| The using of phytosterols as the drugs to reduce blood total cholesterol and low-densitylipoprotein cholesterol has been a century of history. Recent studies have shown that thephysiological effects of its hydrogenation product phytostanol were better than sterol and lesseffective doses, no side effects. At the same time, the color and flavor was improved. Thepoor solubility of phytostanols in water and oil limited its application in the food industry. Tosolve this problem, this paper focused on improving the oil solubility of stanols byesterification and the water solubility by being embedded in the hydroxypropyl-β-cyclodextrin. These two modified methods and process conditions were explored. After beingobtained by separation, the product was identified. The study provided a theoretical basis forthe better using of phytostanols as an additive in food industry.Esterification of phytostanols with fatty acids was used to improve the oil solubility ofphytostanols. A green reaction mode under moderate conditions in a micellar catalysis systemwas explored. At first, Lewis acid-surfactant combined catalysts were screened out with highefficient catalysis for the esterification. It was found that for the synthesis of saturated fattyacids with stanols, copper salt has a better catalytic effect, particularly when the temperaturewas130oC, and the molar ratio of acid to alcohol was1.2:1, the reaction time reached4h, thecatalyst concentration was1.0%, the esterification rate of phytostanyl laurate was up to94.21%. With the increase of the length of the carbon chain, the esterification rate showed adownward trend under the same conditions. For the synthesis of unsaturated fatty acids withstanols, the result showed that cerium salts had a better catalytic effect. In this system theester esterification rate and the degree of oxidation should be both considered. When thetemperature was170°C, reaction time was4h, the catalyst concentration was1.0%, oleateesterification rate could reach80.5%. Secondly, the reaction product was purified by silica gelcolumn chromatography separation. The purified products were confrmed by FT-IR, MS, andNMR, respectively. Finally, The solubility of phytostanyl fatty acids in peanut oil wasdetermined. The result showed that the oil solubility had been improved significantly. Thesolubility of stanol and phytostanyl esters in different solvents was also investigated. It couldbe useful for the realization of the separation method by the solvent.The water solubility of phytostanols was improved by the method of embedding.hdroxypropyl-β-cyclodextrin was used to embed the phytostanols. It has a non-polar cavitywhich could provide a good space for the non-polar carbon chains of the stanols. Thus theinherent hydroxyl group of stanols which were exposed outer side increased the hydrophiliccharacteristics, together with the hydroxyl of hdroxypropyl-β-cyclodextrin. Thereby the watersolubility was improved. In this study, a certain proportion of hydroxypropyl-β-cyclodextrinand stanols were dissolved into an organic solvent and then the reaction was stirred at acertain temperature. Then the samples were purified and freeze-dried. After that the inclusionproduct was identified and confirmed by X-ray diffraction, IR and DSC. The surfacemorphology of the clathrate was also observed by scanning electron microscopy. The differentreaction in ethanol, isopropanol and n-butanol were compared. Inclusion rate and inclusion efficiency were used as indicators to investigate the embedding effect. The concentration ofstanols, the molar ratio of hydroxypropyl-β-cyclodextrin with stanol, reaction temperature andreaction time were also investigated for the optimization of the embedding process. Theinclusion rate of87.43%was got by the hydroxypropyl-β-cyclodextrin and stanol molar ratioof4:1, the stanol concentration of1.25%, the reaction temperature50oC for10h. Thesolubility of clathrate in water was investigated. The result was shown that the watersolubility had been improved. |
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