How is curd milk made?

The production process of bean curd milk

Overview:

Bean curd milk (Soycheese), also known as curd, is one of China's famous specialty fermented foods, has been thousands of years of production history. All over the world have different characteristics of the product, is a delicious taste, unique flavor, nutrient-rich food, mainly soybean as the willing material, after soaking, grinding pulp, billet making, cultivating bacteria, pickling embryo, ingredients, altar fermentation and refined.

One, the fermentation type of curd

Based on the production process, there are four types of fermentation of curd: ① pickled curd ② hair mold curd ③ root mold curd ④ bacterial curd.

1, pickled curd: tofu billet boiled with water, salt pickling, altar add accessories, fermentation into curd. This processing method is characterized by: tofu blank without fermentation (no pre-fermentation) directly installed altar, post-fermentation, relying on auxiliary materials brought into the microbes and mature. The disadvantages are insufficient protease, long post-fermentation time, low amino acid content, poor color and flavor, such as four Tangchang curd, Hunan Zili mold-free curd.

2, moldy curd: tofu blank culture mold, called pre-fermentation, so that the white mycelium grows all over the surface of the tofu blank, the formation of a tough film, the accumulation of protease, for the curing altar to create conditions for the late fermentation.

The growth of mold requires a lower temperature, its optimal growth temperature of about 16 ℃, generally only in the winter under the conditions of lower temperatures in the production of moldy curd. The traditional process uses the air in the hairy mold fungi, natural inoculation, need to be cultivated for about 10-15 days (suitable for home workshop production). You can also cultivate pure species of Trichoderma, artificial inoculation, 15-20 ℃ under the cultivation of 2-3 days can be.

3, root mold type curd: the use of high-temperature resistant root mold fungi, pure bacteria culture, artificial inoculation, in the summer high-temperature season can also produce curd, but the root mold filaments sparse vegetables, light gray, protease and peptidase activity is low, the production of curd, the shape, color, flavor and physicochemical quality is not as good as the hairy mold curd.

Combined with the above advantages and disadvantages, after experimentation, the use of mixed strains of bacteria brewing tofu milk, not only can increase its flavor. Can also reduce the amount of white wine in the auxiliary materials, reduce costs, improve economic efficiency, the proportion of mold and Huagan mold 7:3 is the best.

Two, strain culture methods

1, test tube slant inoculation medium: caramel 15g peptone 1.5g agar 2g water 100ml PH6

You can also use the potato medium: the potato washed ears listen to the net, peeled, weighing 20g cut into small slices, add water and boil 15-20 minutes, gauze filtration, deslagging to filter juice, add the water, and then add the water. The filter juice, take the slag, add water to supplement to 100 ml, add agar 2g, after boiling dissolved add glucose 2g mix well, divided into test tubes (loading for the test tube 1/5) plugged with cotton plugs, bandaged and sterilized, set into a slant, inoculated with Trichoderma (or root mold) 15-20 ℃ (root mold 28-30 ℃) culture for 3 days or so, that is, for the test-tube Strain of bacteria.

2, triangular bottle strain medium: bran 100g peptone 1g water 100ml, peptone dissolved in water, then mixed with bran, loaded into a triangular bottle, 500ml triangular bottle containing 50g of culture material, plugged with cotton plugs, sterilized and shaken while hot, cooled access to a small piece of test-tube strains, 25-28 ℃ culture, 2-3 days after the full-grown mycelia. -3 days after the full-grown mycelium with a large number of spores standby.

Equipment used: autoclave sterilization kettle wall temperature incubator ultra-clean workbench ... Sterilization conditions: autoclave, 0.1Mpa sterilization 45-60 minutes

Three, curd brewing process

Tofu billet production

Tofu billet production

Tofu billet production: the production of good tofu billet is to improve the quality of the foundation of the curd, tofu billet production is the same as the ordinary for tofu, just point of the marinade to be a little older, the pressing time is a little longer, the tofu billet production is the same as ordinary for tofu, just point of halogen to be slightly older, the pressing time is a little longer. It is the same as ordinary tofu, except that the marinade should be a little bit older, the pressing time should be longer, and the water content of the tofu should be a little bit lower.

The production of tofu blank is divided into: soaking beans, grinding pulp, filtering residue, spotting pulp, squatting brain, pressing and molding, cutting blocks and other processes.

(a) soybean soaking: soaking water temperature, time, water quality will affect the quality of soaking beans. Soaking water temperature should be below 25 ℃, the temperature is too high, so that the soaking water is easy to become acidic, the extraction of soybean protein is not favorable, the summer temperature is high, to change the water several times to reduce the temperature.

(ii) pressing and block cutting: squatting brain after the tofu flower sinking, yellow pulp water clarification. It is suitable to press the water content of the tofu blank at 65-70% and the thickness is even, and cut it into small blocks (4×4×1.6㎝) after pressing and molding.

Pre-fermentation: Pre-fermentation is the process of mold, that is, tofu billet cultivation of mold or root mold process, the result of fermentation is to make tofu billet full of mycelium, the formation of soft, fine and tough film and accumulated a large number of proteases, so that in the late fermentation of the protein will be slowly hydrolyzed, in addition to the selection of good strains of fungi, but also to master the growth of the growth of the law of mold, and to control the cultivation of the temperature, humidity, and time, and other conditions. conditions.

(1) inoculation: the block of tofu billet into the steamer frame or wooden frame bamboo tray, tofu billet needs to be placed on the side, between the rows to leave a space (about 1㎝ or so), in order to ventilate and dissipate heat, regulate the temperature, and is conducive to the growth of the mold fungus. Add 400ml of cold boiled water to each triangular bottle, break the mycelium with bamboo stick, shake well, filter with gauze, add 400ml of cold boiled water to wash the filter residue, filter, mix the two filtrates, and make spore suspension. Spray inoculation can be used, you can also dip the tofu billet dipped in the liquid, immediately after dipping, to prevent moisture from soaking into the billet, increasing the water content affects the growth of mold. General 100 kg soybean tofu billet inoculation of two triangular bottles of seed liquid, high temperature season, you can add a little vinegar in the liquid, so that the liquid becomes acidic (PH4) to inhibit the growth of stray bacteria. Or the growth of good bran inoculation, low-temperature drying and grinding into fine powder, with a fine sieve will be dry powder sieve in the tofu blanks, the requirements of uniformity, each side of the powder, inoculation amount of 1% of the weight of soybeans. (Home workshop type production can also be used directly in the air of Trichoderma and Rhizopus for natural inoculation, but requires a clean, the temperature is more Waki and good control of the natural culture room).

(ii) culture: the culture plate stacked high stacked, covered with an empty plate, surrounded by wet cloth moisturizing, spring and fall generally at about 20 ℃, culture 48 hours, winter room temperature 16 ℃, culture 72 hours, summer temperature, room temperature 30 ℃, culture 30 hours. (Such as natural inoculation, the time required for some longer, about 10-15 days in winter) the termination of fermentation depends on the degree of maturity of the mold fungi, the general production of green square mold is a little more tender, when the mycelium grows into a white cotton wool can be, at this time, mold protease activity has not yet reached the peak of the proteolytic effect of protein decomposition will not be too exuberant, otherwise it will lead to tofu broken (due to the stink of tofu late) (because the late fermentation of stinky tofu is more intense). Red curd pre-fermentation to be slightly older, light yellow.

Pre-fermentation hairy mold growth and development changes are roughly divided into three stages: namely, spore germination stage, mycelium growth stage, spore formation stage. (Note: when the surface of the tofu billet began to grow mycelium, that is, after the growth of plush mycelium, to turn the cage, generally three times or so)

(3) pickled billet: when the mycelium began to turn pale yellow, and a large number of gray-brown spore formation, this is to be scattered cage, open the window and ventilation, cooling cool flowers, to stop mold, and to promote the production of protease trichothecenes, 8-10 hours after the end of the pre-fermentation. 8-10 hours after the end of the pre-fermentation, immediately rubbed hair pickling. In the process of pickling, firstly, separate the mycelium which is attached to each other and wipe it by hand to wrap the tofu billet, and put it into the vat for pickling, and then supplement a round board with a hole in the middle of about 15cm in diameter about 20cm from the bottom of the vat, and then put the billet on the board, and then line up the billet along the wall of the vat to the center, and line up the billet tightly with each other, and pay attention to make the side which has not grown the mycelium leaning against the edge when pickling the billet, and don't face the down, and prevent the finished product from being shaped. The use of layered salt method of pickling blanks, the amount of salt increased in layers, and finally sprinkle a layer of cover salt. Every thousand blanks (4×4×1.6cm) use 6㎏ of salt in spring and fall, 5.7㎏ of salt in winter, and 6.2㎏ of salt in summer. The pickling time is about 7 days in winter, 5 days in spring and fall, and 2 days in summer. The NaCl content of pickled billet is 12-14%, after 3~4 days of pickled billet, it should be pressed billet, that is to say, add brine again, pickle over the surface of billet, the pickling time is about 3-4 days. After the end of pickling, open the bottom of the tank through the mouth, release the brine and leave it overnight to make the salt billet dry and shrink.

Post-fermentation

Post-fermentation is the process of using the hairy molds growing on the tofu blanks and various microorganisms in the ingredients to make the curd mature and form the process of color, aroma, and taste, which includes the processes of loading the altar, filling the soup, and storing.

(a) load the altar to take out the salt billet, drain the brine, points loaded into the altar, loaded can not be too tight, by avoiding the impact of the late fermentation, so that the fermentation is not complete, there is a sandwich in the middle of the salt billet in order to arrange, flatten the hand, add ingredients in layers, such as a small amount of red currant, noodle currant, paprika, full of filling into the soup.

(2) ingredients filling soup with good soup filling into the altar or bottle, the amount of filling depending on the variety you need, but should not be too full, so as not to ferment the soup material gushed out of the altar or bottle outside.

The preparation of curd soup, due to the different ingredients, the formation of curd a variety of varieties and flavors.

Red Square Curd Soup Ingredients: 3㎏ of red curd, 1.2㎏ of noodle curd, 12.5㎏ of yellow wine, soak for 2-3 days, add 57.8㎏ of yellow wine and 4㎏ of white sugar after grinding into pulp. Add 150g of curved surface, 1-2 lotus leaves, 150g of cover salt, 150g of cover shochu in the order. the production process of red wine: Because the production process of red wine is quite complicated, it is not suitable for the family workshop production, generally available in the market, so we won't discuss it in detail here.

The green side of the curd soup: 450g of cold boiled water, 75g of yellow slurry water, and then hair flower brine and brine to make up for the concentration of about 8%, each altar plus cover shochu 50g.

White side of the curd soup: 16% of the brine with 12 degrees of rice wine as a soup (the amount of wine is generally 2-4%) in the season of higher temperatures can be added to add a little bit of rice wine to increase the temperature. Add a little yellow syrup water to increase the flavor.

Spicy Square Curd Soup Ingredients: 1,000 pieces of 46-degree shochu 9㎏, chili powder 0.9㎏, 12-degree sweet wine 10㎏, 1㎏ of red wine, 1.2㎏ of sugar, 10g of monosodium glutamate (MSG).

Preparation of Ingredients: Unique Mixed Aroma Spice Seasoning is used, which is mixed as follows: 1㎏ of Mixed Aroma Spice, 0.20㎏ of ginger, chili powder (1㎏), 1㎏ of chili powder (1kg), 1kg of ginger, 0.20㎏ of chili powder (1kg), 1kg of chili powder (1kg), 0.20㎏ of chili powder (1kg). chili powder (chili powder requires fine and no mold, top quality) 0.50㎏, 0.12㎏ pepper, 0.04㎏ dingpi, 0.04㎏ cinnamon, 0.03㎏ licorice, 0.03㎏, sesame 0.03㎏ (requires pepper, dingpi, cinnamon, licorice kunhap to be added after drying and grinding), 0.04㎏ sugar (such as the use of the soup is a spicy side of fermented bean curd soup may not be added), 0.02㎏ monosodium glutamate (such as the use of soup is a spicy side of fermented bean curd soup may not be added), 0.02㎏ MSG (such as the use of soup is a spicy side), 0.02㎏ MSG (such as the use of soup is a spicy side of fermented bean curd soup may not be added). MSG 0.02㎏ (if the soup is spicy curd soup, it can not be added). The above ingredients are mixed together and mixed well, add a little hot boiling oil can be white wine, can also add Xu's yellow pulp water to dampen.

(3) sealing storage altar filling soup after the cover (recommended the use of porcelain altar and the bottom of the altar with one or two washed and cooled dry lotus leaves, and then in the mouth of the altar covered with lotus leaves), and then cement or pig's blood mixed with cooked gypsum sealing. Stored at room temperature, it usually takes more than 3 months to reach the quality that curd should have, while green and white curd need only 1~2 months to mature due to the high water content.

Note: The altar should be sterilized by boiling water and then drained and cooled down to room temperature before it is filled.

The quality requirements of bean curd milk

According to the ministry standard SB-80 "red curd quality standard", SB76-80 "white curd quality standard", SB77-80 "green curd quality standard" and the national food hygiene standard GB2712 -81 Hygienic Standard for Fermented Soybean Products.

1, sensory indicators

***The same indicators: delicious taste, salty and mild, no peculiar smell, neatly shaped, uniform, fine texture, no impurities.

Red curd: red or date-red surface, apricot-yellow interior, with fat and wine aroma.

White curd: milky yellow, with the unique aroma of white curd.

Green curd: bean green color, with special aroma of green curd.

2, microbiological indicators of E. coli group approximate value (个/100g) less than 30.

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Curd (moldy tofu)

Moldy tofu practice 1:

Cut the tofu into 2 cm wide and 1.5 centimeters thick small block, put on the cover curtain to control the water for a day, the block of tofu with a plastic wrap cover to be born red fungus, prepare chili powder, salt, MSG mixing Jun well, will be raw! Red fungus tofu block in the mix of good chili noodles dip two sides on the line, put in the bottle yard neatly, to the bottle to a little white wine sterilization seal, a week later you can eat, a little longer will be more delicious. It should be noted that the production process do not dip oil, easy to break, open the bottle to pour salad oil or sesame oil and air isolation, not easy to bad, try it!

Practice 2:

Do moldy tofu to wheat stalks, summer wheat harvest with a sickle cut down the wheat stalks to the head of the collection, when used to peel off the outside leaves. To the beginning of winter, buy a few pounds of fresh tofu, first cut into small pieces on the pot to steam, or just put in a ventilated place to dry for a few days, if steamed to cool, mainly to remove excess water. Find a cardboard box, a layer of wheat straw a layer of tofu arranged, the top and then cover a layer of wheat straw, placed in about fifteen degrees Celsius temperature fermentation for about five days, see the tofu become red or long fine hair on the line. To pre-blanch the cabbage leaves with boiling water to dry half-dry, peeled on a large bowl of garlic, finely chopped, ready chili powder, pepper, salt, monosodium glutamate (depending on personal taste, almost on the line, ten pounds of tofu about seven, eight taels of salt) and a piece of the fermented tofu into white wine first dip, and then rolled and a piece of the seasoning powder, and then dipped in garlic (garlic is intended to go to the moldy flavor of the tofu), the external The bread on the cabbage, put into the water-sealed altar after three or five days can be eaten. Used to hold moldy tofu altar to be clean, can not have a little water and oil, can not be used to pickle salted duck eggs altar, wash can not be, that can not be too long on the bad, do not know why. When you take it out, you should also pay attention not to bring in water, oil, etc., or it will also be bad. This way out of the tofu and salty and spicy, there is a special flavor, on steamed bread and rice, the more you eat the more addictive.