*2.5.Validation of Biomass Production in Optimum Medium*

In order to confirm the optimized conditions obtained by the central composite design, an experiment was carried out on 250 mL shake flasks. To do this, 100 mL of date extract (mentioned above) was seeded with 11 mL of the yeast pre-culture and the pH of the medium was adjusted to 5.35 (optimum value). Shake flasks were sterilized at 120 ◦C for 20 min, and incubated at 32.9 ◦C (optimum value) for 18 h.
