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L. E. METZGER, Dept. of Food Science & Nutrition, Univ. of Minnesota, 1334 Eckles Ave., 165 Food Science & Nutrition Bldg., Saint Paul, MN 55108-6099 The Rapid Visco Analyzer (RVA) is a computer-integrated instrument developed to determine the viscous properties of cooked starch, grain, batter and other foods. This instrument continuously measures apparent viscosity under variable conditions of shear and temperature. We have recently utilized the RVA to measure apparent viscosity in several dairy related applications including cheese melt analysis, rennet casein hydration, and process cheese manufacture. For melt analysis a heating, holding, cooling profile was used to characterize the apparent viscosity of process cheese and the apparent viscosity vs time curve obtained was used as an index of melt properties. In the second application the hydration properties of rennet casein in the presences of a solution of emulsifying salt (trisodium citrate) were monitored during continuous mixing in the RVA. During this test an increase in apparent viscosity was observed which corresponded to manufacturing characteristics of the rennet casein when it was used as an ingredient in rennet casein based cheese products. The RVA has also been utilized to manufacture process cheese on a small scale. This small scale manufacturing procedure is currently being used to evaluate the effect of formulation and manufacturing parameters on process cheese characteristics. Each RVA application has required extensive testing to determine the optimal RVA operating conditions and sample handling requirements. However, the wide variety of current applications of the RVA indicates that it is a useful tool for viscosity analysis of dairy products.
Session 109, The rheology of dairy foods
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