Extraction of local fish waste by subcritical water

Production from fish processing activities leads to enormous amounts of waste. This waste is substantially composed of non-edible parts, for instance viscera, gills and others. This fish waste has incredible potential as raw materials or as one of the ingredients needed for the preparation of protein foods for pets. Fish industries should recover the leftovers from fish processing into another valuable product. This can be as a good reduction strategy for industries to minimize their wastes. Hence, it helps to reduce harmful impact to the environment. Therefore, this fish waste has big potential to be commercialized. Additionally, the fish waste available in the markets actually has its own excellent probability. It can be utilized as an ingredient in animal food production such as fish palatant. So, in this study, fish waste originated from ocean fish was collected from local market in Selayang. Its nutritional compositions were firstly analyzed. Fish viscera was selected to undergo extraction as it showed up with high protein content of 84.68% rather than fish gills with protein content of only 44.62%. In order to produce safe food for cats, subcritical water extraction (SWE) method was applied in the extraction process instead of using conventional extraction method. This extraction method is considered as a green process because of usage of water as a solvent since water can replace aqueous solvent during extraction process. SWE was then heated to the desired temperature of 140 degrees C-220 degrees C with pressure in the reactor was fixed at 3.0 MPa. The extraction time for each sample was 5 minutes. At a temperature of 180 degrees C, it has the highest protein content with 1.705 g/L BSA.