Mineral Composition and Effect of Boiling Time on Vitamin C in Extract of Fresh and Dried Nigerian Vegetables with and Without Addition of Potash : Iree, Nigeria as a Case Study

Abstract

Vitamin C content of six fresh and dried Nigerian vegetable extracts [Venonia amygadlina (ewuro),  Telfaria occidentalis (ugwu), Indian spinach (amunututu), Talinum triangulare (gbure), Amaranthus Spp (tete) and  Solanum notrifiolum (gbagba)]  at different cooking time with and without the addition of potash was investigated using standard methods. The study showed that gbagba was stable throughout with and without the addition of potash for fresh vegetables (3.99%) and gbure was also stable at all the cooking time with and without addition of potash (3.99%) for dried vegetables. Other vegetables such as ewuro, ugwu and tete were observed to be best eaten at two minutes of boiling.  Calcium and sodium had their highest concentrations in gbagba (87.1±2.16 mg/kg and 115±2 mg/kg respectively. The highest level of potassium was obtained in tete with a value of 112±1 mg/kg. Two sample t-tests analysis using the Aspin-Welch unequal-variance revealed no significant difference at p < 0.05.

Keywords: Vitamin C, Vegetables, Cooking time, Potash, Extraction