Effect of thermal Processing Time on the Physicochemical and Sensory Properties of Lebanese Tfayfiha Verjuice Variety

Abstract

Verjuice is an unfermented, acidic, and sour-tasting juice abundant in beneficial bioactive compounds obtained from the mechanical pressing of unripe grapes. The effect of prolonged traditional thermal processing (for 0, 0.5, 1, 2, 3, 4, and 5 hours) on the physicochemical properties of ‘Tfayfiha’ verjuice was investigated. Polyphenol content and antioxidant capacity increased reaching their maximum (8348.6 mg/L) at 4 hours and (77.30%) at 3 hours respectively; indicating that the ideal processing time to obtain a nutritious functional food ingredient with high bioactivity is between 3-4 hours. At 5 hours, verjuice had the lowest pH (1.09), lowest moisture content (26.94%), and thus the highest shelf-life, density (1.187 g/mL), soluble solids content (60.06°Brix), color intensity, and sensorial scores on the preference test. Caloric content was below detection limits (in all samples) and thus neglected. Verjuice boiled for 1 hour can be used as an excellent alternative to fresh lemon juice, where only 16.6% of the participants recognized the difference in taste between tabbouli made with fresh lemon juice and that made with verjuice boiled for 1 hour. It can be concluded that different virgins of verjuice could possibly be released to the Lebanese market by changing waste unripe grape during thinning period into a valuable product.