Effect of Traditional Pre-Culinary Hot Water Infusion Time on the Micronutrients and Health Protecting Phytochemicals in <i>Heinsia crinite</i> Leaf

Abstract

Abstract:One of the common traditional methods of improving the palatability and acceptability of Heinsia crinita leaves involves pre-culinary infusion of the cut leaves in already boiled water for period ranging from 5-20min or longer. In this study, the harvested leaves (dark variety) were washed in potable water, spread under shade to air dry, cut (2mm width) and shared into four equal portions of 1kg each. Portions 2, 3 and 4 were separately infused in hot water (1:3w/v) and maintained at 95 o C for 5, 10 and 15 min, drained and cooled while the first portion was not treated with hot water (control). Each portion was oven dried (50 o C) for 36h, cooled, and packaged. The effect of the treatments on the minerals, vitamins and health benefiting phytochemicals were investigated. The untreated dried leaves had higher K, Ca, Na, Mg, Fe, Zn, ascorbic acid, beta-carotene, riboflavin, thiamine, alkaloids, flavonoids, saponins and tannins than the dried leaves from hot water infusion. Percentage losses of minerals, vitamins and health promoting phytochemicals to the infusion water that was discarded increased with increase in infusion time. Percentage losses of K, Ca, Na, Mg, Fe and Zn ranged from 11. 01, 7.77, 16.72, 15.51, 9.55 and 8.50% for 5 min infused leaves to 34.34, 18.73, 45.07, 41.76, 24.85 and 29.92% for 15 min infused leaves, respectively. Similarly, percentage losses of ascorbic acid, beta-carotene, riboflavin and thiamine ranged from 38.43, 15.69, 17.39 and 38.78% for 5 min infused leaves to 70.60, 35.29, 57.97 and 68.38% for 15 min infused leaves, respectively. Losses of alkaloids, flavonoids, saponins and tannins ranged from 20.92, 39.39, 4.65 and 16.67% for 5 min infused leaves to 62.24, 69.70, 10.08 and 47.22% for 15 min infused leaves. The study demonstrated that for the consumers of H. crinita leaves to derive substantial nutritional and health benefits from the consumption of the leaf, it should be subjected to 5 min hot water infusion period prior to use for culinary preparation.