Although the content of some individual free amino acids was decreased, most free amino acids were increased.
Table 2. Changes in amino acid content of fish paste during 8 and 32 days of fermentation time.
No Amino acid
8 days fermentation time 32 days fermentation time
Average + SD (%) Average + SD (%)
1 L-aspartic acid 3.08 + 0.62 3.69 + 0.16
2 L-serine 1.14 + 0.26 1.32 + 0.03
3 L-glutamic acid 4.61 + 1.00 5.52 + 0.13
4 Glycine 1.98 + 0.10 2.36 + 0.32
5 L-histidine* 0.97 + 0.20 1.26 + 0.18
6 L-agrinine* 2.02 + 0.36 2.49 + 0.20
7 L-threonine* 1.61 + 0.09 1.85 + 0.22
8 L-alanine 1.97 + 0.22 2.38 + 0.17
9 L-proline 1.37 + 0.13 1.71 + 0.10
10 L-Cystine 0.37 + 0.01 0.34 + 0.08
11 L-Tyrosine 1.30 + 0.27 1.30 + 0.22
12 L-Valine* 1.87 + 0.29 2.21 + 0.12
13 L-Metheonine* 1.15 + 0.02 1.29 + 0.09
14 L-LysineHCL* 2.87 + 0.59 3.12 + 0.00
15 L-isoleucine* 1.61 + 0.18 1.79 + 0.06
16 L-Leucine* 2.56 + 0.33 2.80 + 0.01
17 L-Phenylalanine* 1.84 + 0.44 1.71 + 0.37
Total 32.32 + 3.49 37.15 + 2.43
Note: *: essensial amino acid.
Fish fermentation is the transformation of organic substances into simple compounds such as peptides, amino
acids, and other nitrogenous compounds either by the action of microorganisms or endogenous enzymes (1). The
research of (18), reported that the content of some individual free amino acids in fermented oyster sauce fluctuated
during the fermentation period. These compound are released by microbial action (mainly by microbial enzymes),
through the biochemical reactions taken place during fermentation. Fish paste also had high contents of glutamic
acid which are regarded as important contributors to the flavour and taste of fish paste (19).
The research of (1) reported that shrimp paste trough prolonged fermentation give result total free amino acid
content increase dramatically in the beginning fermentation time, stable in the mid fermentation time and then
decreased along with the fermentation time. The decline in the free amino acid content could be due to its
degradation to amines, volatile acids, and other nitrogenous substances as by-products of bacterial metabolism or
enzymatic decomposition. Ammonia, an index of the degradation has distinctly increased during prolonged
fermentation and manifested by the increase of odour. The observed decline in amino acids would be also
responsible for the formation of MRPs (Maillard Reaction Products) and should be manifested by the increase in
brown colour and fluorescence intensity.
Free radicals are generally reactive and attack molecules such as sugars, protein and lipids. This may result in
damage from oxidation such as deterioration of foods, protein modification and enzyme inactivation. Antioxidant
substances can prevent these damages by inhibiting the production of primary catalyst of lipid peroxidation (20).
Maillard Reaction Products (MRPs) that could formed during fermentation was responsible for the increase in
antioxidant activity of the salt-fermented shrimp paste during prolonged fermentation salt fermented shrimp was
found to exhibit antioxidant activity, and the composition of fatty acid (%) did not change during fermentation for
36 days (use 25% w/w salt) (1).
62 A