Effect of ultrasound waves pretreatment on quantity and antioxidant capacity of extracted beta-carotene from carrot residue

Nowadays, the tendency towards the extraction of phytochemicals by ultrasound method has been increased. In this research, the effect of ultrasound waves pretreatment on extraction of beta-carotene from carrot residue was studied. Carrot residues were treated with ultrasound waves with 205 W power, constant 35 KHz frequency during six stages of 0 (without ultrasound), 16, 20, 30, 40 and 44 min and at temperatures of 66, 70, 80, 90 and 94 ºC and using ethyl acetate as solvents. Then, the extract from each sample was evaluated considering the amount of total phenolic components as well as beta-carotene and antioxidant capacity of beta-carotene. According to the results, it was observed that, there was a significant difference (P<0.01) between samples in the case of beta-carotene amount with increasing of temperature and time. In order to achieve the highest extraction of carotene from carrot residues, the temperature of 90 ˚C and 40 minutes was determined as the best temperature and time. The results also revealed that at low temperatures the antioxidant capacity was higher. With increasing time of ultrasonic at low temperatures, the antioxidant capacity was enhanced. Moreover, the temperature of 70 ˚C and 40 min was determined as the optimum condition to achieve the highest antioxidant capacity of carrot residues. The result showed that the total phenolic compounds are greater at low temperature compared with high temperature. Besides, at all selected temperatures, with the increasing of ultrasonic duration the amount of total phenolics increased. Most phenols obtained at 66˚C for 40 min of ultrasonic treatment.