15C-14 |
Extruded corn snacks fortified with whey protein concentrate: effect of particle size |
R. P. KONSTANCE1, C. I. Onwulata, and R. J. Wildermuth. (1) USDA-ARS-Eastern Regional Research Center, 600 E. Mermaid Ln., Wyndmoor, PA 19038-8598 The food extrusion industry depends heavily on grains for the creation of snack foods. The protein quality of these products is constrained by low levels of certain amino acids. The addition of milk proteins to these foods would offer a method of improving nutrition, but is limited by adverse effects on extrudate properties. Particle size of the ingredients also plays a significant role in extrudate properties. Our hypothesis is, that by using components of similar particle size, the limiting effects of protein addition can be minimized. Our objective was to determine the effects of various size corn-meal fractions, with added whey protein concentrate (WPC), on the physical and textural properties of the extrudate. Blends of corn meal fractions , separated into four particle size distributions, and WPC (75/25 ratio) were evaluated to determine the effects of added protein on viscosity. The blends were extruded at two moisture conditions (23 and 28%), dried , and analyzed to determine the effect of particle size on the solubility, porosity, expansion ratio and breaking strength of the extrudate. Smaller corn-meal fractions had higher viscosity both with and without added protein. When whey protein concentrate was added, a large reduction in viscosity was observed regardless of the particle size. Blends with similar particle size distributions were twice as viscous. The expansion ratio, porosity and breaking strength of this blend, when extruded at the lower moisture content, was improved to the extent that it behaved similarly to extrudate made from corn meal alone. Utilization of components with similar particle size allows for the addition of up to 25% WPC with minimal impact on the properties of the extrudate. This result suggests that fortification of extruded snack foods to improve their nutritional value can be accomplished.
Session 15C, Dairy Foods
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