| Tilapia has a history of seventy to eighty years in China, and China is the largest country in tilapia culture and processing industry, also it plays an important role in the world. Now the tilapia products are mainly frozen fish fillets.Its prosperity and development had emerged new problems: large amounts of by-products during processing, which were not been reasonably used, have resulted in waste of resources, environmental pollution and reducing the economic benefit. So research on tilapia by-products has been a hotspot, and mainly focus on visceral, skin, scales and fish bones, few studies focus on tilapia head. Tilapia head oil rich in UFA and phospholipids, which has good nutritional value and beneficial physiological effects on humans, so research on tilapia head focused on fish oil and phospholipids in this study to provide theoretical support for higher value application and deep processing of tilapia head, also it will be important to solving resource waste and environmental pollution problems.Firstly, the extraction process by supercritical CO2 extraction from tilapia head was optimized. The signal factors were chosen by single-factor experiments and the optimal extraction condition of tilapia oil by supercritical CO2 extraction was optimized by response surface method. The results showed that the optimum condition was extraction pressure 36 MPa, extraction temperature 41℃ and extraction time 3.1 h with an extraction of 79.5%. Supercritical CO2 extraction was better than cooking method, alkali hydrolysis method and enzymatic method.Then the quality and fatty acid composition of tilapia head oil were analyzed. The results showed that the iodine value, POV and acid value was 5.36±0.15 mg/kg, 4.27±0.33 m mol/kg and 139.0±8.9 g/100 g respectively, which had better color and odor and achieved the primary standard level of the national fish oil standard. The content of SFA, MUFA and PUFA was 37.60%, 24.74% and 37.66% respectively. The MUFA species mainly included C16:1、C18:1、C20:1、 C22:1 and C24:1, the PUFA species mainly included C18:2、C18:3、C20:2、C20:3、C20:4、C20:5(EPA)、C22:5 and C22:6(DHA), especially the content of EPA and DHA was 2.45% and 10.32% respectively. The composition of tilapia head oil extracted by supercritical CO2 extraction was better than that by traditional methods and that from tilapia eyes, muscle and other fish. It showed that tilapia head oil extracted by supercritical CO2 extraction had rich fatty acid composition which also indicated excellent nutritional value and functionality.The extraction and separation of phospholipids from tilapia head, phospholipids composition, molecular species and content of phospholipid classes were studyed. The results showed that the total phospholipids content was 26.3mg/100 g, which was higher than that of other seafood and soybean. Various physicochemical indicators achieved the primary standard level of powdered phosphatide except ether insoluble metter, which indicated good phospholipids quality. The phospholipids composition, molecular species and content of phospholipid classes were analyzed by infrared spectrum, thin layer chromatography, and mass Spectrometry. The results showed that phospholipids composition mainly included PS, PE, PC and PI. Among them, PE had the highest content and PS had the lowest content. The molecular species of PE included C14:0, C18:0, C19:0, C22:0, C23:0, C15:3, C16:4, C18:2, C18:3, C18:4, C19:1,C20:1, C20:5 and C22:6, while PS: C12:0, C18:0, C22:0, C20:5 and C22:6, PC: C12:0, C14:0, C19:1, C20:5 and C22:6, PI: C12:0, C15:1, C20:4,C20:5 and C22:6. |
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