Impact of Olive leaf yellowing associated virus on olive (Olea europaea L.) oil

Summary

Among the fifteen virus species detected in olive trees, Olive leaf yellowing associated virus (OLYaV) was found with high incidence and frequency in Southern Italy in particular. Effects of OLYaV on virgin olive oil yield and quality of 'Leccino' and 'Ottobratica' cultivars in Calabria region (Southern Italy) were analysed. Oil yield, free acidity, number of peroxides, spectrophotometric indexes, total content of chlorophylls and carotenoids, total phenol content, composition of the fatty acids, total tocopherols and total sterols content were determined on oil obtained from olive fruits collected in healthy/virus‐free and OYLaV‐infected trees. Almost all analysed oil parameters were not statistically different with some exceptions. Oils derived from 'Ottobratica' OLYaV‐infected plants had free acidity significantly lower than oil from healthy plants. K₂₃₂ of oil from virus‐free 'Leccino' trees was significantly lower than oil from infected trees. Even though some quality parameter differences between healthy and OLYaV‐infected oils were found, it is important to highlight that all oils can be considered in extra virgin olive oil category, within the UE maximum limit acceptance range. Results suggest a no negative interference by OYLaV in oil yield and quality, except for K₂₃₂ values, whereas surprisingly suggested a positive effect of virus infection on free acidity parameter.

Practical applications: Based on the evidence that OYLaV does not interfere negatively in oil yield and quality parameters, it seems appropriate that the European Union Council Directives (2014/96/EU, 2014/97/EU, 2014/98/EU) introduced in the last olive certification scheme only ArMV, CLRV and SLRSV. The application of compulsory EU directive, in Italy as in other countries, will improve the facilities of olive plants commercialization, guaranteeing enough their sanitary status. The findings here reported support the suggestion that the Italian Ministry of Agriculture could be less restrictive in voluntary Italian regulation (D.M. 20/11/2006).

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