Lipase-catalyzed Synthesis And Property Research Of Glycerol Monocaprylate

Glycerol Monocaprylate is a metabolism product of the fat which is one of the three major nutritions, it is a high secure material with no adverse accumulation and reaction in persons'body. Glycerol Monocaprylate can be used to improve the food quality as a surfactant and to extend the food storage period as a preservative. In this paper, Glycerol Monocaprylate was synthesized by glycerol and octanoic acid in a solvent free system.In all enzymes, the immobilized lipase-Novo435 was found the most effective for esterification. The optimum conditions of synthesis were obtained through single factor test and response surface method successively. When the ratio of glycerol to octanoic acid 1:1, the lipase dosage 0.88% (W/W) based on the reactant was employed in the reacting system, the conversion rate of octanoic acid could reach 93.53% at 66.8℃for 11.5h reaction. The content of glycerol monocaprylate was about 47.69% in the reacting production .There were monoester, diester and triester in the product when analysed by LC-MS. The analysis condition for the Thin Layer Chromatography (TLC) was confirmed, chloroform: acetone: formyl (96:4:0.5) was used as the mobile phase, and the product was detected by iodine steam. The retention factor (Rf) of the monoester, diester and triester was 0.15, 0.5 and 0.65, 0.94, respectively. Then, the conditions of HPLC was applied to the Lichrospher C18 column chromatography for separating and purifying the Glycerol Monocaprylate, methanol: water (60%, 70%, 80%, 90%) was used as mobile phase, every mobile phase volume was 3 times of the C18 column volume. The LC-MS and IR were used to analyze the production, the result showed that the content of Glycerol Monocaprylate was more than 90%.The surfactant properties of Glycerol Monocaprylate were also studied, the HLB value was 4.7, the CMC was 0.8g/L, and the surface tension was 28.4mN/m which the mass concentration was 0.3%. The emulsion activity of Glycerol Monocaprylate was good and had excellent emulsion stability when the concentration was more than the CMC. The foam activity of Glycerol Monocaprylate was not good and had no foam stability.The results of antimicrobial activity of Glycerol Monocaprylate showed that its minimum inhibition concentration was 0.8g/L for Eschericheae coli, 0.7g/L for Staphylococcus aureus, 0.6g/L for Saccharomyces cerivisiae, 0.8g/L for Saccharomyces cerevlsiae, 0.8g/L for Aspergillus niger and 0.9g/L for Penicillium citrinum. It suggested that Glycerol Monocaprylate had a wide antimicrobial spectra. The Glycerol Monocaprylate could effectively prolong adaptive and decrease growth quantity of the Eschericheae coli, Saccharomyces cerivisiae, Aspergillus niger and milk spoilage microorganisms, and the effect was superior than the potassium sorbate which was in commom use. Furthermore it had better heat stability and acid and alkali stability when was used as preservative.