Study On The Preparation And Stability Of Water Dispersible DHA Emulsion

DHA, an importantω-3 polyunsaturated fatty acid, has a variety of physiological functions .On the market, polyunsaturated fatty acids are processed into encapsulation and oil-based form. There are few reports about preparing polyunsaturated fatty acid emulsions. This study is to prepare a more stable and more convenient DHA oil-in-water emulsion which has lower processing costs than microencapsulated DHA and provides a new choice for application of DHA. The main research contents and the results gotten are as follows.Hydrophilic-lipophilic balance(HLB),one of the most classic methods for choosing emulsifiers, was applied in this paper. Firstly, the HLB value for emulsion was 11.3. Furthermore, several common emulsifiers were mixed and the compound emulsifiers were composed of Distilled Monoglyceride and Tween40 and the ratio was 9:16. The optimum additive amount of emulsifiers was 1.2%. Xanthan gum, sodium alginate and CMC were chosen as thickening agents and the relative emulsion layer volume was as index to judge of emulsion stability. The better one is Xanthan gum, its additive amount 0.06%.According to orthogonal test and single-factor test, the optimized processing conditions for preparing DHA emulsion were that emulsification temperature 60℃, stirring intensity19000rpm, emulsification time 15 min. Homogenization pressure, homogenization temperature and homogenization times were 60Mpa, 55℃and 3, respectively.Prepared emulsion was stored at 25℃and 4℃, respectively. Study on the physical and chemical properties changes of DHA emulsion. At 25℃, the POV of crude oil rapidly increased from10.57meq/ kg to 46.09meq/ kg, and the POV of the emulsion slowly increased from10.85meq / kg to 23.16meq/ kg. At 4℃, the POV of crude oil increased from 10.57meq/ kg to 30.83meq/ kg, and the POV of DHA emulsion slowly increased from 10.85meq/ kg to 17.52meq/ kg. At the same time, the total content of DHA and EPA in emulsion was determined by GC before and after storage .The total content of DHA and EPA before storage ,at 25℃and 4℃were 33.3230%, 30.8853%, 31.0047%, respectively. Stability test results show that the emulsion system could retard the oxidation of oils and fats.