99E-20 |
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M. MIYAWAKI, J. I. Reyes-De-Corcuera, J. R. Powers, and B. G. Swanson. Dept. of Food Science and Human Nutrition, Washington State Univ., PO Box 646376, Pullman, WA 99164-6376 High Hydrostatic Pressure (HHP) utilization for food processing offers advantages over conventional thermal processing improving retention of "fresh-like" natural flavors and essential nutrients. One of the research objectives of HHP processing is focused on inactivation of endogenous detrimental enzymes in plant foods. Polyphenol oxidase (PPO) in apples is partially inactivated by HHP following mechanisms dependent on tissue status and process conditions. Our objectives are to establish optimal conditions of HHP treatments combined with antibrowning agents to inactivate PPO in apples and minimize undesirable browning during storage, and to develop shelf stable foods containing apples. HHP treatments were carried out at 600 MPa for up to 10 min at ambient temperatures to simulate potential commercial applications, followed by PPO assays and color observations for 2 days at ambient temperature. Diced apples and apple homogenates were subjected to HHP treatments to compare the effects of tissue and cell disruption on PPO inactivation. The soluble solids concentrations selected to simulate apple products, as well as organic and inorganic antibrowning agents were evaluated to determine their effects on the discoloration of HHP treated diced apples and apple homogenates. HHP inactivates PPO in diced apples more effectively than in apple homogenates. However, after HHP treatment at 600 MPa for 5 min at ambient temperatures, diced apples exhibited 8% PPO activity and slight brown discoloration. The decrease in PPO inactivation in apple homogenates during HHP treatments as soluble solids concentration increased is attributed to baroprotective effects and reduced water activity. Among the antibrowning agents, ascorbic acid and calcium chloride inhibited discoloration of apple homogenates before and after HHP treatments. Complete inactivation of PPO in apple homogenates by HHP treatments alone is unlikely. Inactivation of PPO in apple homogenates containing selected antibrowning agents by HHP treatment will slow the development and extent of undesirable brown discoloration.
Session 99E, Nonthermal Processing: General II
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |