PROTEASE ACTIVITY OF Streptococcus thermophilus TISTR 894 IN FERMENTED MILK

ALDI RIPALDI, Dr. Ir. Tyas Utami, M.Sc. ; Asst. Prof. Jirawan Apiraksakorn, Ph.D.

2020 | Skripsi | S1 TEKNOLOGI PANGAN DAN HASIL PERTANIAN

Susu fermentasi merupakan produk susu yang difermentasi oleh mikrobia, umumnya bakteri asam laktat. Selain menggunakan laktosa untuk pertumbuhan dan produksi asam, protease yang dihasilkan oleh bakteri asam laktat akan mendegradasi protein susu menjadi peptide rantai pendek dan asam amino. Bakteri asam laktat tidak dapat mensintesis asam amino yang diperlukan untuk pertumbuhan dan pemeliharaan fungsi sel bakteri. Oleh karenanya tujuan penelitian ini adalah mempelajari aktivitas protease selama fermentasi susu oleh Streptococcus thermophilus TISTR 894. Kultur S. thermophilus TISTR 894 diinokulasikan ke dalam susu dan diinkubasi selama 48 jam pada suhu 30 derajat Celcius dan diamati pertumbuhan, dan aktivitas proteasenya. Produksi protease juga diamati selama fermentasi susu pada berbagai suhu fermentasi. Aktivitas protease duji pada berbagai suhu pH (4, 5, 6, dan 7) dan suhu (30, 40, 50 derajat Celcius). Aktivitas enzim protease tertinggi diperoleh pada jam ke-24 dengan nilai aktivitasnya sebesar 0.0003 U/ml. Produksi protease tertinggi diperoleh pada fermentasi susu pada suhu 30 derajat Celcius. Kondisi optimal aktivitas enzim protease diperoleh pada pH 5 dan suhu 40 derajat Celcius.

Fermented milk is product of milk that is fermented by microorganism, it is commonly used lactic acid bacteria (LAB). In addition to use lactose for growing and lactic acid producing, protease is also produced by LAB to cleave protein into small peptides and free amino acids that cannot be synthesized by lactic acid bacteria. Amino acids are essential for the growth and maintenance the cell of bacteria. Therefore, this research aims to study the protease activity during milk fermentation by Streptococcus thermophilus TISTR 894. Milk was inoculated with S. thermophilus TISTR 894 and incubated to be grown at 30 Celcius degree for 48 hours. Its growth and protease activity was observed during fermentation. Protease production determined at various milk fermentation temperatures. Enzyme activity was assayed at various pHs (4, 5, 6, and 7) and temperatures (30, 40, and 50 Celcius degree). The highest protease activity was obtained at 24 hours, which was 0.0003 U/ml. The highest protease production was obtained at milk fermentation of 30 Celcius degree. The optimum protease activity were obtained at pH 5 and 40 Celcius degree.

Kata Kunci : Susu fermentasi, aktivitas protease, Streptococcus thermophilus TISTR 894, pH, dan suhu/Fermented Milk, the activity of protease, Streptococcus thermophilus TISTR 894, pH, and temperature