MICRONIZATION PRETREATMENTS FOR REDUCING THE COOKING TIME OF LENTILS

For many grain and grain legume crops, a pretreatment step is often em ployed prior to processing to improve the quality of the final product . The pretreatment may be tempering, where a uniform specified moistur e content in the grain is desired, or soaking, where moisture content is high and unevenly distributed. This study evaluated the effect of m oisture contents and reagents as potential pretreatments for microniza tion (infrared heat treatment) of lentils, the objective being to redu ce lentil cooking times. The texture of over-, under-and optimally coo ked lentils was defined by sensory methods and by peak force values at 40% compression. As cooking time increased, sensory scores for hardne ss, chewiness and particle size decreased, as did peak force values. T he peak force for optimally cooked lentils receiving no pretreatment w as the control used to assess the effectiveness of a given pretreatmen t. The pretreatments studied were soaking of lentils, tempering of len tils to 20 or 40% moisture with water alone, and tempering to 20 or 40 % moisture with solutions of various reagents: sodium salts of carbona te, bicarbonate, phosphate, tripolyphosphate and EDTA, and mixtures of citric and ascorbic acids. For tempering pretreatments, cooking time was reduced as moisture increased, but it was only at 40% moisture tha t added reagents were effective in reducing lentil cooking times. It w as postulated that free water must be available in the cotyledon to al low reagents in the tempering water to reduce cooking time beyond that attainable with water alone. Potential reagents for tempering solutio ns used as successful micronization pretreatments were 2% sodium tripo lyphosphate, mixtures of 1% citric and 2% ascorbic acid, and 150 ppm d isodium EDTA. (C) 1998 SCI.