Structure and characteristics of lipase-catalyzed rosin acid starch

Cassava starch was esterified with rosin acid, an abundant raw material from pine trees, by using lipase as catalyst. The physicochemical properties of esterified starches with degree of substitution (DS) ranging from 0.031 to 0.092 were compared with native starch. Esterification of cassava starch was confirmed by Fourier transform infrared spectroscopy. The results of scanning electron microscopy and X-ray diffraction analysis revealed that the morphology and crystallinity of the cassava starch were largely destroyed, and the esterification took place in both the non-stereotyped area and inside the crystalline regions of starch. Thermal gravimetric analysis indicated that thermal stability of rosin acid starch decreased compared with native starch. Rosin acid starch exhibited higher viscosity as well as emulsifying properties. Esterified starch decreased its swelling power, solubility and transparency in water. Rosin acid starch has potential applications in food and biomedical materials.