The optimal treatment conditions for achieving high MM and DDA of chitosan were identified as: 40% NaOH at 90 °C for 6 h with three separate steps (2 h + 2 h + 2 h) or 50% NaOH at 90 °C for 6 h with one step, or 50% KOH at 90 °C for 4 h with three steps (1 h + 1 h + 2 h) or 6 h with one step.