Changes in Quality and Antioxidant Properties of Virgin Olive Oil of 'Cornicabra' According to Fruit Maturation in Longnan, China.

This work aims to study the influence of olive fruit maturity on physicochemical properties and antioxidant activity which determine the quality of virgin olive oils (VOO). According to the results, the values of all parameters were within the range specified by the Codex Alimentarius (2017). With the increase of fruit maturity, the oil content continued to increase until reached the maximum value (20.05%) in the 7th maturity (M7). K232, K270 and peroxide value (PV) decreased with the increase of maturity, while ΔK increased linearly with the increase of maturity. Free fatty acidity (FFA) first decreased and then increased, until reached the maximum value of (0.52 ± 0.03) % in M7. The total polyphenols (TP) and total flavonoids (TF) that characterized the antioxidant properties of olive oil increased with the increase of fruit maturity, which indicated that the oxidative stability (OS) of VOO of 'Cornicabra' increased with the increase of fruit maturity. The oleic acid (C18:1) content remained above 70 % and reached the maximum of (76.68 ± 0.17) % at M7. The values of monounsaturated fatty acids (MUFA) / polyunsaturated fatty acids (PUFA) and oleic acid (C18:1) / linoleic acid (C18:2) showed a decreasing trend with the maturity stage. Principal component analysis (PCA) showed that the quality of FFA, PV, K232, K270, TP, TF and OS were higher at the 5th maturity (M5), the quality of fatty acid were higher at M7. It can be seen from the analysis that the olive fruit maturity was an important parameter to characterize and distinguish olive oil.

Evolution of Phenotypic Traits and Main Functional Components in the Fruit of 'Chenggu-32' Olives (Olea europaea L.) Cultivated in Longnan (China).

China has taken olive cultivation as a significant part of its agricultural development. Longnan city of Gansu province was marked into the world olive distribution map by International Olive Oil Council in 1998. However, so far, little research has been done on the growth and development stages of Chinese olives. The objective of this study was to investigate the dynamics changes of several quality characteristics of olive oil at different sampling times. Olive fruit of 'Chenggu-32' grown in Longnan were harvested at twenty-four time periods and used for determination of phenotypic traits and oil quality characteristics: total polyphenols and flavonoids contents, as well as fatty acid composition by using Gas Chromatography-Mass Spectrometer (GC-MS) and analysed by using Principal Components Analysis (PCA). Towards maturation, fruit moisture content decreased while oil content increased. Levels of both total flavonoids and total polyphenols contents slightly decreased first then increased. The ratio of unsaturated to saturated fatty acids was close to three. The ratio of monounsaturated fatty acids (MUFA)/ polyunsaturated fatty acids (PUFA) was from 2.28 to 4.05. The oleic acid (C18:1)/linoleic acid (C18:2) ratio was varied between 5.23 and 10.67 according to different sampling dates. The olive oil had lower oleic acid (C18:1) levels, higher linoleic acid (C18:2), linolenic acid (C18:3), and palmitic acid (C16:0) levels compared to Codex values (2017) in some periods, which is the characteristics fatty acid composition of 'Chenggu-32' variety in Longnan, China.