Initiator reactor

Milled rice straw was pretreated by using a BIOTAGE® Initiator + reactor (Biotage AB, Uppsala, Sweden). 4 samples (each 0.75 mg) had been weighed into 20 ml microwave pressure tubes. Water (14.25 ml) was then added into each of those tubes to give a 5% (w/w) suspension. Capped tubes were treated at severities 1.57, 3.65, 5.15, 5.45 (pre-treatment severities were adapted from report of Jacquet, et al.^{50 (link)} as those severities were selected from different thermal degradation zones. Tubes were cooled with compressed air to ambient, and stored at −20 °C before further experimentation.

Rice husk and straw were pre-treated by using a BIOTAGE^® Initiator + reactor (Biotage AB, Box 8, 751 03, Uppsala, Sweden). Milled husks and straw (0.75 mg for each tube) had been added separately into 25 of 20 ml microwave pressure tubes (containing 14.25 ml distilled water individually) to give a 5% (w/w) suspension. The tubes were then capped and treated at pre-designed pre-treatment severities. Pre-treatment severity was calculated from temperature and duration using the following equation (adapted from Overend et al. [39 (link)]): $$\text{Severity}(Ro)={log}_{10}\left(t·ex{p}^{\frac{T-100}{14.75}}\right).$$ The range of severities as a function of time and temperature is shown in Table 3 (conditions of empty cells had not been tested because their severities were already provided by other conditions). Those tubes were frozen before further experiment after tubes were cooled with compressed air to room temperature.Table 3

Pre-treatment severities

Time (min)	Pre-treatment severities
	Temp (°C)
	140	150	160	170	180	190	200	210
2.5	1.57	1.87	2.16	2.46	2.75	\	\	\
10	2.18	2.47	2.77	3.06	3.35	3.65	3.94	4.24
40	2.78	3.07	3.37	3.66	3.96	4.25	4.55	4.84
160	\	\	\	4.27	4.56	4.85	5.15	5.44

Italic values indicate severities used during the SSF studies