Extraction And Purification Of Fish Oil From Mackerel Processing Byproduct And Its Antioxidant Activity

Mackerel(Pneumatophorus japonicas), a marine fish which contains abundantnutritional ingredient. Which is widely distributed in every sea area of our country, thelargest distribution is in the East China Sea. A large amounts of byproducts (such as fishhead and visceral) derived from the mackerel processing. The extraction and utilization offish oil from the byproducts processing, which can solve the problem of the utilization ofthe byproducts. Fish oils are rich in EPA, DHA and other polyunsaturated fatty acid, whichhas the activity of regulating lipid of blood, preventing blood clotting, the prevention ofAlzheimer’s disease, providing nutrition for the brain, improving memory, anti-cancereffect, enhancing immunity and physiological activities of many other kinds.In this paper, the extraction of fish oil by enzymatic hydrolysis and the process of fishoil refining are studied. In vitro antioxidant activities of different part of fish oil arecompared. The main research contents and results are as follows:1. Analysis of the ingredient of the mackerel fish head, visceral and tailsWe used the direct drying method for the determination of water content, Kjeldahlmethod for the determination of the content of crude protein, Soxhlet extraction method forthe determination of the crude fat, combustion method for the determination of ash content.Results showed that water content, crude protein, crude fat and ash in mackerel fish headare66.9%,7.8%,5.2%and22.1%, respectively. Water content, crude protein, crude fat andash in mackerel visceral are71.9%,14.2%,10.2%,3.7%, respectively. Water content, crudeprotein, crude fat and ash in mackerel tails are63.9%,16.9%,12.9%,6.3%, respectively.2. Extraction of mackerel fish oil from mackerel by enzymatic hydrolysisThe effects of trypsin, alkaline protease, papain, pepsin and neutral protease on theextraction ratio of fish oil from Pneumatophorus japonicus meat and byproducts werestudied. Neutral protease was selected to extract fish oil, and the extraction conditions wereoptimized using orthogonal test. The optimal hydrolysis conditions for fish head wereenzyme dosage2.0%, liquid-to-solid ratio1:1, pH7, temperature47.5℃and reaction time6h, the hydrolysis degree of the samples was53.86%with the optimal parameters. Theoptimal hydrolysis conditions for fish meat were enzyme concentration2.0%,liquid-to-solid ratio1:1, pH7.0, temperature50℃and contact time6h, the degree ofhydrolysis was63.29%with the optimal parameters. The optimal hydrolysis conditions forfish visceral were enzyme dosage2.0%, liquid-to-solid ratio1:0.75, pH7, temperature52.5 ℃and reaction time6h, the hydrolysis degree of the samples was58.47%with the optimalparameters.3. Refining of mackerel fish oilThe fish oil degumming process was performed using dilution phosphoric acidsolution. The optimum conditions are temperature70℃, phosphoric acid solution (60%) tofish oil ratio1:100(V/V). After deacidification, the recovery ratio of fish oil is94.45%, theacid value is2.85mg/g and the peroxide value is4.75mmol/kg. The fish oil deacidificationprocess was performed using dilution NaOH solution. The optimum conditions aretemperature70℃, NaOH solution (9%) to fish oil ratio8:100(V/V). After deacidification,the recovery ratio of fish oil is79.8%, and the acid value is1.83mg/g. The removal of colorfrom fish oil by attapulgite was studied. The optimum conditions are: temperature controlin60℃, adsorption time is30min, adding amount of attapulgite is10%, and the recoveryrate of decolorized fish oil is68.7%, the peroxide value is3.64mmol/kg. The deodorizationof fish oil is used yeast powder. The optimum conditions are: the amount of yeast is4%,temperature control in40℃, deodorization time is30min, the peroxide value of fish oilafter deodorization is3.15mmol/kg, the recovery rate is62.8%. The score of fish smellsensory is2.4. Determination of EPA and DHA in mackerel fish oilEPA and DHA in mackerel fish oil are determined by gas chromatography. Resultsshow that the content of EPA and DHA are9.15%and8.88%, respectively. Content of EPAand DHA are16.71%and17.43%, respectively. Content of EPA and DHA are6.17%,6.71%, respectively.5. In vitro antioxidant of mackerel fish oilThe comparison of in vitro antioxidant activities of the different parts in fish oil isstudied. Results show that the capacity of scavenging DPPH free radical of the fish oil frommackerel meat is higher than that from fish head and viscera. The capacity of scavengingsuperoxide free radical of the fish oil from fish head is higher than that from fish meat andviscera. The capacity of chelating Fe+2of the fish oil from fish meat is higher than that fromfish head and viscera. The capacity of restoring of the fish oil from fish meat is higher thanthat from fish head and viscera. The capacity of scavenging hydroxyl free radical of the fishoil from fish meat is higher than that from fish head and viscera.