Complex coacervates from gelatin and octenyl succinic anhydride modified kudzu starch: Insights of formulation and characterization

The formulation of complex coacervates between gelatin and octenyl succinic anhydride (OSA) modified kudzu starch was investigated by turbidimetric analysis as a function of pH and ratio of gelatin and OSA-modified kudzu starch. The interaction between gelatin and OSA-modified kudzu starch yielded a dense liquid coacervate phase, leading to phase separation, and the optimum conditions for their coacervation was pH 6.0 and the mixed ratio of 1: 1 (w/w). To characterize the complex coacervates, differential scanning calorimetry (DSC) thermograms revealed that the endothermic peak temperature of coacervates increased due to the interaction between these two polymers, and scanning electron microscopy (SEM) suggested that gelatin and OSA-modified kudzu starch were interconnected, forming a network structure through electrostatic attraction. Moreover, Fourier transform infrared spectroscopy (FT-IR) spectra indicated that coacervates were formulated between the carboxyl groups of OSA-modified kudzu starch and the amino groups of gelatin. The astaxanthin (AST) extract was encapsulated in complex coacervates and its stability was observed during 10 days of storage time. The results revealed higher retention of AST encapsulated in complex coacervates in comparison with gelatin. (C) 2018 Elsevier Ltd. All rights reserved.