engleski

Policosanol changes in olive oil as a result of variety, ripening and storage

Policosanol is a common term that refers to a mixture of long-chain (20-36 carbon atoms) aliphatic primary alcohols. It is naturally present in the unsaponifiable fraction of vegetable oils, mainly represented by docosanol (C22), tetracosanol (C24), hexacosanol (C26), and octacosanol (C28). As well as other bioactive constituents in olive oil, such as phenols, tocopherols and phytosterols, policosanol attracts the attention of scientist because of its beneficial physiological effects, which include reducing platelet aggregation and endothelial damage, as well as cholesterol-lowering, anti-aggregant, anti-inflammatory, and anti-nociceptive activities. Despite that, the response of policosanol alcohols in olive oil to many important sources of variation has not been investigated thoroughly. To investigate policosanol changes in olive oil as a result of olive variety, degree of ripening, and oil storage temperature, 36 samples (3x varieties x 3 ripening degrees x 3 storage conditions and a control) were subjected to gas chromatographic (GC-FID) and mass spectrometric (GC-MS) analysis, and results were statistically elaborated. Seven long-chain aliphatic alcohols were identified. Their content was found to be strongly dependent on variety and ripening degree, and significant differences were obtained by three-way ANOVA for all aliphatic alcohols. Variability as a result of storage temperature and storage in general was of a much smaller magnitude and not statistically significant. It means that investigated olive oil samples were rather stable with respect to the content of policosanol, and essentially retained its beneficial features throughout shelf-life. The concentration (mg/100 g) of alcohols with longer aliphatic chain (C25-C28), as well as relative amounts (%) of docosanol (C22) and pentacosanol (C25) accounted for the most variation due to varietal origin. Oils from Rosinjola variety were the most abundant. The largest influence of ripening degree was observed for docosanol (mg/100g and %) and pentacosanol (%). The content of shorter chain alcohols (C22-C24) was found to increase, while that of those with a longer chain was found to decrease during ripening. Statistically significant changes were observed between oils made from green and spotted olives, with the same pattern for all varieties. It suggests the possibility to use policosanol alcohols as molecular indicators of ripening degree. Among other results, this investigation provided the first, to our knowledge, experimental evidence of the effect of storage on policosanol in olive oil.

Olive oil; policosanol; ripening; storage; variety

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