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IRREVERSIBLE SHEAR THINNING AND THICKENING OF TOMATO JUICE
Author(s) -
MIZRAHI S.
Publication year - 1997
Publication title -
journal of food processing and preservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.511
H-Index - 48
eISSN - 1745-4549
pISSN - 0145-8892
DOI - 10.1111/j.1745-4549.1997.tb00782.x
Subject(s) - thinning , thickening , dilatant , shear thinning , fruit juice , chemistry , food science , rheology , materials science , composite material , biology , polymer science , ecology
Tomato juice behaves as a weak gel of pulp network. Shearing of the juice disrupts that pulp network causing an irreversible loss of viscosity, that follows a first order kinetics with a time constant that is shorter the higher the shear rate (e.g. 900, 80 and 15 s for rates of 10, 100 and 1000 s −1 , respectively). However, at a high enough shear rate (e.g., 1000 s −1 ) the disruption of the pulp structure is immediately followed by a counteracting process that partially restores the capability of the suspended particulates to reform a new network and in turn recover a large part of the lost viscosity. Unfortunately, that recovery process requires high enough shear rate and long time, a combination which is rare in common industrial practice. Normally, the mechanical shearing during processing of tomato juice might be a major cause of an irreversible loss of viscosity.