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.

Simultaneous Optimization of Deacetylation Degree and Molar Mass of Chitosan from Shrimp Waste

“…The content of N-deacetylated groups and amino groups in the chitosan structure are also very important in defining chitosan properties. It cannot be neglected that different values for the degree of deacetylation DD as well as for the molar mass MM of the obtained chitosan samples can influence the chitosan performance and its various applications [ 4 , 5 ].…”

Strategies to Prepare Chitin and Chitosan-Based Bioactive Structures Aided by Deep Eutectic Solvents: A Review

“…Among natural biopolymers, chitin stands out as the second most abundant natural polymer on Earth (only after cellulose, the principal component of plant cell walls and the most abundant source of renewable polysaccharides on Earth [26]). It can be found in a plethora of living beings [27], with some notable sources being crustacean shells [28][29][30][31][32], arthropods [33], mollusks [34], insects [35][36][37], and fungi [38]. Chemically, chitin is a linear polysaccharide composed by a repetition of subunits of 2-amino-2-deoxy-D-glucose (N-acetyl-glucosamine, GlcNAc, Figure 1a) connected by (β1→4) glycosidic bonds (Figure 1b,c).…”

“…Chitin present in its primary natural reservoir, namely crustacean shells [28][29][30][31][32], adopts an antiparallel orientation (α-chitin), in which not only intramolecular but also intermolecular hydrogen bonding is present (Figure 1d, red color), resulting in an orthorhombic crystal structure [27,43]. Conversely, β-chitin (present in squid pens, clams, oyster shells, and bones of cuttlefish, [34]) features a parallel chain alignment, with no interchain bonding, giving rise to a monoclinic crystal symmetry [43] with higher solubilizing properties. Finally, γ-chitin, less abundant and only present in some insects, comprises a blend of both αand β-chitin, with two parallel chains followed by an antiparallel chain [44].…”