Research of the process of enzymative extraction of fat from secondary fish raw materials for use as a biotechnological substrate

The relevance of using fish oil from secondary fish raw materials in microbiological synthesis as a substrate for the production of proteins and biodegradable plastics is due to its valuable properties and the demand for these bioproducts. Fish oil has a liquid consistency and a high content of long-chain polyunsaturated fatty acids, but is quickly subject to hydrolysis and oxidation. The work investigated an enzymatic method for extracting fat from the heads of smoked sprat and mackerel, and the insides of pike perch when treated with three types of proteolytic enzymes (alcalase, protosubtilin, protozyme). Enzymelysis allows you to isolate 44-63.4 % of fat from its content in raw materials under reasonable rational conditions: temperature 40-50 °C; duration 30-40 minutes; enzyme dosage is 0.2-0.4 % by weight of raw materials. The quality of secreted fats was studied in terms of acid and peroxide numbers. In all samples, the presence of hydrolysis and oxidation products was established, to the least extent - in fats from sprat waste (CN 6.2-6.7 mg KOH/1 g; CN 9.0-18.7 mmol active oxygen/kg), to the greatest extent - in mackerel fats (CN 14.5-18.8 mg KOH/1 g; CN 43.7-164.7 mmol active oxygen/kg). The fatty acid composition of enzymatically extracted fish oils was studied. The predominance of long-chain fatty acids in fats was shown (63.6-68.3 % of the sum of all FAs) with a high content of PUFAs (23.7-47.8 %). Comparison of the quality indicators of extracted fats with published data allows us to consider them a promising carbon source for use as a biotechnological substrate in the microbial synthesis of protein and biodegradable polyhydroxyalkanoate plastics.