Total phenolic contents and antioxidant activities of pulp, seed and skin of 22 grape varieties (7 white and 15 red) grown in the Marmara region of Turkey were determined (common, registered or candidate cultivars). The total phenolic contents of grape pulp, seed and skin parts ranged from 9.26 to 62.29, from 162.29 to 326.18 and from 96.61 to 167.42 mg gallic acid equivalents/100 g fresh weight, respectively. Seasonal changes were noticeable in the total phenolic contents and antioxidant activities of different grape parts. The antioxidant activity of grape seeds of registered or candidate cultivars was the highest, followed by skins and pulps. The antioxidant activities of grape skins were higher in red varieties than in white varieties. The results indicated that registered and candidate red or white grape cultivars may have high amounts of phenolics and possess a superior antioxidant activity in comparison to popular cultivars, such as Bilecik İrikarası, Hamburg Misketi, Alfons and Isabella.
Phenolic compounds make up 2-3% (w/w) of olive flesh, whose most abundant part is oleuropein which is responsible for the characteristic bitter taste of olive fruits. Oleuropein is a heterosidic ester of elenolic acid and hydroxytyrosol and possesses beneficial effects on human health. But most fundamental and important step of table olive processing is to reduce level of oleuropein because olive fruits can only be consumed after de-bittering procedures. Oleuropein accumulates during fruit growth and is slowly converted to elenolic acid glucoside and demethyloleuropein as the fruit ripens. Harvest maturation affects the table olive processing factors, according to change on oleuropein content of olive fruits. More severe applications are required for processing of olive which has high oleuropein content. Also oleuropein and its hydrolysis end products (elenolic acid and aglycone) inhibit the activity of a number of microorganisms involved in the lactic fermentation of olives. Oleuropein was significantly affected by both acid and base treatment, resulted in the liberation of hydroxytyrosol. Bitter taste of olive fruit can be eliminated by removing the oleuropein out of the olive or chemical or enzymatic hydrolysis of oleuropein in table olive processes. Understanding the characteristics of oleuropein for table olive processing helps manufacturer to produce high quality table olives and researchers to develop innovative methods for table olive production. So that this research was aimed to explore the characteristics of oleuropein and its effects on table olive processes.
Golden berry (Physalis peruviana L.) has scientifically proven medicinal properties. This research was aimed to investigate the effect of alkaline ethyl oleate and sucrose solution pretreatments as well as drying temperature on the drying kinetics of golden berry. Based on this, golden berries were dipped in alkaline ethyl oleate solution (2% ethyl oleate + 4% potassium carbonate) at 25°C or in osmotic solution (40% sucrose) at 60°C. After those pretreatments, air drying characteristics of golden berry (P. peruviana L.) were investigated at 70, 75, 80 and 85°C with 1.5 m/s air flow rate. Also, golden berries were dried without pretreatment and taken as a control. The experimental data was fitted to Page model. Two statistical tools were used to quantify the goodness of fitting: the determination of coefficient and the reduced chi-square. Obtained effective diffusivity for pretreatment of alkaline ethyl oleate and sucrose solution and untreated samples varied between 1.94 to 3.19·10 -9 m 2 /s, 1.21 to 2.93·10 -9 and 1.66 to 2.67·10 -9 m 2 /s respectively.
This is the first study in Turkey that evaluated olive fruit and oil characteristics of 23 cultivar candidates selected among 393 olive genotypes, on the bases of agronomical characteristics; the candidate cultivars were obtained by cross breeding between standard cultivars ('Gemlik', 'Edinciksu', 'Uslu', 'Tavşan Yüreği', 'Karamürselsu') and foreign cultivars ('Lucques', 'Belle d'Espagne' and 'Manzanilla'). Fruit traits such as fruit weight, flesh to seed ratio, fruit and seed size, as well as oil characteristics such as moisture, oil content, specific absorption at ultraviolet light, free acid content, peroxide value, chlorophyll and fatty acid composition were determined. Fruits and oils of intensely cultivated 'Gemlik' and 'Ayvalık' olive cultivars were also analyzed to compare them with the new candidate cultivars. According to the oil content, 'GE067' (23.30%), 'GE181' (23.97%), 'GE366' (22.52%), 'GE417' (22.16%), 'GT009' (24.14%), 'GT014' (21.02%), 'GU247' (22.48%), 'GU320' (27.15%) and 'GU434' (21.89%) gave better results, thus having good potential for registration as new cultivars for oil production. 'GE366' and 'GU434' were determined as the best cultivar candidates for producing dual purpose olives (table olives and oil). 'GE363' had the best fatty acid composition, which is an important feature in terms of oxidative stability and disease prevention.
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