Deep eutectic solvents for the extraction of β-chitin from Loligo vulgaris squid pens: a sustainable way to valorize fishery by-products

Abstract

β-chitin, a promising biopolymer for the production of chitosan and biomaterials, is sourced from fishery by-products. Herein, β-chitin has been extracted using Deep Eutectic Solvents (DES) for the first time, only the α-polymorph having been extracted using these solvents until now. Six acid, neutral, and alkaline DES systems were trialed, with only the alkaline DES systems, in particular potassium carbonate: glycerol (KGLY) at 100 or 120 °C for 2 or 3 h, resulting in high-purity β-chitin. The ensuing β-chitin was characterized in terms of chemical and physical structure, morphology, crystallinity, and thermal properties. Under the best extraction conditions, using the DES KGLY system, the β-chitin samples were highly pure, presenting an acetylation degree between 77 and 88%, a high crystallinity between 88 and 91%, and a maximum degradation temperature of around 350 °C. Moreover, the solvent system was easily recyclable with consistent performance over 3 cycles of re-use. The extraction method is 2 well-suited for the extraction of crystalline β-chitin and could be integrated into future works in the production process of chitosan.

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

“…DES coupled with potassium carbonate: glycerol enhances the purity of β-chitin from snail shell and squid pen at 100 or 120 • C for 2 or 3 h. So far, this combination of solvents has been used only for α-polymorph. But, these results proved that DES is efficient β-polymorph as well (Kimi & Hamdi, 2023;McReynolds et al, 2022). Other physical properties such as acetylation degree and crystallinity improved between 77% and 88%, and 88% and 91%, respectively, and a maximum degradation temperature was around 350 • C. DES used in this extraction was recovered and recycled over three times without modifying the final yield of chitin (30%) and C/N ratio (6.45-6.52).…”

“…The extraction process requires an acidic solution to act as a co-solvent hydrogen bond donor. Recently, McReynolds et al (2022) reported that DES breaks strong hydrogen bonds between chitin amino groups and H + by using citric acid, malonic acid, and lactic acid. These green solvents are highly biodegradable and less or nontoxic nature compared to conventional alkali extraction (Zhang et al, 2012).…”

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

“…In this sense, although Lv et al did not mention the residual protein and mineral content in chitin, they proved that, using an alkaline DES (K 2 CO 3 -Glycerol), they were capable to remove 64.53% and 1.07% of proteins and minerals, respectively [150]. McReynolds et al [151] also investigated the extraction of chitin from squid pens using acidic, neutral, and alkaline DESs. They conducted a comparison with yields obtained through conventional chemical methods and observed significantly higher yields with acidic and neutral DESs, attributed to their limited demineralization and deproteinization capabilities.…”

Current and Expected Trends for the Marine Chitin/Chitosan and Collagen Value Chains

“…The scientific publications related to the chitin/chitosan and collagen value chains analysed in the present study focused mostly on how these bioactive compounds and/or their derivatives were obtained rather than on the later steps of both value chains and market-related information. Interestingly, more publications mentioned [70,[149][150][151] the origin of raw materials, inputs/feedstock, and the pre-treatment and pre-processing steps in the collagen value chain than in the chitin/chitosan value chain, but the opposite trend was found [65,110,152] for processing and product manufacturing, consumption, chain outputs, and the interaction between stakeholders. This switch may indicate that the focus of scientific publications related to the chitin/chitosan value chain is changing towards the final steps.…”