Study On Preparation And Microencapsulation Of Litsea Cubeba Kernel Oil Rich In Medium-Chain Diacylglycerol

Litsea cubeba is a unique economic tree species in China.Jiangxi is one of the provinces with more resources of Litsea cubeba.For a long time,the main by-product of Litsea cubeba kernel has not been effectively used after extracting essential oil.The oil content of Litsea cubeba kernel is more than 40% which is rich in medium-chain fatty acids.Diacylglycerol have many physiological functions and are widely used in various fields.Medium-chain diacylglycerol have both the biological functions of medium-chain fatty acids and the functional characteristics of diacylglycerol.In order to improve the additional value of Litsea cubeba,promote the development of its production,and provide a theoretical basis for the research of medium-chain diacylglycerol,the paper was made.In this paper,the ultrasonicassisted extraction method was used to extract Litsea cubeba kernel oil,and the fatty acid composition and physicochemical properties of the Litsea cubeba kernel oil were studied.Based on screening lipase,the technological conditions for the preparation of Litsea cubeba kernel oil,which is rich in medium-chain diacylglycerol,by lipase hydrolysis were optimized and the oil was microencapsulated by freeze-drying.The main contents and results were as follows:1.The oil of Litsea cubeba kernel was extracted by ultrasonic-assisted extraction.The effects of ultrasonic temperature,solid-liquid ratio,ultrasonic time and ultrasonic power on the oil extraction rate of Litsea cubeba kernel were investigated.Through orthogonal test to optimize the process conditions,the best process parameters were obtained: the ultrasonic temperature was 60℃,the solid-liquid ratio was 1:16(g/m L),the ultrasonic time was 30 min,the ultrasonic power was 100 W,and the yield of oil from Litsea cubeba kernel was42.08%.The physical and chemical properties were measured according to national standards.The results showed that the free fatty acid content,low peroxide value and iodine value of Litsea cubeba kernel oil were relatively low,and the saponification value was relatively large.Gas chromatography was used to detect the fatty acid composition of Litsea cubeba kernel oil.The results showed that the saturated fatty acid of Litsea cubeba kernel oil was relatively high,in that 8 kinds of fatty acids were detected,which was 98.75% of the total fatty acids.Among them,the content of lauric acid was the highest,followed by capric acid and lauroleic acid.The saturated fatty acids accounted for 74.31% of the total fatty acids,the unsaturated fatty acids accounted for 24.44% of the total fatty acids,and medium-chain fatty acids(C10-C12)accounted for 87.91% of the total fatty acids.It can be seen that Litsea cubeba kernel oil is a natural oil resource of middle chain fatty acids with potential development.2.The oil of Litsea cubeba kernel rich in medium-chain diacylglycerol was prepared by the lipase partial hydrolysis method,and the content of medium-chain diacylglycerol was determined by high performance liquid phase.The three lipases of Lipozyme RM IM,Lipozyme TL IM and Novozyme 435 were screened,and Lipozyme RM IM was found to be the best lipase catalyst.Using Lipozyme RM IM as the catalyst and medium-chain diacylglycerol content as indicators,the effects of water addition,enzyme addition and reaction time on the lipase-catalyzed partial hydrolysis process were investigated.The orthogonal method was used to optimize the process parameters to prepare Litsea cubea kernel oil rich in medium-chain diacylglycerol.The results showed that the water addition was the most important factor,followed by the enzyme addition and reaction time.The best process conditions were 5% water addition,16% enzyme addition,reaction time 7 h.Under these conditions,the content of medium-chain diacylglycerol was 47.51%,while the content of medium-chain diacylglycerol in the crude oil of Litsea cubeba kernel was 17.24%.Compared with the content of medium-chain diacylglycerol in crude oil of Litsea cubeba kernel,it was increased by 2.76 times.3.The process parameters of microcapsule preparation by freeze-drying were studied by using the oil of Litsea cubeba kernel which is rich in medium-chain diacylglycerol as raw material.Appropriate conditions were selected after the effects of single factors such as coreto-wall ratio,shear rate,and shear time on emulsion particle size,emulsion stability,and embedding rate of microcapsule were being investigated.The optimum conditions of microencapsulation were obtained by orthogonal experiments.The results showed that the optimum process conditions were as follows: the core-wall ratio 1:5,the shear rate 13500r/min,and the shear time 9 min.Under these conditions,the embedding rate of the oil microcapsule rich in medium-chain diacylglycerol was 81.74%.The color of the oil microcapsule was milky yellow,which was in the form of a relatively loose powder,and it presented irregular clumps when observed under the scanning electron microscope.