Chemical and Microbial Changes in Fish Viscera During Fermentation Ensiling at Different Temperatures

Fermentation ensiling of fresh water fish viscera with
10% (w/w) molasses, 0.5% (v/w) propionic acid and
0.02% (w/w) ethoxyquin at 26+2°C and 37°C was
investigated. The pH values and reducing sugar con-
tents were significantly (P<O.O01) lower, and lactic
acid contents higher (P < O. 001), in mixtures fermented
at 370C than those fermented at 26°C. Col•forms,
Escherichia col•, enterococci, staphylococci and sal-
monella were absent from 48 h or 72 h onwards in
fermentation at 37 and 26°C. Clostridium perfringens
was absent after 48 h, and spores after 72 h, of fer-
mentation at both temperatures. Markedly lower
(P <O.O01) bacterial total viable count and marginally
lower (P > O. 05) yeast and mould counts were noted in
samples held at 37°C. Lactic acid bacterial counts
were higher initially (up to 48 h) at 37°C than at 26°C.
The ensiling was thus faster at 37~C than at 26°C. ©
were separately incubated at ambient temperature
of 26_+ 2°C or at 37°C. Periodically the samples were
analysed for pH changes (Ahmed & Mahendrakar,
1995), general microbial profile (Ahmed et al.,
1996), Salmonella and Clostridium perfringens
(APHA, 1984) up to 8 days of fermentation. Reduc-
ing sugars and lactic acid were estimated according
to the methods of Miller (1959) and Lawrence
(1975), respectively•
The experiment, which had a factorial design,
with incubation temperature as one factor and fer-
mentation period as the other, was repeated six
times and results are means of six determinations.
Analysis of variance technique and Duncan's New
Multiple Range Test (Steel & Torrie, 1980) were
used to segregate treatment means.