10-2 |
Effect of maltodextrin molecular size on viscosity of starch-maltodextrin systems |
B. M. PRADO, Dept. of Food Science, Purdue Univ., 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009, O. H. Campanella, Dept. of Agricultural & Biological Engineering, Purdue Univ., 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009, and B. R. Hamaker, Whistler Center for Carbohydrate Research, Purdue Univ., Dept. of Food Science, 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009. Structure-function relationships have been used in the food industry to redesign processes and produce specific ingredients, so as to obtain the most desirable textural properties of foods. Ingredient manufacturers and product developers need to understand how specific starch molecular weights and types affect rheological properties such as viscosity of foods during cooking and cooling. In this research, branched water-soluble fractions of low polydispersity were obtained to determine molecular weight and functionality relationships by 1) ball milling starch at 1, 14 and 23% moisture contents for 5 min, 2) precipitating maltodextrin with dextrose equivalent DE 1 at 40 and 50% ethanol, and 3) using maltodextrins with DE 1, 5, and 10 from three commercial manufacturers. High performance size exclusion chromatography, coupled with multi angle laser light scattering and RI detectors (HPSEC-MALLS-RI) were used to detect the distribution of molecular weights of all glucans (1.7 C104 to 7.3C105g/mol). The resultant fractions were used to substitute 5 and 10% of starch and pasting characteristics of 10.7% solids-gels were evaluated using a Rapid Visco Analyzer (RVA). Ten percent substitution of starch with glucans caused greater reduction in pasting viscosity than 5% substitution. Also, higher molecular weight glucan fractions caused more pronounced decrease in pasting profiles. In this regard, correlations were found between peak viscosity (5% substitution, r=-0.8988, 10% substitution, r=-0.9002), trough (r=-0.9075, -0.8478) and final viscosity (r=-0.8274, -0.7869) vs molecular weight of glucans substituting starch (P< 0.0001). It was hypothesized that glucans with higher molecular weights had greater effect in reducing viscosity than glucans with lower molecular weight because the former filled the interstitial spaces within the starch component increasing the maximum packing volume.
Session 10, Carbohydrate: General
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