Autolysis and rancidity development in tropical freshwater fish viscera during fermentation

To develop an ensiling process to preserve the nutrients in fish viscera, the offal was homogenised with 10% (w/w) molasses. Propionic acid (0.5% v/w) was added as an antimycotic agent. NaCl (2% w/w) and ethoxyquin (0.02% w/w) were added to see the effect on autolytic changes and rancidity development, respectively. Fermentation was carried out under microaerophilic condition at 26+/-2 degrees C. Total volatile nitrogen, non-protein nitrogen, alpha-amino nitrogen (autolytic changes) and free fatty-acid content increased (P<0.001) rapidly during the first 4 days and then remained constant up to 8 days. Salt had no influence on autolysis. Peroxide value (PV) increased (P<0.001) initially;up to 3-4 days and then decreased. A rapid increase (P<0.001) up to 2 days and small (P>0.05) subsequent increase in iodine value (IV) were observed Thiobarbituric acid (TEA) number increased linearly up to 8 days of fermentation period. Ethoxyquin was effective in controlling oxidative rancidity, as indicated by significantly (P<0.001) lower PVs and TEA numbers and higher Ns. Copyright (C) 1997 Elsevier Science Ltd.