【作者】 王秀华；

【导师】 刘伟；

【作者基本信息】 河南工业大学 ， 食品科学与工程， 2024， 硕士

【摘要】 植物甾醇和甾烷醇具有降胆固醇、抗炎、抗氧化等多种生理功能,被誉为“生命的钥匙”。研究表明植物甾烷醇在降胆固醇效果、有效剂量、溶解性、色泽和风味等方面优于植物甾醇。但由于水不溶性和低油溶性的特点,甾烷醇的应用受到限制。针对该问题,本文通过氢化法制备植物甾烷醇,进一步利用化学法催化植物甾烷醇与不饱和脂肪酸酯化合成植物甾烷醇酯,并研究其对葵花籽油氧化稳定性的影响,从而为植物甾烷醇酯的开发和应用提供技术与理论支撑。首先,以植物甾醇(S)为原料,利用钯碳催化剂催化氢化反应合成植物甾烷醇(PS),在钯碳催化剂用量0.5%(以植物甾醇质量计)、反应温度65℃、转速100 rpm/min条件下反应6 h后,植物甾醇转化率为96.21±0.68%,产物纯度为94.43±1.29%。氢化制备的植物甾烷醇为白色针状固体,并通过核磁和红外对产品进行结构鉴定。其次,利用DBSA能形成油包水乳液自动分离水的特性,以DBSA为催化剂催化植物甾烷醇与不饱和脂肪酸(油酸和亚油酸)酯化合成植物甾烷醇酯。在DBSA用量10%、酸醇摩尔比3:1、反应温度60℃、反应时间12 h、氮气做保护气的条件下合成植物甾烷醇油酸酯(PSO),植物甾烷醇的转化率为95.45±0.41%,植物甾烷醇油酸酯的产率为86.84±0.80%。在DBSA用量10%、酸醇摩尔比3:1、反应温度90℃、反应时间12 h、氮气做保护气的条件下合成植物甾烷醇亚油酸酯(PSLO),植物甾烷醇的转化率为93.60±0.37%,植物油甾烷醇亚油酸酯的产率为84.91±1.22%。经硅胶柱层析纯化后PSO和PSLO的纯度分别为97.43%和94.98%,且反应过程中无反式脂肪酸生成。通过核磁和红外对产品进行结构鉴定。最后,通过热重分析比较S、PS、PSO和PSLO的热稳定性,结果表明酯化可以提高甾烷醇酯的热稳定性,且PSO热稳定性优于PSLO。测定20℃下PS、PSO和PSLO在葵花籽油中的溶解度,结果表明PS和PSO的溶解度分别为2.45 mg/100g和26.29mg/100 g,PSLO能完全互溶。为探究PS、PSO和PSLO对葵花籽油氧化稳定性的影响,研究了不同加热温度(60℃、120℃、180℃)、不同PS、PSO和PSLO添加量下(0、0.1%、0.5%、1.0%)葵花籽油体系过氧化值、共轭二烯值和茴香胺值的变化规律。结果表明,添加PS、PSO和PSLO能降低葵花籽油的过氧化值和茴香胺值,但对葵花籽油的共轭二烯值无显著影响,且添加量越大,温度越高,葵花籽油的过氧化值和茴香胺值越低。PS、PSO和PSLO可以提高葵花籽油的氧化稳定性,且抗氧化性大小依次为:PSO>PSLO>PS。更多还原

【Abstract】 Phytosterol and phytostanol have many physiological functions,such as lowering cholesterol,anticancer,antiinflammatory and antioxidant,and are known as "the key to life".Studies have shown that phytostanol is more effective than phytosterol in terms of cholesterol-lowering effect,effective dose,solubility,color and flavor.However,due to the characteristics of water insolubility and low oil solubility,the application of phytostanol is limited.To solve this problem,in this paper,phytostanol was first prepared by hydrogenation,and then esterified with unsaturated fatty acids to synthesize phytostanol esters by chemical catalysis,and effect on oxidation stability of sunflower oil was studied,which can provide technical and theoretical support for the development and application of phytostanol esters.Firstly,phytostanol(PS)was synthesized by hydrogenation of phytosterol(S)with palladium carbon catalyst.The conversion rate of phytosterol was 96.21±0.68% under the conditions of palladium carbon catalyst content 0.5%(measured by phytosterol mass),reaction temperature 65℃,reaction time 6 h and rotation speed 100 rpm/min.The purity of the product was 94.43±1.29%.The phytostanol obtained finally was white needle-like solid,and the structure of phytostanol was identificated by NMR and FTIR.Secondly,using DBSA to form water-in-oil emulsion to automatically separate water,the esterification of phytostanol and unsaturated fatty acids(oleic acid and linoleic acid)to produce phytostanol esters was catalyzed by DBSA.Under the conditions of DBSA dosage of 10%,molar ratio of acid to alcohol 3:1,reaction temperature 60℃,reaction time 12 h,nitrogen as protection gas,the conversion rate of phytostanol was 95.45±0.41%,and the yield of phytostanol oleate was 86.84±0.80%.Under the conditions of DBSA dosage of10%、molar ratio of acid to alcohol 3:1、reaction temperature of 90℃、reaction time of 12 h and nitrogen as protection gas,the conversion rate of phytostanol was 93.60±0.37%,and the yield of phytostanol linoleate was 84.91±1.22%.Separation and purification of products using silica gel column chromatography,the purity of obtained phytostanol oleate phytostanol linoleate was 97.43% and 94.98%,respectively,and no trans fatty acids were generated during the reaction.The strctures of phytostanol esters were identificated as by NMR and FTIR.Lastly,the thermal stability of S,PS,PSO and PSLO was compared by thermogravimetric analysis.The results showed that esterification could improve the thermal stability of steranol ester,and the thermal stability of PSO was better than that of PSLO.The solubility of phytostanol and phytostanol ester in sunflower seed oil at 20℃ was determined.The results showed the solubility of PS and PSO was 2.45 and 26.29 mg/100 g,respectively,and PSLO was completely miscible.In order to explore the effects of PS,PSO and PSLO on the oxidation stability of sunflower oil,the changes of peroxide value,anisidine value and conjugated diene value of sunflower oil system under different heating temperatures and different dosages of PS,PSO and PSLO were studied.The results showed that the addition of PS,PSO and PSLO could reduce the peroxidation value and anisidine value of sunflower oil,but had no significant effect on the conjugated diene value of sunflower oil,and the higher the addition amount and the higher the temperature,the lower the peroxidation value and anisidine value of sunflower oil.PS,PSO and PSLO could improve the oxidation stability of sunflower oil,and the antioxidant activity was PSO > PSLO > PS.更多还原