Dynamic assessment of the fruit quality of olives cultivated in Longnan (China) during ripening

As an emerging olive planting country, olive growing area in China is expanding to southwest. The fruit quality changes of five main olive cultivars in Longnan City, Gansu Province during ripening were evaluated. The olive fruits introduced and cultivated in Longnan experienced a period of growth and maturity from June to October, and the suitable harvest time is from late October to mid-November. The appearance, colour and main biochemical components of olive fruits changed significantly during ripening. There was a significant relationship between the changes of total sugar contents in fruit and leaf, and oil accumulation in fruit, showed that as the oil content in olive fruit was increasing, while the sugar content in fruit and leaf was decreasing. Although the oil content in olive fruits increased continuously during ripening, the fatty acid types and proportions of different varieties do not change significantly, the main fatty acids are: C18:1 > C16:0 > C18:2 > C18:0 > C16:1. Flavonoids and polyphenols content in olive leaves increased constantly during fruits ripening, while the evolution of those components in fruits was different due to the cultivars and maturity degree. The PPO activity in olive fruit reached a peak in mid-September, and there was no correlation between PPO activity and polyphenol content in fruits. The results showed that the five main olive cultivars introduced and cultivated in Longnan exhibited good production performance. Fruit quality and its evolution mainly depend on cultivars, genetic characteristics and also related to grade of maturity, environmental and agronomic conditions.