Protein and albumin contents in several freshwater fish species of Makassar, South Sulawesi, Indonesia

Albumin of snakehead fish has been widely used in the health and nutritional applications for the past 10 - 15 years. An intensive exploitation to produce fish albumin has placed the natural stock of snakehead fish under a great pressure. Furthermore, its aquaculture production has not been significantly developed to balance the industrial demands. Therefore, the present work aimed to look for the potential sources of fish albumin of freshwater origin as an alternative to that of snakehead fish. The present work analysed seven freshwater fish species namely catfish (Clarias gariepinus), common carp (Cyprinus carpio), eel (Monopterus albus), Nile tilapia (Oreochromis niloticus), pangas catfish (Pangasius pangasius), snakehead fish (Channa striata), and three-spotted gourami (Trichogaster trichopterus). Albumin extraction was done by mixing 50 g of pre-homogenised fish meat with 200 mL of distilled water, homogenised in a laboratory homogeniser for 1 min, and heated in a water bath at 50°C for 60 min. The mixture was filtered using a Whatman No. 40 filter paper under reduced pressure. The filtrate volume was recorded and stored at -20°C until further analysis. The parameters analysed were total protein, total soluble protein, and albumin level. Results indicated that the total protein content of meat was 17.93 - 21.87% (w/w), the lowest being in catfish and the highest in snakehead fish; total soluble protein was 2.43 - 5.43 g/100 g (w/w), the lowest being in eel and the highest in snakehead fish; and albumin content was 0.83 - 3.35 g/100 g (w/w), the lowest being in Nile tilapia and the highest in common carp. The higher albumin content in the common carp (3.35 g/100 g) and pangas catfish (3.22 g/100 g) as compared to that of snakehead fish (2.97 g/100 g) indicated that common carp and pangas catfish are highly potential to be used as alternative fish albumin source.