Chitin biorefinery: A narrative and prophecy of crustacean shell waste sustainable transformation into bioactives and renewable energy

Chitinaceous biomaterials received great attention towards producing functional transformed products and biofuel. Chitin biorefinery is an emerging concept that can utilise different components present in crustacean shell biomass and their intermediate byproducts, escalating value of derivatives from the biomass feedstock. It can also assist in maximising the energy potential of organic wastes while addressing waste management and greenhouse gas emissions issues. Limited literature is available on the chitin biorefinery concept aiming towards concerted translation of chitinous residual resources into bioactives and bioenergy in the circular economy realm. Chitin could efficiently be converted into chitosan, oligomers, and glucosamine by employing two-stage conversion process consisted of pretreatment and enzyme hydrolysis. The review provides detailed knowledge on the development of chitin biorefinery, recent advances of chitin-transformed products, and their applications. The study will also provide an insight into the systematic development of various production approaches viz. traditional chemical, enzymatic, green chemicals and chemoenzymatic for the generation of different transformed products. The article also presented detailed review on the progress made and prospects of the research in the bioenergy generation from chitinous biomass and the market status of the chitin biorefinery. Moreover, a range of acetylated and deacetylated products of the chitin biorefinery in terms of properties, production, applications, and prospects have been reviewed, which would be beneficial in a better understanding of the chitin-derived value-added products. Further, the less studied aspect of the chitin biorefinery, i.e., bioenergy, has also been discussed to determine chitin's efficiency in competing with lignocellulose.