Extraction optimization and characterization of pectin from sesame (Sesamum indicum L.) capsule as a new neglected by-product.

Abstract

With production of over 6 million tonnes a year of sesame, its capsules are considered to be an unutilized waste. In this study, extraction of pectin from this novel source was optimized using a green method, and the functional and physiochemical characteristics of the resultant pectin were compared to commercial pectin. In this study, the sesame capsule pectin (SCP) extraction conditions were optimized to reach maximum yield, and the results showed that the maximum pectin extraction yield (138 g kg-1 ) was obtained under optimal conditions (microwave power 700 W, irradiation time 5 min, pH 1.5, and liquid-to-solid ratio 41.8 (mL g-1 ). The results showed that the pectin was low methoxyl type with a galacturonic acid content of 670 g kg-1 . The extracted pectin had a high molecular weight (341 kDa) and surface charge (34.09 ± 1.88 mV) and exhibited 66% DPPH radical scavenging. The obtained results from 1 H-nuclear magnetic resonance and Fourier transform infrared spectra validated the presence of pectin structure in the extracted sample. Sesame capsule pectin, when compared to commercial pectin, demonstrated better functional properties in terms of emulsifying properties, oil holding capacity, foaming capacity and antioxidant activity. SCP showed similar properties in comparison to its commercial counterpart, which suggests that it could well be considered as a new and suitable source for pectin extraction. © 2022 Society of Chemical Industry.