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Rheological Properties of Starch and Whey Protein Isolate Gels

Embrapa Food Technology, Av. das Américas, 29501, Guaratiba, 23020-470 Rio de Janeiro, Brazil

C.I. Onwulata

Dairy Processing and Products Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA, Charles.Onwulata{at}ars.usda.gov

P.M. Tomasula

Dairy Processing and Products Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA

The paste viscosity of starches Amioca (~0.5% amylose), native corn (~27% amylose), Hylon VII (~70% amylose), tapioca (~19% amylose), and their whey protein isolate (WPI; 50/50) mixtures at varying solid concentration of 2.5, 5, 10, 15 and 20% were determined. At higher gel concentration (20%) during the cooling cycle, WPI paste measured by rapid visco-analyser (RVA) showed a tremendous increase in viscosity over that of the micro visco-amylograph (MVA), 5784 and 184 cP, respectively. RVA gels had a more uniform network of coarse particles (~250—500 nm) than the fine structures (~50 nm) in those of the MVA. Inclusion of WPI reduced the paste viscosity of all starches by at least 50%, except for Hylon VII at 20% solid concentration. The strength of Hylon VII and corn starch gels was reduced by WPI. In contrast, gels of WPI/tapioca (G' = 45.4 Pa) and WPI/amioca (G' = 18.3 Pa) had similar rheological properties as their pure starch control (G' = 47.4 Pa and G' = 15.3 Pa for Tapioca and Amioca, respectively).

Key Words: whey protein • starch • viscosity • gel • rheology

Food Science and Technology International, Vol. 13, No. 3, 207-216 (2007)
DOI: 10.1177/1082013207079897


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