A. ARORA1, G. W. Chism, III1, and T. A. Shellhammer2. (1) Dept. of Food Science & Technology, Ohio State Univ., 230 Parker Hall, 2015 Fyffe Ct., Columbus, OH 43210, (2) Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97330
High Pressure Processing (HPP) is a non-thermal food processing technique that extends the shelf life of food while preserving its nutrition and fresh flavor. However, the structure of the food can undergo pressure induced changes that may have direct bearing on the foods' sensory attributes. Earlier studies have shown that food components like water and lipid undergo volume contraction to differing degrees under high pressure. We hypothesized that pressure related volume changes of the two phases, along with changes in the surfactant structure, could alter the rheological characteristics and physical stability of the pressure treated emulsions.
The objective of this study was to characterize the effects of surfactant and dispersed phase on the rheology and stability of high pressure treated model food emulsions.
Different oil-in-water pre-emulsions (pH 3.7), having dispersed phase (Canola oil) concentration ranging from 0% to 50% w/w and surfactant levels of 0.1% to 1% w/w were formed in Ultra-Turrax blender followed by valve homogenization at 20oC. Lecithin, Polysorabte-60 and whey proteins were used as surfactants. The samples were pressurized at 500 MPa for 5 min at 25oC and compared with non-pressurized control for their rheological properties using a controlled stress rheometer. Particle size was analyzed using Malvern Mastersizer while stability was determined by a centrifugation test.
HPP did not have a significant effect on the particle size, Zero stress viscosity, loss modulus and emulsion volume index. Variation of surfactant type and level, along with lipid level, had a greater influence than pressure on the rheological properties and stability of the acidified emulsions.
High pressure may be very effective in extending shelf life of low pH emulsions without significantly altering emulsion structure or stability.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
2:00 PM - 5:30 PM, 2002-06-18
2002 Annual Meeting and Food Expo - Anaheim, California
|