Non-thermal processing of black carrot juice using ultrasound: Intensification of bioactive compounds and microbiological quality

Ultrasound is a developing technology used to enhance the quality properties of beverages. Influence of ultrasonic process (0, 4, 8 and 12 min at 24 kHz) on quality characteristics of non-thermally produced black carrot juice throughout storing for 15 days at ambient temperature was investigated. An FTIR spectrophotometer was used to analyse chemical functional groups of the vegetable juice. Ultrasound increased phenolic content, ascorbic acid and antioxidant properties; however, pH, total soluble solids (degrees Brix), viscosity and turbidity of the samples under ultrasound treatment did not show significant changes. None of the samples showed a significant change in colour characteristics throughout storing. Also, microbial population of the specimens handled with ultrasound showed a considerable decrease. The FTIR diagram showed that the application of ultrasonic process intensified the peak of the compounds containing hydroxyl group (phenolic compounds). Also, scanning electron microscopy images showed a more irregular cell structure with more holes in the ultrasonically treated juices. Ultrasound could be deemed an emerging technology in beverage industries to enhance various quality characteristics of fruit juices using non-thermal processing.

Automated summary

Ultrasound treatment improved the quality characteristics of non-thermally produced black carrot juice, increasing phenolic content, antioxidant properties, and reducing microbial population. The color characteristics of the treated juice remained stable throughout the storage period.