The Research On Enzymatic Extraction Of Litsea Cubeba Kernel Oil For Preparation Of Monoglyceride Laurate

The Litsea cubeba kernel has a high oil content with rich lauric acid.The utilization rate of Litsea cubeba kernel is very low at present.If the Litsea cubeba kernel oil can be extracted and its effective ingredients are reasonably used,it will play an important role in the full utilization of Litsea cubeba resources.In order to solve the problem of environmental pollution and waste of resources by discarded Litsea cubeba kernel,the research used Litsea cubeba kernel as raw material to extract oil with aqueous enzymatic method,and explored the impact of different oil extraction processes on the quality of Litsea cubeba kernel oil.Finally,the reusable and environmentally friendly immobilized lipases was used to catalyze GML.The main results of the study are as follows:(1)The study analyzed the composition of Litsea cubeba kernel and explored the effect of baking and crushing on the oil extraction.The results showed that Litsea cubeba kernel had a high oil content,about 47%,suitable for oil extraction.High-temperature baking would significantly reduce the emulsification and effectively increase the oil yield.There was high extraction rate when the temperature was 120℃,kernel baked for 70 min.When the pulverizer crushed for 120 s and the particle size was about 35 μm,it could effectively destroy the material structure,increase the effective contact area of the enzyme preparation and then increase the oil yield.(2)The technology optimization test of aqueous enzymatic method for extracting Litsea cubeba kernel oil found that:when the enzyme preparation was neutral protease and cellulase and the mass ratio was 1:1,the compound enzyme dosage was 3%,the enzymatic hydrolysis time was 7 h,the liquid-to-material ratio was 3 mL/g,pH was 6.40,and temperature was 46℃ the extraction rate of Litsea cubeba kernel oil reached 86.10%;The surface structure of Litsea cubeba kernel and kernel powder after oil extraction were observed by scanning electron microscope,and it was found that the surface structure of the kernel after enzymatic treatment was damaged seriously.Serious damage to the structure was conducive to the release of oil.(3)The Litsea cubeba kernel oil extracted by the methods of pressing method,solvent extraction and aqueous enzymatic were compared.It was found that the extraction rate of solvent extraction and aqueous enzymatic method was higher than pressing method.The oil extracted by the aqueous enzymatic method was of good quality and had the characteristics of light color,high iodine value,low peroxide value and low acid value.The structure of kernel oil was detected by FT-IR,and found that functional groups such as OH,C=O,CH3,CH2,C=O,C-O.The fatty acids containing these structures were found in GC-MS analysis.The fatty acid components of Litsea cubeba kernel oil extracted by different processes were similar.(4)The immobilized lipase Novozym 435 and Lipozyme TL IM were used as catalysts to catalyze the reaction of Litsea cubeba kernel oil with glycerin to prepare GML.Finally,the GML generated under the optimal reaction conditions was purified by two-stage molecular distillation.From the test results,it can be seen that the immobilized lipase Novozym 435 was repeatedly used for 6 times with the high enzyme activity,and the product had a high GML content.However,Lipozyme TL IM was reused 4 times,and the enzyme activity decreased significantly.The optimal reaction conditions for the catalytic synthesis of GML by Novozym 435 were that the mass ratio glycerol to Litsea cubeba kernel oil was 2.5:1,the amount of enzyme added was 8%,the reaction temperature was 52℃ and the reaction time was 18 h.Under the optimal reaction conditions,the GML content in the mixed fatty acid glycerides was 33.21%.The GML content could reach 90.36%after purification by the secondary molecular distillation.