In recent years, the development and utilization of soybean food has received increasing attention from countries around the world. In developing countries, because of the low conversion rate of animal protein, animal protein often fails to meet the nutritional needs of 75 grams of protein per capita per day, thereby focusing attention on the development of plant protein.

In China, the National Advisory Committee on Food and Nutrition has initiated a “Soybean Action Plan” and set specific development goals for soybeans. In developed countries, due to the fear of cholesterol in animal food and the latest nutritional and epidemiological studies have shown that soy food has the effect of lowering cholesterol and preventing cancer and other health effects. Therefore, the development of soybean food research, is constantly strengthening and deepening. With the accelerated pace of life of our people, the demand for nutritious, tasty and flavorful leisure food is also increasing.

At present, most of the leisure and convenience foods on the market are high in fat and carbohydrates, low in protein and puffed with starch as raw material. The purpose of this study is to explore, suitable for protein raw materials (soy protein content of about 40%) of the puffed processing technology, so as to develop a high protein content, crunchy texture, easy to digest soybean puffed food. The production process is briefly described as follows:

Lifting and coagulation modulation
Soaking
Soak the soybeans in tap water or 0.5% sodium bicarbonate solution that is three times its own weight. Depending on the season, the soaking time of 8 to 16 hours, the degree of soaking to the soybean weight of about 2.2 times the original weight, the skin of the beans smooth and tight, and then rinsed, drained.

Pulping
This test in order to prevent the crushing of soybeans, soybean odor and take the hot grinding method, that is, the whole grain of soybeans mixed into 85 ℃ ~ 90 ℃ of clean hot water, and then grind into pulp with a pulper. Soybeans and hot water ratio of 1:6 ~ 7. Then separate, grind the pulp, remove the dregs, to get soy milk-like products.

Preparation
Soy milk is heated and kept at 75℃～80℃, and then calcium sulfate is added in the proportion of 0.2%, mixed and left to stand for 10 minutes, so that soy protein is coagulated and tofu-like products are obtained.

As the digestibility of tofu is 92.7%, higher than other soy products (such as baked soybeans, boiled soybeans) digestibility, so, tofu as the base material made of puffed food, the digestibility of its corresponding also increased.

Add puffing aids and flavor substances
In order to improve the puffing performance and nutritional quality of the products to enhance their taste and flavor, the following substances will be added in the appropriate amount:
1, to improve the puffing rate of products need to add a certain amount of starch, such as tapioca starch.
2, complementary amino acid components due to the lack of soy protein sulfur-containing amino acids, grain crops such as rice, wheat protein lack of lysine, so, such as mixing and matching the two, so that its mixture of protein amino acid components complement each other to improve the physiological effectiveness of the products of the protein or bioeffectiveness. Ground into a powder and evenly added is appropriate.
3, to improve the flavor of products can be added a little sugar, onion and garlic powder into.

Paste drying technology processing
Mix the tofu with the above three substances in a certain proportion, then heat it in the microwave oven for 1 minute, and then steam it for 15 minutes for pasteurization. After the pasteurized mixture was cooled to room temperature, it was cut into thin slices. Dry at 50°C for several hours to make semi-finished products similar to shrimp chips.

Secondary puffing treatment
The above semi-finished products by microwave or deep-frying (180 ℃ ~ 190 ℃, 6 ~ 10 seconds) puffing process, you can make a crispy, tasty flavor of soybean puffed leisure convenience foods. Excess oil after deep-frying can be wiped off with clean oil-absorbing paper towel.

Product Packaging
Pack the puffed food in linear low-density polyethylene film or aluminum foil, and store it at room temperature for 10 weeks. At 2-week intervals, the crispiness and moisture content of the products were determined. It was found that there was no change in the quality of the packaged puffed soy foods after 6 to 8 weeks at room temperature.