Natural fermentation of dried fish stick (Arabushi) of skipjack tuna (Katsuwonus pelamis) and frigate mackerel (Auxis thazard) in desiccator

Inglés. The experiment on the natural fermentation of dried fish stick (arabushi) of skipjack tuna (Katsuwonus pelamis) and frigate mackerel (Auxis thazard) was carried out in a desiccator with 10 cm height, and 40 cm diameter. Arabushi was arranged in dessicator in which cotton sheets that have been moisted with 50 ml tap water were laid down on the bottom of desiccator. Natural fermentation was carried out 5 steps. Every step of fermentation was stopped when moulds completely covered the surface of arabushi and colour change from white to gray greenish or grayish occured. The result of fermentation showed that phenolic content of dried fish skipjack tuna and frigate mackerel decreased during natural fermentation i.e. 4.9 percent db (dry basis) and 3.8 percent db, respectively. Aw value of skipjack tuna tend to be constant by 0.87, while frigate mackerel decreased from 0.84 to 0.812. Total crude protein digested to simple amino acids were 13.69 percent db and 80.75 percent db for skipjack tuna and frigate mackerel katsuobushi. Decomposition of protein into amino acids such as alanine, leusine, and phenylalanine occured on the skipjack mackerel katsuobushi, while proline was occured during fermentation of frigate mackerel. Species of moulds grew on the surfaces of both arabushi were Eurotium repens, Aspergillus flavus, Penicillium citrinum, and Penicillium spp.

Indonesio. Percobaan fermentasi alami ikan kayu (arabushi) cakalang (Katsuwonus pelamis) dan tongkol (Auxis thazard) menjadi katsuobushi telah dilakukan di dalam desikator berdiameter 29 cm dan tinggi 26 cm. Arabushi disusun di dalam desikator secara bersilangan dan untuk meningkatkan kelembaban relatif udara ruangan fermentasi diletakkan kapas yang telah dibasahi dengan air sebanyak 50 mL pada dasar desikator. Fermentasi dilakukan melalui lima tahap dan setiap tahap diakhiri bila kapang tumbuh merata dan telah terjadi perubahan warna kapang dari putih menjadi abu-abu kehijauan atau abu-abu. Hasil percobaan fermentasi arabushi menjadi katsuobushi cakalang dan tongkol menunjukkan terjadinya penurunan kadar fenol sebesar 4,9 persen bk (bobot kering) dan 3,8 persen bk, nilai aktivitas air (aw) katsuobushi cakalang cenderung konstan sebesar 0,87, sedangkan katsuobushi tongkol cenderung menurun dari 0,84 menjadi 0,81 setelah akhir fermentasi tahap V. Jumlah protein kasar yang dapat diuraikan menjadi asam-asam amino sederhana sebesar 13,69 persen bk dan 80,75 persen bk masing-masing untuk katsuobushi cakalang dan tongkol. Jenis asam amino yang tidak terdeteksi selama proses fermentasi pada katsuobushi cakalang adalah asam amino alanin, leusin, dan fenilalanin, sedangkan pada katsuobushi tongkol hanya asam amino prolin. Jenis kapang yang tumbuh selama tahapan fermentasi adalah Eurotium repens, Aspergillus flavus, Penicillium citrinum, dan Penicillium spp.