71A-57

K. MANOI and S. S. H. Rizvi. Institute of Food Science, Cornell Univ., Stocking Hall, Ithaca, NY 14853

Whey protein (WP) is often modified to create new functional food ingredients. Useful textural changes in WP, alone or in combination with starch and hydrocolloid, can be induced by rate of heating, pH, and ionic strength. We hypothesized that extrusion processing of whey protein in the presence of supercritical carbon dioxide (SC-CO₂) may impart conformational and rheological changes that would lead to new functional properties. The objective was to develop a new process for whey protein modification that utilized controlled heating and alkaline treatment with SC-CO₂ as a reactive media. A mixture of whey protein, corn starch, xanthan gum, sodium chloride, and calcium chloride was extruded in a twin screw extruder at 82 to 90 °C with 1% injected SC-CO₂. All samples were air dried, ground into powder, reconstituted into 30% w/w dispersion in deionized water, and evaluated for rheological properties. The results indicated that the alkaline-modified, WP-based material extruded with SC-CO₂ displayed higher dynamic viscosity (η'=140.2 Pa.s) and elastic modulus (G'=5606.3 Pa) compared to the unmodified samples (η'=7.8 Pa.s, and Gè'=251.4 Pa). All samples exhibited a shear thinning behavior. The SC-CO₂-based alkaline samples showed little variation in η' and Gè' in the temperature range of 25 to 90 °C. The results suggested that SC-CO₂ had significantly affected WP properties and gave the product a unique thickening characteristic over a wide range of temperature. This may open up a new avenue for utilization of WP as a thickening agent in food formulations.

Session 71A, Dairy Foods: General
8:30 AM - 12:00 PM, Tuesday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana