Fermentative recovery of lipids and proteins from freshwater fish head waste with reference to antimicrobial and antioxidant properties of protein hydrolysate

Abstract

Effectiveness of fermentation using lactic acid bacteria (LAB) for recovering lipids and proteins simultaneously from freshwater fish head (FWH) was evaluated. Three different proteolytic LAB (Pediococcus acidilactici NCIM5368, Enterococcus faecium NCIM5335 and Pediococcus acidilactici FD3) isolated from fish processing wastes were employed in the fermentation process. The fermentation conditions involved 10 % (w/w) glucose, 2 % (w/w) NaCl and 10 % (v/w) LAB cultures at 37 °C. The process resulted in 38.4 % of degree of hydrolysis (in case proteins) and a recovery of 63.6 % of the oil present in the material. The fermentation process did not affect the fatty acid profile of lipids. The hydrolyzed protein rich fermentation liquor exhibited DPPH radical scavenging activity (EC50 – 5.1 mg protein) as well as antagonistic properties towards several bacterial and fungal pathogens. The minimum inhibitory concentrations (MIC) of fermentated liquor (with E. faecium NCIM5335 as starter) were 10 and 12 mg/ml for Listeria monocytogenes and Salmonella itridicus, respectively. A higher MIC (60 and 96 mg/ml for Aspergillus ochraceus and Penicillium chrysogenum, respectively) was observed in case of fungal pathogens. Both the oil and protein hydrolysate rich liquor from fish head can be used as biofunctional ingredients in both human food as well as livestock feed formulations.