Preparation Of Lycopene-containing Microemulsion System

Lycopene, a kind of liposolubility carotenoids, has the strong hydrophobicity. The poor solubility of lycopene in water and water-containing food system seriously limits its utilization in food processing. Therefore, developing a water-dispersible lycopene product is of great importance . In this paper, the preparation of lycopene-containing microemulsion and the change of lycopene structure during microemulsification was studied, then the stability of the microemulsion and its application were investigated. The main contents are described as follow:This paper studied the ingredients used to prepare the microemulsion, including oil to solubilize lycopene, kinds of emulsifier, co-emulsifier, Km and preparation temperature,which were investigated by single-factor experiments. The optimal formula and processing technology were screened via orthogonal experiments using microemulsion stability as an index. The result is that the optimal microemulsion system was composed of median chain triglyceride oil, Tween-40 and ethanol, the ratio of these ingredients was 1:5:8 (W:W:W). The concentration of lycopene in the new product is 4 mg/mL. The results of Particle size test indicate that the particle size of lycopene is 14.34 nm in average.Based on the existing identification method of lycopene isomers,the change of lycopene structure was analyzed before and after microemulsion. By using the UV-Vis whole wavelength scanning and HPLC testing, isomers were detected after microemulsion. LC-MS analysis showed that main isomers were 9-Z and 13-Z. Before microemulsion, It proved that Z-lycopene and all-E were 7.33% and 92.67% respectively; after microemulsion, the system contained 55.5% Z-lycopene, which was improved significantly, and 44.5% all-E lycopene .It was found that the addition of antioxidant in the process could reduce the degradation of lycopene. Based on the antioxidant activities and investigation of different antioxidants, the optimal antioxidant was determined as 0.1 g/kg L-ascorbic usions palmitate.Storing lycopene emulsions in different conditions, including different temperature, avoid light/ light, air/flooding oxygen was also investigated. It was found that when the microemulsion were restored in 4℃, 25℃and 37℃for 60 days,the corresponding survival rate were 70.38%, 62.66% and 46.16%, respectively; the lycopene survival rates were 62.66%, 49.81% in avoid light and sun conditions stored 60 days, respectively; the lycopene survival rate were 48.76%, 82.26% when the lycopene was stored 60 days in the air, flooding oxygen conditions, respectively; In avoid light, flooding oxygen conditions, lycopene emulsion were respectively stayed in environments of 4℃and 25℃, after 30 days, there still remaining above 90% in 4℃. After 60 days, the survival rate was 84.9%. In the 25℃stored 60 days, the survival rate is 79.86%, so that the best storage condition was: 4℃, avoid light, and with the protection of flooding oxygen. The deposit height ratio w was used as the evaluation index of the product quality and structure stability. After 10, 20 and 60 days, w was 0, 3.3% and 6%, respectively. It was proved that microemulsion could be stable and homogeneous in a certain period. The lycopene-containing microemulsion could be used in drink which has the function of health care.