Abstract:Soybean lecithin was acylated by acetic anhydride.The effects of acetic anhydride dosage,reaction temperature and reaction time on the acetylization rate were investigated.The reaction conditions were optimized by response surface methodology a follows:acetic anhydride dosage 5%,reaction temperature 72¡æ and reaction time 30 min.Under the optimal conditions the acetylization rate was 82.26%.