Compositional Changes in Functional Attributes of Vacuum Concentrated Beetroot Juice

Beetroot was processed into juice and concentrate was obtained using rotary vacuum evaporation. The study investigated the effects of concentration temperature (45C, 50C, 55C and 60C) and time (5–30 min) on total solids, betalain, color, total phenolic content (TPC), antioxidant activity and nitrate content of concentrated beetroot juices. Betalain (composed of betacyanin + betaxanthin) and color value changed significantly (P < 0.05) with processing temperature and time. Betacyanin and betaxanthin of beetroot juice concentrate (BJC) increased up to concentration temperature of 55C thereafter it decreased notably. Same trends have been followed by total phenolic and nitrate content of BJC. Also, nitrate content varied significantly over vast range nevertheless below the safety range defined by WHO. "L" and "a" value of BJC decreased substantially due to loss of the red color as heat destroyed betacyanin pigments. A highly significant correlation (r2 = 0.9775) was demonstrated between TPC and radical scavenging activity (%RSA) of BJC samples. Practical Applications Preservation of vegetables for consumption exposes the physicochemical, color, antioxidant characteristics to detrimental factors that may lead to alterations in their concentrations and health-related quality. Beetroot (Beta vulgarius) juice contains antioxidants along with nitrates with potential health benefits and hence has an aptitude as functional ingredients. Moreover, pigment (Betalains) found in beetroot juices are well-established colorant for various food uses under regulation, having E.No.-162. Preferably, this study is focused on the determination of the effects of processing temperature and time on the quality components of beetroot juice. The results can be a guide to having a processing method under vacuum that can be used in producing beetroot juice concentrate with good sensory properties and high bioactive compounds.