Effect of soaking time and fermentation on the nutrient and antinutrients composition of Canavalia ensiformis (Kacang Koro)

Abstract

The increasing demand in developing countries for alternative protein sources, coupled with the relatively high cost of importing protein, has led to the search for alternatives, particularly for novel legumes native to the tropics. Canavalia ensiformis or Jack Bean (Kacang Koro) could provide adequate protein sources for human consumption if the presence of various antinutrients can be reduced. The most cost-effective processing technique for the detoxifying method is the soaking process. Therefore, the aim of this study was to determine the effect on the nutritional, antinutritional and mineral content of C. ensiformis of soaking time and fermentation. The samples were treated by soaking in 1% sodium bicarbonates (NaHCO₃) solutions for 12 h, 24 h and 36 h (at chilled temperature, 10 °C) and fermented (40 °C). The treated samples were analysed for their proximate values and antinutrient factors (hydrogen cyanide (HCN), phytic acid, tannin, saponin and oxalate content). The results showed that proximate values were not significantly affected by soaking treatment and fermentation. After 36 h of soaking in 1% of NaHCO₃ solution, the HCN level in C. ensiformis and fermentation process, the HCN level to be reduced to 7.43 ± 0.76 mg/kg while phytic acid was reduced to 0.64±0.00, saponin to 1.27 ±0.01, tannins to 0.01± 0.001 and oxalate to 39.96 ± 5.85. These results suggest good prospects for substituting C. ensiformis for any existing protein source as the antinutrient factors could be reduced to an acceptable level. The soaking of C. ensiformis in 1% NaHCO₃ coupled with fermentation would also allow the use of C. ensiformis in food production.