Pempek adalah produk pangan berbahan baku ikan dan tepung. Pada umumnya pempek menggunakan tepung tapioka yang mengandung kandungan serat dari pengolahan fermentasi ubi kayu memiliki manfaat dapat meningkatkan kesehatan jantung, mengurangi resiko timbulnya kanker, mengurangi transit makanan di usus sehingga mencegah konstipasi, dan menghambat absorbsi lemak maupun kolesterol. Tujuan dari penelitian ini adalah untuk menganalisis pengaruh perbedaan lama perendaman terhadap kadar air, kadar abu, kadar protein, kadar lemak, kadar serat pangan dari tepung mocaf yang dihasilkan serta menentukan pengaruh rasio tepung mocaf dan tepung tapioka pada kandungan serat pangan, karakteristik fisik, dan kimia. Berdasarkan hasil penelitian tepung dengan perendaman tepung mocaf selama 48 jam menghasilkan rata-rata kadar serat pangan total sebesar 6,47%, hasil ini dapat disimpulkan bahwa tepung yang memiliki kadar serat tinggi memiliki 6 g kadar serat dari 100 g sampel. Berdasarkan hasil penelitian yang diperoleh, dapat disimpulkan bahwa pempek terbaik diperoleh dengan rasio 30 tapioka : 70 mocaf dengan kadar air 1.31% ± 0.07, kadar protein 13.13% ± 0.00, warna 82,45 ºHue ± 0.66, dan kadar serat sebesar 7.70% ± 0.02. / Pempek is a food product consisting of raw fish and flour. Generally speaking, the use of tapioca flour, which contains the fiber from the processing of fermentation, has benefits that can improve heart health, reduce the risk of developing cancer, reduce food transit in the intestines, thereby preventing constipation, and inhibit the absorption of fat and cholesterol. The aim of this study is to analyze the influence of the differences in the length of immersion on the moisture levels, ash levels, protein levels, fat levels, food fiber levels of the produced butterfly flour as well as to determine the effect of the ratio of butterfish flour and tapioka flour on the fiber content of the food, the physical, and chemical. Based on the results of the study of flour with the immersion of mocaf flour for 48 hours produced an average total food fiber content of 6.47%, this result can be concluded that the high fiber flour contained 6 g of fiber from 100 g of sample. Based upon the results obtained, it can be inferred that the best pempek was achieved with a ratio of 30 tapioca: 70 mocaf with a water content of 1.31% ± 0.07, protein content of 13.13%, color of 82,45 ºHue ± 0.66, and a fibre content of 7.70% ± 0.02.