Supercritical Carbon Dioxide Extraction And Microencapsulation Of The Oak Silkworm (Antheraea Peny) Pupal Oil

As insect oil, the oak silkworm oil which is rich in unsaturated fatty acids, hasimportant economic and nutrition value. The unsaturated fatty acids prone to oxidation anddeterioration, while microencapsulation can protect the wrapped materials to make it isolatefrom the external environment. The microencapsulation of the fish oil can provide manybenefits such as providing an oxygen barrier resulting in an extended shelf life.Supercritical carbon dioxide （SC-CO₂） extraction of oil from the oak silkworm pupae wasperformed in the present research. Response surface methodology （RSM） was applied tooptimize the parameters of SC-CO₂extraction and microencapsulation. To determinate thetypes and relative contents of fatty acid composition of different silkworm pupal oils, theoils were transesterificated with KOH/CH3OH, and then analysis by the gaschromatography/mass spectrometry method. In accordance with the GB, the acid value,saponification value and peroxide value of four silkworm oil were determinated andcomparated.The major components in four pupal oils were linolenic acid （LNA）, palmitic acid （P）,stearic acid, oleic acid and a-linolenic acid, but the relative contents are different. Amongthe four pupal oils, the relative content of unsaturated fatty acids in oak silkworm pupal oilwas the highest, with the value77.29%; the relative content of a-linolenic acid in erisilkworm pupal oil was the highest （50.52%）; the relative content of unsaturated fatty acidsin desilked pupal oil was lower than that unsilked silkworm pupal oil.With SC-CO₂, the yield of oak silkworm pupal oil was found to be dependent on thelinear term of extraction pressure, time, and the quadratics of pressure, temperature, andextraction time as well as the interactions between extract pressure and temperature, andtemperature and CO₂flow rate. A polynomial regression model was established to describethe experimental results. The optimal condition for oak silkworm pupal oil yield was at28.03MP,35.31°C,1.83h, and20.26L/h. In this condition, the predicted value of oil yieldreached26.18%.For the conditions used in this work, we conclude that the microencapsulation for oaksilkworm pupal oil was dependent on the linear term of the ratio of wall material and core material, and the quadratics of the mass fraction of solids, the ratio of wall material andcore material, and homogeneous time, as well as the interactions between the mass fractionof solids and homogeneous time. A polynomial regression model was established todescribe the experimental results, the optimal condition for microencapsulate efficiencywas at6.13min,2.37:1,20.37%. At this condition, the predicted value of microencapsulatesefficiency reached53.95%. The freeze-dried microcapsules have two types of structures,small spherical units of less than10μm.