Fish waste valorisation through production of biodiesel and biopolymers for sustainable development: A mini review

Abstract

Fish processing waste accounts for one of the major classes of food waste generated worldwide in terms of the high volume of waste generated. The presence of high amounts of organic compounds (proteins: 15–30 %, lipids: 5–20 %) in fish waste makes them highly susceptible to autolysis which when not managed properly pose adverse effects on the environment like production of offensive odor, generation of hydrogen sulfide, higher biological oxygen demand (1000 mg/L to 12,000 mg/L or even higher) (BOD), and multiplication of pathogenic bacteria. Fish waste is rich in lipids and polysaccharides that can be channelized for biodiesel and biopolymer production respectively. Biodiesel refers to the biofuel produced from transesterification of plant and animal fats. Extraction of oils from fish waste followed by transesterification reactions can yield biodiesel through a biorefinery approach. Biorefinery concept emphasizes the conversion of biomass into commercially important byproducts. Biopolymers refers to the natural polymers that can be extracted from the natural sources or produced through microbial fermentation process. Furthermore, commercially important biopolymers like chitosan and polyhydroxyalkanoates (PHAs) can be used as biorefineries. This review work presents the sequential strategies for conversion of fish waste to biodiesel, PHA and chitosan through various physicochemical and biological methods. The review also presents the existing challenges and the future in the fish waste biorefinery concept. The scope of this review is to present a broader concept of integrating fish waste biorefinery for production of multiple value added products like biodiesel and biopolymers.