Kitosan berasal dari proses deasetilasi kitin yang banyak terdapat pada cangkang crustacea seperti kepiting. tujuan penelitian ini menentukan waktu yang optimal pada proses pembuatan kitosan dari cangkang kepiting bakau (scylla spp.) terhadap karakteristik kitosan. dilaksanakan pada bulan februari sampai april 2017. proses ekstraksi, analisis fisik dan kimia cangkang kepiting bakau dilakukan di laboratorium fakultas perikanan dan ilmu kelautan universitas borneo tarakan. prosedur kerja penelitian yaitu persiapan alat dan bahan, ekstraksi kitosan, analisis fisik dan kimia serta analisis data. penelitian terdiri atas 5 perlakuan yaitu 30 menit, 60 menit, 90 menit, 120 menit, dan 150 menit dengan 4 kali ulangan. hasil penelitian menujukkan bahwa kitosan yang paling baik memiliki derajat deasetilasi paling tinggi sebesar 43,93% yang diperoleh dengan menggunakan waktu deasetilasi (proses) 150 menit. perbedaan waktu deasetilasi tidak berpengaruh nyata (p > 0,05) terhadap rendemen namun berpengaruh nyata (p > 0,05) terhadap kadar air, kadar abu dan derajat deasetilasi. kata kunci: cangkang, scylla spp., kitosan, derajat deasetilasi

Chitosan was stated from the chitin deacetylation process which has in crustacea shell likes crab. the purpose of this research is to determine the optimal times in the chitosan process of mangrove crab (scylla spp.) shell with the chitosan characteristics. this research had been conducted in february to april in the year of 2017. the process of extraction physical analysis and mangrove’s crab shell chemistry had been analyzed in the marine science and fisheries faculty of borneo university tarakan. in addition, the research instruments being evaluated were the chitosan extractions, physical analysis of chemistry and data analysis. this research was composed 5 treatments. there are 30 minutes, 60 minutes, 90 minutes, 120 minutes, and 150 minutes with 4 times replied. this result proves that the chitosan is the high deacetylation degrees with 43,93% being used the temperature of deacetylation (process) 150 minutes. the differences times was not given the real influence to rendemen (p > 0,05) but can gives the real influences to water content, ash content, and deacetylation degrees (p > 0,05). keywords: shell, scylla spp., chitosan, deacetylation degrees