Maturity impact on physicochemical composition and polyphenol properties of extra virgin olive oils obtained from Manzanilla, Arbequina, and Koroneiki varieties in Iran

This study investigated the physicochemical properties and polyphenol composition of extra virgin olive oils (EVOOs) extracted from three olive cultivars. The investigated cultivars were Arbequina, Koroneiki, and Manzanilla, grown in Olive Research Station in Rudbar county, Gilan province, Iran, at three ripening stages. Several parameters were analyzed, including peroxide and acidity values, unsaponifiable matter, oxidative stability, total aliphatic alcohols, fatty acids (FAs), sterols, and triacylglycerol composition. The results showed that as maturity increased, parameters such as oil content, acidity value, and iodine value, rise, while parameters including peroxide value, oxidative stability, aliphatic alcohols, and unsaponifiable matter decreased (p < .05). The saponification value was slightly reduced in the developing ripening process (p > .05). The MUFA/PUFA ratio and total sterol content declined during the olive ripening stages (p < .05). The triterpenes decreased in Arbequina and Koroneiki cultivars but increased in Manzanilla cultivar during the maturity stages. According to the data, oleuropein decreased while oleuropein aglycone, oxidized aldehyde, and hydroxylic form of oleuropein increased for all EVOOs during maturation. Apigenin, quercetin, ligstroside aglycone, aldehyde and hydroxylic form, ferulic acid, caffeic acid, and catechin decreased during the ripening of fruits (p < .05). The main triglycerides were triolein (OOO), palmitodiolein (POO), dioleolinolein (OOL), and palmitooleolinolein (PLO) in all EVOOs. In addition, the olive cultivar and harvesting date influence the physicochemical properties and polyphenol composition of EVOOs extracted from olive varieties grown in one region. In conclusion, the results can present helpful information to determine the optimum maturity stage for the investigated olive cultivars.