Metabolomic, nutritional, and sensory insights into hydroponic vs. substrate-cultivated lettuce (Lactuca sativa L.)

This study aimed to compare the nutritional and sensory profiles of hydroponic and substrate-cultivated lettuce across four cultivars using metabolomics and targeted quantitative analyses. Results showed that hydroponic enhanced protein, potassium (1.61-2.14-fold), and free amino acids, likely due to enhanced nitrogen and potassium uptake. Conversely, substrate cultivation promoted the accumulation of sugars (1.24-2.43-fold), sesquiterpene lactones (1.36-4.20-fold), and most secondary metabolites. Glycolysis emerged as a central pathway driving metabolic divergence, linking soluble sugar conversion to terpenoid/phenolic synthesis. Consumer preference, evaluated by a trained panel using a 9-point scale, correlated negatively with bitterness intensity. This bitterness intensity was associated with polyphenols and the ratio of total soluble sugar/ total sesquiterpene lactones. Hydroponic lettuce demonstrated higher acceptability due to reduced chlorogenic acid and lactucopicrin content. These findings highlighted the trade-off between sensory quality and phytochemical content, providing insights for optimizing soilless lettuce production.