| Docosahexaenoic acid(DHA) is a kind of omega-3 polyunsaturated fatty acid. It has been the investigative focus in recent years for its biological functions of anti-aging, protecting vision, improving cerebrum growth, reducing blood pressure for prevention of atherosclerosis, anti-cancer and anti-inflammatory, and so on. The physicochemical properties, constituents and antioxidant ability of algae oil were studied in our study. The potential natural antioxidants and microcapsulation technology were investigated for improving the oxidative stability of algae oil.Both palmitic acid(38.3%) and docosahexaenoic acid(DHA)(34.5%) were identified as major fatty acids of algae oil by GC–MS analysis. The contents of total phenolics and flavonoids were 39.33 ug Gallic acid/g and 16.08 g rutin/g, respectively. The results displayed that the contents of β-carotene, α-tocopherols, β- and γ-tocopherols(not separated) and δ-tocopherols were 136 g/100 g, 164.4 g/g, 317.3 g/g and 43.2 g/g, respectively. Concerning sterols, cholesterol was the principal sterol at 4210.5 mg/kg and the other six main sterols were campesterol(121.4 mg/kg), 24-methylene cholesterol(192.8 mg/kg), 24-methyl-colest-7-en-3β-ol(144.6 mg/kg), ergosterol(144.8 mg/kg), stigmasterol(260.1 mg/kg) and △7, 24-Stigmastadienol(150.5 mg/kg), respectively. A Schaal oven test was used to evaluate the oxidative stability of algae oil and it showed that the oil had a good oxidative stability. Furthermore, in vitro simulated gastrointestinal digestion was performed, and the antioxidant ability of digested oil was great in the 2,2-diphenyl-1-picrylhydrazyl(DPPH) radical-scavenging assay, 3-ethylbenzothiazoline-6-sulfonic acid(ABTS) radical cation decolourisation activity assay, reducing power assay, β-carotene bleaching assay and oxygen radical absorbance capacity(ORAC) antioxidant assay. Thus, the oxidative stability and antioxidant ability of the algae oil were mainly contributed by its abundant antioxidant constituents such as phenolics, flavonoids, tocopherols, carotenoids and sterols.It was found that the algae oil was senstive to the temperature, light, air and metal ions. The results showed that these conditions can accelerate the oxidation and destroy the oxidative stability of the oil. Hence, we should produce or store the oil under the condition that out of light, air, metal ions and keep it at low temperature to enhance the oxidative stability of the oil.Based on the study of determination of DPPH(2,2-diphenyl-1-picrylhydrazyl)scavenging activity and the reducing power of rosemary together with synthesis antioxidant BHT(2,6-di-tert.-butyl-4-methylphenol),the antioxidation effect of rosemary on algae oil was studied by Schaal oven-storage method with POV value, TBA value and DHA content as index,and the synergistic antioxidant activity of rosemary with synergist was analyzed. The results displayed that rosemary had good antioxidant ability and great antioxidant effects on algae oil; 0.02% of rosemary and 0.01% of Vc palmitate exhibited excellent synergistic antioxidant activity. In order to improve the oxidation stability of the algal oil, the additon of the antioxidants combination in algal oil was optimized. Using Box- Behnken experimental design combined with response surface analysis, with rosemary powder, VE and Vc palmitate as the experimental factors, with algal oil POV value, TBA value and DHA content as response value, quadratic regression design model was established. The best combination of antioxidants was that 0.37 ‰ of rosemary spices, 0.11 ‰ of VE and 0.20 ‰ of Vc palmitate. Meanwhile, the consistent results between the predicted value and actual value indicated the established model in this study is feasible.Algae oil microcapsule was prepared by spray-drying using a wall system consisting of soy protein isolate and maltodextrin. The formula and technology of microcapsule preparation was investigated by single factor and the optimal preparation technology was optimized by orthogonal array design as following: the soy protein isolate and maltodextrin as the wall material with its ratio at 1∶2, the solid content in the wall material 15%, the suitable proportion of core material and wall material 1∶1 and the amount of emulgator(the ratio of fatty acid monoglyceride and sucrose fatty acid ester was 3:7) was 3%. The optimum spray drying conditions for microencapsulation of algae oil were: the inlet temperature was 170℃, outlet temperature was 70℃, the pressure of homogeneous was 45 MPa,and under these conditions the capsulation efficiency was 92.8%. The algae oil microcapsules produced under the optimal conditions had good sensory quality, solubility and oxidative stability with low water content. |
PDF Full Text Request