Determination of physicochemical characteristics, organic acid and sugar profiles of Turkish grape juices

Abstract

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.

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“…The main sugars are glucose and fructose in Vitis vinifera grapes, with contents of 45.86 to 122.89 mg mL −1 and 47.64 to 131.04 mg mL −1 , respectively. While sucrose and other sugars are rarely found 42,43 . However, other sugars such as maltose and rhamnose have been identified in Vitis labrusca L. grape juice samples 44 .…”

“…Sugar is one of the main components of grape juice contributing to taste balance and is an important indicator of ripeness and defines grape harvest 41,42 . The main sugars are glucose and fructose in Vitis vinifera grapes, with contents of 45.86 to 122.89 mg mL −1 and 47.64 to 131.04 mg mL −1 , respectively.…”

“…After veraison there is a considerable accumulation of glucose and fructose in the vacuoles of mesocarp cells 41 . Güler and Candemir 42 reported concentration of glucose and fructose from 28.45 to 48.00 g L −1 and 15.88 to 48.75 g L −1 , respectively in unripe grape juices, while Öncül and Karabiyikli 17 showed a mean of 6.721 g L −1 of total sugar content in unripe grape juices.…”

“…The main organic acids found in ripen grapes are tartaric acid, malic acid and citric acid 46 . While during the green growth phase, the berry is green and hard, and it accumulates tartaric and malic acids, which are the main contributors to its osmotic potential 42,47 . Tartaric acid synthesis in grape berries occurs in flesh before veraison and during ripening 47 .…”

“…Tartaric acid synthesis in grape berries occurs in flesh before veraison and during ripening 47 . Smirnoff‐Wheeler pathway is dominant 40,42 . An increase in the concentration of tartaric acid occurs up to the beginning of veraison, then the concentration tends to decrease until the end of veraison, after which it remains unchanged until harvest 48 .…”