Effects of Processing Methods on the Nutritional and Anti-Nutritional Properties of Soybeans (Glycine max)

Abstract

Soybean is a leguminous vegetable that grows in tropical, subtropical, and temperate climates and it is a principal vegetable protein source in animal feed industry in Nigeria. The study investigated the effects of traditional processing methods on the nutritional and anti-nutritional properties of soybean. Soybeans were subjected to different processing methods which were sun drying and milling which serves as the control (sample A); soaking for 24h, sun drying and milling (sample B); soaking for 12h, de-hulling, sun drying and milling (sample C) and sprouting for 120h, sun drying and milling (sample D). Results from the proximate composition of soybean showed that protein content of the samples were in the range from 23.98 to 28.44% with a significant increase in sample B, C and D. The fat content ranged from 20.51 to 26.20%, while crude fibre ranged from 4.68 to 6.58%. The moisture content which ranged from 7.23 to 10.92% showed a significant decrease in the control. The anti-nutritional properties of the samples showed that phytic acid was in the range of 5.45 to 8.05% which significantly decrease in sample B, C and D. The tannin content ranged from 19.23 to 25.23 mg/100g while the protease inhibitor ranged from 4.91 to 7.09% with a significant decrease in sample B, C and D. The study showed that tradition processing methods can significantly increase the nutritional properties of soybeans while it can also significantly reduce the anti-nutritional properties of soybeans thereby increasing the bioavailability of its nutrients.