The results of pre-treatment 1 using 0.1 M NaOH are described in Fig. 1A. During the first 6 h, the reducing sugar yield increased slowly for the four dosages. We suggest that this lag time could be due to the soaking time required for the NaOH to start working on the yeast cells. After 18 h pre-treatment, the reducing sugar yield (w/w) from 20% WBY reached the highest value of 20.48%. While all other WBY dosages reached a plateau after 30 h pre- treatment. The maximum sugar yield values achieved were 20.59%, 22.26% and 28.98% for 5%, 10% and 15% WBY respectively. The reducing sugar yield increased with the WBY dosage with the exception of 20% WBY. When 20% WBY was treated, the highest value reached faster (18 h) but it was the lowest yield, similar to that obtained from 5% WBY. This suggests that the concentration of NaOH used was not enough to treat the 20% WBY and a higher concentration could potentially improve the reducing sugar yield of 20% WBY.