Abstract:

Fish oil was extracted from the viscera of channel catfish (Ictalurus punctatus) by aqueous enzymatic extraction method. The optimum extraction parameters were as follows: initial hydrolysis pH 7.5, ratio of viscera to water 1:1, amount of papain 3500 U/g, hydrolysis temperature 55 ℃, hydrolysis time 0.5 h. Under these conditions, the extraction ratio of fish oil was up to 80.94%. The extracted fish oil (namely crude fish oil) was yellow-brown in appearance with fishy smell and light rancidity odor, and it had a lower peroxide value and high acid value. The relative content of the saturated fatty acids accounted for 19.42% of the total fatty acids. The relative content of monounsaturated fatty acids and polyunsaturated fatty acids were 61.76% and 16.83%, respectively. The ratio of n-3 to n-6 polyunsaturated fatty acids is 3.63. The above results show that the viscera of channel catfish are a good resource for fish oil production.

Key words: Ictalurus punctatus, viscera, fish oil, aqueous enzymatic extraction method