Where’s the fat? Freeze-fracture analysis of ingredient interactions in food systems

Abstract

An important trend in the food industry today is reduction in the amount of fat in manufactured foods. Often fat reduction is accomplished by replacing part of the natural fat with carbohydrates which serve to bind water and increase viscosity. It is in understanding the roles of these two major components of food, fats and carbohydrates, that freeze-fracture is so important. It is well known that conventional fixation procedures are inadequate for many food products, in particular, foods with carbohydrates as a predominant structural feature. For some food science applications the advantages of freeze-fracture preparation procedures include not only the avoidance of chemical fixatives, but also the opportunity to control the temperature of the sample just prior to rapid freezing.In conventional foods freeze-fracture has been used most successfully in analysis of milk and milk products. Milk gels depend on interactions between lipid droplets and proteins. Whipped emulsions, either whipped cream or ice cream, involve complex interactions between lipid, protein, air cell surfaces, and added emulsifiers.