Characterization of fresh unripe grape juice (verjuice) and evaluation of some physicochemical properties changes of pasteurized unripe grape concentrate juice during storage

Verjuice is a popular fruit juice mainly consumed as salad dressing. However, there is very little information regarding its characteristics. The objective of the present study was to determine verjuice and its concentrate physicochemical properties during storage at 4 °C. Firstly, verjuice characteristics such as pH, acidity, specific weight, density, total soluble solids, total solid, reducing sugar content, ash, rare minerals, vitamin C, phenolic content and antioxidant activity were evaluated. In the next phase variation of acidity, pH, total solid and colour parameter (L, a, b) and total phenolic content of pasteurized concentrate verjuice during 6 months storage at 4 °C were assessed. Findings revealed that not only verjuice has a high acidity value but also it is a good source of bioactives such as vitamin C, antioxidant and phenolics components. Storing the concentrate at 4 °C resulted in reduced acidity, phenolic content, parameter L and b but increased value of parameter a, and total solid.