Organic synthesis of maize starch-based polymer using Rhizopus oryzae lipase, scale up, and its characterization

The industrial utilization of native starches is limited because of their inherit nature, with characteristics such as water insolubility and their tendency to form unstable pastes and gels. In this investigation, a lipase produced from Rhizopus oryzae was used for modification of maize starch with palmitic acid at a reaction temperature of 45°C for 18 hr in the presence of dimethyl sulfoxide (DMSO). The synthesis of maize starch palmitate was confirmed by Fourier-transform infrared (FT-IR) and (1)H-nuclear magnetic resonance (NMR) spectra with a higher degree of substitution (DS) of 1.68. Thermal gravimetric analysis (TGA) showed that the maize starch palmitate is more stable even up to 496°C as compared to unmodified maize starch (231.4°C). Maize starch palmitate possesses high degree of substitution and thermal properties and thus can be widely used in food and pharmaceutical industry.