Aekkaphon Thammayod, Wuttichai Roschat, Nathaporn Jirawattanasomkul, Sunti Phewphong, Tappagorn Leelatam, Janeeya Khunchalee, Preecha Moonsin, Prawit Nuengmatcha
This study explores the nutritional, phytochemical, and antimicrobial properties of spent coffee grounds (SCGs) collected from cafes in Sakon Nakhon Province, Thailand. Proximate analysis showed high contents of carbohydrates (48.23%), crude fiber (19.69%), and protein (10.10%). Fatty acid profiling revealed linoleic acid (41.06%) and palmitic acid (36.27%) as major components, along with essential omega-6 and omega-3 fatty acids. Phytochemical screening indicated the presence of flavonoids and phenolics (16.11 mg GAE/g DW), which may contribute to bioactivity. SCGs also exhibited favorable soil-enhancing properties, with high organic matter (66.89%) and organic carbon (38.81%), and moderate levels of N, P, K, Ca, and Mg. The extract demonstrated selective antibacterial activity against Escherichia coli (15.20 ± 0.98 mm inhibition zone) but not Bacillus subtilis, likely due to differences in cell wall structure. These findings suggest the potential use of SCGs in soil amendment, composting, and bioactive compound recovery. However, pretreatment is recommended due to their low pH and moderate phytotoxicity, underscoring their potential as a sustainable, value-added resource for agricultural, cosmetic, and chemical applications.