy shortage at night, you can drink some low-fat yogurt after meals, which can increase satiety and reduce calorie intake!

7. Salted yogurt will make you fat.

The sodium contained in Xianyouge salt will keep water in the body, but it will increase weight. Not only can't you lose weight, but it will make you fatter and fatter. Studies have shown that people can only consume 6g of salt in 1 day. In addition to normal diet, salty yogurt diet will lead to excessive salt intake, which is also one of the drinks that hinder weight loss.

8. Yogurt is a good helper for wrinkle removal and beauty.

Yogurt contains lactic acid, citric acid and other organic acids, and its diluent has obvious bactericidal and antiseptic effects. It is known as the "cleaner" of mucosal tissue, which helps to soften the sticky surface of skin and remove dead old cells. In the process of digestion and absorption of yogurt, wrinkles on the face will be eliminated. Vitamin A, vitamin E and carotene contained in yogurt can prevent skin from keratinization and dryness, make skin white, tender, elastic and shiny, and avoid wrinkles.

9. The larger the quantity, the better.

Many people like to drink yogurt, and even regard it as a drink, several bottles a day. Experts pointed out that the more yogurt you drink, the better, especially the yogurt with the status of health food, which needs to be controlled. Experts pointed out that health food is a functional food with specific effects, and it can't be eaten in large quantities at will like ordinary food. But pay attention to the appropriate crowd, usage and dosage, and don't eat too much.

10. Don't drink on an empty stomach after meals.

Because gastric acid has bactericidal effect, it is best not to drink yogurt containing probiotics on an empty stomach, but it is better to drink it after meals. In order to keep the activity of probiotics contained in yogurt, it is best not to drink hot drinks before and after drinking yogurt.

1 1. It can only be refrigerated but not heated.

Many people know that Qian Qian "bacteria" in yogurt is a good thing, but they don't know how to preserve it. Professor Nan Qingxian introduced that when yogurt was first produced, it was full of live bacteria, and only by refrigeration can live bacteria be well preserved. Some people like to drink hot yogurt, which is more luxurious.

12. You can add your own fruit yogurt if you want.

Experts remind that if you want to enrich the taste of yogurt, you may wish to add it at home. Fruit, jam and pulp are all processed by multiple processes, and the naturalness is definitely not as good as that of fresh fruit. If you want to increase the taste of yogurt, you might as well cut the fruit into pieces and make yogurt at home.

13. The thicker the yogurt, the better.

Many consumers think that the thicker the yogurt, the better, but in fact, many very thick yoghurts just add various thickeners, such as hydroxypropyl distarch phosphate, pectin, gelatin and so on. Too much thickener can satisfy the taste, but it is not good for the body.

Drink a large cup of yogurt (about 200ml) and eat a whole wheat bread/a bowl of oatmeal. Buy low-sugar yogurt or low-fat yogurt (fat content 1.0~ 1.5%). If not, use protein content >; 2.3% ordinary yogurt doesn't matter. Be careful not to buy anything with protein content > 1.0%, which is not real yogurt.

Matters needing attention in drinking yogurt

1. No fruit can be added to all yogurts, let alone fruit yogurts.

2. If the temperature of heated milk is too high, it will kill lactic acid bacteria in yogurt, leading to fermentation failure. Too low a temperature will cause slow fermentation, so don't burn it to the touch (microwave heating often causes uneven heating, so stir it with a spoon and try the temperature again).

3. Don't use the heat preservation file of the rice cooker for fermentation, because the heat preservation temperature is too high, and the rice cooker must be powered off during heat preservation fermentation. If you make yogurt in winter, you can put the porcelain cup on the heating for fermentation.

4. It is best to use a porcelain cup with a lid or a hard plastic cup for fermentation containers, but if the quality of the cup is not up to standard, it will be easily deformed when heated and disinfected. Cover is very important, lactic acid bacteria are anaerobic, and anaerobic environment is more conducive to fermentation.

5. It is best not to use disinfectants for disinfection of containers, because not cleaning will kill lactic acid bacteria and make fermentation fail. Heating disinfection is the safest method.

6. There are also anti-milk (including antibiotics) or reduced milk (milk reduced by milk powder) that are not suitable for cooperative production of yogurt.

7. Due to the unstable quality, the strain yogurt occasionally leads to fermentation failure. In order to ensure the quality of yogurt, you can go to the pharmacy to buy some golden bifid as pure strains.