When soybeans are exposed to high temperatures for a short period, they roast .
If the roasting process is done optimally, the quality of soybean proteins is improved, and all its anti-nutritional factors are destroyed. For this reason, roasted soybeans can be recommended as an excellent source for making soy milk.
Roasting processing is mainly done in two ways:
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Fluidized bed drying:
In this method, raw soybeans with a specific moisture content are suspended in hot air at a temperature of 110-130 degrees Celsius for 20-40 minutes, and the raw soybeans are roasted. In other words, roasting in this method occurs by suspending soybeans in 130-degree hot air. This processing method is capable of eliminating anti-nutritional factors of raw soybeans and results in the least change in the quality of soy flour. Additionally, in this method, there is the least amount of product burning.
- Drum Roasting:
In this method, there is a meshed drum where soybeans pass through at a temperature of about 200 degrees Celsius for 1-3 minutes. Then, they remain in a steeper space for 15-30 minutes to complete the roasting process effectively. Because soybean oil is available in the beans during the processing, it can be used in diets with high forage content for energy, fat, and protein supply up to a maximum of 18% dry matter. However, when other diet components are added, limitations on the amount of RUP (rumen undegradable protein) and fat in the animal's diet restrict the consumption of roasted soybeans even further.