This study investigated the physicochemical properties, sugar and organic acid profiles of 21 grape juice and 3 sour grape juice samples in Turkey. The pH, acidity and soluble solids were ranged from 2.64 to 4.19, 3.58 to 30.75 g L -1 and 5.45 to 25.45 °Bx, respectively. The turbidities varied between 1.59 and 109.50 NTU and the lowest value was in the Sultani Çekirdeksiz sour grape juices. The Denizli Karasi sample had the highest color index. The tartaric and malic acid amounts of the samples ranged from 0.53 to 13.16 g 100 -1 g -1 and 0.45 to 30.80 g 100 -1 g -1 , respectively. The major acid was malic acid in the sour grape juice samples and tartaric acid in the grape juice samples. For all samples, glucose and fructose constituted a great part of total sugars. The glucose, fructose and total sugar contents changed from 28.45 to 48.00 g 100 -1 g -1 , 15.88 to 48.75 g 100 -1 g -1 and 53.67 to 97.27 g 100 -1 g -1 , respectively. The highest sugar content was observed in Kara Erik and the lowest in Yediveren. As a result; some physiochemical characteristics, sugar and organic acid contents of the examined 24 grape juice samples were revealed by the current work.

Abstract. This study was carried out to determine the effects of cane girdling on coloration, maturation, yield and some quality characteristics of Vitis vinifera L. cv. Flame Seedless table grape variety. Cane girdling practices were treated at pea-size stage (G2) and veraison period (G1) over two growing seasons, 2013-2014, at the facility of Manisa Viticultural Research Institute in Turkey. Cane girdling was performed on the canes after first shoot was left from the bottom and 4 mm-wide ring of bark was completely removed with a doubleded knife. On the other hand control vines were left untouched. Statistical analyses showed that TSS, berry length, colour parameters, CIRG index and anthocyanin content of Flame Seedless was significantly affected by the cane girdling treatments in both years, 2013 and 2014. In addition it was detected that any effect of girdling treatments cannot be determined statistically significant on total yield, marketable yield, titrable acidity and 50 berry weight. Total and marketable yields of girdled vines had higher value than control vines although they were not statistically significant. Furthermore it was observed 9 and 12 days earliness with G2 treatments compare to the control vines in 2013 and 2014, respectively.

This paper describes an investigation on the effects of deficit irrigation treatments on phenolic compounds and physiological activities of Fantasy Seedless table grape variety. Research was conducted in Viticultural Research Institute of Manisa, located in Aegean Region of Turkey, during two consecutive years (2016–2017). Three irrigation treatments were assayed; namely full irrigation (T-F), deficit irrigations (T-35 and T-65). In T-F, soil water deficit in the 90 cm within the one week intervals was completed to the field capacity. T-35 and T-65 treatments received 35% and 65% of water applied to T-F. Sub-surface drip irrigation system was used in the research and soil water content was measured by MobiCheck probe while vine water status was monitored through midday leaf water potential before the irrigations. Results showed that water deficit treatments (T-35 and T-65) affected berry composition particularly individual phenolics [Gallic acid, (+)(−) Catechine, (−)-Epigallocatechin gallate, (−)-Epicatechin gallate, Caftaric acid, Chlorogenic acid, Caffeic acid, p-Coumeric acid, Ferulic acid, Sinapic acid, Trans-Resveratrol, Myricetin, Quercetin hydrate, Kaempferol, Oenin Chloride, Delphinidin Chloride, Cyanidin Chloride, Malvidin Chloride] differently. The highest Catechine content in the samples was obtained from T-65, T-35 and T-F treatments, respectively. Furthermore it was determined that DI treatments did not change the Myricetin and Quercetin hydrate contents in 2017. On the other hand minimum Ψmd value was observed from the T-35 treatment in both years. Last of all, our findings show a strong relationship between the amount of water and berry composition values especially individual phenolics which are benefical to health.

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In this study, clarified koruk juice was manufactured by using Sultani Çekirdeksiz and Cabernet Sauvignon koruk grape samples, and the effects of process stages on physicochemical quality of koruk juice were investigated. The processing effects were searched by collecting samples from six different stages during koruk juice processing. In Sultani Çekirdeksiz and Cabernet Sauvignon samples, soluble solid values were 7.47-8.33 and 7.07-7.60 °Brix, pH values 2.67-2.77 and 2.75-2.93, titretable acidity 2.56-2.77 and 2.55-2.79 g 100 mL-1, dry matter 8.03-9.96 % and 8.11-16.38 %, respectively. The koruk juice turbidity decreased by depectinization, clarification and filtration treatments. The turbidity values were 1.33 and 1.51 NTU in Sultani Çekirdeksiz and Cabernet Sauvignon samples, respectively. The color properties improved and yellowness was increased depending on the process. Tartaric acid, malic acid and citric acid contents were 36-49 %, 43-58 % and 6-8 % of the total acidity of koruk juice samples, respectively. Total phenolic contents decreased about 71-88 % and 1-27 % according to koruk samples and the pressing samples while these decrease rate was 97 % and % 33-36 for total flavonoid contents, respectively. In addition, antioxidant capacities decreased by about 72-82 % and 89-93 % for ABTS and DPPH, respectively, in the juice samples according to koruk samples. The decrease of the total phenolic and flavonoid contents and antioxidant capacity was due to both pressing and separation processes of the grape skin and seeds as well as clarification treatments.

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