Evaluation of Water-soluble Vitamins and Optimum Cooking Time of Fresh Edible Portions of Elephant Grass (Pennisetum purpureum L. Schumach) Shoot

Abstract

Fresh edible inner tender stem (matrix) and base of domesticated elephant grass shoot were evaluated for water-soluble vitamins B₁, B₂, B₃, B₆ and vitamin C. The B-vitamins were determined using high performance liquid chromatographic (HPLC) technique, while vitamin C was evaluated using 2, 6 dichlorophenolindophenol (DCIP) titration method. The optimum blanching time of the matrix was also determined. Samples were water-blanched from 0 to 16 min at intervals of 2 min. Optimum cooking time was determined to be the time at which vitamin C showed maximum retention after the intervals of blanching. Vitamins B₁, B₂, B₃, B₆ and C concentrations (mg/100 g fresh weight) in the samples were respectively 1.23 mg/100 g, 4.37 mg/100 g, 12.35 mg/100 g, 2.40 mg/100 g and 17.23 mg/100 g in the matrix and 0.86 mg/100 g, 3.72 mg/100 g, 6.40 mg/100 g, 1.59 mg/100 g and 18.30 mg/100 g in the base. The amounts of the B-vitamins in 100 g portion of the samples adequately satisfy the RDAs for the respective B-vitamins for normal healthy adults. The matrix was significantly higher (p < 0.05) than the base in vitamins B₁, B₃ and B₆. The matrix showed an optimum blanching time of 10 min. This was considered the optimum cooking time required to avoid significant loss of vitamin C and other heat-labile nutrients in elephant grass matrix.