Effect of heat treatment on viscosity of yolk

TLDR: In this paper, the authors used a Wells-Brookfield microviscometer to measure the viscosity of a pseudoplastic, non-Newtonian fluid with a solids content of 52.5% with an increase in shear rate from 1.9 to 19.2 sec-1.8 sec.

Abstract: 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.