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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food Processing and Sensory Quality Research » Research » Publications at this Location » Publication #229023

Title: Effect of variable parboiling on crystallinity of rice samples.

item Manful, J.t.
item Gayin, J.
item Grimm, Casey
item Coker, R.d.

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2007
Publication Date: 1/4/2008
Citation: Manful, J., Gayin, J., Grimm, C.C., Coker, R. 2008. Effect of variable parboiling on crystallinity of rice samples. Cereal Chemistry. 85:92-95.

Interpretive Summary: Parboiling is a process which soaks and steams rice before milling. Pockets of micro-crystallization within the starch structure are disrupted and allowed to reform. The process results in a less sticky rice kernel, and higher milling yield is obtained. This work looks at the effects the process has on the formation of crystallinity as the severity of the parboiling process is increased. Even in the most severe conditions, no discernable increase in crystallinity was observed. This work is of interest to the rice industry and researchers within the area of cereal science.

Technical Abstract: Rice parboiled at various combinations of cooking time and temperature, were analyzed by differential scanning calorimetry and X-Ray diffraction. Generally, gelatinization enthalpy decreased as the soaking temperature increased from 30ºC through 50ºC, and 70ºC to 90ºC, and gelatinization enthalpy decreased as steaming times increased from 4 and 8 minutes to 12 minutes. As expected, a distinctive A-pattern was observed in the XRD of raw rice. The most severely parboiled laboratory sample (90°C for 12 minutes), showed no discernable change towards the V-pattern. Crystallinity decreased from the raw rice (24.6 %) with increased cooking temperature.