Autoxidation of oil emulsions during the Artemia enrichment process

Abstract

Autoxidation in three Artemia enrichment emulsions (cod liver oil, tuna orbital oil, and Super Selco (Artemia Systems N.V., Belgium)) were monitored over a 23-h period. Percentage concentrations of docosahexaenoic acid (DHA, 22:6n − 3), eicosapentaenoic acid (EPA, 20:5n-3), total polyun-saturated, monounsaturated and saturated fatty acids, as well as DHA:EPA ratios were measured in (a) the enriched Artemia nauplii (b) control enrichment media from which Artemia were absent and (c) enrichment media in which Artemia were present. Concentrations of thiobarbituric acid reactive substances (TBARS) were also assayed in the three emulsions. Polyunsaturated fatty acid levels in all the control oil emulsions remained steady over the 23-h enrichment period. However, there were significant relative decreases in DHA, EPA and total polyunsaturated fatty acids in all enrichment media containing Artemia, with a corresponding significant increase in total saturated and monounsaturated fatty acids in the final stages of the enrichment period. Furthermore, percentage and absolute concentrations of DHA and the DHA:EPA ratios in the enriched Artemia decreased significantly in the 23-h sample from the tuna orbital oil and Super Selco emulsions compared to their respective 18-h and 19-h samples. The significance of these results in view of the common aquacultural practice of employing Artemia enrichment periods of 24 h is discussed.