Improved carotenoid extraction from Bulgarian tomato peels using ultrasonication

Abstract

Ultrasound-assisted extraction (UAE) of carotenoids from tomato peels of two of the most widely used Bulgarian industrial tomato cultivars was investigated in this study. The carotenoid content in raw tomato peels was established by HPLC analysis. The application of UAE was compared to conventional organic solvent extraction, where the carotenoid content of the samples was spectrophotometrically determined. The effects of the extraction time and temperature on the carotenoid content of the extract were studied. It was found that the application of UAE led to 1.5 to 3.0-fold shortening of the extraction time and increase in the carotenoid content compared to the conventional extraction using acetone. The total carotenoid, lycopene and -carotene contents
increased by 27.2±1.1%, 11.9±0.7% and 28.2±0.1% respectively for tomato peels of the Stella cultivar, and by 23.9±2.4%, 15.3±0.8% and 26.5±1.0% respectively for the Karobeta cultivar. The increase in the UAE temperature from 20C to 40C resulted in extraction time reduction of up to 5 min and 22.1±0.6 and 24.4±1.2% increase in the lycopene content of the extract from Stella and Karobeta cultivars, respectively. The results of this study clearly demonstrate the advantages of UAE compared to the conventional solvent extraction of tomato carotenoids.