Biological and chemical synergy in chitin and chitosan production: The role of process sequencing in shrimp shell waste treatment

A combined biological and chemical methodology was applied to valorize shrimp shell waste into chitin and chitosan. This strategy aims to enhance process efficiency and sustainability. Various sequences of deproteinization (DP) and demineralization (DM) were evaluated, using Bifidobacterium lactis and Lactobacillus delbrueckii as biocatalysts, respectively. The DP-DM sequence removed up to 96 % of the protein and 98 % of the calcium, surpassing chemical methods. This also eliminated the need to control the pH of the fermentation, resulting in a simpler process. In contrast, the DM-DP sequence required controlling the pH of the process to optimize protease activity. Enzymatic deacetylation preserved the chitosan structure but produced lower molecular weight oligomers. Therefore, an additional chemical step was necessary to achieve a higher degree of deacetylation and improve the purity and structural integrity of chitosan. This combined biological-chemical methodology offers a more efficient and sustainable pathway for producing high-quality chitin and chitosan, showing a superior alternative to purely chemical processes for the treatment of shrimp shell waste. The obtained biopolymers possess desirable physicochemical properties suitable for diverse industrial and biomedical applications, highlighting the potential for scalable and environmentally friendly bioprocessing.