Characterization of Citric Acid Treated Partially Cold‐Water Swellable Sorghum and Corn Starch Extrudates; A Green Approach

The present study investigates a green approach for tailoring the properties of sorghum and corn starches. Since, citric acid is a harmless chemical; therefore, starches modified via citric acid as well as extrusion can be labeled as “Green.” Citric acid modification at two different levels 20% and 40% prior to the extrusion technique influence the functional, thermal, structural, and rheological properties of starch extrudates. The swelling index is found to be lower for CA‐treated extrudates and decreases as CA level increases from 20% to 40%. Prior citric acid modification is found to lower the viscosity of the starch extrudates while increases in water retention capacity is observed. All CA‐treated extrudates show signs of more viscous behavior with Gʺ > Gʹ at lower frequency. Creep recovery curves imply that deformation of S40‐Ex (40% w/v citric acid treated sorghum starch extrudate) and C40‐Ex (40% w/v citric acid treated corn starch extrudate) gel shows the minimum value of instantaneous strain indicating their higher recoveries. The induced properties of starch extrudates after modification with citric acid urge the possible use of these extrudates as industrial cold water swell‐able instant starch in ready to eat food products. Green modification of sorghum and corn starch using citric acid coupled with an extrusion technique can be used to manipulate or modify the functional and rheological behavior of their native starch. The improved storage stability and higher swelling power of citric acid starch extrudates suggest the application of these starch additives in frozen and ready‐to‐eat food products.