Effect of Rennet Casein and Whey Protein Concentrate on Extrusion Behavior of Maize Flour

Abstract

The present study was carried out to find out the effect of blending of maize flour (MF) with varying levels of Rennet casein (RC 6, 8%) and Whey protein concentrate-70 (WPC-70  4, 8%) at different feed moisture content (12,14%) on the physico-chemical characteristics (pasting properties, colour, expansion  ratio, bulk density, hardness, water absorption and water solubility index, resistant starch), sensory properties of extrudates and their changes in physico-chemical (TBA and Free Fatty acids) as well as sensory properties of extrudates during storage. Physical parameters like, bulk density, WAI, WSI, expansion ratio, texture profile (hardness and crispiness) shown significant (p<0.05) variation among the treatments. Addition of RC and WPC-70 increased the setback viscosity and decreased the peak, breakdown and final viscosity. The hunter L* value, a* value and b* value were significantly (p< 0.05) affected by the type and level of addition of protein. Incorporation of RC and WPC-70 upto 8% to maize flour was more suitable for protein enriched snack base with good overall acceptability of product. The developed extrudate was packaged in metallized Low Density Polyethylene (LDPE) pouches and stored under 25±1°C and 37±1°C for 1 month and monitored at weekly interval. The resistant starch content of extrudates increased from 45 to 128 mg/ 100 g and 132 mg/ 100 g of sample stored at 25°C and 37°C at the end of storage. Changes in TBA value was non-significant and FFA value increased significantly (p<0.05) due to hydrolytic rancidity. The sensory scores obtained for color and appearance, texture and overall acceptability did not have any significant variation (p>0.05), however the flavour scores decreased significantly (p<0.05) which can be correlated with FFA and TBA value.