(2) Biochemical changes: hydrolysis of protein
1. The main part of the production of all fish sauces is the conversion of insoluble fish protein into a
soluble or ‘suspended’ form
2. The agents are the enzymes present in the fish, although enzymes from microorganisms may assist
3. The main products are amino acids and polypeptides
4. Side products are ammonia and other low molecular mass nitrogenous compounds
- The free amino acid, total nitrogen, and polypeptides content increased steadily during fermentation
5. The enzymes derived from the fish are responsible for the proteolysis
6. In the fermentation of Budu, the changes in nitrogen distribution :
① The first phase (0-25 days) was an increase in volume of the supernatant liquid and soluble
nitrogen due to osmosis
② In the second phase (80-120 days), the cellular tissue begins to breakdown and cellular protein comes
into contact with the enzymes. All fish tissue disappears after 120-140 days
③ In the third phase (140-200 days), the enzymes are liberated and attack the partially solubilized proteins
This causes the change in the distribution of nitrogen compounds
7. Many enzymes have been implicated in the proteolysis
① Main enzymes involved appeared to be ‘trypsin-like’
② Other proteases such as cathepsin B are significant
③ Other enzymes have been implicated in the breakdown of polypeptides to amino acids
7. Some microorganisms survive in sauces and may contribute to the proteolytic breakdown
① This may not be the main agent of proteolysis
② It could contribute to the development of particular peptides and ammo acids involved in flavor