Cereal Chem 63:27-30   |  VIEW ARTICLE
Rice Grain Hardness and Its Relationship to Some Milling, Cooking, and Processing Characteristics.

B. D. Webb, Y. Pomeranz, S. Afework, F. S. Lai, and C. N. Bollich. Copyright 1986 by the American Association of Cereal Chemists, Inc. 

Hardness was determined on milled, brown, and rough rice forms of 28 long-, medium-, and short-grain rice varieties varying widely in milling, cooking, and processing characteristics. Hardness was determined by five indirect methods: time to grind (BMHT), particle size index (PSI), near-infrared reflectance (NIR), resistance to grinding (RES), and crushing force (KIYA). Each hardness test showed a relatively wide range in values among one or more of the milled, brown, and rough rice forms. BMHT, NIR, and KIYA hardness methods differentiated between all three rice forms, whereas PSI and RES distinguished only one form of rice. Correlations among hardness indices and the three rice forms and among rice forms for each hardness test were significant but of a relatively low order of magnitude. Correlations between hardness and rice grain quality parameters (milling yield, amylose, alkali spreading value, gelatinization temperature, protein, and grain size and shape) showed some associations but were generally either low or insignificant.