Abstract:

The release kinetics of microencapsulated micro-algal oil was investigated under different storage conditions. The Avrami equation was employed to analyze the release mechanism parameters and release rate constant (K) and measure the change in retention ratio of DHA, one of the major functional components of micro-algal oil, under different levels of light intensity, temperature and relative humidity. The results indicated that the K value of micro-algal oil microcapsules was smaller though stored at a higher storage temperature (60 ℃) and the DHA retention ratio was 66.69% after 12 days of storage at 60 ℃. DHA retention ratio, however, was very sensitive to humidity and the value was only 3.45% after 12 days of storage at 90% humidity, and K increased obviously. This indicates that micro-algal oil microcapsules should be stored at lower humidity. Light intensity had no remarkable effect on the stability of micro-algal oil microcapsules, and the DHA retention ratio was still 78.33% after 12 days of 10000 lx illumination. Higher storage temperature, relative humidity and light intensity all could result in an increase in K. It is obvious that microalgal oil microcapsules should be stored in light-avoiding, low-temperature and low-humidity environment.

Key words: micro-algal oil, microcapsule, DHA, release kinetics