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EFFECT OF HEAT TREATMENT ON VISCOSITY OF YOLK
Author(s) -
CHANG P. K.,
POWRIE W. D.,
FENNEMA O.
Publication year - 1970
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1970.tb02014.x
Subject(s) - yolk , shear thinning , viscosity , chemistry , shear rate , apparent viscosity , reduced viscosity , rheology , urea , chromatography , materials science , food science , composite material , biochemistry
SUMMARY– Apparent viscosity readings at different shear rates for yolk or albumen‐containing yolk in the native or heated conditions were obtained by a Wells‐Brookfield microviscometer. The viscosity‐shear rate curves for these yolk samples are typical for a pseudoplastic, non‐Newtonian fluid. The apparent viscosity of native yolk with a solids content of 52.5% dropped gradually from 23 to 18 poises with an increase in shear rate from 1.9 to 76.8 sec ‐1 . The apparent viscosity of pasteurized yolk (65.6°C for 3 min) dropped drastically from 200 to 100 poises with an increase in shear rate from 1.9 to 19.2 sec ‐1 . Addition of thin albumen at levels of 5, 10 and 20% to native yolk brought about a considerable decline in the viscosity. The heat damage to the albumen‐containing yolk as reflected by viscosity increase was reduced as the content of thin albumen increased. The viscosity increase of urea‐treated yolk and yolk with 5 and 10% thin albumen was related to the temperature of heat treatment prior to urea addition.