Submitted to: Starch/Starke
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/22/2009
Publication Date: 5/1/2010
Citation: Guraya, H.S., Lima, I.M., Champagne, E.T. 2010. Method of creating starch-like ultra-fine rice flour and effect of spray drying on lipid components. Starch/Starke. 62:173-180. Interpretive Summary: Ground rice flour is widely used in infant foods, noodles, extruded breakfast cereals, snack foods, and pet food. Finely ground waxy rice flour is known to reduce fat in fried foods. Ultra fine flour would reduce the amount of flour needed for frying and probably impart a crispier mouth feel due to thinner fried layer. Traditional grinding procedures do not work. The only way to produce flour with desirable functional properties would be to wet grind the rice and then dry the deagglomerated rice flour slurry. We developed a method of making ultra fine rice flour by homogenizing wet rice flour slurry, followed by drying. Since rice flour contains fat, it is prone to rancidity. Drying has been known to increase rancidity. We studied the effect of drying conditions and storage on development of rancidity.
Technical Abstract: Rice flour from long, medium, and short grain cultivars were processed by passing a 32% rice flour slurry through a microfluidizer at 100 MPa, and spray dryer at three different outlet temperatures, OT (50°C, 80°C, and 115°C). Spray drying conditions were controlled by the flow-rate of the slurry and inlet temperature. Spray dried rice flours and unprocessed rice flour were examined for their lipolytic stability during storage for 210 days by measuring free fatty acid (FFA) formation. The percentage of fat and FFA in rice flour was significantly reduced by spray drying. The resulting amount of fat and %FFA was rice type dependent and related to the amylose content and outlet temperature. Upon storage, the formation of FFA was lowest for rice flours processed at 115°C outlet temperature as compared to 80°C, 50°C and control. Pin milling of the spray dried flour resulted in the breakdown of loose re-agglomerated rice flour formed during spray drying with a particle size similar to rice starch but increased starch damage by about 1% per pass through pin mill.