Elevated Temperature Studies on Stability of Ascorbic Acid in Certain Fruit Juice and Aqueous Vehicles

Abstract

The stability of ascorbic acid was investigated in certain fruit juice and aqueous vehicles between pH 2.5–6.5 at 37 and 55° in the presence of 0.2 per cent citric acid, 0.01 per cent EDTA, 0.01 per cent propyl gallate, 0.2 per cent ferrous gluconate, 0.2 per cent cysteine hydrochloride, and 0.2 per cent potassium m -bisulfite. Lime juice—sorbitol—glycerol (2:2:1) retained 70 per cent ascorbic acid at pH 6.5 after 120 days. Citric acid also protected ascorbic acid. EDTA gave little protection to ascorbic acid. The loss of ascorbic acid in aqueous solution at some pH values was counteracted by 0.9 per cent sodium chloride. Dihydrosteptomycin sulfate in the concentration of 0.33 mg./ml. gave protection to ascorbic acid at all pH levels, except at pH 6.5 (37°) and at pH 5.5 (55°), where a destructive effect was noticed. Stability of ascorbic acid was a function of pH, temperature, vehicle, and head space in the container.