Determining the Effect of Different Concentrations of Spent Coffee Grounds on the Metabolomic Profile of Swiss Chard

In the coming decades, the agricultural system will predictably rely on organic material to produce crops and maintain food security. Currently, the use of inorganic fertilizers to grow crops and vegetables, such as Swiss chard, spinach, and lettuce, is on the rise and has been proven to be detrimental to the soil in the long run. Hence, there is a growing need to use organic waste material, such as spent coffee grounds (SCGs), to grow crops. Spent coffee grounds are made of depleted coffee beans that contain important soluble compounds. This study aimed to determine the influence of different levels (0.32 g, 0.63 g, 0.92 g, and 1.20 g) of spent coffee grounds on the metabolomic profile of Swiss chard. The 1H-nuclear magnetic resonance (NMR) results showed that Swiss chard grown with different levels of SCGs contains a total of 10 metabolites, which included growth-promoting metabolites (trehalose; betaine), defense mechanism metabolites (alanine; cartinine), energy-reserve metabolites (sucrose; 1,6 Anhydro-β-D-glucose), root metabolites (thymine), stress-related metabolites (2-deoxyadenosine), caffeine metabolites (1,3 Dimethylurate), and body-odor metabolites (trimethylamine). Interestingly, caprate, with the abovementioned metabolites, was detected in Swiss chard grown without the application of SCGs. The findings of the current study suggest that SCGs are an ideal organic material for growing Swiss chard for its healthy metabolites.