Quality of carrot juice as influenced by blanching and sonication treatments

A study was conducted to evaluate the influence of blanching and sonication on important quality parameters of carrot juice. Blanching of carrots was done in normal water and acidified water (45 g/L citric acid, pH 13) at 100 degrees C for 4 min and juice was extracted. Sonication of juice was done (frequency 20 KHz and amplitude level 70%) at 15 degrees C for 2 min. Significant increase (P < 0.05) was observed in total carotenoids, lycopene and lutein in blanched samples, however, this increase was more in simultaneously blanched and sonicated samples. Additionally, highest increase was observed in all these pigments as a result of combined treatment of acid blanching and sonication. Sucrose, glucose, fructose, chlorogenic acid and mineral elements (Na and K) were decreased significantly in all blanched samples while increased significantly (P < 0.05) in all sonicated samples. Significant decrease was observed in some minerals (P and Mg), total plate count, yeast and mold in all samples treated with blanching and sonication but this decrease was more in samples treated with acid blanching and sonication. The results suggest that combined treatment of blanching and sonication may successfully be employed for processing of carrot juice to improve quality. (C) 2013 Elsevier Ltd. All rights reserved.