| Polyglycerol medium chain fatty acid ester is a kind of polyglyceryl fatty acid ester which was directly prepared by polyglycerol and medium chain fatty acid. It has good emulsifying, dispersion, stability, and foaming properties, also it has a special nutritional function. Polyglycerol medium chain fatty acid ester is a food emulsifying agent which has great development potential.This paper studied the synthesis technology of tripolyglycerol, synthetized and chose the ionic liquid catalyst which had good catalytic and reused activities, studied the synthesis technology of polyglycerol medium chain fatty acid ester by the single factor tests and orthogonal analysis tests, and preliminary studied the structure, physical and chemical properties and emulsifying properties of polyglycerol medium chain fatty acid ester. The main process parameters and conclusions were as follows:Tripolyglycerol was prepared through catalyzing by KOH and protecting by nitrogen. The synthesis technology of tripolyglycerol was determined by studying the effects of reaction temperature, reaction time and dosage of catalyst on reactions. The synthesis technology was as follows:reaction temperature was260℃, reaction time was3h and dosage of catalyst was2%. The average degree of polymerization of polyglycerol which was prepared under optimized synthesis technology was3.08. The results of MS detection showed that the product was straight-chain polyglycerol-based, light-colored, non-irritating odor polyglycerol.The structure of [Hmim]+[HS04]-,[HSO3-pmim]+[HSO4]-and [HSO3-pmim]+[pTSA]-were identified by IR. This paper studied the single and reused catalytic capabilities of ionic liquid. The results were as follows:[HSO3-pmim]+[HSO4]-has the best single catalytic capability, and it has the best reused catalytic capability, especially added0.5%. So [HSO3-pmim]+[HSO4]-was chose as the catalytic of preparing polyglycerol medium chain fatty acid ester.The synthesis technology of polyglycerol medium chain fatty acid ester was determined and optimized by the single factor tests and orthogonal analysis tests. The structure and the physical and chemical properties were preliminary studied. The results were as follows:①Polyglycerol medium chain fatty acid ester was prepared from polyglycerol and medium chain fatty acid which were catalyzed by ionic liquid catalyst [HSO3-pmim]+[HSO4]-. The effect of reaction temperature, reaction time, ratio of polyglycerol and medium chain fatty acid and dosage of catalyst on the esterification rate was studied by the single factor tests. On that basis, the synthesistechnology of polyglycerol medium chain fatty acid ester was optimized by the orthogonal analysis tests. The optimal reaction temperature for the synthesis of polyglycerol medium chain fatty acid ester was200℃, the reaction time3h, ratio of polyglycerol to medium chain fatty acid was2.5:1, and dosage of catalyst was4.5%.②The verification experiments were did at the optimal technologic conditions. The results showed that the average esterification yield was93.4%.③The structure of polyglycerol medium chain fatty acid ester sample was identified by IR. The results showed that:The absorption peak at1736cm-1in IR spectra of polyglycerol medium chain fatty acid ester sample was specific absorption of ester. Compared with the IR spectra of medium chain fatty acid, there were two absorption peaks at3887cm-1,1119cm-1, they were stretching vibration of O-H and specific absorption of C-O-C So the samples were polyglycerol medium chain fatty acid ester.⑤The physical and chemical properties were detected by GB/T5530-1998. The results showed that:the product was light yellow liquid, the acid value was272.82mg KOH/g.⑤The physical and chemical properties were detected by GB/T13510-92,GB/T5534-1995and GB/T5532-2008. The results showed that:the product was yellowish-brown thick liquid, the acid value, saponification value, iodine value, and melting point were1.80mg KOH/g,147.9mgKOH/g,2.6g/100g and0-5℃, respectively.This paper preliminary studied the emulsifying properties of polyglycerol medium chain fatty acid ester. The results were as follows:①HLB value of polyglycerol medium chain fatty acid ester was9.89which was calculated by the method suggested by Griffin, so it is hydrophilic emulsifying agent.②The emulsifying capability in different ratios of oil to water was determined by spectrophotometry and GB/T11543-2008. The results showed that:At the same emulsifying agent concentration, polyglycerol medium chain fatty acid ester had the best emulsifying properties when ratio of oil to water was4:6. At the same ratio of oil to water, the emulsifying properties increased with the increase of emulsifying agent concentration.③The stability of polyglycerol medium chain fatty acid ester was determined after the stewing, decentering and high temperature treatments. The results showed that:The static stability, centrifugal stability and heat stability could be enhanced effectively while increasing the emulsifying agent concentration. To keep static stability, centrifugal stability and heat stability, the min adding amount of polyglycerol medium chain fatty acid ester was4%,4%,5%,6%, respectively. |
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