Introduction:
Soycheese, also known as fermented bean curd, is one of the famous fermented foods in China, which has a production history of thousands of years. There are different products in different places, which are delicious, unique and nutritious. They are mainly made of soybeans, which are refined through soaking, pulping, blank making, bacteria cultivation, preserved embryos, ingredients and jar fermentation.
1. Fermentation types of sufu
According to the production technology, there are four types of fermented sufu: ① pickled sufu; ② Mucor sufu; ③ Rhizopus sufu; ④ bacterial sufu.
1, pickled sufu: After the bean curd is boiled with water, it is salted, put in a jar and added with auxiliary materials, and fermented into sufu. This processing method is characterized in that the tofu blank is directly put into the jar without fermentation (no pre-fermentation), and then fermented, and matured by microorganisms brought in by auxiliary materials. Its disadvantages are insufficient protease, long fermentation time, low amino acid content and poor color and fragrance, such as Sitangchang sufu and Hunan Zili mildew-free sufu.
2. Mucor fermented bean curd: Mucor is cultured with bean curd blank, which is called pre-fermentation, so that white hyphae grow all over the surface of bean curd blank, form tough skin film and accumulate protease, creating conditions for post-fermentation of pickling and canning.
The growth temperature of Mucor is low, and its optimum growth temperature is about 16℃. Generally, Mucor sufu can only be produced under the condition of low temperature in winter. Traditional technology uses Mucor in the air to inoculate naturally, which takes about10-15 days (suitable for family workshop production). You can also cultivate pure Mucor, inoculate artificially, and culture at15-20℃ for 2-3 days.
3. Rhizopus-type fermented bean curd: It can be produced by using high-temperature resistant Rhizopus after pure bacterial culture and artificial inoculation, but Rhizopus is thin and light gray, with low protease and peptidase activities, and the shape, color, flavor and physical and chemical quality of fermented bean curd produced are not as good as Mucor's.
Combined with the above advantages and disadvantages, through experiments, fermented bean curd with mixed strains can not only increase its flavor. It can also reduce the amount of liquor in the auxiliary materials, reduce the cost and improve the economic benefit. The best ratio of Mucor to Rhizopus chinensis is 7: 3.
Second, the strain culture method
1, test tube slant inoculation medium: maltose 15g peptone 1.5g agar 2g water 100mlPH6.
You can also use potato culture medium: listen to the potato, peel it, weigh 20g and cut it into small slices, add water to boil for15-20min, filter with gauze, remove the residue and take the filtrate, add water to 100ml, add 2g agar, add 2g glucose after boiling, mix well, and sub-package the test tube (the volume of test tube is/kloc-0).
2. culture medium for triangular flask: bran 100g peptone 1g water 100ml, dissolve peptone in water, then mix it with bran, put it into triangular flask, put 50g culture material in 500ml triangular flask, plug it with cotton plug, shake it while it is hot after sterilization, cool it, and inoculate a small piece of test-tube strain, 25-28.
Equipment used: high-pressure sterilization pot wall temperature incubator clean bench ... sterilization conditions: high-pressure sterilization pot, 0. 1Mpa sterilization for 45-60 minutes.
Third, the brewing process of sufu
Tofu blank making → pre-fermentation → post-fermentation → canning (or bottling) → finished product.
Making bean curd blank: Making bean curd blank is the basis of improving the quality of fermented bean curd. The making of bean curd blank is the same as ordinary bean curd, except that the bittern is a little older, the pressing time is longer and the water content of bean curd blank is lower.
The production of bean curd blank is divided into: soaking beans, grinding, filtering residue, ordering, squatting, pressing and shaping, cutting into pieces and other processes.
(1) Soaking of soybeans: The water temperature, time and water quality of soaking beans will all affect the quality of soaking beans. The water temperature of soaking beans should be below 25℃, and the temperature is too high, which makes the soaking water easy to turn sour, which is not good for extracting soybean protein. In summer, the temperature is high, so it is necessary to change the water several times to reduce the temperature.
(2) Squeezing and dicing: After squatting, the bean curd flower sinks and the yellow slurry water is clarified. It is advisable to squeeze the bean curd blank with water content of 65-70% and uniform thickness, and cut it into (4×4× 1.6㎝) small pieces after squeezing.
Pre-fermentation: Pre-fermentation is a moldy process, that is, the process of cultivating Mucor or Rhizopus in tofu blank. As a result of fermentation, tofu blank is covered with hyphae, forming a soft, fine and tough skin film and accumulating a large amount of protease, so that protein can be slowly hydrolyzed in the later fermentation. Besides selecting excellent strains, we should master the growth law of Mucor and control the conditions such as culture temperature, humidity and time.
(1) Inoculation: Put the diced tofu blank into a steamer grid or a wooden frame bamboo chassis. The tofu blank should be placed on the side, leaving a space (about 1㎝) between rows, so as to ventilate and dissipate heat, adjust the temperature, and be beneficial to the growth of Mucor. Add 400ml of cold boiled water to each triangle bottle, break the mycelium with a bamboo stick, shake it thoroughly, filter it with gauze, wash the filter residue with 400ml of cold boiled water again, filter, and mix the filtrates twice to make spore suspension. Spray inoculation can be used, or tofu blank can be dipped in bacterial liquid and taken out immediately after soaking to prevent water from soaking into the blank and increase water content to affect the growth of Mucor. Generally 100㎏ bean curd blank is inoculated with two triangular bottles of seed liquid. In high temperature season, a little vinegar can be added to the bacterial liquid to make the bacterial liquid sour (PH4) and inhibit the growth of miscellaneous bacteria. Or inoculate that grown bran koji, drying at low temperature and grin into bacterial powder, and sieving the dried bacterial pow on the bean curd blank with a fine sieve, wherein the bacterial powder is required to be uniform on each side, and the inoculation amount is 1% of the soybean weight. Family workshop production can also directly use Mucor and Rhizopus in the air for natural inoculation, but it requires a clean, well-controlled natural culture room.
(2) culture: stack the culture plates on top of each other, cover them with an empty plate, and keep them moist with wet cloth. In spring and autumn, the temperature is generally around 20℃, and the culture lasts for 48 hours. In winter, the temperature is kept at room temperature 16℃, and the culture lasts for 72 hours. In summer, the temperature is high, and the room temperature is 30℃, and the culture lasts for 30 hours. (If natural inoculation is adopted, the required time is longer, and it is about10-15 days in winter). The fermentation termination depends on the maturity of Mucor. Generally, it is milder when producing green square, and it can be done when the mycelium grows into white cotton wool. At this time, the protease activity of Mucor has not reached the peak, and the protein decomposition will not be too strong, otherwise it will lead to the breaking of tofu (because of the late fermentation of stinky tofu) The early fermentation of red sufu is a little older and pale yellow.
The growth and development of Mucor in the early stage of fermentation can be roughly divided into three stages: spore germination stage, mycelium growth stage and spore formation stage. (Note: When the surface of the bean curd blank begins to grow hyphae, that is, after the hairy hyphae grow, the cage should be turned over, usually about three times.)
(3) Pickled blank: When the hyphae begin to turn pale yellow and a large number of grayish brown spores are formed, it is possible to loosen the cage, open the window for ventilation, cool the flowers, stop the mildew and promote Mucor to produce protease, end the early fermentation after 8-10 hour, and immediately rub the hair and pickle. In the process of pickling, first separate the hyphae which are connected with each other, and wipe them by hand to wrap the bean curd blank, and then put them into a vat for pickling. A circular wooden board with a hole diameter of about 15㎝ in the middle is attached to the underside of the vat, and the blanks are placed on the wooden board and arranged to the center along the wall of the vat, so that they should be closely arranged with each other. Attention should be paid when pickling the blank. The blank was marinated by adding salt in layers, and the salt content was increased in layers. Finally, a layer of covering salt was sprinkled. Salt is 6㎏ in spring and autumn, 5.7㎏ in winter and 6.2㎏ in summer per thousand billets (4×4× 1.6㎝). The curing time is about 7 days in winter, 5 days in spring and autumn and 2 days in summer. The content of NaCl in the cured blank is required to be12-14%, and the blank should be pressed 3-4 days after curing, that is, salt water should be added and the blank surface should be cured for about 3-4 days. After the pickling is finished, open the through hole at the bottom of the tank, let out salt water and leave it overnight to make the salt blank dry and shrink.
Late fermentation
Post-fermentation is a process of maturing fermented bean curd by using Mucor growing on bean curd blank and various microorganisms in ingredients, and forming color, fragrance and taste, including canning, soup filling and storage.
(1) Take out the salt blank from the jar, drain the salt water, and put it into the jar with a few points. When filling, it should not be too tight. After the later fermentation is not affected, the fermentation is incomplete, and there is a sandwich in the middle. Arrange the salt blank in turn, flatten it by hand, add ingredients in layers, such as a little red yeast, flour koji and red pepper powder, and fill it with soup.
(2) The ingredients are poured into the jar or bottle. The amount of the filling depends on the variety you need, but it should not be too full to avoid the fermented soup pouring out of the jar or bottle.
The preparation of sufu soup material, due to different ingredients, forms various varieties and flavors of sufu.
Red bean curd soup: red koji 3㎏, flour koji 1.2㎏, yellow rice wine 12.5㎏, soaked for 2-3 days, ground into slurry, and then added with yellow rice wine 57.8㎏ and white sugar 4㎏. Add curved surface 150g, lotus leaf1-2, cover salt 150g and cover shochu 150g in sequence. Production technology of monascus: Because the production technology of monascus is quite complicated, it is not suitable for family workshop production, and it is generally available in the market, so I will not discuss it in detail here.
Soup material of Qingfang sufu: 450g of cold boiled water and 75g of yellow serous water, supplemented by maohua halogen and salt water, the concentration used is about 8%, and 50g of cover shochu is added to each jar.
White bean curd soup base: Rice wine with 12 degree is prepared with 16% salt water as soup base (the amount of wine is generally 2-4%), and a little yellow slurry water can be added to enhance the flavor in the high temperature season.
Spicy bean curd soup: 1 1000 pieces of 46-degree shochu 9㎏, Chili powder 0.9㎏, 12-degree sweet wine/kloc-0 ㎏, red yeast 1㎏, sugar.
Preparation of ingredients: a unique mixed spice is used, and the proportion of the mixed spice is: 1㎏ In the mixed spice, 0.20㎏ of galangal and 0.50 ㎏ of chilli powder (the chilli powder requires fine quality without mildew). 0. 12㎏ Zanthoxylum bungeanum, 0.04㎏ Cortex Cinnamomi Japonici, 0.03㎏ Glycyrrhrizae Radix, 0.03㎏ Sesame (it is required that Zanthoxylum bungeanum, Cortex Cinnamomi Japonici, and Glycyrrhrizae Radix are dried and ground before adding), and 0.000% sugar. Mix all the above ingredients together and mix well. Add a little boiling oil or white wine, or add some yellow syrup to adjust the humidity.
(3) Seal the jar, store it, fill it with soup and cover it (it is recommended to use a porcelain jar and add one or two washed and dried lotus leaves at the bottom of the jar, and then cover the jar with lotus leaves), and then seal it with cement or pig blood mixed with cooked gypsum. It usually takes more than 3 months to reach the quality of sufu when it is stored at room temperature, and it takes only 1~2 months for Qingfang and Baifang sufu to mature because of their high water content.
Precautions: The jar should be sterilized by boiling water, and then it can be put into the jar after cooling to room temperature.
Quality requirements of tofu milk
According to the ministerial standards SB-80 Quality Standard of Red Sufu, SB76-80 Quality Standard of White Sufu, SB77-80 Quality Standard of Green Sufu and the national food hygiene standard GB2712-81Hygienic standard of fermented bean products.
1, sensory index
* * * Same index: delicious taste, salty and palatable, no peculiar smell, neat and uniform block shape, delicate texture and no impurities.
Red fermented bean curd: the surface is red or jujube red, and the inside is apricot yellow, with fat and wine fragrance.
White sufu: milky yellow, with the unique aroma of white sufu.
Green sufu: bean blue, with a special aroma of green sufu.
2. The approximate value of microbial indicator coliforms (one/100g) is less than 30.