Fish Products and Byproducts Technology

Unit 10 - Fish By- products

10.1. Isinglass
Air bladder, also called sound or swim bladder consists of several membranous layers rich in collagen. Located in the abdominal cavity below the vertebral column, air bladder helps the fish in regulating its specific gravity. Cleaned and dried air bladder is called as Fish Maw, which is an excellent raw material for production of Gelatin.
Hake, Sturgeons and carps are good sources for air bladder.
Processing
The air bladder after washing with water and scraping of the outer layer is split open longitudinally and washed well further, sundried to 15 % moisture level by hanging or placing in trays. Dried product is Fish Maw.
Dried air bladder is immersed and soaked in water until it becomes soft. It is then rolled after cutting into small pieces between water cooled iron rollers to convert them into thin strips. They can be further compressed by ribbon rollers into ribbons about 0.4mm thick which are air dried and rolled into coils. This is Isinglass.

Uses

• Clarifying agent for beer, cider, wine, vinegar etc.
• Can be used as adhesive waste
• Isinglass dissolved in acetic acid forms a strong cement base
• Can be used as a sizing agent in textiles
• It is an ingredient in Indian ink.