Physicochemical and Structural Characterization of Microfluidized and Sonicated Legume Starches

Abstract

Modified starches gained importance in food industry due to their improved functional properties. In this study, two legume starches (chickpea and lentil) were modified by using ultrasonication (US) and microfluidization (MF) techniques. The objective of the study was to investigate the effects of these methods on the functional, rheological thermal properties and particle size, morphology, and crystal structure of modified starch samples. Time domain NMR relaxometry experiments were also conducted to understand the changes in the microstructure. Results showed that swelling power of starches increased, but their solubility values decreased significantly with both treatments (p < 0.05). Apparent viscosities of both samples showed a decreasing trend with increasing shear rate. Gelatinization temperatures of starches decreased with treatments significantly (p < 0.05). Both methods resulted in significantly lower volume mean diameter (D [4,3]) and span values as compared to the native ones. SEM images demonstrated that morphology of the starches changed significantly. Time domain (TD) NMR results showed that modified starch samples had longer T2 relaxation times. After treatments, the structural change was also observed through FTIR experiments. Both ultrasonication and microfluidization were found to be effective and novel technologies for the modification of chickpea and lentil starches.