Response Surface Optimization of Lipase-catalyzed Surface Esterification for Modification of Cassava Starch with Rosin Acid

In this work, RAS was synthesized by lipase-catalysis, using native cassava starch and rosin acid as starting materials in a two-phase system. The effects of reaction time, solvent types, material ratio, reaction temperature and enzyme addition amount on DS were explored. Based on the single factor experiments, optimization of reaction conditions were carried out by applying Box–Behnken response surface methodology. The optimal condition was as follows: reaction temperature 59 ℃, m_{rosin acid}: m_starch = 4.1 and lipase dosage 264 μL. The experimental DS value of 0.0608 perfectly matched with the predicted value of 0.0613, which verified the practicability of this optimum strategy. Contact angle, emulsion capacity and emulsion stability of the RAS progressively improve with the increase of DS.