Maryam Rahimi; Narges Pakravan; Rouhollah - Karimi
Abstract
Grapes are one of the richest sources of different phenolic compounds with high antioxidant, antibacterial and nutritional properties among fruits. The aim of this study was to investigate the different classes of phenolic including flavonols, flavanols, flavone, anthocyanins, stilbenes and phenolic ...
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Grapes are one of the richest sources of different phenolic compounds with high antioxidant, antibacterial and nutritional properties among fruits. The aim of this study was to investigate the different classes of phenolic including flavonols, flavanols, flavone, anthocyanins, stilbenes and phenolic acids in eleven Vitis vinifera cultivars. Based on the result, the highest catechin, epicatechin, ferulic acid and chlorogenic acid was related to ‘Yaghooti’ grape cultivar. However, catechin gallat, kaempferol, myricetin and p-coumaric acid of ‘Bidaneh Ghermez’ showed a higher content (p < 0.05) compared to other cultivars. Berry quercetin (as main flavonols) was found to be highest (9.48 μg g-1; p < 0.05) in ‘Yaghooti’ . The berry skin luteolin as a flavone ranged from 0.49 μmol g-1 in ‘Rishbaba’ to 0.88 μmol g-1 in ‘Bidaneh Ghermez’ cultivar. The content of delphinidin-3-glucoside and malvidin-3-glucoside of ‘Yaghooti’, cyanidin-3-glucoside and peonidin-3-glucoside of ‘Angoor Siah’ and petunidin 3-glucoside of ‘Bidaneh Ghermez’ was found to be higher (p < 0.05) compared to other cultivars. Berry resveratrol varied from 22.7 μg g-1 in ‘Monaqa and Fakhri’ cultivars to 54.8 μg g-1 FW in ‘Bidaneh Ghermez’ with an overall average of 36.9 μg g-1 FW. Among different cultivars, the antioxidant capacity of ‘Angoor Siah’ was the highest (71.3%; p < 0.05) and ‘Monaqa’ was the lowest. Also, the ‘Angoor Siah’ cultivar has more antibacterial activity compared to other cultivars. Totally, the berry skin of ‘Yaghooti’, ‘Angoor Siah’ and ‘Bidaneh Ghermez’ showed the highest health promoting bioactive compounds, which could be considered further in future studies.
Rouhollah Karimi; Seyed Mehdi Mirbagheri; Maryam Davtalab
Abstract
Raisins are good sources of bioactive compounds with beneficial effects on human health. Mineral nutrition is one of the main viticultural practices affecting grape and raisin phytochemical compositions. In this study, the effect of preharvest foliar application of potassium (K2SO4; 0, 1.5 and 3%) and ...
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Raisins are good sources of bioactive compounds with beneficial effects on human health. Mineral nutrition is one of the main viticultural practices affecting grape and raisin phytochemical compositions. In this study, the effect of preharvest foliar application of potassium (K2SO4; 0, 1.5 and 3%) and iron (Fe-EDDHA; 0, 0.5 and 1%) was evaluated on some nutritional and biochemical properties of raisins produced from ripped ‘Red Sultana’ grape (Vitis vinifera L.). The experiment laid on a factorial arrangement of variables using a completely randomized block design. The highest soluble sugars of fructose and glucose were related to raisin produced from the vines treated with 3% potassium in combination with 0.5% iron fertilizers. However, 3% K2SO4-treated vines in combination with 1% Fe- EDDHA showed a considerable increase in raisin sucrose and also putrescine concentration. The raisin organic acids of succinic acid, fumaric acid, citric acid, and malic acid increased significantly in treated vines with both fertilizers at final doses; however, tartaric acid showed the highest amount in 3% potassium in combination with 0.5% iron treatments. The vines treated with a high level of potassium in combination with moderate level of iron produced raisin with the highest phenolic acids of kaempferol, quercetin, chlorogenic acid and resveratrol and also showed the lowest polyphenol oxidase activity. Furthermore, raisin cinnamic acid, rutin and catechin concentration showed a peak in vines sprayed with a high level of potassium and iron and also most anthocyanidins such as petunidin-3-glucoside, peonidin-3-glucoside, cyanidin-3-glucoside and delphinidin-3-glucoside reached their highest concentration by this treatment. Likewise, the highest antioxidant capacities (measured by FRAP, DPPH and ABTS methods) were achieved in 3% potassium–treated vines in combined with iron at a moderate level. In conclusion, results indicated that preharvest application of potassium and iron are highly effective to improve the Red Sultana raisin bioactive compositions.
