Combining hot-compressed water and ball milling pretreatments to improve the efficiency of the enzymatic hydrolysis of eucalyptus

Table 3 Yields of glucose and xylose recovered from the soluble fraction and residue of eucalyptus pretreated with combined hot-compressed water and ball milling

Temperature (°C)	Yields of hydrolyzed sugars from		Total yield (%)	CrI^a (%)
SR³(%)	Soluble fraction		HCW-BM residue
	Glucose (%)	Xylose (%)	Glucose (%)	Xylose (%)
Untreated	-	-	42.8	32.5	40.7	7.6
140	0.3	0.7	49.4	48.2	49.5	9.1
160	0.3	29.9	63.0	49.9	66.7	13.2
200	2.3	15.7	49.4	6.2	45.6	16.9

The glucan and xylan in the soluble fraction were analyzed as described in Table 2. To prepare combined hot-compressed water (HCW) and ball milling (BM) residues, HCW residues were milled for 20 minutes with pulverisette 7 as described in materials and methods. The HCW-BM residue (5%) was hydrolyzed with an enzyme cocktail (4 FPU/g substrate) for 72 hours. The yields of glucose and xylose are calculated based on the glucan and xylan contents, respectively, in the dry weight of untreated biomass. Total yield of hydrolyzed sugars is calculated from the combined contents of glucan and xylan in the dry weight of untreated biomass. ^aCrystallinity index of the HCW-BM residue.

ISSN: 2731-3654