| There are many kinds of insect in world, which is the largest nature resources that have not been fully development and utilization. Insects were rich in fat and the composition of its fatty acids were very reasonable, the proportion of saturated acids and unsaturated acids was less than 40%, and the content of unsaturated fatty acids was higher than saturated fatty acids. Some insects were rich in oleic acid、linoleic acid and linolenic acid, which are the human essential fatty acids because they cannot be synthesized in human body and must be absorbed from environment. Research results showed that the fatty acid composition of insects fat was similar with fish oil, so insects fat was potential resources of edible oil and fatty acids, and also can be used in food、medicinal、health care and cosmetic areas in the future as the substitute goods of some fatty acids.In this thesis, in order to get the optimal extraction conditions、the composition of fatty acids、the content of fat-soluble vitamin and the antioxdant activity of insect fat, Periplaneta Americana adult and Lucilia sericata larva were choised as the experimental materials, petroleum ether was selected as impregnant,soxhlet extraction method、solvent extraction method、ultrasonic wave-microwave assisted extraction method and enzyme-assisted aqueous extraction method were used to extract the insect fat. Then the physic and chemistry properties、the composition of fatty acid、the content of fat-soluble Vitamin and antioxidant function of fat were measured respectively. Main contents and results are listed as follows:(1) Results of 2 kinds of insect fat extractPeriplaneta Americana fat: The content of fat is 36.28%, The optimum conditions of Solvent extraction were extraction temperature 52.14 ℃, extraction time 7.07 h, ratio of solvent to material 20:1, the actual extraction yield is 29.44%. Ultrasonic wave-microwave assisted extraction were extraction time 10 min, extraction yeild of solvent to material 12:1, ultrasonic power 321.35 W, microwave power 179.84 W, extraction temperature 50.07 ℃, the actual extraction yield is 30.65%. Enzyme-assisted aqueous were extraction time 7 h, PH 7.26, extraction temperature 37.89 ℃, enzyme activity 515.65 U/g, the actual extraction yield is 24.95%.Lucilia sericata larva: Solvent extraction were extraction temperature 40 ℃, extraction time 7.93 h, extraction yeild of solvent to material 19.71, the actual extraction yield is 27.89%. Ultrasonic wave-microwave assisted extraction were extraction time 10 min, extraction yeild of solvent to material 12:1, ultrasonic power 339.10 W, microwave power 446.64 W, extraction temperature 57.77 ℃, the actual extraction yield is 24.67%. Enzyme-assisted aqueous were extraction time 7 h, PH 8.17, extraction temperature 58.10 ℃, enzyme activity 800 U/g, the actual extraction yield is 13.56%. The results indicated that the optimized conditions by RSM is feasible. Ultrasonic wave-microwave assisted extraction is the best extraction method of the 2 kinds of insects by considering the extraction time and extraction yield.(2) Physic and chemistry properties analysis of 2 kinds of insectsPeriplaneta Americana fat: The hue-saturation-intensity values of four kinds of fat were 0.78, 0.60、0.67 and 0.24 respectively, the color of Enzyme-assisted aqueous fat is the shallowest. The meilting points and crystallization points of four different methods were 1.63 ℃and-46.43 ℃、-3.29 ℃ and-44.66 ℃、-6.52 ℃ and-41.58 ℃、-13.09 ℃ and-51.35 ℃ respectively. Lucilia sericata larva: The hue-saturation-intensity values of four kinds of fat were 0.73、0.63、0.53 and 0.32 respectively, the color of Enzyme-assisted aqueous fat is the shallowest. The meilting points and crystallization points of four different methods were-9.87 ℃and-24.73 ℃、-9.82 ℃ and-24.73 ℃、-9.91 ℃ and-22.11 ℃、-7.80 ℃ and-12.70 ℃ respectively. The color of Periplaneta Americana fat was deeper than Lucilia sericata fat, and the melt point were different among different fat which extracted by four methods.(3) Composition and content of 2 kinds of insects fatty acidsPeriplaneta Americana fat: There were 12 kinds of fatty acids, and among them, oleic acid、linoleic acid、and palmitic acid were the major compositions, and the content of these three kinds of fatty acid accounted for about 90% of the total fatty acid, were 109.63 mg/g、154.60 mg/g and 171.88 mg/g respectively. Palmitic acid and atearic acid were the major contennt of saturated fatty acid while oleic acid、linoleic acid and arachidonic acid were the major contents of unsaturated fatty acid. Unsaturated fatty acid had a higher percentage,and there were also a little amount of Arachidonic acid and Pentadecanoic acid.Lucilia sericata larva: There were 17 kinds of fatty acid in other three kinds of fat. Among them, oleic acid、linoleic acid、palmitic acid and palmitoleic acid were the major compositions, accounted for about 89% of total fatty acid. The results of quantitative analysis show that the oleic acid、palmitic acid and palmitoleic acid content were 248.47 mg/g、243.51 mg/g、174.96 mg/g respectively. Palmitic acid and atearic acid were the major contennt of saturated fatty acid while oleic acid、linoleic acid and arachidonic acid were the major contents of unsaturated fatty acid, Unsaturated fatty acid had a higher percentage The content of oleic acid and linoleic acid in Lucilia sericata larva fat were obviously higher than Periplaneta Americana fat while the content of palmitic acid was similar.(4) Fat-soluble vitamin content of 2 kinds of insectsVitamin A、Vitamin A acetate、vitamin E and vitamin K were detected both in Periplaneta Americana fat and Lucilia sericata larva fat, and the content of these 4 kinds of vitamins were 98.40 μg/ml, 3.19 μg/ml, 3.07 μg/ml, 12.31 μg/ml and 123.77 μg/ml, 5.63 μg/ml, 5.38 μg/ml, 23.69 μg/ml respectively. The content of all these four kinds of fat-soluble vitamin were higher in Lucilia sericata larva fat compared with Periplaneta Americana fat.(5) Antioxidant activity of 2 kinds of insectsThe results showed that both of the two kinds of fat had a certain remove hydroxyl free radicals, superoxide anion free radical, the ability of DPPH free radical and limit reducing power. The antioxidant activity of Lucilia sericata larva fat was better than Periplaneta Americana fat, and both of these two kinds of fat had limited antioxidant activity and far below the control’s antioxidant of Vitamin E.In short, Ultrasonic wave-microwave assisted extraction is the best extraction method of the 2 kinds of insects by considering the extraction time and extraction yield. The color of Periplaneta Americana fat was deeper than Lucilia sericata fat, and the melt point were different among different fat which extracted by four methods,which may caused by the different composition of fatty acids. Oleic acid、linoleic acid、and palmitic acid were the major compositions both in the two kinds of insects fat, and the content of oleic acid and linoleic acid in Lucilia sericata larva fat were obviously higher than Periplaneta Americana fat while the content of palmitic acid was similar, in addition, the content of all these four kinds of fat-soluble vitamin in Lucilia sericata larva fat were also higher compared with Periplaneta Americana fat and the antioxidant activity of Lucilia sericata larva fat was better than Periplaneta Americana fat. These results may had some relationship with the unsaturated fatty acids and the fat-soluble vitamins. |
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