Mechanisms of fat/oil stabilization in meat emulsion
The main goal of this research was to investigate the mechanisms involved in meat emulsion stabilization. The effects of substituting beef fat (25%) with rendered beef fat, canola oil, palm oil, or hydrogenated palm oil at varying meat protein levels (8 to 14%) were studied. There was no significant difference in fat loss among meat batters prepared with beef fat, rendered beef fat, or palm oil. Hydrogenated palm oil provided the most stable batters at all protein levels. Canola oil showed significant fat and water separation when the protein level was raised to and above 14%; this did not occur in the other treatments. The difference was related to the physicochemical characteristics of the canola oil. Light microscopy revealed coalescence of fat globules in the canola oil meat batters prepared with >= 14% protein, as well as formation of fat channels and more protein aggregation. Substituting 1.5% of meat proteins with non-meat proteins (low gelling soy protein isolate, high gelling soy protein isolate, native and preheated whey protein isolates) caused a reduction in cooking losses of the canola oil meat batters. Non-meat proteins with low gelling ability and high emulsifying capacity provided the most stable meat batters. Light microscopy revealed that non-meat proteins decreased the amount of fat agglomeration and protein aggregation. Using pre-emulsified beef fat and canola oil (25%) with Tween 80 or sodium caseinate, at different protein levels (9, 12, 15%), were studied. Replacing beef fat with pre-emulsified beef fat (BF-T80) showed significant fat and water losses during cooking. Light microscopy revealed a widespread of irregular fat globules and more protein aggregation in BF-T80 treatment. However, pre-emulsified canola oil with Tween 80 resulted in reduced fat losses at the 15% protein level compared to the control (no pre-emulsification). Pre-emulsified canola oil, using sodium caseinate, resulted in higher fat and water binding capacity than the control and meat batters prepared with Tween 80. The results indicate an important difference in the lipid holding mechanism between beef fat and canola oil.