Beetroots are vegetables with high antioxidant capacity owing to their content of bioactive compounds such as betalains, polyphenols, and other antioxidants, which serve as quality markers for beetroot products. Conventional methods for determining these compounds rely on time-consuming solid-liquid extractions requiring large amounts of solvents, which is a drawback in the food industry. This study, the first to evaluate the usefulness of the liquid present in ready-to-eat cooked beetroots for functional characterisation, aimed to develop a faster, more sustainable alternative in collaboration with the beetroot industry. Beetroot liquid and extracts (from beetroot flesh after conventional extraction) from 44 beetroot samples were analysed for betalain and polyphenol content and profile, and total antioxidant capacity. Results showed that beetroot liquid reliably indicated changes in bioactive compounds and bioactivity under increasing intensities of thermal treatment, with an identical betalain and polyphenol profile to that obtained via mass spectrometry in extracts. A linear regression model enabled the prediction of beetroot functionality, reducing pre-quantification time from 105 min to 5 min and eliminating the need for 10 mL of solvent per gram of sample. Validation with commercial ready-to-eat beetroots confirmed the method's reliability. This novel approach offers the beetroot industry a rapid, capable of being automated, and more sustainable alternative for quality assessment, ensuring efficient monitoring of beetroot functionality.
