How does liquid milk become solid cheese? This is a rather complicated process.
There are several key links here.
Filtering and sterilizing milk, adding starter, adding chymosin, cutting, fermenting, molding and aging, and cheese.
New fresh milk must be filtered and disinfected first.
The key is to close the raw materials, filter and sterilize them. Filter out impurities and kill pathogenic bacteria and harmful bacteria in milk through sterilization.
Sterilization at low temperature for a long time is generally adopted in production, and the temperature is controlled at 63.5℃ for 30 minutes.
The heating of milk can be exquisite, but direct heating is not. You must use a special cheese jar.
Because milk is other milk, such as protein, direct heating is easy to denature and paste in protein. Protein burns directly above 120 ~ 130℃. This tank is an interlayer, which heats the medium in the interlayer, and the medium is water. Heat the water first, then the milk.
Using water bath heating, milk is heated more evenly, which can effectively reduce the loss of protein in milk.
Cheese processing requires milk to have a certain acidic environment. So how do you make the solution sour? This depends on fermentation.
Fermentation uses lactic acid bacteria to decompose lactose in milk into lactic acid, which gradually forms an acidic environment with the accumulation of lactic acid, creating conditions for protein transformation; In the past, liquid microbial agents were mostly used in production, so it was difficult for farmers to master the strains manually. It is much easier to use direct pouring solid starter now.
Using solid starter is as convenient as adding salt in cooking. According to a certain amount (14U/ 100 kg milk), put it directly into a cheese tank and stir it evenly. The favorite temperature of lactic acid bacteria is 30℃ ~ 32℃.
At this temperature, lactic acid bacteria are extremely active. It only takes 1 ~ 2 hours, and the acidity of milk rises to about 0.2%. At this time, the milk began to solidify. So how to speed up this process?
Chymosin is equivalent to the "catalyst" of milk coagulation, and there are many kinds of chymosin.
Usually this piece is made of animal chymosin. Where did you extract it? It is extracted from the stomach of a calf.
Milk in liquid state becomes solid cheese, and chymosin plays an important role.
Protein in milk is 80% casein, which becomes paracasein under the action of chymosin, and paracasein forms micelles, which combine with fat to form a network structure with the participation of calcium ions. When they are big enough, they will condense into lumps.
When chymosin is used, it should be dissolved with 1% physiological saline, and the amount of chymosin is 0.02 ~ 0.06g/L milk. Pay attention when adding cheese cans.
Try to avoid mixing air when adding. Generally, when we add it, we pour it gently and low along the edge of the curd trough.
After adding chymosin, stir for 3 minutes to disperse it evenly, and then let it stand for 30 minutes. The seemingly calm milk has undergone qualitative and structural changes.
Milk solidifies quickly and has a certain hardness, but the clot still contains a lot of water, so we have to find a way to separate the water. Cutting should be a good way.
Cutting is to cut a large clot into small pieces with a special tool, that is, to promote the shrinkage of the clot and the seepage of water through physical methods.
The specific method is to cut along the long axis of the cheese can first, and then switch positions to cut along the short axis. When cutting, the action should be light and steady to prevent the clot from being too broken and uneven, which will affect the quality of cheese. Cut it into cubes as much as possible, with a side length of 7 ~ 10 mm, which is more conducive to the drainage of the network structure and is natural.
In order to speed up this process, it is necessary to stir continuously after cutting. At this time, the temperature should be raised from 30℃ to 40℃ ~ 42℃. It should be noted that the heating rate should not be too fast, and it is more appropriate to heat up 1℃ every 3 ~ 5 minutes.
Blood clots are getting smaller and smaller, a bit like tofu brain, and more and more water is oozing out. How to drain this water? This also requires special tools.
Squeeze it gently to the other side with a knife with eyes, and the water will be discharged from this side.
At this time, the clot is still soft and looks a bit like a big piece of tofu, and the water inside needs to be further separated. We must continue to brew.
Cut the whole block into small pieces with a cutter, turn it regularly at a certain temperature, and the water will seep out further. This process is called composting. In the process of fermentation, the texture of the clot has also changed, becoming more tough, a bit like good white flour. This fermentation takes about 1 hour.
On the basis of fermentation, in order to form a special flavor, there is a unique process in processing mozzarella cheese, which is stretching.
During the stretching process, the texture of protein is made to have a chewy feeling similar to that of meat, and the milk flavor is thickened.
To put it bluntly, after stretching, cheese will become more chewy and chewy. At this time, you can finalize the design and mold installation.
In order to be beautiful and easy to store, the stretched clothes need to be shaped. Knead the stretched clots into dough, put them into a cheese mold, compact them, and cut them into pieces and vacuum package the next day.
However, cheese can't be sold at this time. Cheese, like wine, has an aging process, which is technically called aging process.
At the temperature of 65438 00℃ and humidity of 85%, a large number of probiotics in cheese still remain active in this storage environment.
After ripening, the macromolecular substances inside are decomposed into small molecular substances, which are more easily digested and absorbed by the human body. Moreover, after ripening, its flavor, unique milk flavor and unique flavor substances can be better displayed.
The ripening time of different cheese varieties is different. For example, it takes about 1 ~ 2 weeks for mozzarella cheese and about 1 month for cheddar cheese to be stored.