Extraction of mannooligosaccharides from spent coffee grounds and its application for functional jelly with improved physical properties and immunomodulatory effect

Mannooligosaccharides (MO) were extracted from spent coffee grounds (SCG) via combinational enzyme treatment with pectinase and mannanase from Aspergillus niger. Among 18 commercial enzymes to improve the accessibility of galactomannan, pectinase XL exhibited the highest yield, producing 235 mg hemicellulose/g of SCG. Pectinase treatment before mannanase resulted in coffee mannooligosaccharides (CMO) production 6.8 times higher than mannanase alone. This approach facilitated a 70% CMO extraction efficiency compared to the hemicellulose content present in the SCG. Additionally, HPLC analysis validated the composition of CMO, revealing 28.2% mannobiose (M2), 32.4% mannotriose (M3), 5.9% mannotetraose (M4), and 3.9% mannopentaose (M5). The CMO at different concentrations, along with fructose syrup, gelling agent, coffee extract, and coconut milk, was used to prepare jelly. CMO20 (20% CMO, w/w) jelly outperformed in both product stability and functional properties. The antioxidant activity of CMO20, measured by DPPH and FRAP assay, was 4.57 mM, with a Vit C equivalent and 15 mM FeSO4 equivalent, respectively. Furthermore, CMO20 showed 48% greater alpha-glucosidase inhibition than acarbose (5 mg/mL). CMO20 showed improved immunomodulatory effects with 4.7 and 16-fold higher nitric oxide and cyclooxygenase-2 content than methotrexate-suppressed RAW264.7 cells. center dot Coffee mannooligosaccharides (CMO) obtained from spent coffee grounds (SCG) using pectinase and mannanase center dot Combined treatment attained 70% CMO extraction efficiency relative to SCG hemicellulose content center dot Inclusion of CMO in the jelly showed the improved physical properties and product stability center dot CMO jelly showed increased antioxidant activity and alpha-glucosidase inhibitory effect center dot CMO jelly showed improved immunomodulatory effect in immunosuppressed RAW264.7