An integrative evaluation of drying methods in relation to bioactive properties and metabolomic profiles of four Nymphaea cultivar petals.

Nymphaea species (water lilies) exploited for their dual use as food and medicine. We systematically quantified the quality and bioactive properties activities of four water lily petals subjected to different drying methods. Our findings showed freeze drying maintained the superior external quality and aroma of the petals, whereas shade drying was successful in preserving bioactive compounds like 1,2,3,4,6-O-pentagalloylglucose (PGG) in most cultivars. In contrast, microwave oven drying exhibited superior antioxidant, antibacterial, and tyrosinase inhibitory activities. As a potential key functional compound, PGG possesses multiple bioactive properties, including antioxidant, whitening, lipid-lowering, antidiabetic and anti-tumor effects. Nymphaea 'Blue Bird' is promising as a functional food candidate, attributed to its high accumulation of PGG. The metabolite profiles of N. 'Blue Bird' were analyzed using non-targeted metabolomics with full-MS/MS analysis. During drying, the DAMs were mainly linked to ABC transporters and tryptophan metabolism. Collectively, these findings provide a scientific basis for optimizing industrial processing protocols.