Cereal Chem 65:417-423   |  VIEW ARTICLE

Laboratory Parboiling Procedures and Properties of Parboiled Rice from Varieties Differing in Starch Properties.

S. K. Biswas and B. O. Juliano. Copyright 1988 by the American Association of Cereal Chemists, Inc. 

Differences in rate of water absorption during steeping and steaming of rough rice due to differences in starch gelatinization temperature (GT) may be minimized by soaking for 8 hr at 60 C and steaming for 10 min at 1.0 kg/cm2 steam pressure (120 C) or 30 min at 100 C. The water content of parboiled rice was higher for low-GT rice than for intermediate-GT rices steamed at 100 C only. In 12 rices parboiled at 100, 120, and 127 C, apparent amylose content was the major factor influencing parboiled rice properties such as brown rice bending hardness, head rice yield, equilibrium water content, gel consistency and viscosity, and cooked rice hardness and stickiness. Gelatinization temperature was an important factor only in rices parboiled at 100 C, probably because it affected parboiling rate at that temperature. Differences in degree of parboiling because of differences in GT resulted in different relations between parboiled rice properties and raw rice quality factors in samples parboiled at 100, 120, and 127 C. Thus, raw rice quality factors, particularly apparent amylose content, may be used in breeding programs as in index of parboiled rice quality. Gel consistency of brown and milled rice in 0.2N KOH was confirmed to soften on parboiling.