Combined effect of temperature and pulsed electric fields on pectin methyl esterase inactivation in red grapefruit juice (Citrus paradisi)

• Published in: European food research & technology 2009-01, Vol.228 (3), p.373-379
• Main Authors: Riener, Joerg, Noci, Francesco, Cronin, Denis A., Morgan, Desmond J., Lyng, James G.
• Format: Article
• Language: English
• Subjects: Agriculture; Analytical Chemistry; Biological and medical sciences; Biotechnology; Chemistry; Chemistry and Materials Science; Citrus fruits; Cooling; Electric fields; Electrodes; Enzymes; Food; Food additives; Food industries; Food Science; Forestry; Fruit and vegetable industries; Fruit juices; Fruits; Fundamental and applied biological sciences. Psychology; General aspects; Heat; Inactivation; Kinetics; Original Paper; Stainless steel; Studies; Temperature; Temperature effects
• ISSN: 1438-2377; 1438-2385
• DOI: 10.1007/s00217-008-0943-6

Pulsed electric fields (PEF) were applied to freshly prepared grapefruit juice using a laboratory scale continuous PEF system to study the feasibility of inactivating pectin methyl esterase (PME). Square wave PEF using different combinations of pre-treatment temperature, electric field strength and treatment time were evaluated in this study. Inactivation curves for the enzyme were plotted for each parameter and inactivation kinetics were calculated. Results showed that the highest level of inactivation (96.8%) was obtained using a combination of preheating to 50 °C, and a PEF treatment time of 100 μs at 40 kV/cm. Inactivation of grapefruit PME activity could be described using an exponential decay model. Calculated D -values following a 50 °C preheat were 77.5, 76.0 and 70.4 μs at 20, 30 and 40 kV/cm, respectively. The activation energy for the inactivation of PME by PEF was 36.2 kJ/mol.