The basic principle of homemade yogurt is to inoculate lactic acid bacteria into milk and let it reproduce at a suitable temperature (usually 40-42 degrees Celsius). Because of lactic acid, the acidity of milk fermentation broth gradually decreases. When the pH value reaches about 4.6, casein in milk will slowly precipitate and form delicate jelly. Although other miscellaneous bacteria also exist in milk, compared with lactic acid bacteria, the number is too small to become a climate. Antibacterial substances such as lactic acid produced by lactic acid bacteria also make miscellaneous bacteria feel uncomfortable and unable to multiply in large quantities. This ensures the safety of yogurt.
Homemade yogurt is best made by yogurt machine, because it can provide a stable temperature and ensure that lactic acid bacteria, not other miscellaneous bacteria, will multiply in large quantities. The temperature of the yogurt machine is 40-42 degrees Celsius, which is just the best breeding temperature for Lactobacillus bulgaricus and Streptococcus thermophilus used to make yogurt.
2. Is it better to sow with mushroom powder or with commercially available yogurt?
The answer is either. When using bacterial powder, freeze-dried strains can be added to play a role in a warm environment. When using commercially available yogurt, we must pay attention to buying the latest refrigerated yogurt, because with the extension of storage time and the increase of storage temperature, the number of live bacteria will continue to decrease, which will affect the effect of making yogurt. It must be noted that yogurt sold at room temperature should not be used as seeds, because the number of live bacteria has been seriously reduced, and the safety of making yogurt cannot be guaranteed.
3. When buying bacterial powder, do you buy a lot of health bacteria or the simplest two kinds of bacteria?
The basic requirement of yogurt production is to have enough Lactobacillus bulgaricus and Streptococcus thermophilus, and you can buy the powder of two basic bacteria. Other health-care bacteria, such as some strains of Lactobacillus acidophilus, Bifidobacterium and Lactobacillus casei, have been proved to be beneficial to health if they can colonize the human large intestine. But if you need the benefits of these bacteria, the premise is that there are enough live bacteria after fermentation. However, the optimum fermentation conditions of these bacteria are not necessarily the same as those of the above two basic bacteria. Bifidobacterium, in particular, belongs to anaerobic bacteria in the strict sense, that is, they will die at the sight of oxygen. Therefore, it is difficult to get live Bifidobacterium in the process of making yogurt in ordinary families. Therefore, there is no need to expect too much from the healthy bacteria in the strain.
4. If yogurt is made from commercially available yogurt, how much should I add?
Generally speaking, it is appropriate to add about 10% of commercially available yogurt as a strain. For example, fermenting 500 grams of milk and 50 grams (half a cup of small yogurt) is enough. This amount is to make lactic acid bacteria establish an absolute quantitative advantage from the beginning, and have enough ability to suppress other miscellaneous bacteria, even inexperienced people can ensure the success of yogurt production. In industrial production, due to the standard operation, the activity of bacteria is relatively strong, and the amount of bacteria used accounts for 1-2% of fermented milk.
5. Can my own yogurt be used to ferment the next batch of yogurt?
If you make yogurt with the bought strains, you can use it for two or three strains fermentation. If you use yogurt on the market as seeds, use it once or twice at most. When using the last kind of yogurt as a strain, it should be noted that the taste of yogurt must be pure and fresh enough. The taste is pure, which shows that there is not much pollution to other miscellaneous bacteria, and the activity of bacteria in yogurt which is moderately fermented and refrigerated in time and not stored for a long time is still relatively high. The number of lactic acid bacteria will decrease if yogurt is fermented for too long or not refrigerated in time after cooking, or if it is refrigerated for too long. If the taste of yogurt is found to be alcoholic or slightly musty, it means that many miscellaneous bacteria have been polluted and can't be used any more.
6. When making yogurt, does the milk need to be heated in advance?
If it's not the milk just poured out from Tetra Pak, it's best to heat the raw milk to 60-80 degrees Celsius, which will not boil but kill most bacteria, and then lower it to above 40 degrees Celsius (it feels a little hot, but it doesn't feel uncomfortable) before inoculation. The box for making yogurt and the spoon for adding strains should also be scalded with boiling water, or put a spoonful of water in the cup and box for making yogurt, turn it in the microwave oven, and kill the contaminated microorganisms with hot steam to minimize the pollution opportunities of miscellaneous bacteria.
7. Using different milk to make yogurt, the solidification speed is different, and the frozen taste is different. Why?
Similarly, when the protein content of milk is high and the molecular weight is large, frozen yogurt is "firm" and has a large consistency. On the other hand, if the protein content of milk is too low or the molecular weight is small, the freezing conditions will be fragile or even impossible. Milk protein has a large molecular weight. If the molecular weight becomes smaller, it is usually because there are too many microorganisms in the raw milk, so the microorganisms will secrete too much protease. Protease, like scissors, will chop up the macromolecules in protein. If there are too many antibiotics in milk, it is difficult for lactic acid bacteria to multiply quickly, then the freezing speed of yogurt will be very slow, or even difficult to freeze. So in a sense, a kind of milk (regardless of adding thickener) can be made into yogurt quickly, and its consistency is good, which shows that its quality is satisfactory.
8. How to save homemade yogurt after it is made? How long can you keep yogurt that can't be eaten at one time?
Homemade yogurt is best put in the refrigerator in time. If you can't eat it all at once, scoop out a part with a clean spoon every time, and the rest is still in the refrigerator. It is recommended that the storage time should not exceed 3 days.
In fact, in the process of yogurt fermentation, there is a solidification process. Freshly solidified yogurt has the most delicate texture. If you continue to ferment after solidification, you will find that there is water or a small depression on the surface of yogurt, the texture is not so delicate, the acidity is too strong, and the total number of living bacteria is gradually decreasing. Therefore, when making yogurt, we should pay attention to opening and observing it several times. As long as it is solidified, it should be taken out in time and put in the refrigerator for refrigeration. Overnight refrigeration will make yogurt more flavor.
How to choose yogurt
First of all, we should distinguish between Chu yogurt and lactic acid bacteria drinks. Those sour and sweet lactic acid bacteria drinks on the market actually do not contain probiotics at all, and the quality and quantity of probiotics are the standard to measure the quality of a yogurt.
At the same time, it can be seen from the ingredient list of lactic acid bacteria drinks that they are made of water, milk, sugar, citric acid or lactic acid. Generally speaking, when you look at the ingredient list, the ranking order of ingredient names is sorted according to their content from more to less. Yogurt is generally fermented naturally with fresh milk and various probiotics, and contains no preservatives.
Secondly, when we face all kinds of yogurt on the market, we should have the mentality of simplifying the complex. No matter how the merchants give you psychological hints with all kinds of exquisite advertising copy, you should know several basic guidelines for purchasing yogurt, instead of following other people's suggestions. We don't choose expensive ones, we only sell good ones that suit us.
Then, first of all, choose "good bacteria" for yogurt. Good probiotics help to maintain the ecological balance of intestinal flora, form a biological barrier and inhibit harmful bacteria from invading the intestine. Streptococcus thermophilus and Lactobacillus bulgaricus are two commonly used probiotics in yogurt. Some yogurts also add Bifidobacterium, but because Bifidobacterium is anaerobic, it is usually added with the other two bacteria.
After selecting probiotics, we should also "select the amount of bacteria", that is to say, a good yogurt depends on how many probiotics it contains. We should know that the probiotics in a cup of yogurt are all produced and sold in the market, and then after consumers buy it home, the number of probiotics that can survive is a little less, and then after being digested by our bodies, the probiotics that can reach our stomachs are even less. Generally speaking, a cup of yogurt contains 50 to10 billion active bacteria.
The quantity of probiotics is good, but the activity of probiotics is more important. Because only living bacteria have the effect of regulating the stomach. Generally speaking, yogurt needs to be stored in a refrigerator or freezer at 0-6 degrees Celsius to improve the activity of probiotics. Usually, when choosing yogurt, we should focus on the production date and the length of time between the production date and the purchase date. Generally speaking, two to three days is best.
Finally, talk about the problem of old yogurt. I believe everyone has heard of the "old yogurt incident" that happened some time ago. The so-called old yogurt is solidified yogurt, which means adding gelatin, agar, carrageenan and other plant gums to yogurt, which can turn liquid yogurt into solid and make yogurt taste better. In April, 20 12, it was reported that industrial gelatin boiled with a broken shoe was added to the old yogurt jelly, which attracted people's attention.
In fact, as long as you choose the regular products produced by large enterprises, and the gelatin contained in them is extracted from fresh animal skins and aggregates, you can choose such qualified old yogurt. Food additives such as gelatin are properly added to old yogurt to maintain its taste and appearance. Although yogurt is good for your health, you should not eat more. Take it properly, one or two cups a day. And yogurt is best to drink after meals, which helps digestion and improves the survival rate of probiotics. After drinking yogurt, remember to rinse your mouth in time to avoid eroding enamel. When buying yogurt, you should read the nutrition label carefully as needed, choose products with high protein content, and try to buy products of big brands.
Finally, I hope everyone can have a healthy and energetic body!
The efficacy of yogurt
This "milk factor" has the natural function of lowering blood lipid and cholesterol, which hinders the body's absorption of fat. Moreover, yogurt also contains lactic acid, which can effectively inhibit the proliferation of spoilage bacteria in the intestine, inhibit the production of harmful substances, and promote the peristalsis of the intestine, so it has great weight loss and slimming value.
We say yogurt is a good diet food because it is rich in lactic acid bacteria. After entering the intestine, lactic acid bacteria will proliferate Bifidobacterium, inhibit the activity of harmful bacteria, improve the intestinal environment and effectively treat chronic constipation.
Meanwhile, yogurt is also a dairy product. Calcium in dairy products will reduce the amount of parathyroid hormone, thus hindering the activity of enzymes and slowing down the process of fat burning in the body.
Weight loss effect of yogurt
After fermentation, the protein of milk remains, and the content of calcium is not lost. Yogurt has a better calcium supplement effect than other calcium sources. What surprises women who lose weight most is that B vitamins, an important element of burning fat, will increase after fermentation. Yogurt is full, full after drinking, and rich in nutrients, including carbohydrates, fat, protein, and so many vitamins, and the calories are not high, so drinking a small cup before meals can reduce your appetite. You can even fill your hunger with yogurt instead of dinner. Yogurt contains a lot of active lactic acid bacteria and short-chain fatty acids, which can promote intestinal peristalsis, thus treating constipation and losing weight.