Changes in tissue structure and textural characteristics of maize grain during cooking process

Abstract

Both whole and debraned maize grains were cooked under atmospheric pressure at 100 °C and in a pressure cooker at 121 °C with sample to water ratio of 1:1.5 (w/w) to study the moisture uptake, hardness and microstructure of the cooked samples. Moisture content of maize grain increased sharply in pressure cooking and took 90 and 120 min for debraned and whole maize grains, respectively to achieve about 62/100 g moisture content (w.b.). The hardness decreased with cooking time for both whole and debraned grain as the moisture content increased and starch got gelatinized. Cooking of debraned maize samples for 90 min resulted in a homogeneous mass by rupturing of the histological cell walls with complete gelatinisation as indicated by scanning electron microscopy at moisture content of 62.9 % (w.b.). The hardness of cooked maize samples dried in hot air dryer at 70 °C increased with drying time. Cooked debraned maize samples dried for 45 min was non-sticky and recorded hardness of 387 N at 44.7 % moisture content (w.b.). Considering the extent of starch gelatinization and textural property, it is recommended to cook debraned maize grains under pressure at 121 °C for 90 min followed by drying in hot air dryer at 70 °C for 45 min before flaking. The outcome of the present study will have great potential for preparation of cornflake by small entrepreneurs at house hold level.