Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 13, 2005
Publication Date: August 25, 2005
Citation: Onwulata, C.I., Muir, Z.E., Tunick, M.H., Tomasula, P.M. 2005. Properties of dairy proteins and alginic acid gels. ACS National Meeting AGFD 0075. Technical Abstract: The linking of milk protein and food gums increases their viscosity and forms the bases for various foods such as ice cream, milk based beverages and caramel candies. Protein based viscous gels are needed to replace carbohydrate-based ones for reduced calorie or low-fat food applications. In this study, slurries of whey protein isolates and calcium caseinate mixed with alginic acid (20% T.S.) were subjected to high shear homogenization (microparticulation) at 27,000 rpm for 2, 3, 4, and 6 min; and then were incubated with mushroom tyrosinase (E.C. 220.127.116.11) enzyme at levels of 3, 6, 9 mg/100 g to facilitate gel formation by crosslinking alginic acids to whey proteins. After microparticulation and incubation with tyrosinase for 15, 30, 60 and 90 min, the slurries were evaporated at 45 EC for 60 min under a partial vacuum (20 to 45 mm Hg) to form composite gels at 0 min (66 cP) and 6 min 279 (cP), respectively. The viscosities of the gels were measured using a Brookfield rheometer. The results indicate that the time of high shear homogenization had significant (P<0.05) effect on the viscosities of the gels. Optimum gel viscosity was obtained with 6 mg tyrosinase at 60 min, but increases in gel viscosity depended on time of shear with 2 and 4 min shear resulting in stronger incubated gels 484 and 6143 cP, respectively. Gels were stable in refrigerated storage up to 240 hr, strengthening with time of refrigeration storage, and became significantly more viscous. Optimal viscous properties were obtained at 4 min microparticulation, 60 min incubation and with 6 mg tyrosinase treatment. There was significant evidence of protein and alginic acid crosslinking as indicated by the increased viscosities of the tyrosinase treated samples.