Effect of blanching time on the mineral contents of selected green leafy vegetables commonly consumed in southwest Nigeria

Abstract

This study was carried out to determine the effect of blanching time on selected mineral contents of four frequently consumed GLVs in South western, Nigeria. Fluted pumpkin (Telfairia occidentalis), feather cockscomb (Celosia argentea) and spinach (Amaranthus cruentus) which are usually excluded and Water leaf (Talinum triangulare) which is allowed in the diets of patients with Chronic Renal Failure (CRF) were subjected to 10, 30 and 60 minutes blanching times. Four samples were generated from each vegetable species: sample A (unblanched raw vegetable), sample B (blanched vegetable for 10 minutes), sample C (blanched vegetable for 30 minutes) and sample D (blanched vegetable for 60 minutes). Calcium, magnesium, potassium, phosphorus and sodium content of the vegetables were determined according to AOAC method and Phosphorus by the Vanodo-molybdate method. Data were analysed using ANOVA and Duncan Multiple Range test at p<0.05. The result showed that increase in blanching time significantly increased the calcium while the potassium and sodium content of all the vegetables significantly reduced with 10 minutes blanching (p<0.05). Blanching for 30 minutes or more had significant reducing effect on the magnesium and phosphorus concentrations of the GLVs. Thirty minutes blanching time had significant reducing effects on the mineral contents of the vegetables except for calcium content which increased with increase in blanching time. The GLVs could be recommended for patients suffering from CRF provided they are blanched for 30 minutes.

Keywords:  Blanching time, Mineral content, Green leafy vegetables