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E. A. FOEGEDING, Dept. of Food Science, North Carolina State Univ., Schaub Hall, Box 7624, Raleigh, NC 27695-7624 The formation of a protein or polysaccharide gel network is essential to the textural and water-holding properties of many foods. Besides protein and/or polysaccharides and water, food gels often contain lipids and sugars that contribute to the overall quality. Therefore, in order to lower the caloric content of food gels, the precise function of lipid and sugars in the system must be understood so that overall quality can be maintained when lipid and sugars are reduced. Lipids function as a non-polar phase for flavor compounds, and as a filler component in the gel network. Therefore, altering the lipid content can change the flavor release profile and product texture. These effects are seen in heat-induced whey protein isolate emulsion-gels when the lipid content and network structure are changes. A network with lower water-holding ability was associated with a rapid release of flavor. As the lipid content of the gel increased, the difference in flavor release due to network type became less apparent, and the lipid content became the main factor controlling flavor release. Rheological properties indicated that the emulsion-gel fit a “filled gel” model, with the lipid functioning as an “active filler.” By interacting with the gel network, active fillers cause an increase in the rheological (fracture modulus) and sensory properties associated with firmness. Sugars have the general function in food gels of stabilizing protein structure, adding sweetness, and generating flavor compounds (e.g., Maillard reaction). As with lipids, other means to achieve these functions would be required for successful formulation of low calorie foods. These will be highly dependent on the sugar concentration, sugar type and pH of the food gel. Various strategies and research needs will be discussed with the ultimate goal of reducing calories and maintaining quality.
Session 8, Physics and chemistry of modifying food for caloric reduction
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