Sustainable Extraction and Characterization of Chitin and Chitosan from Insect Frass

Several insects hold great promise as vital organisms of the future due to their ability to eliminate various types of organic waste under benign conditions while serving as nutritious protein sources for humans and other animals. During their lifecycle, insects produce a significant volume of excrement, commonly known as frass. The utilization or valorization of insect frass is crucial for ensuring the sustainability of insect-related biodegradation processes. In this paper, we present a seamless process for upgrading insect frass. Specifically, we demonstrate that mealworm (Tenebrio molitor) frass, produced through the biodegradation of plastic (polystyrene) or food waste (shrimp shells), can be straightforwardly used to produce high-quality chitin and chitosan, two essential biopolymers. Depending on the insect feed, chitin and chitosan can be isolated with high purity and N-acetylation, exhibiting physicochemical properties similar to those of commercially obtained products through either acid/base treatment or ionic liquid treatment. Moreover, unlike extraction from other major sources, these carbohydrates can potentially be isolated in a one-pot process with good purity using only base treatment, without the need for corrosive acid solutions for demineralization. These findings suggest that insect frass could serve as a more sustainable source of these two crucial biomaterials.