کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6402470 | 1330888 | 2015 | 9 صفحه PDF | دانلود رایگان |
- HHP treatment (1000Â MPa/1Â min) had little influence on PPO activity.
- PPO was almost completely inactivated after treatment at 1600Â MPa for 1Â min.
- The HHP decreased ζ-potential and increased average particle and molecular diameter.
- The disruption of the catalytic environment and the aggregation of PPO after HHP.
- Heat played a major role in the inactivation at pressures â¥1000 MPa.
To elucidate the mechanism of the high-hydrostatic-pressure (HHP)-induced inactivation of mushroom polyphenoloxidase (PPO), the enzyme was treated under the pressures ranging from 100 to 1600 MPa for 1 min. The PPO activity and molecular microstructure were examined using SDS-PAGE, native-PAGE, particle size distribution (PSD) analysis, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The results showed that HHP treatment had little influence on PPO activity below 1000 MPa for 1 min, but it was almost completely inactivated at 1600 MPa for 1 min. Based on electrophoretic pattern, the pressure treatment had little influence on the primary structure of the PPO. Considering the molecular microstructure, the HHP-treated PPO exhibited a lower ζ-potential, higher average particle (PSD) and molecular diameters (TEM) and a blurred PPO boundary (AFM), indicating the aggregation of PPO after HHP treatment (>1000 MPa). Moreover, the changes in PPO after treatment at 80 °C for 1 min were similar to those observed after treatment at 1600 MPa. Combined with previous results for the molecular secondary and tertiary structure, a possible enzyme inactivation mechanism is proposed, in which the inactivation of PPO by HHP treatment was attributed to the disruption of the catalytic environment and the aggregation of the enzyme.
Journal: LWT - Food Science and Technology - Volume 60, Issue 2, Part 1, March 2015, Pages 890-898