Ensiling of wheat straw decreases the required temperature in hydrothermal pretreatment

Table 4 Xylose conversion after enzymatic hydrolysis of raw wheat straw (RWS), hydrothermal treated wheat straw (HTT WS), ensiled wheat straw (EWS) and of hydrothermal treated ensiled wheat straw (HTT EWS)

	Released xylose	Xylose conversion yield	Overall xylose conversion yield
			Liquid fraction	Solid fraction	Total
	In (w/w) % of DM in solid fraction	In % of xylose in solid fraction	In % of xylose in raw material	In % of xylose in raw material	In % of xylose in raw material
RWS				14.8 ± 1.7^e	14.8 ± 1.7^e
HTT WS 170°C	11.1 ± 0.3^c	40.0 ± 1.0^d	3.1 ± 0.0^f	39.5 ± 0.9^d	42.6 ± 0.9^d
HTT WS 180°C	14.6 ± 0.7^b	51.6 ± 2.6^c	6.2 ± 0.3^e	48.6 ± 2.4^c	54.9 ± 2.4^c
HTT WS 190°C	18.0 ± 1.6^a	71.8 ± 6.2^b	21.1 ± 1.8^c	55.6 ± 4.8^b	76.7 ± 4.8^b
EWS				10.5 ± 0.4^e	10.5 ± 0.4^e
HTT EWS 170°C	17.2 ± 1.0^a	76.3 ± 4.6^ab	14.5 ± 0.0^d	67.5 ± 4.1^a	82.0 ± 4.1^ab
HTT EWS 180°C	16.7 ± 0.8^a	81.0 ± 5.0^a	26.7 ± 2.3^b	61.1 ± 3.1^a	87.8 ± 4.9^a
HTT EWS 190°C	11.7 ± 0.7^c	88.2 ± 5.5^a	30.6 ± 0.0^a	37.9 ± 2.3^d	68.5 ± 2.3^d

Released xylose is expressed as (w/w)% of DM in solid fraction after HTT. Xylose conversion yield is expressed as xylose release in % of xylose in the solid fraction after HTT. Overall xylose yield is the xylose release in the liquid fraction after HTT- and in the solid fraction after enzymatic hydrolysis in % of xylose in the raw wheat straw. The results in each row are grouped according to significance (p = 0.05%), where ‘a’ is significantly higher than ‘b’ and so forth.

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