Polyphenoloxidase activity and color of blanched and high hydrostatic pressure treated banana puree

The effects of blanching and high hydrostatic pressure (HHP) treatments on natural flora evolution, polyphenoloxidase (PPO) activity and color of banana puree adjusted to pH 3.4 and water activity (a(w)) of 0.97 were evaluated during 15 days storage at 25 degrees C, Standard plate as well as yeast and mold counts of HHP treated purees were <10 CFU/S throughout storage. Blanching time was found to affect (p<0.05) puree color. HHP treatments retained the initial color of the banana purees, Longer browning induction times and slower browning rates were observed when a longer blanching time was combined with a 689 MPa pressure treatment. A residual PPO activity < 5% was observed in the puree when a 7 min blanch was followed by HHP treatment at 689 MPa for 10 min.