14B-7 |
Functional properties of extruded rice flours |
R. S. KADAN, Food Processing & Sensory Quality Research Unit, USDA-ARS-Southern Regional Research Center, 1100 Robert E. Lee Blvd., PO Box 19687, New Orleans, LA 70179-0687, A. B. Pepperman, Jr., Commodity Utilization Research Unit, USDA-ARS-Southern Regional Research Center, 1100 Robert E. Lee Blvd., PO Box 19687, New Orleans, LA 70179-0687, and R. J. Bryant, USDA-ARS-Dale Bumpers National Rice Research Center, 2890 Hwy. 130 E., PO Box 1090, Stuttgart, AR 72160-1010. Rice grain, because of its unique attributes, such as ease of digestion, bland taste, white color, hypoallergenic properties, and absence of gluten has become a popular ingredient for developing novel cereal foods. This is especially true for persons suffering from gluten sensitivity such as celiac sprue and other chronic diseases. Extrusion has become a popular, economical, and convenient process to produce novel cereal-based foods. There is a need to characterize the physicochemical/functional properties for extruded rice flours. This paper describes two functional properties of long-grain, high amylose (LG) and short grain, low amylose (SG) extruded rice flours at six temperatures between 70-120 ̊C. The flours were also incorporated into a fried snack to evaluate the functional properties with the product characteristics. The extrudate was either dried at room temperature or frozen overnight and then dried. Dried material was evaluated for its functional properties such as rapid viscosity (RVA), water absorption index (WAI), water solubility index (WSI), and fat absorption index (FAI). The results showed that in LG, the WAI and WSI increased with extrusion temperature. With the SG, WAI decreased but WSI increased as the temperature increased. The RVA showed that both setback and final viscosities decreased with the increase in extrusion temperature whereas the cold paste viscosity increased. These results suggest that flour extruded at higher extrusion temperatures are suitable for making soups, beverages and batter-type products whereas lower temperatures or unextruded flours are suitable for bread or rice-fry-like products. This was confirmed by substituting 25% rice flour into a wheat-based fry snack. The fat absorption decreased 35-50% showing that a substantial decrease in fat absorption can be achieved by incorporating rice flour into fried foods and batters. This showed that physicochemical and functional properties of extruded rice flour can be related with their performance in novel foods.
Session 14B, Food Chemistry: Physicochemical properties
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