EFFECT OF BLANCHING TIME ON THE NUTRIENTS AND PHYTOCHEMICAL COMPOUNDS IN DRIED Lasianthera africana LEAF

Prior to culinary application, Lasianthera africana leaves are usually soaked or blanched in hot water for 5 to 30 minutes to reduce or eliminate the bitter taste and enhance palatability and acceptability of soup prepared with the leaf. In the current study, L. africana leaves (“afia” variety) were blanched in hot water at 100°C for 3, 6, 9, 12 and 15 minutes, drained, cooled and dried at 50°C for 36 hours. The unblanched dried (50°C for 36 h) leaf was used as control sample. The effects of the treatments on the mineral, vitamin and phytochemical contents in the dried samples were investigated. The unblanched dried leaf had higher K, Na, Ca, Mg, Fe, Zn, P, ascorbic acid, beta-carotene, riboflavin, thiamine, alkaloid, flavonoid, saponin, tannin, hydrogen cyanide, phytate, oxalate and trypsin inhibitor than the hot water blanched and dried samples. The losses of aforementioned parameters increased with blanching time. Sample blanched for 3 minutes and dried had the highest contents of minerals, vitamins and phytochemicals while 15 minutes blanched and dried sample had the least values. For maximum retention of nutrients and health protecting phytochemicals, blanching L. africana leaf for 3 minutes is recommended. The anti-nutrient contents in the 3 minutes blanched and dried sample were low and would not pose serious threat to health.