15A-15 |
Effect of phosphates and protein concentration on physical properties of sterilized whey protein emulsions |
G. PEREZ-HERNANDEZ, R. Suhareli, and R. Richter. Department of Animal Science, Texas A&M University, Kleberg Building, Room 305, College Station, TX 77843-2471 Whey protein emulsions are unstable after heat treatment; phosphates are widely used to improve the stability of emulsions. Different phosphates are available and should be selected for the improvement of specific emulsions. Our objective was to investigate the effect of phosphates and protein concentration on physical properties of sterilized whey protein emulsions. Whey protein emulsions were prepared with WPC-35 with varying final protein composition of 3, 5, and 7%. The composition of fat was constant throughout the experiment at 3%. Sodium metaphosphate, sodium polyphosphate, and sodium orthophosphate were added at 0.5%. Samples were homogenized at 20MPa and sterilized at 121°C for 15 minutes. Differences in rheological properties and particle size were analyzed using a Brookfield DV-III Rheometer and Coulter LS 130 respectively. Our results showed that phosphates and protein concentration had a significant effect in particle size and rheological properties of the emulsions. Dvs and viscosity increased as protein concentration was increased. Emulsions with higher protein concentration were less stable. Emulsions prepared with sodium polyphosphate had the lowest dvs and viscosity when the pH was adjusted to 6.68 prior to the heat treatment. The addition of sodium polyphosphate caused the pH of the emulsions, which contained 3, 5, and 7% protein to decrease 0.3, 0.2 and 0.1 units. This decrease was greater than the decrease noted for the other phosphates and probably contributed to a larger dvs in these emulsions compared to the other emulsions that did not have pH adjustment. This was more evident in emulsions containing 3% protein. Physical properties of sterilized whey protein emulsions can be enhanced by adding phosphates. The pH and protein compositions of the emulsions have to be considered when selecting the appropriate phosphate to improve the particular emulsion. These results provide a guideline for creating superior heat-treated whey protein products.
Session 15A, Dairy Foods
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