by Green Plastics
Philip Edward wrote in to ask:
I am a student from Philippines and I’m currently making our thesis about bioplastics.
I really need your help, sir. Is it possible that we can produce bioplastics from fermented fish scales?
Thanks for your question, Philip! It is a very interesting question, too.
Fish scales are an example of a bio-composite. A large part of fish scales is made up of the protein collagen, a biopolymer. In fish scales the collagen in combined with a hard inorganic crystalline material to form a composite that is strong and waterproof.
Scientists have found a way to separate the collagen from fish scales, which could provide a potentially abundant source of commercial collagen. The denatured (disordered) form of collagen is gelatin. Gelatin can be plasticized, for example with glycerol, and cast films of gelatin plus plasticizer form a bioplastic that has some good properties, including tensile strength. (We have some good recipes for making home-made gelatin-based bioplastics on this website!)
These films, however, are not water resistant; in time they would simply dissolve. (The inorganic component in fish scales is what gives the water resistance to fish scales.) So, although the collagen in fish scales might be used to make bioplastics, they would not be water resistant.
Fermenting fish scales might be a way of providing partially hydrolyzed collagen (gelatin) from fish scales, but once the bio-component is destroyed the water resistance (from the inorganic component) is lost. Nature was very clever in producing this bio-composite. Learning how to put the collagen back together again with the waterproofing (and stengthening) inorganic component might be a technology of the future.