Effect of pH and ascorbic acid on high hydrostatic pressure-processed mango puree

Mango puree containing ascorbic acid (AA) (500 ppm) standardized at low pH (3.5) with phosphoric acid and inoculated or noninoculated with Saccharomyces cerevisiae was treated at high pressure (207, 345, 483 and 552 MPa) for selected times. High hydrostatic pressure (HHP)-processed (552 MPa/5 min) standardized mango puree (SMP) was stored at 3C for 1 month and periodically analyzed for color, residual polyphenoloxidase (PPO) activity and microbial load. The remaining PPO activity average in SMP, after HHP processing at 207, 345, 483 and 552 MPa, at all times, was 35.8 +/- 6, 21.5 +/- 13.2, 46.8 +/- 53.2 and 61.8 +/- 5.8% PPO activity units, respectively. The D-207 values of 8.5 and 7.2 min for total count and yeasts were observed, respectively, after 207 MPa of pressure. A log reduction of 1.62 and 1.35 was observed after applying 345 MPa of pressure (2 s) for total count and yeasts, respectively. However, no microbial growth (< 10 cfu/g) was observed after applying 483 or 552 MPa at any time. The addition of AA and the standardization at pH 3.5 reduced the rate of browning during storage.