Effects of the storage of Turkish Gemlik olives under CO2 and N2 on the phenolic compounds and fatty acid compositions of olive oils

Abstract

Because of the limited number and size of the oil extraction opportunities, olives are generally piled and stored at ambient temperatures for weeks before processing. Under these conditions biochemical changes could result a negative affect on the olive quality. The changes in the olive result poor stability in olive oil because of the oxidation and decomposition of bioactive compounds such as phenolic substances. Indeed, it is known that polyphenols are a large family of compounds found in plant tissues, which show strong antioxidant activity. The healthy characteristic of the phenolic compounds is associated to their radical scavenging activities. In this study, Gemlik olives cultivated from Osmaniye area were stored for 25 days at 5 °C under three different conditions (20 kPa CO2 atmosphere, 20 kPa N2 atmosphere and air). Olive oil was extracted following of 0, 5, 15 and 25 days of olive fruits storage. Qualtiy markers (free fatty acidity, peroxide value, K270 and K232) together with the phenolic compounds and fatty acid compositions of oils were determined. The physical properties of olives (flesh/pit ratio, average weight and fruit firmness) were well-preserved under CO2 and N2 atmospheres. The phenolics (tyrosol, syringic acid, vanilin, p-coumaric acid, oleuropein, cinnamic acid and luteolin) and fatty acids (palmitic, palmiteloic, heptadecanoic, heptadecenoic, stearic, oleic, linoleic, linolenic, arachidic, behenic, docosadienoic and lignoceric acids) composition were generally unchanged during storage. Oleuropein, the bitter principle of olives disapperead faster in the oils obtained through storage under N2 than other storage conditions.