Functional properties of thermally treated legume flours

Abstract

Functional properties of four thermally treated decorticated legume flours namely, bengal gram (Cicer arietinum), black gram (Phaseolus mungo Roxb.), green gram (Phaseolus aureus Roxb.) and lentils (Lens esculenta) were studied. Samples with moisture levels of 3.2, 3.3, 1.3 and 5.0% for all four were subjected to dry heat treatment in a covered vessel in pressure cooker. Untreated flours served as controls. Thermal treatment lowered nitrogen solubility profiles of all flours and increased water absorption capacities in bengal gram (146) black gram (451) and lentils (206) over control values of 138, 441 and 180ml/100g of flour respectively. Fat absorption capacities decreased in thermally treated bengal gram and black gram (242 and 292) as against 298 and 303ml/100g for untreated samples respectively. Foaming capacity also showed a decrease in thermally treated bengal gram and black gram by 28 and 53% respectively over controls. Two deep fat fried Indian products namely, ‘Seviya’ and ‘Chakli’ were prepared using two of the legumes. Proximate compositional analysis revealed that products prepared with thermally treated flours absorbed less fat. The sensory scores for appearance, texture, flavour and overall quality obtained by Seviya were 6.04, 6.20, 5.98 and 6.40 for products prepared with untreated flour and 5.74, 5.78, 5.70 and 5.68 for product prepared with treated flour respectively. Chakli prepared with thermally treated flour obtained significantly lower scores of 6.08, 5.2, 5.42 and 5.88 as against 6.78, 6.68, 6.68 and 6.88 obtained by products prepared with untreated flour for similar attributes.