| Abstrakt: |
In this work, the co-production of manno-oligosaccharides (MOS) and fermentable monosaccharides from spent coffee grounds (SCG) was achieved through aqueous ammonia pretreatment and enzymatic hydrolysis. Aqueous ammonia was found to improve the conversion yields of mannan and cellulose in SCG to MOS and fermentable sugars. However, the MOS generated during the enzymatic hydrolysis of aqueous ammonia-treated SCG (AA-SCG) strongly inhibited cellulase activity, reducing the efficiency of cellulose conversion to glucose. To address this issue, a two-step hydrolysis process was implemented: mannanase was first used to hydrolyze AA-SCG, resulting in the degradation of 60% of the mannan and a yield of 52.7% MOS. After separating this hydrolysate, cellulase and mannanase were added to further hydrolyze the remaining polysaccharides. The removal of the mannanase hydrolysate alleviated MOS inhibition on cellulase, resulting in the conversion of 90.6% of cellulose in AA-SCG into glucose. Additionally, about 30% of the mannan was further degraded in the second step, achieving an overall mannan degradation rate of 89.4% and a MOS yield of 63.8%. |
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