Background: Microcrystalline cellulose (MCC) Cladophora agardhii has a rigid and compact surface that inhibit water penetration and makes unable to swelling. This cause MCC less effect as a disintegrant or gelling agent. It can be improved by mercerization. This method will convert cellulose I into cellulose II which has better hygroscopic properties by using NaOH. Objective: This study aimed to determine the effect of mercerization process with variations in the concentration of NaOH solution (15, 20, and 25%) on microcrystalline cellulose of algae Cladophora agardhii on physical and chemical properties of the products. Materials and Methods: During mercerization process, MCC was soaked in NaOH solution with different concentration (15, 20, and 25%) for 1 hour in room temperature. Alpha, beta, and gamma cellulose in unmercerized MCC and mercerized MCC Cladophora agardhii was determined. Other test in physical and chemical properties of MCC with SEM and XRD. Results: MCC Cladophora agardhii has a brownish-green colour with a crystalline solid form and odorless. MCC unmercerized and MCC mercerized with NaOH (15%; 20%; and 25%) had cellulose alpha contents (96,93±0,09%); (98,07±0,09%); (98,26±0,07%); (98,35±0,06%), beta cellulose contents (2,98±0,10%); (1,87±0,09%); (1,69±0,06%); (1,59±0,05%), and gamma cellulose contents (0,09±0,00%); (0,06±0,00%); (0,05±0,00%); (0,06±0,00%). The following result of physical and chemical test from MCC unmercerized and MCC mercerized are lost of drying (6,67±0,12%); (7,20±0,12%); (9,65±0,20%); (11,50±0,20%), moisture content (3,30±0,28%); (3,93±0,19%); (4,07±0,11%); (5,30±0,1%2), pH degrees (6,77±0,05); (7,95±0,09); (8,66±0,22); (9,01±0,06), compressibility (10,47±0,16%); (12,47±0,11%); (13,30±0,09%); (16,68±0,23%), flowability (9,07±0,11g/s); (8,42±0,35g/s); (7,41±0,07g/s); (6,61±0,24g/s), viscosity (0,00±0,00cP); (4,80±0,20cP); (6,40±0,20cP); (7,60±0,20cP), and index crystallinity (54,39±0,08%); (37,42±0,05%); (35,57±0,07%); (34,30±0,10%) respectively. SEM showed that the morphological changes between MCC unmercerized and MCC mercerized with NaOH. MCC unmercerized is seen to have a smooth and flat surface, where the surface will be rigid so that water is difficult to penetrate. However, MCC mercerized with NaOH has a more coarse surface due to the formation of gaps or pores. Conclusion: Based on that, variation of NaOH concentration in the mercerization process gave a significant different of alpha, beta, gamma cellulose contents and significant effect for the physical and chemical properties of MCC Cladophora agardhii.

Key words: Microcrystalline cellulose, Cladophora agardhii, Mercerization, NaOH, Hygroscopic.