Effects of blanching, acidification, or addition of EDTA on vitamin C and -carotene stability during mango puree preparation

The impact of acidification with citric acid, addition of EDTA or water blanching at high temperature, and short time (HTST) conducted at 90 degrees C for 4min, on the retention of vitamin C (L-AA and DHAA) and -carotene was studied in mango puree 30min after crushing. HTST blanching prior to matrix disruption into puree resulted in complete inactivation of polyphenol oxidase (PPO) and minor residual activity (8%) of ascorbic acid oxidase (AAO). The retention of total vitamin C was 100% in blanched purees and in puree with EDTA and about 90% in purees at pH 3.9 and 5.0. Acidification, blanching, and addition of EDTA preserved vitamin C mainly as L-AA, while complete conversion into DHAA was observed in puree at pH 5.0. The retention of all-trans--carotene was between 65 and 72%, with the highest value in puree with EDTA and the lowest value in puree of blanched mango. The ratio of 13-cis--carotene in fresh mango was 8.2 +/- 0.5% that increased significantly after blanching and in puree at pH 5.0.