β-Chitin and chitosan from waste shells of edible mollusks as a functional ingredient

Abstract

The marine food-processing industries were producing large quantities of shell wastes as a discard. Currently, this waste material was underutilized and leads to the landfill as a significant environmental issue. The outer shells or exoskeletons of mollusks serve as the best source of chitin. Three different allomorphs of chitin (γ, β, and γ) were extracted from different species of crustaceans, mollusks, and fungi. β-Allomorphs predominantly exist in the shells of mollusks. β-Chitin and its deacetylated product chitosan has been utilized for its special characteristic features, including biocompatibility, environmental friendly, and nontoxic properties. The extraction of β-chitin and chitosan from the mollusk shell waste were evaluated in this work. Hence, this review aims to explore edible mollusk shell waste sources and its suitable extraction techniques, characterizations, and functional properties of mollusk-based β-chitin and chitosan. Further, the genetic pathway of synthesizing mollusk chitin was discussed. The entire life cycle assessment with techno-economic aspects were extrapolated to study the bottlenecks and tangible solution for the industrial upscaling of obtaining β-chitin and chitosan from the edible mollusk shell waste have been reviewed herein.