Effect of High-Pressure Treatment on Lipoxygenase Activity

Solutions of commercial soybean lipoxygenase (100 μg/mL) in 0.2 M citrate−phosphate and 0.2 M Tris buffer were subjected to pressures of 0.1, 200, 400, and 600 MPa for 20 min. The enzyme was stable at atmospheric pressure (0.1 MPa) over a wide pH range (5−9). In citrate−phosphate buffer, the enzyme...

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Published inJournal of agricultural and food chemistry Vol. 48; no. 7; pp. 2896 - 2902
Main Authors Tangwongchai, Ratchada, Ledward, Dave A, Ames, Jennifer M
Format Journal Article
LanguageEnglish
Published Washington, DC American Chemical Society 01.07.2000
Subjects
Biological and medical sciences
Electrophoresis, Polyacrylamide Gel
Food industries
Fruit and vegetable industries
Fundamental and applied biological sciences. Psychology
Glycine max - enzymology
Hydrogen-Ion Concentration
Lipoxygenase - metabolism
Pressure
Solanum lycopersicum - chemistry
Solanum lycopersicum - enzymology
Taste
Volatile compound
Biochemical analysis
Stability
Enzyme
Fruit vegetable
Soybean
Tomato
Flavor
High pressure
Enzymatic activity
Quality
Freshness
Chemical composition
Oxidoreductases
Lipoxygenase
Quantitative analysis
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Summary:Solutions of commercial soybean lipoxygenase (100 μg/mL) in 0.2 M citrate−phosphate and 0.2 M Tris buffer were subjected to pressures of 0.1, 200, 400, and 600 MPa for 20 min. The enzyme was stable at atmospheric pressure (0.1 MPa) over a wide pH range (5−9). In citrate−phosphate buffer, the enzyme had maximum stability over the pH range 5−8 in untreated samples and after treatment at 200 MPa, but with increasing pressure, the pH stability range become narrower and centered around pH 7−8. The enzyme was more sensitive to acid than alkali, and at pH 9, it lost virtually all activity after pressurization at 600 MPa for 20 min in both buffers. The activity of the crude enzyme extracted from tomatoes treated at 200 and 300 MPa for 10 min was not significantly different from that of the untreated tomatoes, while a pressure of 400 MPa for 10 min caused a significant decrease in activity and treatment at 600 MPa led to complete and irreversible activity loss. Compared to unpressurized tomatoes, treatment at 600 MPa gave significantly reduced levels of hexanal, cis-3-hexenal, and trans-2-hexenal, which are important contributors to ‘fresh‘ tomato flavor, and this was attributed to the inactivation of lipoxygenase. Keywords: High-pressure treatment; tomato; lipoxygenase; pH; flavor
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ISSN:0021-8561
1520-5118
DOI:10.1021/jf9913460