3.4. Protein degradation
One of the advantages of fungal food fermentation is the
improved digestibility of food and the enrichment of peptides and
amino acids through surimi protein degradation by protease produced
by the fermentation starters. Aswas in most cheese varieties,
proteolysis is also the principal and most complex biochemical
event occurred in surimi fermentation (McSweeney & Fox, 1997).
To determine the protein degradation during the surimi fermentation
process, index including amino nitrogen, TCA-N and free
amino acids profile were analyzed.
As shown in Table 1, both amino nitrogen and TCA-N levels
increased significantly after 12 h of fermentation: from the original
0.03% and 0.06 g/100 g to 0.20% and 0.47 g/100 g, respectively
(P < 0.05). After 48 h fermentation, amino nitrogen and TCA-N
levels reached to 0.49% and 0.69 g/100 g, respectively. This suggested
the protease produced by A. elegans XH-22 was able to
degrade surimi proteins as well. However, the degradation rate
seemed to decline thereafter, and this may be related to the change