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Factors Affecting Viscosity of Slurries of Oat Groat Flours
Author(s) -
Zhang Decai,
Doehlert Douglas C.,
Moore Wayne R.
Publication year - 1997
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem.1997.74.6.722
Subject(s) - chemistry , slurry , food science , steaming , viscosity , raw material , wheat flour , avena , agronomy , organic chemistry , materials science , composite material , biology
Oat grain is routinely kilned and steamed before milling to develop flavor and to inactivate lipid‐degrading enzymes. Heat treatments can significantly affect viscous properties, which have functional and nutritional importance. Oat flour slurries (23%, w/w, solids dry basis) made from steamed (for 20 min) or autoclaved (at 121°C, 15 psi, for 10 min) grain developed high viscosities, whereas flour slurries made from raw or kilned (105°C for 90 min) oats did not. Flour slurries made from raw groats, surface‐sterilized by 1% hypochlorite, were more viscous than untreated raw groat flour slurries, suggesting that β‐glucan hydrolases on the surface of the groat caused the viscosity losses observed in raw or kilned groats. However, because viscosities developed by surface‐sterilized groats were not as great as in steamed oat‐flour slurries and because some roasting treatments also inactivated enzymes without enhancing viscosity, it appears steaming might also affect the β‐glucan polymer, resulting in its greater hydration in solution. Smaller particle size and higher incubation temperature also resulted in increased flour slurry viscosity, presumably because of increased hydration of the β‐glucan. Rmoval of lipids from steamed oat flour significantly increased the oat flour slurry viscosity, apparently by increasing the β‐glucan concentration in the flour.