On the Squalene Content of CV Chondrolia Chalkidikis and Chalkidiki (Greece) Virgin Olive Oil

Abstract

This work is a continuation of efforts to establish the nutritional profile of virgin olive oil (VOO) from cv. Chondrolia Chalkidikis and Chalkidiki and to strengthen its positioning in the global VOO landscape. VOOs produced at an industrial scale in different olive mills of the Chalkidiki (Greece) regional unit as well as VOOs obtained at the laboratory scale from drupes of different maturity stages for four consecutive harvesting years were examined for their squalene (SQ) content using both HPLC and GC procedures. The mean values of SQ were found to be 4228 (HPLC) and 4865 (GC) mg/kg oil (n = 15) and were of the same magnitude as that in VOOs from cv Koroneiki (4134 mg/kg, n = 23). Storage of VOOs in the dark at room temperature for 18 months indicated an insignificant mean SQ content loss (~2%) in comparison to a mean loss of 26% for alpha-tocopherol content. This finding strengthens our view that SQ does not act as a radical scavenger that donates hydrogen atoms to the latter. The four consecutive harvest years studied indicated a clear declining trend in VOO SQ concentration upon olive ripening. To our knowledge, this is the first systematic work concerning the SQ content of Chondrolia Chalkidikis and Chalkidiki VOOs.

Keywords: Chalkidiki cultivar; Chondrolia Chalkidikis cultivar; GC-FID; HPLC-UV; maturity index; squalene; stability study; virgin olive oil.

Figure 1

Chemical structure of squalene (SQ, C₃₀H₅₀, 2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22-hexaene).

Figure 2

Principal component analysis (PCA) biplot of VOOs from cv. Chondrolia (n = 15) and cv. Koroneiki (n = 23). The scores were plotted for PC1 and PC2. The proportion of variance explained by each PC is shown in parentheses. The variables used were acidity (% oleic acid), PV (meq O₂/kg), K232, K270, total polar phenol (TPP), total hydroxytyrosol and tyrosol (Total HTyr + Tyr), α-Tocopherol (α-T), squalene (SQ), oleic acid (C18:1) content and C18:1/C18:2 (linoleic acid) ratio, and MUFA/PUFA ratio. MUFA: Monounsaturated fatty acids; PUFA: Polyunsaturated fatty acids.