Relation Between Thermal Properties of Butter and Its Hardness1,2

Abstract

The heat capacity of commercial and experimental butter as a function of temperature was measured in an electrical input calorimeter. Hardness of the samples was measured either as sectility and viscosity at 10C, or as lubricity value at 22C. Plots of the heat capacity curves of commercial butter showed major phase changes centering at −24, −11, 5, 12, 20, and 30C. Curves for experimental butter were similar, except that the peak at −24C was missing. Comparison to curves for butteroil showed that the changes at −24 and −11C were associated with the aqueous phase of butter. The change at −11C represents the melting of a salt solution, the exact melting point being related to the salt content of the butter. Summer butter contained more liquid fat between −8 and 12C, and was less sectile and less viscous Liquid fat contents at 10C were 41% in the summer and 35% in the winter. Printing reduced butter hardness, but did not affect the liquid fat content. Experimental butter made according to the winter method or by vat processing of the cream was softer, and had higher liquid fat contents, especially at 20C.