Comparative analysis of chitin isolation techniques from mushrooms: toward sustainable production of high-purity biopolymer†

Chitin, an abundant and versatile biopolymer, is widely used across industries such as biomedicine, agriculture, and materials science. Traditionally sourced from crustacean waste, its extraction poses environmental and allergenic challenges, driving the exploration of alternative sources. Fungal biomass, particularly from white mushrooms (Agaricus bisporus), offers a renewable, hypoallergenic, and non-animal alternative, but its complex cell wall structure demands innovative extraction techniques. This study compares traditional alkaline pulping with environmentally-conscious methods, including ionic liquids 1-ethyl-3-methylimidazolium acetate ([C₂mim][OAc]) and 1-butyl-3-methylimidazolium hydrogen sulfate ([C₄mim][HSO₄]), and a deep eutectic solvent made of lactic acid and choline chloride (LA : [Cho]Cl), for chitin isolation from mushroom biomass. Results indicate that thermal [C₂mim][OAc] and extended NaOH pulping produced isolates with superior purity (77%), retaining the structural integrity of α-chitin. The produced fibers demonstrated mechanical properties of fungal chitin comparable to crustacean-extracted chitin, highlighting the viability of fungal sources for high-value applications. By addressing critical challenges in fungal chitin extraction, this work advances the understanding of eco-friendly methods and their potential for scalability. The ability to source chitin from mushrooms rather than from traditional animal-based sources like crustaceans is a game-changer for ethical and sustainable biomass to C-based products industries. In addition, the findings underscore fungal biomass as a valuable yet underutilized resource in the context of carbon-efficient biomass utilization. Mushrooms grow on various agricultural and industrial wastes, have minimal environmental impact, and their cultivation emits significantly fewer greenhouse gases compared to other agri- and aquacultural processes. In addition, the presented extraction method using [C₂mim][OAc] reduces chemical waste compared to traditional alkali-based methods for obtaining fungal chitin. Integrating this type of chitin into numerous applications reduces reliance on traditional supply chains and reinforces a circular economy approach.