Impact of Pasteurization on Ascorbic Acid in Orange Juice (Overview)

Loss in Ascorbic Acid contents of orange juice heated under different situations and pH was researched. In this experiment, Navanila oranges from Spain were squeezed and filtered by using a vacuum pump to make orange juice samples. These samples were extracted and make up with 0.1% Formic Acid in HPLC water, HPLC water and phosphate buffer solution (pH=6). Pasteurization was achieved at 60, 65 and 70℃ over 15, 25 and 35min period by using the water bath method and cooled to room temperature immediately. After that, Ascorbic Acid contents were analyzed by HPLC and 0.1% Formic Acid in HPLC water, HPLC water and phosphate buffer solution (pH=6) were used as mobile phases separately for their solutions. HPLC standard samples of Ascorbic Acid were prepared which means 0.1g Ascorbic Acid was weighted and then diluted into 50-250mg/ L solutions to make calibration lines for three solutions. The wavelength of Ascorbic Acid was 245nm but it changed to 296nm when samples in phosphate buffer solution (pH=6). Results showed that Ascorbic Acid concentration is more at 60℃ at 15min and there was a total decline trend with the increase of time and temperature. After statistics analysis, it has a significant affect (P<0.5) related to Ascorbic Acid contents with temperature and pH.