Changes in olive properties and oil quality, oxidative stability, phenolic and chemical composition of two common Turkish varieties (Memecik and Edremit) during maturation were investigated. Olive samples were collected in their own growing region for five different harvest dates and processed to oil with a laboratory scale mill. Metabolic behaviors of these two varieties along with the maturation were different in terms of some compositional parameters. Oleic acid, triolein, b-sitosterol, oleuropein, hydroxytyrosol, and tyrosol contents of olive or olive oils fluctuated with maturation. However, changes in average weight, flesh/pit ratio, water and oil contents of the olives were observed. Phenolics such as trans cinnamic acid contents of both olive fruits decreased whereas cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside anthocyanins increased. Free fatty acids of virgin olive oils were found independent of maturity although some slight changes were determined in peroxide value, dien and trien conjugations. Some compositional parameters such as pigment concentration, tocopherols, stearic acid, linolenic acid, palmitodiolein and monounsaturated/polyunsaturated fatty acid ratio decreased while linoleic acid, dioleolinolein, palmitooleolinolein and D-5-avenasterol percentages increased with the maturation. A clear discrimination was observed with principal component analysis. The data obtained can also be considered useful for providing information to determine the ideal maturity stage.

Effects of the industrial refining process on some properties of hazelnut oilHazelnut (Corylus avellana L.) oil was chemically refined using industrial refining conditions. Crude hazelnut oil was obtained by pre-pressing-solvent extraction methods and refined by neutralization, bleaching and deodorization in industrial scale. The changes in color, free fatty acids, fatty acid composition, tocopherol and phytosterol contents were determined after each step of refining. The main color change was observed during bleaching. Fatty acid composition, mainly oleic acid (81%), did not change significantly during the process. At the end of the refining, the amounts of total tocopherol and phytosterol decreased from 51.89 to 46.67 mg/100 g and from 168.04 to 141.48 mg/100 g, respectively. The biggest losses of both tocopherols and sterols were observed after neutralization. Deodorization caused a slight decrease in the amount of sterols. a-Tocopherol (36.19 mg/100 g), b-tocopherol (9.3 mg/100 g), and gsitosterol (120.28 mg/100 g) were the predominant unsaponifiables in refined hazelnut oil.

Phenolic compound distribution of Turkish olive cultivars and their matching olive oils together with the influence of growing region were investigated. One hundred and one samples of olives from 18 cultivars were collected during two crop years from west, south and south-east regions of Turkey. The olives were processed to oils and both olive and olive oil samples were evaluated for their phenolic compound distribution. The results have shown that main phenolics of Turkish olives were tyrosol, oleuropein, p-coumaric acid, verbascoside, luteolin 7-O-glucoside, rutin, trans cinnamic acid, luteolin, apigenin, cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside. Oleuropein and trans cinnamic acid were present in higher amounts among all phenolics. Principal component analyses showed that the growing region did not have drastic effect on phenolic profile of olives. The major phenolic compounds of olive oils were tyrosol, syringic acid, p-coumaric acid, luteolin-7-O-glucoside, trans cinnamic acid, luteolin and apigenin. Luteolin is a predominant phenolic compound in almost all oil samples. Total phenol concentrations of Southeast Anatolian oils were found to be lower than those of the other regions.Abbreviations: PCA, principal component analysis; VOO, virgin olive oil Eur.

A characterization study of Turkish monovarietal olive oils using chemical variables such as fatty acid, sn-2 fatty acid, triacylglycerol, and sterol composition is presented. A total of 101 samples of Olea europaea L. fruits from 18 cultivars were collected for two crop years from west, south, and southeast regions of Turkey. Olives were processed to oil and olive oil samples were evaluated for their triacylglycerol structures and sterol composition. Oleic acid content ranged from 60.15 to 80.46 % of total fatty acids and represented 70.90-89.02 % of sn-2 position triacylglycerols. Major triglycerides of oil samples were triolein, palmitodiolein, dioleolinolein, palmitooleolinolein, dipalmitoolein, and stearodiolein. Triolein values were between 24.72 and 48.64 % and compatible with the fatty acid composition. Total sterol content varied from 1,145.32 to 2,211.77 mg/kg and Edremit yaglık stood out because of its high sterol content. A one-way analysis of variance revealed significant differences for variables among cultivars. Principle component analysis enabled the classification of common varieties on the basis of analytical data. Sterol composition achieved more relevant discrimination than fatty acid and triglyceride composition. Classification according to geographical origin was performed by discriminant analysis.

Effect of destoning and malaxation in nitrogen atmosphere on oxidative stability, fatty acid and sterol composition of extra virgin olive oil (EVOO) were investigated in industrial scale. Olives of 'Edremit yaglik' cultivar were processed with a two phase centrifugal system with or without stones, in nitrogen or air atmosphere. Results have shown that either N 2 flush or destoning did not make any contribution to the sterol and fatty acid composition. Malaxation in nitrogen atmosphere extended induction time, raised phenolic, tocopherol contents and antioxidant potential of oils. Destoning also increased oxidative stability but lowered carotenoid and chlorophyll contents of oils. Among all treatments, the combined effect of destoning and malaxation in nitrogen atmosphere achieved the production of EVOO with the highest quality.