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item Onwulata, Charles
item Tunick, Michael
item Tomasula, Peggy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2007
Publication Date: 5/16/2007
Citation: Onwulata, C.I., Tunick, M.H., Tomasula, P.M. 2007. Cold extrusion texturization of whey proteins. AOCS Book of Abstracts: p. 143.

Interpretive Summary: N/A

Technical Abstract: Addition of non-texturized whey protein isolates (WPI) to some snacks or baked products sometimes reduces the textural quality of the food. Texturization, the protein-modifying effect of extrusion processing, produces textured proteins using moderate shear under near and/or sub-ambient extrusion conditions. Texturization prevents denaturing of the nutritious WPI, and converts it to a stretched or texturized dough-like gel that is in the form required for its addition to foods. WPI was fed into an APV MPF50 twin-screw extruder at 11 kg/hr; water input to the extruder was at 5 L/hr at isostatic pressure and thermal conditions ranging from 5 to 35 °C. The extruded whey gels ranged in moisture content from 40 to 50%. Rheological properties as indicated by the values for elastic modulus (G'), viscous modulus (G"), and tan delta (G"/G') were measured. Frequency sweeps from 1 to 100 rad/s performed after 1, 3, and 7 d storage at 21ºC showed that samples extruded at 35ºC became liquid-like (tan delta > 1) at frequencies above 50 rad/s, and that the G' values increased with time, indicating the gels were strengthening. The samples extruded at 30ºC were solid-like (tan delta < 1) below 20 rad/s, and their G' values decreased with 21ºC storage. The tan delta values of samples extruded at 15ºC increased with 21ºC storage, but never exceeded 0.86; their G' values fluctuated during the storage period. The behavior of the samples extruded at 5ºC was liquid-like within the first 3 d, and their G' values increased with storage. The results indicate that the temperature of extrusion affects the solid/liquid behavior of the gels, both initially and during storage. Cold-textured WPI forms gels and may be used by food processors in meat analogues, high-protein snacks, and other products to provide health-enhancing benefits.