Quality protein maize based muffins: influence of non-gluten proteins on batter and muffin characteristics

Quality protein maize (QPM) is nutritionally improved maize which has twice the amount of lysine and tryptophan than normal maize. The present study evaluated the effect of different proteins namely egg white proteins (EWP), casein, whey protein isolate, soy protein isolate (SPI) on characteristics of gluten free QPM based muffins. QPM muffins without any added protein served as control and muffins prepared using wheat and EWP served as reference. Effect of addition of different proteins on pasting properties revealed that the thermal stability of QPM flour increased as indicated by decrease in breakdown viscosity. The effect of added proteins on QPM muffin-making properties was evaluated for rheology of batter and physicochemical, texture, color and sensory characteristics of muffins. Dynamic rheology showed that storage modulus (G) and loss modulus (G) of batter with SPI was the highest while batter with EWP showed lowest value. QPM-EWP muffins were softer, chewy and springier and had more specific volume than control muffins and were comparable to reference muffins. Inclusion of all proteins increased L* values (lightness) and decreased a* (redness/greenness) and b* (yellow/blueness) values of QPM based muffins. Sensory analysis revealed that gluten free QPM muffin prepared from EWP were acceptable with a sensory score of 7.97 which was comparable to reference muffins (8.03).