Banca de QUALIFICAÇÃO: SINARA SILVA NEVES MACHADO

SUSTAINABLE POTENTIAL OF CHITIN AND CHITOSAN PRODUCTION FROM ALTERNATIVE SOURCES

biopolymers, insects, residues, Zophobas morio, Tenebrio molitor, Blaptica dúbia.

Insect farms are becoming more common worldwide despite generating expressive waste from their creations. These residues mainly consist of exoskeletons from the early stages and dead adults at the end of their life cycle. Waste is a source of chitin with the potential for technological application. This work aimed to obtain and characterize chitin and chitosan from the rearing residues of three specimens of insects, Tenebrio molitor, Zophobas morio, and Blaptica dúbia. The yield of chitin and chitosan in the percentage of the dry mass of insects ranged from 11.21 to 20.89% and 6.26 to 7.07%, respectively. The sample with the lowest percentage of chitin was the exoskeleton of the larva of Zophobas morio, and the one with the highest percentage was the exoskeleton of the beetle of Zophobas morio. The degree of deacetylation ranged from 75.75 to 89.21%, and the solubility from 69.88 to 94.39%. Micrographs revealed varied surfaces, including pores, roughness, and fibrillar shapes. The infrared spectra corroborated the successful obtainment of chitin and chitosan and the different degrees of deacetylation. The diffractograms obtained confirmed the obtainment of chitin and chitosan obtained from insect residues, with the presence of α-chitin. Relative crystallinity indices ranged from 65.9-89.2%. The TG curves showed two typical thermal events, the first associated with water evaporation and the second with the thermal decomposition of samples with T_onset DTG ~ 300 ºC. The chitosan solutions showed a pseudoplastic behavior with apparent viscosities ranging from 195.96 to 249.86 mPa.s. In general, the characterization of biopolymers extracted from insect residues showed high similarity concerning those obtained from conventional sources. The results of the present study reinforce the feasibility of using alternative sources of chitin and chitosan, providing the use of waste from insect farms, and contributing to sustainability.