2) Enzymes as fish-processing aids
1. Enzymes as an alternative to conventional processing methods
2. Mechanical processes: low yield, quality reduction
3. Enzymes can be used as specific tools in food processing, where the aim is a selective removal or
modification of certain tissue structures
① Deskinning
1. The common method of removing skin from fish fillets is purely mechanical
2. Biochemical method of deskinning works because skin differs fundamentally from tissues
3. Enzymatic deskinning can be done by cold-adapted fish pepsin at low reaction temperatures
4. Proteases are usually mixed with carbohydrases to facilitate skin removal
⑴ Proteolytic enzymes from squid intestines may be used for removing the double-layered skin of squid
- The conventional mechanical deskinning method removes only the pigmented outer skin, leaving the
rubbery inner membrane intact
- Most of the proteases of squid offal extract are also collagenolytic enzymes
⑵ Starry ray
- Mechanical or manual skinning leaves residual skin fragments that must be removed when the
process is repeated
- Enzymatic method for deskinning skate wings has been developed to yield improved product