Effect of freeze-drying and air-drying on the content of carotenoids and anthocyanins in stored purple carrot

摘要

Background. In stored freeze-dried orange carrots, carotenoids are not stable compounds. The aim of the work was to evaluate the stability of carotenoids in products obtained from polyphenol-rich purple carrots which additionally contain anthocyanins. Material and methods. This study compares the effect of air-drying and freeze-drying as well as 6-month storage on the content of carotenoids, anthocyanins and total phenolics in dried products obtained from purple carrot. Results. The phenolic compounds found in the greatest amounts in carrot were ferulic acid cyanidin 3-xylosylglucosylgalactoside, p-coumaric acid cyanidin 3-xylosylglucosylgalactoside, chlorogenic acid, and caffeic-quinic acid. Freeze-drying did not significantly reduce levels of carotenoids and anthocyanin content, while air-drying led to substantial losses of carotenoids, anthocyanins and polyphenols. 6-month storage of freeze-dried products caused losses of carotenoids, anthocyanins and total polyphenols of 42%, 33% and 53% respectively when compared with the raw material. In air-dried products, the losses were 66%, 33% and 36%, respectively. Conclusion. The results indicate that the combined effect of freeze-drying and 6-month storage was reduced losses of carotenoids compared to traditionally dried products.