Relationship between characteristics of oil droplets and solidification ofthermally treated creams

The relationship between the characteristics of oil droplets and the change in appearance of cream was investigated. The model creams (40 wt% oil-in-w ater emulsion), similar to commercial products, were prepared with vegetabl e fat, milk protein, and emulsifier. The thermal treatment, in which the cr eam was exposed to a certain temperature and subsequently recooled, was per formed on the assumption that the temperature was temporarily elevated duri ng transportation and storage of commercial products. Solidification of the cream was observed when it was exposed to a temperature where there was a small percentage in solid fat content (SFC) of fat in oil droplets and reco oled, whereas the cream remained in the liquid state when it was exposed to the temperature where SFC was zero and recooled. When the SFC of oil dropl ets was 0% at the treated temperature, greater supercooling prior to fat cr ystallization occurred and the crystallization rate after the initial forma tion of crystals was much higher. On the other hand, the polymorphism of fa t in the droplets was not directly affected by the thermal treatment. These results indicate that the crystallization in oil droplets at the heating t emperature may be closely connected with the destabilization of oil droplet s via a partial coalescence mechanism, which will cause the solidification of cream.