Valorization of Cactus Cladodes ( Opuntia ficus indica ): The Effects of Different Drying Methods on Antioxidant Compounds and Physicochemical Characteristics

ABSTRACT

Opuntia ficus indica is among the most widely cultivated and consumed cactus species worldwide. Cactus cladodes were dried using convectional drying, microwave drying, and ultrasound pretreatment combined with vacuum‐assisted convectional drying. Total phenolic, flavonoid, and flavonol contents; phenolic profile; ascorbic acid content; antioxidant capacity; color, texture were analyzed in fresh and dried samples, and microstructural changes were examined by SEM. Drying process is effective on phenolic compounds ( p  < 0.05). Ultrasound pretreatment has been important for total phenolic compound preservation. Among the dried samples, the highest total phenolic content was observed in ultrasound pretreated vacuum‐assisted convectional drying with 70°C. Drying treatments significantly affected the Δ E values ( p  < 0.05), with the highest color difference from the fresh sample observed in the ultrasound pretreated vacuum‐assisted convectional drying treatment at 80°C (23.62). Significant decreases were observed in the flavonoid and vitamin C amounts of the samples in the ultrasound pretreated drying method in pure water. As a result of the phenolic profile analysis, a total of nine components were determined. The antioxidant capacity of bioactive compounds did not show a statistically significant change according to different drying processes and drying parameters. In addition, flavonol amounts with drying processes were not affected by drying processes. The change in the skin strength value was found to be statistically insignificant in convectional drying and microwave drying applications. In the SEM analysis, the effects of different drying techniques and the parameters used in drying techniques on the product texture were revealed.