The effect of harvest time and varieties on total phenolics, antioxidant activity and phenolic compounds of olive fruit and leaves

The effect of harvest periods on total phenol, antioxidant activity, individual phenolic compounds of fruit and leaves of Tavşan Yüreği, Memecik, Edremit, Ayvalık and Gemlik olive varieties grown in Turkey were investigated. The highest total phenol (317.70\ua0mg/100\ua0g and 2657.81\ua0mg/100\ua0g) were observed in Tavşan Yüreği olive fruit and Ayvalık leaves harvested in December, respectively. The highest antioxidant activities (83.84%) were determined in Edremit fruit harvested in August and 83.33% in either Edremit olive leaves harvested in November and Tavşan Yüreği leaves harvested in December. The olive fruit contained gallic acid ranging from 7.18\ua0mg/100\ua0g (August) to 35.85\ua0mg/100\ua0g (December) in case of Ayvalık and 2.09\ua0mg/100\ua0g (November) to 21.62\ua0mg/100\ua0g (December) in Edremit. Gemlik olives showed higher gallic acid contents compared to the other varieties, however it depended significantly on harvest time in all cases. 3,4-Dihydroxybenzoic acid contents ranged from 33.11\ua0mg/100\ua0g (October) to 25.17\ua0mg/100\ua0g (September) in Memecik olives; 12.17\ua0mg/100\ua0g (August) to 33.11\ua0mg/100\ua0g (December) in case of Tavşan Yüreği olives depending on harvest time. The 3,4-dihydroxybenzoic acid contents of Memecik leaves ranged between 122.25\ua0mg/100\ua0g (September) to 196.58\ua0mg/100\ua0g (August) and that of Tavşan Yüreği leaves changed between 99.38\ua0mg/100\ua0g (November) and 179.90\ua0mg/100\ua0g (August). The leaves of these two varieties contained significantly (p < 0.01) higher 3,4-dihydroxybenzoic acid contents than other varieties. The highest gallic acid (144.83\ua0mg/100\ua0g) was detected in Memecik leaves (September) whereas lowest were found in Gemlik leaves collected in October

Effect of date varieties on physico-chemical properties, fatty acid composition, tocopherol contents, and phenolic compounds of some date seed and oils

The acid value of date seed oils were determined between 1.09\ua0mg\ua0KOH/g (Taleese) and 1.44\ua0mg\ua0KOH/g (Ghars). Iodine values of oil samples changed between 67.18\ua0g\ua0I/100\ua0g (Allig) and 71.23\ua0g\ua0I/100\ua0g (Deglet Nur) (p\ua

Effect of the harvest time on oil yield, fatty acid, tocopherol and sterol contents of developing almond and walnut kernels

Oil content and bioactive properties of almond and walnut kernels were investigated in developing almond and walnut kernels at 10 days intervals. The oil contents of almond and walnuts after the first harvest (1.H) stage changed between 46.2% and 55.0% to 39.1% and 70.5%, respectively (

The effects of conventional heating on phenolic compounds and antioxidant activities of olive leaves

Phenolic compounds, antioxidant activities and total phenolic contents of leaves from different olive varieties (Gemlik, Kalamata, Yağlık and Sarıulak) were evaluated after conventional drying at different temperatures (50, 60, 70 and 80\ua0°C). The drying process resulted in non-significant effects on olive leaves. The phenolic contents however, varied with drying temperature. The contents of minor total phenolics in Gemlik, Kalamata and Sarıulak leaves were 1457.6, 1899.3 and 2179.8\ua0mg\ua0GAE/100\ua0g, respectively when dried at 60\ua0°C. The highest total phenolic reduction (23.2%) was observed in Kalamata leaves after drying at 80\ua0°C. The major phenolic compounds in olive leaves were gallic acid (101.2–439.7\ua0mg/100\ua0g), 3,4-dihydroxybenzoic acid (66.7–460.4\ua0mg/100\ua0g), (+)-catechin (39.2–667.8\ua0mg/100\ua0g), 1,2-dihydroxybenzene (15.8–584.8\ua0mg/100\ua0g) and quercetin (33.1–277.7\ua0mg/100\ua0g). It was observed that olive leaves from different varieties are rich in phenolic compounds which are sensitive to heat and varied with drying temperature