Thermal Treatment Analysis — Determination of Polymerized Triglycerides and Chlorophyll Degradation Products - - Chromatography Online
Thermal Treatment Analysis — Determination of Polymerized Triglycerides and Chlorophyll Degradation Products

The Application Notebook
pp. 703

The presence of polymerized triacylglycerides or chlorophyll degradation products in olive oil indicates that the oil has been refined or subject to other thermal treatment processes. In this study, several olive oils were analyzed using the Agilent 1260 Infinity LC with refractive index and fluorescence detection.


Table 1: Polymerized triacylglycerides.
Virgin olive oil can be created only by mild, cold pressing of olives (Olea europea L.). In addition to the determination of stigmastadienes (1), the quantification of polymerized triacylglycerides and chlorophyll degradation products in olive oil is another important factor to determine whether thermal treatment was used.


Table 2: Chlorophyll degradation products.
During different refining steps, the oil components are chemically altered (2). Polymerized triacylglycerides are normally not present in crude vegetable oils. During the extraction processes, the chlorophyll a and b pigments are converted into the more stable pheophytins (3), which in turn undergoes slow decarboxymethylation to give pyropheophytin.

Experimental Conditions

Results


Figure 1: Detection of (a) polymerized triacylglycerides and (b) chlorophyll degradation products in partly refined olive oil.
In contrast to virgin olive oil, the partly refined olive oil chromatogram showed dimerized triacylglycerides (Figure 1a). In addition, a higher percentage of chlorophyll a degradation products are found in partly refined olive oils (Figure 1b).

Conclusion

Only negligible amounts of polymerized triacylglycerides were detected in all six virgin olive oils. In addition, in fresh virgin olive oils, only a minor amount of pyropheophytin was detectable, but as it develops slowly during storage, higher amounts were detected in several longer stored virgin olive oils as well as in the partly refined olive oil.

References

(1) Quality Analysis of Virgin Olive Oils – Part 1, Agilent Application Note, Publication Number 5991-1894EN, 2013.

(2) G Billek, European Journal of Lipid Science and Technology 94(5), 161–172 (1992).

(3) K Aitzetmueller, European Journal of Lipid Science and Technology 91(3), (1989).



Agilent Technologies Inc.
5301 Stevens Creek Blvd., Santa Clara, California 95051, USA
Tel: (800) 227 9770
Website: http://www.agilent.com/

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