Determination of neutral lipid hydroperoxides by size exclusion HPLC with fluorometric detection. Application to fish oil enriched mayonnaises duringstorage

A fast (12 min) high-performance size exclusion chromatography (HPSEC) meth od for the separation of neutral lipid class hydroperoxides in the oil phas es from fish oil enriched mayonnaises was developed. Detection and quantifi cation were performed using the postcolumn fluorometric (FL) diphenyl-1-pyr enylphosphine oxidation principle. The reproducibilities judged by intra- a nd interassay variations were 0.64 and 7.2%, respectively. The HPSEC-FL met hod was applied to assess the effect of supplementations with emulsifier, g allic acid, and EDTA on the oxidative processes in the mayonnaises during s torage. Substantial amounts of hydroperoxy triacylglycerols (TAGOOH) and ch olesterol esters (CEOOH), together with traces of TAGOOH-dimers, were detec ted. All supplementations significantly decreased the levels of TAGOOH and to a lesser degree CEOOH. Supplementations with EDTA and gallic acid result ed in constant and slightly increasing levels of TAGOOH, respectively, thus affecting the oxidation mechanisms seen in reference mayonnaise. The emuls ifier Panodan TR DATEM reduced the levels of TAGOOH as compared to the appr opriate controls.