Preparation And Characterization Of Krill Oil Microemulsion

Antarctic krill oil extracted from wild Antarctic krill in pure waters is safe without toxic side effect, containing large amounts of phospholipids, co-3 PUFA, astaxanthin, vitamin A, D, E, animal flavonoids, chitin, microelements and other active components. Besides, many researches reflect that, krill oil is the only natural active multi-effect compound molecule with both high bioavailability and super antioxidant power that bonds with ?-3 as phospholipids and connects with super natural antioxidant keys, since the phospholipids is extremely close to phospholipids in human cells, the phospholipids rich of ?-3 PUFA can be absorbed and ultilized by human body easily. Currently, researches about krill oil at home and abroad focused on the medical value, including hypolipidemic, cardiovascular and cerebrovascular disease prevention, anti-inflammation, premenstrual syndrome alleviation, type ? diabete prevention and learning and memory capacity improvement.However, due to double bonds in EPA and DHA of krill oil, it is sensitive to oxygen, light and heat, oxidized easily. Currently, processing for krill oil is only restricted to capsulation production, although it makes up for the shortcoming of oxidation easily, the solid state of most productions make it complicated for industrializing preparation and largely restrain the further application in food industry. Thus it is urgent to develop a new method to embed krill oil.Microemulsion is a clear, transparent and thermodynamic stable liquid-liquid dispersion system and generally composed of water phase, oil phase, surfactant and cosurfactant. The preparation of microemulsion is a spontaneous process, once the combination of 4 phases gets proper, the evenly transparent or slight opalescence liquid will form. Recently, microemulsion applies in food industry as functional components increasingly. The preparation of stable microemulsion with krill oil through microemulsifying technique can not only overcome those problems in processing limits, make up for the shortcoming of the stinking smell of oil itself, and solubilize water-soluble or fat-soluble substances, it also has low toxicity, high safety and mass production capacity without special equipment. Otherwise, the particle sizes of microemulsions are all less than 100nm, which is benefit for the absorption of human body. This experiment chooses IPM as oil phase solvent of krill oil, mixed Tween80 and Span80 as surfactant, alcohol as cosurfactant to prepare clear, transparent and thermodynamic stable krill oil microemulsion, conducts centrifuge test, high-temperature test, PH test and storage test, and investigates the stability of the microemulsion system.Selection of oil phase:Preliminary experiment show that, due to its poor liquidity, it is difficult to produce microemulsion with the pure krill oil, and the proper solvent is needed for oil's dispersing and dissolving. This experiment chooses bean oil. IPP and IPM as oil phase solvent.Selection of surfactant:Surfactants selected in this experiment include Tween 80, Span 80, Tween 60, Tween 40, Tween 20 and RH-40. Specific method is that, oil phase is determined to be IPM:KO=2:1, then well mixed with a certain amount of surfactants and cosurfactant, stir evenly with magnetism mixer, add water phase by drops, treat with ultrasonic waves at least 30min after adding a certain amount of water, after 24 hours standing in 25? water bath, observe the form of emulsion, draw out microemulsion interval in pseudo-termary phase diagram and choose the proper surfactant.Selection of cosurfactant and Km:choose alcohol, propylene glycol and glycerin as cosurfactants. drop them into oil-surfactant system, observe their impact on microemulsion formation, draw microemulsion phase diagrams and choose the proper cosurfactant.Investigation of microemulsion stability:investigate the stability of microemulsion formulation through centrifuge model test, high-temperature test, PH test and storage test.Analysis of particle size:measure the particle size of microemulsion with DLS and judge whether the stable nanoscale microemulsion can form.Due to the poor liquidity of krill oil, this experiment selects the proper oil phase solvent, investigates the impact of different microemulsion components on microemulsion interval with pseudo-ternary phase diagram, successfully prepares water-in-oil krill oil microemulsion. determines that the optimum formula is KO/IPM/Tween 80/Span 80/alcohol/water system, in which solvent to oil ratio is 3:2. mass ratio of Tween 80 to Span 80 is 6:4, Km=1, the content of krill oil is 6.975% and the maximum water solubilization is 22.8%.Moreover, the particle size of microemulsion is measured by dynamic light scattering technique to study the stability of prepared microemulsion, the results show that, this kind of microemulsion possesses well acid resistance at room temperature and is clear and transparent, whose particle size changes little over time and average size is 10-100nm. Those properties provide the theoretical basis for the further development of krill oil microemulsion in functional food processing field.