Changes in microbial population during fermentation of tropical freshwater fish viscera.

Freshwater fish viscera (FV) was
homogenized, mixed with 10% (w/w of FV) molasses and 0, 2 or 4% salt and allowed to
ferment at ambient temperature (26 f 2°C) under microaerophilic conditions. The
results revealed a reduction in total viable count and the number of spores, coliforms,
Escherichia coli, staphylococci and enterococci and an increase in yeasts and moulds and
lactic acid bacteria during fermentation. Coliforms and E. coli were found to be
absent after 6 d and enterococci on 8th day. The presence of salt resulted in a marginally
lower number of all organisms except yeasts, moulds and lactic acid bacteria.
Inclusion of either 0.5% propionic acid, 0.3% calcium propionate or 0.1% sorbic acid
suppressed growth of yeasts and moulds with propionic acid being the most
effective. The study indicated that a microbiologically stable product could be prepared
by ensiling fish viscera with 10% molasses and 0.5% propionic acid.