Thermal processing effects on phytochemical profiles, antioxidant activity, and anti-inflammatory potential of extracts from dried rhizomes of Curcuma longa L. evaluated by UHPLC–MS/MS and in vitro assays

This study developed and validated UHPLC–MS/MS methods for quantifying seven phytochemicals—five major bioactives (curcuminoids, sesquiterpenoids) and two thermal degradation products (vanillin, dehydrozingerone)—in Curcuma longa L. extracts. Samples were heat-treated (180 °C) in four matrices (dry, water, olive oil, corn oil), and antioxidant and anti-inflammatory activities were evaluated. While curcuminoids degraded significantly under aqueous heating (up to 71.3 % loss), ar-turmerone remained relatively stable, especially in oil-based systems. Vanillin and dehydrozingerone levels increased with heating, reaching 430.3 and 187.4 mg/kg, respectively. Antioxidant activity was best retained in lipid matrices, particularly olive oil. Correlation analysis confirmed curcuminoids as the main contributors to antioxidant potential, with degradation products providing moderate support. These findings highlight the importance of matrix selection in preserving turmeric functionality during processing and suggest that ar-turmerone and heat-derived compounds may compensate for curcuminoid losses. The study also provides a foundation for future research on heat-induced phytochemical transformations.