Agricultural and Food Science (Jan 1995)
Evaluation of conditions for fermentation of fish offal
Abstract
Conditions for the lactic acid fermentation of fish offal were evaluated regarding the effect of substrate concentration (2, 5 and 10% dextrose), preacidification with lactic acid (initial pH of 6.8, to 6.5 or 6.0), and inoculum size of Lactobacillus plantarum (107 , 108 and 109 colony forming units (cfu)/g). pH and lactic acid production were monitored during a two-week storage period. A small-scale silo for fermenting fish offal was also constructed, and measurement of redox potential was evaluated as a means to estimate bacterial growth conditions. The most favourable conditions for fermentation, manifested by a low and stable pH and high lactic acid production, were achieved with an inoculum size of 108 cfu/g and 5% dextrose. Preacidification did not affect final pH. Redox potential was shown to give a reliable estimate of growth conditions for bacteria under anaerobic conditions by rapidly falling to below -550mV in silage with a high lactic acid concentration.