Rate of freezing effect on the colour of frozen beef liver

ZARITZKY NOEMI.; AÑON M C.; CALVELO A.

MEAT SCIENCE

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 1982 vol. 7 p. 299 - 312

0309-1740

One problem that arises when freezing liver b~ plate freezers is the whitish colouracquired by the liver surface when subjected to high freezing rates.The purpose of this paper aims to establish optimum operating conditions forfreezing beef liver pieces in a minimum time while maintaining an acceptable colouron the surface. Samples were subjected to different freezing rates and minimum surf ace freezing time was established in order to obtain an acceptable colour. This was quantified interms of lightness using a surface colorimeter.Histological analysis of the samples showed that the size of the ice crystals formedon the contact surface with the coolant is the factor that determines the changes incolour as a result of diffused light reflection phenomena.On the basis of mathematical heat transfer models with simultaneous change of phase, the minimum characteristic surf ace freezing time was related to the process operating variables (initial temperature of the liver, coolant temperature, interfacial heat transfer resistance, thickness of the piece), and the optimum freezing conditions were determined, reducing total processing times to a minimum.