Thermal, structural and rheological characterization of protein isolate from sesame meal

Abstract

Sesame protein can be considered as a good source of protein due to high content of methionine present in it. In this study, sesame protein isolate (SPI) from sesame meal was isolated and its thermal, structural, and rheological properties were evaluated. X-ray diffraction exhibited two diffraction peaks, one at 10° (small intensity) and other at 19.5° (high intensity). Thermo-gravimetric analysis showed complete degradation of protein on increase of temperature to more than 450 °C. In differential scanning calorimetry, onset temperature for SPI started at 176.0 °C and peak denaturation temperature for SPI was observed at 210 °C. FTIR of SPI indicated the presence of Amide A, Amide B and Amide I to V bands. SPI exhibited shear thinning behaviour characterized with viscosity decrease with increase in shear rate. Minimum viscosity was observed when shear rate varied from 700 to 800 s−1. Visco-elastic behaviour of SPI gel was observed during temperature sweep test, with G′ dominating G″ throughout the test. Overall, observed parameters showed that sesame protein exhibit good thermal stability and appropriate rheological properties necessary for industrial application and hence can be considered as an efficient source of protein supplemented foods.