Oil Extraction By Enzymatic Method From Tilapia Head And Microencapsulation Of The Oil

Tilapia is one of the important farmed fishes in the world aquaculture, and China is one of the biggest countries of the world’s farmed Tilapia in the world. Tilapia is mainly processed into fillets,Therefore wastes produced in the process will cause the wastes of resources and environmental pollution if we don’t make use of it. How to rational utilization of the wastes and improve the added value of Tilapia products will be the hotspots in rhe development of Tilapia processing. The quality of Tilapia head is about one fifth of the whole fish.The fat content of Tilapia head was 13.95%, so it’s the good source for preparing fish oil.Enzymatic extraction of fish oil have some characteristics: high extraction rate, mild reaction condition and batter fish oil quality. Tilapia processed into frozen Tilapia fillets for export generally. So in the article the fish oil was extracted from frozen Tilapia head by enzymatic hydrolysis. The oil yield as evaluation index, the protease catalyzed hydrolysis process was optimized by single factor experiments combined with response surface methodology. The results as follows: Tilapia oil was extracted by compound protease.The extraction conditions were obtained as follows: enzyme dosage(w/w)1.25 %、the ratio of Tilapia head to water(g/m L) 1:1、hydrolyswas at 56 ℃ for 2.5 h. The highest extraction yield could reach 81.3%±1.3%, and 80.4% ±1.9%could also be reached by the further samll scale experiment. Crude oil was refined by decoloration and purification, and the physical and chemical indexes of the refined oil were:the color of Tilapia oil is light yellow and with a touch of fish smell, the content of moisture and volatile matter was 0.1%,acid value was 0.40mg/g, peroxide value was 0.95mmol/kg, unsaponifiable matter was 0.30%, iodine value was 106.0g/100 g, impurity was 0.01%,They were accordance with the first grade standard of the refined fish oil for SC/T 3502-2000 except for iodine value.Due to the high degree of unsaturated fatty acids in fish oil,so it prones to spoilage when exposed to light, oxygen, microorganisms, water and other environments. Microencapsulation of fish oil can effectively prevent external interference. Spray drying method has the characteristics of low production cost, simple process, continuous production, etc. So in the article.The study is to prepare microcapsules of Tilapia oil by using spray-drying method. The encapsulation rate was chosen as an evaluation index. six variables, such as the proportion of two kinds of starch, oil content, homogeneous time, homogeneous pressure, inlet-air temperature, and inlet feed rate were optimized. Oxidation stabilities of fish oil microcapsules and refined fish oil which added vitamin E, sesamol, TBHQ were studied respectively.Then, the optimal technological conditions of microcapsules of Tilapia oil were obtained as follows: 2:3(w/w) for the rate of octenyl succinic acid modified starch Mira CAP to the octenyl succinic acid modified starch Mira mist SE; 30% for the oil content; 3 times for the homogeneous times; 25 MPa for the homogeneous pressure; 170 oC for the temperature of inlet-air; 10 m L/min for the inlet feed rate; the microencapsulation efficiency of Tilapia oil microcapsules reached up to 95.9±0.39%. The sensory and physicochemical indexes(Moisture content: 1.93%, Surface oil content: 0.59%, POV: 2.10mmol/kg) of microencapsulation products met the requirement of fish oil microcapsule standard of the aquatic industry of China SC/T 3505-2006. By scanning electron microscope, the micro-structure observation of the microcapsules of Tilapia oil showed that they had smooth surface, no cracks.This paper analyzed the oxidative stability of fish oil added vitamin E, sesamol, composite antioxidant(vitamin E + sesamol), t-butyl hydroquinone oxidation stability(TBHQ) and microcapsules of fish oils.Among the fish oil added different antioxidant, the fish oil with TBHQ showed the best oxidation stability, next was the fish oil with composite antioxidant,then sesamol and vitamin E, They can be kept good quality for 8 months, 7months,5 months and 4 months, respectively at ambient temperature. After storage at 65±1oC for 12 days, the peroxide value of the microcapsules of Tilapia oil was only 5.22 m mol/kg which was lower than the industrial standard(6m mol/kg),and TBA was also significantly lower than the refined fish oil added TBHQ. It suggested that this product could keep a good quality for more than 1 year at ambient temperature. The fatty acids composition of refined fish oil was determined by Gas Chromatography. The results showed that the unsaturated fatty acids were the main components of fatty acids(72.16 %). The contents of monounsaturated fatty acids were 37.47 %, the major was oleic acid. While the contents of polyunsaturated fatty acids were 34.13 %, the major was linoleic acid.There is no significant different between crude oil, refined fish oil and microencapsulated fish oil at fatty acid composition.This paper described the principle and operating techniques of Tilapia oil extraction, refining, micro-encapsulation. The process of enzymatic extraction and microencapsulation of the oil by spray drying were studied; Physical and chemical indicators and fatty acids composition of crude oil, refined fish oil and microencapsulated oil were analyzed; Different antioxidant stability capacity between fish oil with different antioxidants and microencapsulated Tilapia oil were compared; Some guidance and reference for comprehensive utilization and value-added development of Tilapia processing waste resources were provides.