Digital olfaction potential for quality aroma discrimination in table olive breeding programs

The availability of table olive cultivars with greater tolerance to mechanical impact is key to ensuring good visual appearance and sensorial attributes (olfactory, gustatory and kinaesthetic) of the processed fruits. This work explored, over two years, the ability of an electronic nose (E-Nose) device to discriminate Spanish-style processed olives from six different genotypes and harvesting systems (manual versus mechanical). The data obtained allowed principal component analysis (PCA) to be carried out, which clearly grouped the samples according to genotypes and harvesting method. Also, over two years, the results were compared to the olfactory analysis by a trained panel. All samples, except for mechanically harvested ‘Manzanilla de Sevilla’ olives from the second season (2021/2022), were classified within the ‘Extra’ category. Although "abnormal fermentation" defects were detected in the mechanically harvested samples, the intensity of these defects was below the threshold that would downgrade them to other categories (First or Choice) according to the IOC standard. The ability of the tasting panel and device to discriminate mechanically harvested samples motivated an analysis of volatile organic compound (VOC) profiles in the second year to elucidate the chemical basis underlying the observed differences. Mechanically harvested Spanish-style olives showed higher values for carboxylic acids, phenols, aldehydes and ketones and lower values for alcohols, esters and hydrocarbons.