THERMOSONICATION KEEPS PHENOLIC COMPOUNDS, ANTIOXIDANT CAPACITY AND ENHANCES TOTAL CAROTENOIDS OF ORANGE-CARROT JUICE

Ultrasound is an alternative technology to pasteurization in juice conservation aiming to minimize losses during the conventional thermal treatment. The main action mechanism of ultrasound is cavitation. Cavitation is the formation, growing and collapse of bubbles and it generates intense localized heat and pressure. Thermosonication is the combination of ultrasound with mild temperatures. The aim of study was to evaluate the effect of thermosonication treatment on total phenolic compounds, antioxidant capacity and total carotenoids of orange-carrot juice. Fresh oranges (Citrus sinensisL. Osbeck) cultivar ‘Pêra’ and carrots (Daucus carota) were selected, washed and sanitized with sodium dichloroisocyanurate solution at 100 mg/L for 10 minutes. Orange juice was extracted with a commercial juice extractor (Mondial® Profissional E-10 Bivolt - 250W). The blend juice was prepared in a blender using only 700 mL of orange juice and 300 g of peeled and sliced carrot. Juice was sifted and samples (400 mL) were subjected to pasteurization treatment at 90 °C for 30 seconds and bath ultrasound (Branson®, Model CPX3800H, 110W - 40 KHZ, Danbury, United Estates) treatments at 40 °C, 50 °C, 60 °C for 5 and 10 minutes. The control was the sample without any treatment (natural). After the treatments, all samples were conducted to analyses. Total phenolic compounds of juice samples was determined using the Folin-Ciocalteu method. The antioxidant capacity was tested on the basis of DPPH assay. The total carotenoids were estimated by the spectrophotometric method. All determinations were carried out on duplicates and the experiment was done in triplicate. The mean value of phenolic compounds and antioxidant capacity was 39,85 gallic acid equivalent mg/100mL and 59,66 % respectively. Non-significant changes (p>0,05) were observed for both parameters, indicating that ultrasound kept the characteristics. The natural sample obtained lowest value for carotenoids (107,46 µg/100 mL) while content increased significantly (p<0,05) after ultrasound treatments at 40 °C for 10 minutes (128,83 µg/100 mL), 50 °C (128,87 µg/100 mL) and 60 °C (129,80 µg/100 mL), both for 5 minutes. That behavior can be attributed to the cavitation process. The intense pressure breaks the cell wall, releases the carotenoids in sample and that enhances the total contend. The ultrasound treatments were shown as a good alternative in orange-carrot juice quality conservation.

Funding agency: CAPES (Coordination of Superior Level Staff Improvement).