Abstract

The influence of boiling lima bean, using trona solution, on its phytochemical constituents and selected micronutrients was investigated. Lima bean was initially boiled for 3 h using 0.1, 0.2, 0.3, 0.4 and 0.5% trona solution, respectively at ratio 1:5 (bean/trona solution). The boiled lima bean was subsequently dried in an oven at 55°C for 12 h after which it was subjected to various analyses. Maximum reduction of phytochemicals such as trypsin inhibitor activity (74.1%), haemagglutinin (98%), tannin (68.6%), phytic acid (39.6%), and cyanogenic glycoside (73.8%) was obtained at 0.5% boiling with trona-solution. The reduction profile for the B-vitamins includes thiamine (0.58 to 0.13 mg/100 g), riboflavin (0.37 to 0.21 mg/100 g), niacin (0.97 to 0.28 mg/100 g) and pyridoxine (0.41 to 0.11 mg/100 g). Boiling lima bean in trona solution led to significant decrease (p<0.05) in the concentration of calcium, magnesium and phosphorus while mineral concentration enhancement was observed with potassium, sodium and iron. Maximum in vitro protein and starch digestibilities of 88.6% and 51.9 mg/g, respectively were obtained for 0.5% trona solution boiling of lima bean. Trona usage in the boiling of lima bean therefore served as a beneficial step in the utilization of the legume.

Key words: Lima bean, trona, boiling, phytochemicals, micronutrients.