Extraction,modification and characterization of native litchi seed (Litchi chinesis Sonn.) starch.

Abstract

Litchi seeds, owing to their high starch content, have the potential to serve as a valuable non-conventional source of starch with versatile applications. This study aimed to optimize the extraction of native litchi seed and its modification using citric acid. Response surface methodology was used to determine the optimal combination of independent variables; extraction temperature (30 - 60 ° C) and extraction time (4-20hours) for the attainment of maximum starch yield (%). Starch was then chemically modified with citric acid concentrations of 20 and 40% to investigate its effect on physicochemical, morphological, and functional properties. The second-order polynomial model effectively described the experimental data, demonstrating a satisfactory fit for the observed results. The optimized condition with the highest starch recovery (212.4 g Kg-1 ) was found to have an extraction temperature of 30° C and an extraction time of 11 hours. It was observed that with an increase in concentration of citric acid has resulted in a decrease in amylose content, swelling power, and solubility, while the water absorption capacity of modified starch increased. The SEM micrographs showed that citric acid modification resulted in surface irregularities, while the shape and size of granules remain unaffected. Not much difference has been observed in the XRD pattern of modified starch except for the decrease in intensities of peaks. An effect on the thermal properties of modified starch was also reported. Results obtained from the study reveal that extraction temperature and extraction time are critical factors, exerting a significant effect on the extraction yield of starch. Furthermore, modified starches with improved functional properties can serve as novel and versatile source of starch in various food and non-food sectors. This article is protected by copyright. All rights reserved.