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Effect of Variable Parboiling on Crystallinity of Rice Samples

January 2008 Volume 85 Number 1
Pages 92 — 95
J. T. Manful,1 C. C. Grimm,2,3 J. Gayin,1 and R. D. Coker4

Food Research Institute (CSIR), P.O. Box M.20, Accra, Ghana. USDA-ARS Southern Regional Research Center, 1100 Robert E. Lee Blvd., New Orleans, LA 70124. Corresponding author. E-mail: cgrimm@srrc.ars.usda.gov Food Management and Marketing Group, Natural Resources Institute University of Greenwich at Medway Chatham Maritime; Kent, ME4 4TB, England.


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Accepted August 21, 2007.
ABSTRACT

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



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