Green extraction of chitin from Litopenaeus vannamei shell waste using deep eutectic solvents coupled with ultrasound-generated bulk nanobubbles.

A novel green strategy for chitin extraction from Litopenaeus vannamei shell waste was developed using choline chloride (ChCl)-based deep eutectic solvents (DESs) coupled with nanobubbles. Initially, three DES systems, including ChCl-citric acid (ChCl-CA), ChCl-lactic acid (ChCl-LA), and ChCl-glycerol (ChCl-Gly), were evaluated for chitin extraction performance. Among them, ChCl-Gly exhibited the highest extraction yield (39.85%), significantly outperforming ChCl-CA (26.53%), ChCl-LA (28.45%), and the conventional chemical method (17.91%) (P < 0.05). Therefore, ChCl-Gly was selected for further nanobubble-assisted extraction experiments at ultrasonic powers ranging from 100 to 400 W. The incorporation of bulk nanobubbles significantly enhanced extraction efficiency compared with pristine DES treatment. The maximum extraction yield (41.40%) was achieved by the ChCl-Gly-NB 100 W treatment, whereas ChCl-Gly-NB 400 W provided the best overall performance, with high extraction yield (39.49%), deproteinization efficiency (>96%), demineralization efficiency (>86%), while preserving the characteristic α-chitin structure. The extracted chitin exhibited high crystallinity (77.32%), favorable thermal stability (Tmax = 336 °C), and a porous fibrillar morphology, indicating effective removal of non-chitinous components. Overall, the synergistic DES-BN system offers a sustainable, low-toxicity, and highly efficient alternative to conventional acid-alkali extraction methods for shrimp shell valorization and green chitin production.