Soybeans are high in protein and low in fat, and their protein utilization rate is high, earning them the reputation of "plant meat". In addition, soybeans are also rich in minerals such as calcium, zinc, and iron. The optimal length of bean sprouts is 3-5 cm.
Unfortunately, soybeans contain many "anti-nutritional factors". For example, phytic acid and trypsin inhibitors interfere with the absorption of minerals like iron and zinc, and proteins, respectively. Lectins, saponins, and tannins all have a certain irritating effect on the digestive tract. Additionally, eating soybeans directly often causes bloating, because some oligosaccharides cause gas problems, and trypsin inhibitors also promote bloating. Some literature shows that sprouting soybeans can improve the above situation. But how many days should the soybeans be sprouted, and what is the best length? Researchers from Harbin Medical University conducted relevant experiments.
After washing the soybeans clean, soak them for one day, changing the water frequently. On the second day, drain the water and keep the soybeans moist. Cover the soybeans with a wet towel and place them in a well-ventilated, dark place to prevent direct sunlight. Keep the soybeans and the towel moist, and remember to change the water in the morning and evening every day. Observe and record the germination status of the beans daily and take samples to measure relevant data.
The results found that during the soybean germination process, the activity of phytase (which has the characteristic of hydrolyzing phytic acid) continuously increased, causing the content of phytic acid—the main inhibitory factor in soybeans that hinders the absorption of calcium, zinc, and iron—to decrease by 40%. Free amino acids such as vitamin B2 and aspartic acid, which promote the absorption of calcium, zinc, and iron, as well as some beneficial enzymes for the body, all increased significantly. In addition, vitamin C increased from 0 to 40 mg/100g. The data indicates that sprouts germinated for about 3 days and with a length of about 3-5 cm have the best nutritional value.
By making sprouted beans, the nutrients in soybeans can be retained and enhanced to the greatest extent, while anti-nutritional factors can be significantly reduced. In terms of taste, sprouted beans are especially delicious and savory. In terms of texture, sprouted beans are more delicate and less likely to cause bloating. In addition to being used for cold dishes, soups, and stir-fries, sprouted beans can also be made into soy milk.