Fish Products and Byproducts Technology

Unit 8 - Fish Protein Hydrolysate

8.5. Autolysis assisted hydrolysis of fish protein hydrolysate
Autolysis assisted fish protein hydrolysate preparation involves the digestive enzymes of fish itselfirly rich. The end product of autolysis process is generally a fairly viscous liquid rich in free amino acids and small peptides.
Autolysis also used in fish sauce and fish silage production.
Digestive enzymes

• Serine proteases trypsoin, chymotrypsin
• Thiol proteases pepsin
• All major enzymes of digestive tract
• Lysosomal proteases or catheptic proteases present in fish muscle

Advantage

• No enzyme cost

Disadvantage

• The endogenous enzymes in autolysis are a very complex mixture of enzymes, all with different activity which result in end products of different molecular profile
• Certain digestives enzymes and their concentration are highly seasonal, gender, species, age specific
• Hard to control the hydrolysis process

Fish sauce and fish silage are also autolysis assisted process.
Fish sauce

• Fish sauce contains 10% free amino acids and peptides 25% salt.
• Fish sauce preparation does not improve the nutritional quality but improves the keeping quality and sensory properties

Fish silage

• Animal feed ingredient
• Produced oil and protein fractions readily separated
• Substrates used are secondary raw material from processing plant
• Acid endogenous enzymes actively hydrolyse the fish protein