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| (1) |
The extent of soaking not only affects the yield rate of the product, it also affects the product quantity and quality. The membrane protein beans appear friable after optimum soaking. When grinding, the membrane protein is fully crushed to dissolve the maximum protein content. Without adequate soaking, the membrane protein will be too hard but with excessive soaking, the membrane protein will be too soft. Both conditions will inhibit the crushing of membrane protein by machine and its dissolution. The product yield rate will be low as a result.
The water absorbency ratio of soaked beans is: 1:1~1:2，and the weight increase is2.0~2.2-fold. The bean surface is smooth without folds. The tofu skin does not detach easily and it has a good touch.?The easiest way to determine it is by twisting the soaked beans in half. The soaked inner surface that is level but slightly concave and brakes easily without a hard core is ideal. |
| (2) |
After soaking, the membrane protein of the beans become friable but tin order to dissolve the protein it has to pass through the grinder. From the protein dissolution viewpoint, the more thorough the bean crushing is, the higher the protein dissolution. Nevertheless, in actual production, the extent of bean crushing is limited. The finer the grinding, the more likely it is for the protein to be filtered into the soybean milk. This will result to product coarseness. In theory, the diameter of the membrane protein is between 2~20. Therefore, the grinded diameter should be under 2mm.
Based on the dissolution and separation results in actual production, the crushing fineness is 80~100mesh. During grinding, water has to be added in fixed amounts. The function of the water is to lubricate the beans in the grinder so that the protein of the dissolved beans can be grinded and a good colloidal solution can be formed. When adding water, the pressure should be constant and the water flow should be table. The water and bean speed should be well coordinated so as to produce fine soybean milk. Excessive water flow will reduce the staying time of beans in the grinder blade. The beans will be outputted fast and the grinding will not be fine enough to reach expected results. If the water flow is too limited, the beans will stay too long in the grinder blade and the output will be slow. It will result to grinding blade overheat due to friction and it will in turn denature the protein. |
| (3) |
Boiling is to denature the protein in soybean milk by heating. On the other hand, it reduces the odor, enhances the nutritional value of bean protein, kills bacteria, and keeps it fresh for a longer period of time. |
| (4) |
The purpose of filter is to separate and remove the soybean skin (soy pulp) in the bean mix to obtain the colloidal solution that mainly contains protein, the soybean milk. Moreover, the filter process also regulates the soybean milk concentration. Based on the different bean mix concentrations and products, the amount of water added during filtering also varies. 10-fold of water or regenerated soybean water is added to the separated soy bean skin (soy pulp) based on its dry content. After mixing, it is added to the main tank to heat and boil (cook). The separated soybean is also put in the soybean milk collector for production use. |
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