Effect of ultrafine grinding on functional properties of soybean by-products

Abstract

Introduction. The ultrafine grinding technology of soybean by-products can effectively increase the content of dietary fiber in the bean dregs, and improve the taste and quality of the product. Material and methods. Superfine pulverizer KCW-701S; laser particle size distribution meter BT-9300H; scanning electron microscope. The bean dregs were subjected to ultrafine pulverization treatment at 50, 40, 30, and 20 Hz, and untreated as a control group. Result and discussion. The water solubility and expansion of ultrafine powdered soybean by-products has increased, compare with the control group. As the frequency decreased, the water solubility and expansion of the soybean by-products were significant change. When the frequency was 30 Hz, the water solubility was 20.84%, and the expansion was 11.03 mL/g. As the frequency decrease, the water holding capacity showed a downward trend. When the frequency was 20 Hz, the water holding capacity reached the lowest 6.53g/g, and compared with the control group (10.92g/g), the difference was significant (p<0.05). The oil holding capacity was no significant change. The color of the soybean by-products has a significant change, after ultrafine grinding. The brightness L∗ value of the soybean byproducts has been greatly improved, and it has changed from the original wheat yellow to the creamy-white. The a∗ and b∗ values gradually decreased. The microscopic structure of the soybean byproducts was made changes to scanning electron microscopes. As the pulverization frequency decreased, the soybean by-products powder became finer and smoother. The particle size of the bean dregs gradually reduced. When the frequency was at 30Hz, the median diameter D50 was 47.95 μm, but when the frequency was less than 30 Hz, the particle size of the bean dregs increased, and the same as a result of scanning electron microscope. Conclusion. Ultrafine grinding was used to treat soybean byproducts, in the physical and chemical properties has obvious changes. The water solubility and expansion was significantly improved, and much higher than the control group. The frequency of ultrathin grinding of 30 Hz is rational, and can be used for ultrafine grinding of soybean by-products and their subsequent use in the production of bakery products.