Chitin is mixed with 40% solution of caustic soda and heated by indirect steam at 95-100 C in a steam jacketed kettle. Heating is continued for 90-120 minutes. During heating,samples are drawn at intervals from the reaction mixture, washed free of alkali and tested for its solubility in 1% solution of acetic acid. Completion of deacetylation is indicated by complete solubility of the sample in acetic acid. At the end of the reaction caustic soda is drained off and the residue is washed with water until sample is free from alkali. The residue is then dried in sun or hot air drier. Chitosan is pulverized to desired mesh size and then packed.

Source: Post Harvest Technology of Fish and Fish Products Balachandran K.K

Thank you very much @Natasha Nayak

immersing chitin in hot conc. NaOH solution (40–50% w/v NaOH, at 90 °C

to 120°C for 4 to 5 hrs.

it's better to steep Chitosan into concentrate NaOH for 1 day, deacetylation of chitin

can be highly facilitated by steeping in strong sodium hydroxide solution at room temperature before heating.

source : Bioresource Technology 99 (2008) 1359–1367

I worke in same project

soak with 60% NaOH within 72 hours, then wash until you obtained pH 7

Nuriah Mohd, you don't heat??

What are the pecentages of Chitin, NaOH and Water?