Polyphenoloxidase activity and color changes during storage of high hydrostatic pressure treated avocado puree

The effects of high hydrostatic pressure (HHP) treatments of 345, 517, or 6 89 MPa, for 10, 20, or 30 min at initial pHs of 3.9, 4.1, or 4.3 on polyphe noloxidase (PPO) activity, color and microbial inactivation in avocado pure e during storage at 5, 15, or 25 degrees C were investigated and compared w ith untreated avocado puree. Standard plate as well as yeast and mold count s of HHP treated purees were < 10 cfu g(-1) during 100 days of storage at 5 , 15, or 25 degrees C. Significantly less (p less than or equal to 0.05) re sidual PPO activity was obtained with increasing pressure and decreasing in itial pH. Browning was related mainly with changes in the a color component . Avocado puree with a residual PPO activity <45% and stored at 5 degrees C maintains an acceptable color for at least 60 days. (C) 1999 Canadian Inst itute of Food Science and Technology. Published by Elsevier Science Ltd. Al l rights reserved.