59D-14 |
Effect of heat treatment on the solubility and emulsion stability of whey proteins |
B. MOON and M. E. Mangino. Food Science and Technology, Ohio State University, 110 Parker Food Science and Technology building, 2015 Fyffe Court, Columbus, OH 43210 Liquid nutritional products are sterile emulsions. They require proteins that are able to withstand sterilization. The proteins are also expected to stabilize the emulsions towards gravitational creaming during storage. Proteins that are inherently heat stable tend not to function well at stabilizing emulsions. Whey protein concentrates form very stable emulsions, but are difficult to process at high temperatures. The purpose of this research was to increase the thermal stability of whey protein concentrates while maintaining acceptable emulsion stability. Whey proteins were processed by ultrafiltration from 5 to 20 fold. The retentates were heated for in one of two full factorial designs. In the first samples were processed at 70, 72 or 74 °C for times of 600, 700, 800 and 900 seconds. The second design involved heating at 76, 78, 80, 82 and 84 °C for 15, 30, 45 or 60 seconds. Retentates were dried and heat stability was estimated after heating at 121 C for 5 minutes. Protein in the supernatant after centrifugation at 500 x G was considered as functionally soluble. Treated protein samples were analyzed by differential scanning calorimetry to determine temperatures and enthalpies of denaturation. Model products containing appropriate amounts of protein, lipids, emulsifiers, stabilizers and salts were homogenized and sterilized. Emulsion stability was estimated by the emulsion volume index method. Protein solubility following high heat treatment ranged from 24 to 95%. Emulsion volume index of model nutritional products ranged from 0.08 to 0.43. Proteins that were most soluble following high heat treatment gave the lowest emulsion stability. The highest emulsion stability was recorded for samples that were partially soluble after heating (48 to 55%). These results suggest that it may be possible to produce whey protein concentrates that are more tolerant to thermal processing that still function well in emulsion stabilization.
Session 59D, Food Chemistry: Proteins and Physicochemical Properties
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