The use of ultrasound treatment influenced the carotenoid content
in carrot tissue (Fig. 5). Raw carrot was characterized by total
carotenoids content equal to 7.66 mg/100 g of fresh weight. This
amount was expressed in percent as 100%, in order to simplify
the presentation and interpretation of the total carotenoids content
in research samples. After 20 min of ultrasound treatment at
a frequency of 21 kHz significant increase (12.5%) in carotenoid
content was observed. In the case of samples treated at a frequency
of 35 kHz, carotenoid content increased significantly after 10, 20
and 30 min treatment by 42.3%, 49.9% and 41.1%, respectively. A
similar changes were observed by Abid et al. [48] during the sonication
at 25 kHz frequency of fresh apple juice, where the carotenoids
content increased up to 12% and 27% after 30 and 60 min
of ultrasound treatment, respectively.