Drying characteristics, nutritional and anti-nutritional properties of locust bean seed

Abstract

The need to ensure availability of locust beans when off-season forms the basis of this study. The study investigated the drying characteristics, nutritional composition and some anti-nutritional contents of dried locust beans. Fermented locust beans were dried at 50°C, 60°C, 70°C and 90°C. The moisture contents of the fermented locust seeds were determined at different time intervals between 0 and 480 min. Lower moisture content was achieved in a shorter drying time at higher temperature. The dried locust bean samples had lower moisture contents (12.36–12.76%) compared to control sample (38.76%). Higher drying temperature resulted in low ash content of the samples but increased the fibre, fat and protein content of the samples. The dried samples had low mineral contents compared to the fresh sample, which was used as control. The most abundant mineral in the samples were found to be calcium and zinc. No significant difference was observed in the titratable acidity and the pH of the locust bean samples at varying drying temperature. Increase in temperature resulted to a reduction in the antioxidant, phenolic composition and the anti-nutritional properties of the dried locust bean samples. Panelists preferred samples dried at lower temperature (50°C and 60°C compared with the samples dried at high temperature. The study concluded that locust bean should be dried using a carefully selected temperature to avoid negative impacts on the nutrients of the beans.