Study On Extraction,analysis And Microencapsulation Of Turtle Oil

Turtle,also known as soft shelled turtle,and its nutritive value is very high because of the rich Omega-3 system polyunsaturated fatty acids?Poly-unsatur-ated Fatty acids,PUFA?in the oil.It has many kinds of health care functions,such as reducing blood fat,strengthening brain and improving intelligence and so on.In China,it is mainly distributed in Jiangsu,Zhejiang,Hunan and Hubei.In recent years,with the maturity of breeding technology and mode,the output of turtle has been increasing linearly,and the by-products have also increased.It is a trend to recover turtle oil from by-products.In this paper,the fat of turtle is mainly used as raw material,the best technology of supercritical CO₂ extraction of turtle oil was studied.The antioxidant activity of the turtle oil was determined,and the technological conditions for preparing the turtle oil microcapsule by complex coacervation method were optimized,and the storage stability of microcapsules was studied in order to provide theoretical basis for the study of turtle oil.The results of the study are as follows:1.supercritical CO₂ extraction of turtle oilThe extraction technology of turtle oil was optimized by single factor experiment and orthogonal test.The optimum extraction conditions were extraction pressure45MPa,extraction temperature 55 degrees,and extraction time 5h.Under the conditions,the extraction rate of turtle oil was 96.42%.By comparing with enzymatic hydrolysis,it is found that the extracted turtle oil is of good quality,and its appearance is light yellow and transparent.All indexes have reached the first class standard of national fish oil,which has a slight fishy smell.The whole process does not use any organic solvents,and it has high safety.By gas chromatography,33 kinds of fatty acids were obtained from supercritical CO₂ extraction.The content of unsaturated fatty acids was 79.97%.It contains essential fatty acids,alpha linoleic acid,linoleic acid and four arachidonic acid.The monounsaturated fatty acids accounted for 49.85%of the total,30.12%of the polyunsaturated fatty acids,and10.94%of the total amount of DHA and EPA.2.Study on the antioxidant activity of turtle oil in vitroThe antioxidant activity of DPPH free radical scavenging capacity,superoxide free radical scavenging ability,Fe²⁺ion chelating ability,reducing ability and hydroxyl radical scavenging ability of soft shelled turtle oil was analyzed.The antioxidant index of crude oil and refined oil of turtle was studied with antioxidant vitamin E as control.The results are as follows:?1?The IC₅₀ values of DPPH free radical scavenging rate of crude oil,refined oil and vitamin E were 6.1003 mg/mL,6.9340 mg/mL and 3.5805 mg/mL,respectively.The linear correlation coefficients were 0.99,0.9931 and 0.9909 respectively.The IC₅₀value of the refined oil is the largest,which indicates that the DPPH free scavenging ability of the refined oil is the weakest,and the DPPH radical scavenging rate of the three solutions increases with the increase of the mass concentration,and all of them have certain scavenging capacity.?2?The IC₅₀ value of the scavenging ability of crude oil,refined oil and vitamin E on superoxide radical were 8.5058 mg/mL,9.1981 mg/mL and 3.4503 mg/mL,respectively.The linear correlation coefficients were 0.9858,0.9885 and 0.9853respectively.Compared with vitamin E,the IC₅₀ of crude oil and refined oil is relatively high,which indicates that the scavenging capacity of superoxide radical scavenging of crude oil and refined oil is relatively weak,and the scavenging rate of superoxide radical increases with the increase of the mass concentration of soft shelled turtle oil.In addition,the crude oil IC₅₀ of the turtle is less than the IC₅₀ of the refined oil,indicating that the superoxide radical scavenging ability of the crude oil is greater than the superoxide free radical scavenging ability of the refined oil.?3?The IC₅₀ values of crude oil,refined oil and vitamin E on Fe²⁺ion chelation were10.0667 mg/mL,10.5355 mg/mL and 2.7795 mg/mL,respectively.The linear correlation coefficients were 0.9901,0.9926 and 0.9826 respectively.The IC₅₀ value of two kinds of turtle oil was significantly higher than the IC₅₀ value of vitamin E,indicating that the chelating ability of turtle oil to Fe²⁺ions was weak.In addition,the IC₅₀ value of two kinds of soft shelled turtle oil is not very different,and the ability of Fe²⁺ion chelating is enhanced with the increase of the mass concentration of turtle oil.The ability of crude oil to Fe²⁺ion is slightly higher than that of refined oil.?4?Compared with the vitamin E with strong reducing ability,the absorbance value of crude oil and refined oil was smaller and the reduction ability was weaker at the same concentration.The absorbance value of crude oil was slightly larger than that of refined oil,indicating that the crude oil's reduction ability was greater than that of refined oil.?5?The IC₅₀ values of crude oil,refined oil and vitamin E on hydroxyl radical scavenging capacity of soft shelled turtle were IC₅₀,8.0665 mg/mL,8.6406 mg/mL and 2.7696 mg/mL,respectively,and the linear correlation coefficients were 0.9926,0.9909 and 0.9833 respectively.Compared with the IC₅₀ value of vitamin E,the IC₅₀of crude oil and refined oil of turtle is significantly higher,indicating that the scavenging capacity of hydroxyl radical of turtle oil and refined oil is very weak,but the scavenging rate of hydroxyl radical both increases with the increase of the mass concentration of methyl fish oil.3.Study on microencapsulation of turtle oil and its storage stability by complex coacervation?1?The combination of different wall material of microcapsule of turtle oil was screened,combined with microcapsule morphology,surface oil and total oil content,embedding rate and effective load index,Arabia rubber and gelatin combination were selected as the wall materials of soft shelled oil microcapsule,and the quality of the turtle oil microcapsule was better.?2?The optimum technological conditions for preparing microcapsule of turtle oil by orthogonal optimization complex condensation method are core wall ratio 1:1,emulsification speed 10000r/min,and condensed pH 3.9.Under the conditions,the encapsulation rate of microcapsule of turtle oil was 93.61%.?3?The preparation of turtle oil under optimal conditions of microcapsule product is milky white,uniform color,uniform particles,no impurities and mildew,little turtle oil rancidity smell,no smell,can be dissolved in water,forming an emulsion.The content of water is 2.78%,the surface oil content is 0.19%,the peroxide value is 3.23mmol/kg,and the indexes are all in line with the industry standard of fish oil microcapsule.?4?Under the conditions of freezing and cold storage,the oxidation of microcapsules of turtle oil can be slowed down.With the increase of storage temperature,the microcapsule of turtle oil was oxidized faster.At normal temperature,the POV value of microcapsules increased from the initial 3.23 mmol/kg to 18.27 mmol/kg.?5?The oxidation of turtle oil microcapsule can be slowed down under the storage conditions of strong acid and strong alkali,and the effect of acid environment is better than that of alkaline environment.?6?Ultraviolet irradiation accelerated the oxidation of turtle oil microcapsule.The turtle oil microcapsule was extremely sensitive to UV irradiation.The POV value increased from 14.77 mmol/kg to 3.23 mmol/kg after two hours of irradiation.?7?The addition of a small amount of antioxidant vitamin E,which is beneficial to human health,can effectively reduce the oxidation of turtle oil microcapsules.