| Abstract
| - High-pressure processing (HPP) can inactivate pathogenic microorganisms and degradative enzymeswithout the use of heat, thereby minimizing the destruction of flavors, nutrients, and other qualityattributes. Lipoxygenase plays a role in the off-flavor production of tomatoes, whereas pectinesteraseand polygalacturonase impact tomato texture. The purpose of this study was to determine HPP'sability to inactivate lipoxygenase, pectinesterase, and polygalacturonase in diced tomatoes.Processing conditions used were 400, 600, and 800 MPa for 1, 3, and 5 min at 25 and 45 °C. Themagnitude of applied pressure had a significant effect on inactivating lipoxygenase and polygalacturonase (p< 0.05), with complete loss of activity occurring at 800 MPa. Pectinesterase was veryresistant to pressure treatment. Percent soluble solids, pH, titratable acidity, and color a/b valuesdid not differ significantly among the high-pressure-processed samples as compared to the control,but color L values increased. This change in L values was not considered of practical importance.Apparent protein content decreased in the pressure-processed samples, due possibly to proteindenaturation, loss of solubility, and/or a decrease in dye binding sites to assay protein content. Keywords: Tomato; high-pressure processing; polygalacturonase; pectinesterase; lipoxygenase
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