Analysis of Vitamin C (ascorbic acid) Contents in Various Fruits and Vegetables by UV-spectrophotometry

摘要

Total vitamin C (ascorbic acid + dehydroascorbic acid) has been determined by UV-spectrophotometric method in various fruits and vegetables. In this method bromine water oxidizes ascorbic acid to dehydroascorbic acid in presence of acetic acid. Aftercoupling with 2,4-dinitrophenyl hydrazine at 37 deg C temperature for three hours, the solution is treated with 85% H_2SO_4 to produce a red color complex and the absorbance was spectrophotometrically measured at 521 nm. The content of vitamin C were 10mg/l00g to 80 mg/lOOg in fruits and 16 mg/l00g to 42 mg/l00g in vegetables. A loss of 64% at -10 deg C and 76% at deg C was observed after two months storage period of one leafy vegetable "Enhydrafluctuans" (Helencha shak).