Evaluation of the fruit characteristics and quality of five olive cultivars grown in different orchards in Longnan, China

The quality of virgin olive oil is closely related to the quality of olive fruits. The primary aim of the present work was to assess the olive fruit quality of five major olive cultivars (Frantoio, Leccino, Ezhi-8, Picholine, and Coratina) cultivated in Longnan, which is an emerging region for olive plantation in China. Measurement and gravimetric methods were used to study the biological properties of olive fruits, while the biochemical constituents were analysed by colorimetry. The results of morphological and biochemical analyses showed that the olive fruits of the five cultivars had excellent quality with relatively high oil contents and bioactive components (flavonoids and phenolic compounds). The oil contents in freeze-dried sarcocarp ranged from 49.25 to 71.11%. The shape parameters, biological characteristics, and bioactive components of olive fruits varied with genetic characteristics of cultivar, ripeness, and physicochemical factors of soil. There was a certain negative correlation between total carbohydrate and oil content in sarcocarp, as well as between total polyphenol content and polyphenol oxidase activity. The principal component analysis (PCA) results showed that the evaluation indexes of the olive fruit quality mainly include the biological characteristic parameters (fruit size and weight, sarcocarp, and oil content) and the contents of bioactive components (saccharides, polyphenols, and flavonoids). Furthermore, the soil nutrients and physicochemical properties also affected the fruit quality. Our findings suggest that the olive fruit produced in Longnan has excellent production performance, and the fruit quality is closely correlated with the genotype of olive cultivar, growing environment, and soil conditions.