“…Therefore, by-product formation from pretreatment can be limited by optimising the pretreatment conditions, while still achieving acceptable sugar yields, either as individual sugars such as xylose or glucose, or a combination thereof, from the combined pretreatment-hydrolysis process [23]. Monosaccharides liberated during the pretreatment process may participate in the degradation reactions [21,22], where xylose, the main product of hemicellulose hydrolysis, dehydrates into furfural. Cellulose, on the other hand, which is less susceptible to chemical hydrolysis, can be converted to 5hydroxymethylfurfural (5-HMF) during pretreatment, once glucose becomes available, rendering it unsuitable for downstream biochemical processes [21,22].…”