Diglyceride was synthesized from soybean oil and monoglyceride by immobilized Novozym 435 in a solvent-free system. The effects of reaction temperature, reaction time, enzyme dosage, and substrate molar ratio on the diglyceride content were studied by single factor experiment and response surface methodology. The results showed that the effect of reaction temperature on the diglyceride content was the greatest, followed by reaction time, enzyme dosage and substrate molar ratio. The optimal conditions were obtained as follows: molar ratio of soybean oil to monoglyceride 1∶ 2, enzyme dosage 9%, reaction temperature 83 ℃ and reaction time 6.5 h. Under the optimal conditions, the diglyceride content was (51.2±0.2)%. |