Physico-chemical studies in relation to cracking properties in rice using isogenic lines.

Physical and chemical properties (cracking, shelling breakage, length, breadth and their ratio, husk thickness) and culinary properties (cooking time, bulk vol. and consistency of cooked rice) of one crack resistant var. (Halubbulu) and 3 pairs of isogenic lines from cv. Vani and Pushpa differing in degree of crack resistance were studied. The equilibrium moisture content on soaking of grains decreased slightly with increase in crack resistance (CR). Gelatinization temp. was 66-74 degree C in CR lines and 61-65 degree C in crack susceptible (CS) lines. The milled rices of CR lines took 16.6-18.2 min and CS lines 13.1-15.7 min to cook. Peak viscosity values of CR lines were higher than the corresponding CS lines. Higher CR was associated with lower alkali score [see FSTA (1973) 5 2M151]. There was no difference in the amylose content of CR and CS lines, nor in culinary properties like vol. expansion and pastiness. Pentosan content is closely related to CR; it varied from 3.8 to 4.5 in CR and 1.9 to 2.3% in CS lines.