Correlation of triacylglycerol oligopolymers and oxidised triacylglycerols to quality parameters in extra virgin olive oil during storage

The evaluation of the effect of storage on extra virgin olive oil is usually achieved basing on the concurrence of many analytical methods. With the aim of reducing the number of determinations to carry out, the levels of triacylglycerol oligopolymers and oxidised triacylglycerols, determined by high-performance size-exclusion chromatography (HPSEC) analysis of the polar compounds of the oil, have been evaluated. The obtained results highlighted that the oxidised triacylglycerols were significantly correlated (p < 0.001) in a positive way with peroxide value and K₂₃₂ and in a negative way with total phenols and induction time, hence they can give indications about the primary oxidation level of the oil. The triacylglycerol oligopolymers, instead, were found to be significantly and positively correlated (p < 0.001) with K₂₇₀ that denotes the secondary oxidation of an oil. On the contrary, significant negative correlations (p < 0.001) between triacylglycerol oligopolymers and both the contents of carotenoids and chlorophylls, whose contents in the oil seriously diminish when the secondary oxidation is high, were found.