Optimization and characterization of pectin extracted from sweet potato residue

Abstract

Pectin has been used widely as thickener, stabilizer and gelling agent. However, the source of pectin industrially are still limited. This study aims to optimize the extraction of pectin from sweet potato residue using hydrochloric acid and analyses the properties of the pectin. In this study, the extraction of pectin from sweet potato residues using hydrochloric acid was optimized to maximise its yield and quality using response surface methodology (RSM). Then, the extracted pectin was further analyse for its degree of methylesterification (DM) using Fourier Transform Infrared Spectroscopy (FTIR). In this study, 0.5 %w/v, 1.0% w/v and 2.5% w/v concentration of pectin sugar solution were used to study their rheological properties. The antioxidant activity was assessed using DPPH radical scavenging activity. The optimum condition to extract pectin from sweet potato residues was at extraction temperature (60 °C), pH (1) and extraction time (60 minutes) yielding 24.4 % pectin using hydrochloric acid. The pectin extracted has 57.48% of DM which indicated that it is high methoxyl pectin and able to form gel with the addition of sugar. The rheological properties analysis shows that 0.5% w/v pectin sugar solution shows Newtonian fluid behaviour while 1.0% w/v sugar pectin solution and 2.5% w/v pectin sugar solution showed pseudoplastic fluid behaviour. Moreover, the pectin was show 25.5 to 37.7% of radical scavenging activity.