Ultra high pressure treatment of orange juice: a kinetic study on inactivation of pectin methyl esterase

• Published in: Food research international Vol. 29; no. 7; pp. 601 - 607
• Main Authors: Basak, S., Ramaswamy, H.S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.1996; Elsevier
• Subjects: Biological and medical sciences; enzyme inactivation; Food industries; food processing; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; horticultural crops; orange juice; pasteurization; pectin methyl esterase; ultra high pressure; orange juice; pasteurization; pectin methyl esterase; enzyme inactivation; ultra high pressure; Physical dressing; Enzyme; Pasteurization; Esterases; Solid particle; Inactivation; Fruit juice; Pressurizing; Carboxylic ester hydrolases; High pressure; Pressure effect; Orange juice; Content; pH; Hydrolases; Kinetics; Pectinesterase
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/S0963-9969(96)00068-3

Ultra high pressure treatments ranging from 0 to 720 min were applied to freshly squeezed, non-pasteurized orange juice and reconstituted frozen orange juice at pressures in the range 100 to 400 MPa to investigate the pressure inactivation kinetics of pectin methyl esterase (PME) activity. Freshly squeezed orange juice was adjusted to pH 3.7 or 3.2 (12.6 ° Brix) while the reconstituted frozen concentrate orange juice was adjusted to 10, 20, 30 and 40 ° Brix at pH 3.7. The frozen concentrated orange juice was initially heat treated to inactivate the natural enzymes and then fortified with commercial PME prior to inactivation studies. Analyses of kinetic data revealed the presence of a dual-effect of pressure inactivation: the first one, designated as an instantaneous pressure kill (IPK), which depended only on the pressure level; and a second one, which depended on the holding time at each pressure level, described by first-order reaction kinetics (characterized by a rate constant, k, or by the more familiar decimal reduction time, D). The associated IPK were higher and D values were lower at the lower pH and lower soluble solid contents. The pressure sensitivity of D values were adequately described by a z p value which represented the range of applied pressure between which the D values change by a factor of 10.