*3.5. Fermentability of Pretreatment Liquids*

For elucidating the effect of the inhibitors formed during pretreatment on ethanolic fermentation, the fermentability of the pretreatment liquids by *S. cerevisiae* was investigated. A strong inhibitory effect on yeast cell growth was observed for the A-HTP liquid from pretreatment at 205 ◦C (Figure 6a). Albeit at a lower degree, the cell growth in the medium with SA-190 was also inhibited. Some inhibition was also observed for the pretreatment liquid from A-HTP at 190 ◦C, but it was hardly noticeable after 12 h. The inhibitory effects exerted by the other pretreatment liquids were minor and restricted to the beginning of the fermentation. ‐ ‐ ‐ ‐ ‐ ‐ 

**Figure 6.** Cell growth of *S. cerevisiae* in the fermentation of the pretreatment liquids (**a**) and relative growth rate (**b**) after 12 h (horizontal green pattern bars) and 24 h (vertical blue pattern bars). Same codification of experimental conditions as in Table 1.

‐

The inhibition pattern of the different pretreatment liquids is better revealed by comparing the relative growth rates (RGRs), which were calculated as the ratio between the growth rates in each pretreatment liquid and the reference. The remarkable inhibition of the 205 ◦C A-HTP liquid is highlighted by RGR values around 0.40 ± 0.06 after both 12 and 24 h of fermentation (Figure 6b). On the other hand, the fermentability of the 160 ◦C A-HTP liquid was comparable with that of the control, as indicated by a relative growth rate of 0.98 ± 0.06 after 24 h of fermentation. The other pretreatment liquids displayed RGR values between 0.88 ± 0.03 and 0.96 ± 0.04 after 24 h. Pretreatment liquids from SA-HTP were more inhibitory than those from A-HTP at the same temperature.
