The production of curd:
1, the experimental principle:
(1) microorganisms involved in the fermentation of tofu are Penicillium, yeast, Aspergillus, Trichoderma, and many other kinds of microorganisms, of which Trichoderma plays a major role.
(2) Trichoderma is a filamentous fungus, commonly found in soil, fruits, vegetables, grains, with developed white mycelium.
(3) Proteases produced by microorganisms such as Trichoderma can break down the proteins in tofu into small molecules of peptides and amino acids; lipase can break down fats into glycerol and fatty acids.
2, the experimental steps
(1) The tofu was cut into a number of blocks of 3cmtimes; 3cmimes; 1cm. The water content of the tofu used is about 70%, too much water is not easy to form curd.
(2) the tofu block is placed flat on the disk covered with dry rice dumpling leaves, rice dumpling leaves can provide strains, and can play the role of heat preservation. Each block of tofu is discharged equidistant from each other, leaving a certain amount of space around it. Top the tofu with clean rice dumpling leaves. When the climate is dry, the flat plate will be wrapped in plastic wrap, but do not seal tightly, so as not to be too high humidity, not conducive to the growth of hairy mold.
(3) Put the flat disk into a place where the temperature is maintained at 15 to 18℃. Trichoderma grow gradually, about 5d after the surface of the tofu clustered with erect mycelium.
(4) When the hairy mold grows vigorously and is light yellow, remove the plastic wrap wrapped around the flat plate as well as the rice dumpling leaves spread on it, so that the heat and moisture of the tofu block can be quickly dissipated, while dispersing the moldy smell. This process generally lasts more than 36h.
(5) When the tofu is cool enough to handle, the mycelium connected between the tofu is pulled off and neatly arranged in a container ready for pickling.
(6) full of hairy mold tofu block (hereinafter referred to as blank) and salt mass fraction ratio of 5:1. will cultivate blank near the flat plate did not grow upright mycelium side uniformly towards the side of the glass jar, will be arranged in layers of blank plate upright in the container. Add salt in layers, and increase the amount of salt as the layers get higher, and spread the salt thicker on the surface of the bottle mouth to prevent stray bacteria from entering through the bottle mouth. About 8d.
(7) will be yellow wine, rice wine and sugar, according to different tastes and with a variety of spices (such as pepper, pepper, aniseed, cinnamon, ginger, chili pepper, etc.) mixed to make brine soup. Halogen soup alcohol content control in about 12% is appropriate.
(8) will be wide-mouth glass bottles brush clean, steam sterilized with an autoclave at 100 ℃ for 30 min. curd salted blanks arranged into the bottle, add brine broth and auxiliaries, the mouth of the bottle heated with an alcohol lamp sterilized with adhesive tape seal. At room temperature, generally six months can be mature.
Knowledge Points:
1, when pickling with salt, pay attention to the amount of salt are. Salt concentration is too low, not enough to inhibit the growth of microorganisms, may lead to tofu * spoilage; salt concentration is too high, will affect the flavor of curd.
2, the level of alcohol content and the late fermentation of curd has a great relationship with the length of time. The higher the alcohol content, the greater the inhibition of protease, so that the curd maturation period is prolonged; alcohol content is too low, protease activity is high, accelerate the hydrolysis of proteins, the rapid reproduction of stray bacteria, the tofu is easy to *, it is difficult to form blocks.
3, in the marinating process of bean curd milk, the role of salt: salt can not only prevent the tofu *, but also with the decomposition of the formation of amino acids combined into sodium amino acids, so that bean curd milk taste delicious.
4, tofu milk before and after the production of temperature and air conditions: the pre-production of tofu milk temperature control in the 15 ℃ ~ 18 ℃ environmental conditions, because mold is an aerobic micro-organisms, and therefore placed in the air can be; tofu milk in the late production of temperature control in the conditions of 30 ℃ and to be put into the altar to seal the mouth of the altar.
5, in the late production of bean curd milk, can prevent the growth of stray bacteria, conducive to the later maturation of the factors: salt in the marinade, brine broth in the wine, spices, as well as the altar disinfection, altar sealing with an alcohol lamp flame to deal with the altar mouth, etc., have inhibited the growth of microorganisms.
6, factors affecting the quality of curd
(1) salt: full of hairy moldy tofu block (blank) and salt mass fraction ratio of 5:1, salt concentration is too high, affecting the taste, the concentration is too low, not enough to inhibit the growth of microorganisms, curd is easy to * spoilage.
(2) wine: the preparation of the brine soup needed to make curd should be added to the appropriate amount of wine (about 12%), the purpose is to inhibit the growth of microorganisms, too little alcohol can not achieve the purpose, too much will inhibit enzyme activity, affecting the ripening of the curd, and at the same time, affect the flavor of the curd.
(3) Spices: have the role of flavoring and sterilization, thus affecting the flavor or quality of curd.
(4) Temperature of fermentation: The temperature of pre-fermentation should be kept at 15-18°C for a certain period of time to facilitate the growth of hairy molds.
Knowledge Expansion:
1, the main production process of brewing curd is the pre-fermentation and post-fermentation of tofu. The main change that occurs in the pre-fermentation is the growth of mold in the tofu (white blank). Fermentation temperature of 15 ~ 18 ℃, this temperature is not suitable for bacteria, yeast and Aspergillus growth, but suitable for mold growth slowly. Trichoderma growth about 5d after the white blank into blank. The role of pre-fermentation, one is to make the surface of the tofu has a layer of fungal film encapsulated, the formation of fermented bean curd "body"; Second, Trichoderma secretion of protease-based enzymes, which is conducive to the hydrolysis of tofu contains proteins into a variety of amino acids. Post-fermentation is mainly enzymes and microorganisms synergistically involved in the biochemical reaction process. Through pickling and with a variety of auxiliary materials (red, noodles, wine), so that the role of protease slow, to promote other biochemical reactions, to generate the aroma of curd.
2, Trichoderma is a kind of low-grade filamentous fungi, with multiple nuclei, asexual reproduction. Trichoderma is an important microorganism in the food processing industry, it can produce protease that can break down soy protein, commonly used in the production of curd and tempeh.
Related high school biology knowledge: the production of fruit wines and fruit vinegars.