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1. Material selection

In some places, in order to produce yuba with a lighter color, soybeans from different origins are used in a certain proportion.

2. Peeling

Most yuba factories do not have their raw materials peeled; however, in most enterprises in Guangdong and Guangxi, their soybeans have undergone the process of peeling. There are 2 yuba villages in the Lingnan area. The drying and peeling of soybeans are almost all processed by professional peeling households, and a processing fee of about 5 yuan is charged for every 50 kilograms of soybeans. The small bean curd factory in Jiangmen area dries the soybeans by the local method. After peeling, the bean kernel and the bean skin are separated by the exhaust fan on the peeling machine, while the small and medium-sized bean curd factories use bucket elevators, which can lift 600-800 kg at a time. The soybeans are transported to the soybean drum dryer for drying, and then transported to the peeling machine for peeling by the bucket elevator. Drying soybeans with special equipment for soybean drying saves fuel and labor, and greatly reduces labor intensity. The grinding wheel of our peeling machine is self-made. The shape of the grinding wheel is horn-shaped. The two adjusted grinding wheels are installed to form a gap from large to small. When working, soybeans enter the center of the grinding wheel, and then go to the grinding wheel. In the process of going out around, the largest soybean first hits the grinding wheel and wipes off the bean skin, then the second largest soybean hits the grinding wheel, and the smallest soybean hits the grinding wheel at the edge of the circumference with the smallest gap between the grinding wheels. The bean skin is wiped off, so our peeling machine can peel the soybean regardless of the size of the soybean, and the peeling rate is the highest. 99% of the yuba factories in Guangxi use my peeling machine. There are many shortcomings in the production of yuba without peeling the soybeans. When the soybeans are soaked without peeling, it can be seen that their soaking degrees are not synchronized. Some are over-soaked, and some are not soaked well. All these bring waste to production and reduce the yield.

After the soybean is dried and peeled, the soaking time of the watercress can be greatly shortened, and the chance of decomposing and destroying the soybean protein by the inherent protease and foreign bacteria of the watercress itself is reduced, so that the product yield is high. Soymilk, soymilk, bean brain (tofu flower) and tofu produced from peeled douban have a pure, rich aroma and no bitterness. Using peeled watercress to produce yuba, soybean oil skin and tofu, etc., not only has high output rate, but also has good toughness and good taste. Yuba is resistant to cooking and foaming, and has excellent quality, resulting in large sales, high price and high profits.

Small workshops usually spend half a day drying and peeling soybeans every week, producing a weekly feed. In large enterprises, soybeans are dried and peeled every day.

3. Soak beans

Most companies use a pool with white ceramic sheets to soak beans. The design of the soaking pool is reasonable. It is very easy and effortless to wash beans, soak beans, and change water. Some small workshops use unreasonably designed soaking pools or plastic buckets. Zinc and iron buckets, washing beans and changing water are time-consuming and laborious. Some companies have used electric regulating valves, timers and liquid level gauges in the soaking bean pool, which solved the problem of soaking beans in water at night. The new soaking bean process uses a food additive, which not only shortens the soaking time, removes the bitterness and astringency in the beans, improves the solubility of water-insoluble proteins, but also prevents the soybeans from being damaged and reduces the soy milk foam. The protein in soybean is divided into soluble protein (globulin) and insoluble protein (albumin), the former contains about 90%, and the latter contains about 5%. Therefore, soaking beans with soaked beans can slightly improve the extraction rate of protein, thereby increasing the Product yield.

4. Grinding

Before 2009, most yuba factories in Guangxi used electric stone mills to grind soy milk. After that, most yuba factories eliminated electric stone mills and switched to vertical type with better quality and easier maintenance than electric stone mills. Grinding the soy milk with a grinding wheel refiner that does not separate the pulp and slag, each batch of bean kernels only needs to be ground once. We assemble and produce the vertical grinding wheel refiner with no separation of pulp and slag. The quality of the grinding is good, and the color of the yuba produced is more uniform and consistent with that of the yuba made by electric stone grinding, and is more consistent with the horizontal 250 grinding wheel. Compared with the machine, the grinding wheel is more durable, does not burst (there are several springs with moderate strength, which can effectively avoid the damage of impurities such as small sand and gravel), and it is easy to replace (stainless steel screws). Some yuba factories in Fujian and Jiangxi and other places use steel mills to grind soy milk; small workshops in Henan, Shanxi, and eastern Guangdong use pulp and residue separators (also called separate grinders) to grind pulp to automatically separate soy milk. And bean dregs, each batch of bean kernels must be ground at least three times, the workload is heavy, the grinding quality is poor, the price is the cheapest, and the yield of yuba is low.

It is worth mentioning that the yuba factories in Henan, Hunan, Fujian and other places have widely used vacuum bean suction machines. Soybeans are automatically dropped into the hopper of the refiner for refining, eliminating the need to manually pour the beans into the refiner. As labor costs continue to rise, it is imperative to use a vacuum bean suction machine to assist in the grinding of soy milk.

5. Filter

There are generally three types: raw pulp filtration, cooked pulp filtration and both raw and cooked pulp filtration. Raw pulp filtration and cooked pulp filtration have their own advantages and disadvantages. The filtration method used for both raw and cooked pulp filtration is to take the advantages of both and overcome its shortcomings, which is the best filtration method. Most enterprises in Guangdong and Guangxi use semi-automatic filters and raw pulp filtration. Compared with the semi-automatic filters used in Guangxi and other places, the ones in Jiangmen are safer and the belt replacement is more convenient. Many manufacturers in Fujian and Jiangxi use filters with arc-shaped electric slag scrapers for filtration. The relative movement and friction between the cloth bag and the slag scraper are easy to break, and it is also possible to scrap several of them every day. In 2013, several bean curd factories in our Jiangmen area adopted an improved semi-automatic filter. The filter was equipped with a bean dregs disperser to automatically disperse the bean dregs, which greatly reduced the labor intensity of workers and improved production efficiency. This improved semi-automatic filter can be used in either the south or the north. The arc-shaped bean dregs disperser and the filter bag rotate synchronously, and there is no friction, so the filter bag has a long service life, generally up to 1 to 2 years. Since 2013, several large-scale yuba factories in Jiangmen, Guangdong have used vertical automatic pulp filtering systems to filter pulp: automatic pulp feeding, slag washing and slag discharge. This slurry filtering method is the most efficient, occupies less land, has the lowest labor intensity, and is less wasteful in the loss of soybean milk. With the rising wages of workers, it is worthwhile to use equipment with a high degree of automation.

6. Boil the pulp

There are two production processes for the production of yuba: one is raw pulp and the other is cooked pulp. Both processes have their own advantages and disadvantages. The biggest advantage of the raw pulp process is that it saves labor. The operation of adding soy milk to the yuba machine is simple. It is not necessary to add soy milk to each cell one by one like the cooked pulp process. Yellower products. Most of the more than 200 yuba factories in Jiangmen (except for a few yuba factories) use the raw pulp method to cook the pulp without setting up a boiling pot, and pour the soy milk directly into the yuba machine. In eastern Guangdong, Guangxi, Fujian, Jiangxi and Henan, the vast majority of yuba are produced by the traditional cooked pulp process, and the pulp is cooked in a pulping pot. Soybean milk is generally boiled with steam from an industrial boiler or directly at the bottom of the cooking pot to burn wood or coal over an open fire. Some people use a hot water boiler to cook soy milk. Because the steam of the hot water boiler has almost no pressure and low temperature, the cooking time is long, the concentration of the soy milk is thin, and the bean curd skin takes a long time. We do not agree to use a hot water boiler to cook soy milk, but I can barely make tofu.

7, pick bamboo

Some enterprises have complete auxiliary equipment and reasonable plant design, so the efficiency of picking bamboo is very high. One person is responsible for a 9-meter-long yuba machine. Picking bamboo has not stopped. After picking the left side, pick the right side. The same grid is picked every 4 minutes, which greatly improves the output.

8. Slime

Also called hanging or dragging. Few manufacturers in the Pearl River Delta produce pulped yuba. Many people in Xuchang, Henan, Guangxi, Heyuan and Meizhou in eastern Guangdong produce yuba with sticky pulp. It is a kind of sweet pulp that cannot be crusted at the end. After simple treatment, it sticks to the yuba that has been dried or baked to a certain degree of dryness. The yuba obtained in this way has a sweet taste and a high output rate, with the highest soybean per kilogram. Seven taels can be produced. If the whitening agent is used and the technology is not good enough, the yuba will not be resistant to blisters, not resistant to cooking, rotten or scattered after cooking.

9. Dry

①Dry it under a tent made of sunshine tiles and stainless steel gauze (only the yuba skin that is as large as a towel can be completely dried, and the rest, such as flat bamboo and branch bamboo, should be dried at night with a yuba machine or drying room , such as Jiangmen, Guangdong, etc.);

②In the thermal insulation room built with red bricks, splicing ceramic pipes or welding thick and thick seamless steel pipes into a "mountain"-shaped heating pipe, and burning wood or coal outside the wall to dry the iron pipes red. , This kind of structure is simple, consumes a lot of firewood, and the heating temperature is uneven. The yuba in this corner is dry, while the yuba in that corner is still wet; the yuba directly above the fire is burnt, and the yuba at the other end is just dry. The steel pipe is not durable, because the local temperature is very high, and it is quickly burnt out.

③Bend a cylinder with a length of about 2 meters and a diameter of about 0.5 meters with a thick iron plate, burn one end of the cylinder, and weld a few-meter-long iron pipe chimney at the other end, and install a fan on the inner wall of the drying room to blow air to the cylinder. This kind of structure is simple, uses less steel, but consumes a lot of firewood.

④Use many heat exchangers made of seamless steel pipes as oven heaters, burning wood or coal for heating, burning red seamless pipes, energy saving, uniform heating, and ideal effect.

⑤In the red brick thermal insulation room, use an air heater and a drying room with steam as the heat source to dry it. Some factories lay it in the pit of the central floor of the drying room, and some factories put it against the wall.

⑥In the red brick thermal insulation room, use the fine seamless steel pipe as the heater and the drying room with steam as the heat source for drying.

⑦In the red brick insulation room, use the fine seamless steel pipe with aluminum or stainless steel fins as the heater, and use the steam as the heat source to dry in the drying room. The yuba hanging on the bamboo poles is hung directly on the bracket in the drying room by human hands, or it is hung on the trolley first, and then the trolley is pushed into the drying room. The drying rooms of some yuba factories in Fujian and Jiangxi are long and narrow, and each drying room has 3-5 small doors.

⑧ Drying yuba with electric heating is easy to achieve automatic control, which is very convenient, but the cost is very high, because the moisture content of wet yuba is about 55%, which requires a lot of electricity.

⑨ Designing and constructing an ideal drying room with energy saving and uniform heating is not a small challenge, and many people have gone through detours. The above is just a rough introduction, and the above rough introduction alone cannot make a drying room. It is more difficult to keep the dried yuba from becoming darker and redder, and there is a lot of knowledge in it. The drying technology and the heating area of ​​the heater are different for the production of light yellow yuba and the production of dark yellow yuba.

10. Stove

The stove is built with red bricks (preferably hollow bricks) and covered with white tiles, which has better thermal insulation performance and is more energy-saving than the iron frame supported (non-metallic heat transfer performance is poor, and the heat loss is less). At the same time, the production workshop is usually wet. , The floor of the workshop needs to be washed every day after production. Therefore, the floor washing area made of red bricks is doubled, the water consumption is less, and the time spent washing the floor is also less; It is inconvenient to wash the floor directly below, and you have to bend over to wash the floor. The vast majority of factories in Guangdong and Guangxi build stoves with red bricks; in Fujian and Jiangxi and other places, some factories that use industrial boilers use iron frames to support yuba machines. In some yuba factories, the stove burns the fire at one end and exhausts the smoke at the other. The smoke exhaust port (chimney) is on the same end, and people burn the fire directly under the fontanelle; the burning port and the smoke exhaust port (chimney) of some pots and stoves are also at the same end, but the burning port is on the right side, and the smoke exhaust port is on the right side. On the left side, the heat energy utilization is high, and the soot will not get on the pot surface at all. Most of the fontanelles in Jiangmen are square, thick and short, while most of the fontanelles in Guangxi are round, thin and tall. Stove-burning stoves and grate structures in Jiangmen area are reasonable, and wet sawdust can be burned without blower. In some yuba factories in Yulin, Guangxi and Heyuan, Guangdong, their stoves for burning wood and wood chips use blowers to support combustion. Some yuba factories in Jiangxi and other places have to dig a pit with a depth of about 1 meter, so that the fire can burn vigorously, while most furnaces in Guangdong and Guangxi do not need to dig deep pits, and the fire still burns vigorously. .

11. Add fuel to industrial boiler furnace

In some yuba factories, the boilers do not need to manually send sawdust and chaff into the furnace with a shovel, but use a blower, a suitably thick iron pipe, and a gap in the iron pipe to make use of airflow movement. The generated negative pressure sucks the fuel into the iron pipe, and then is sent into the furnace by the airflow, which shortens the time for adding fuel and reduces the labor intensity.