Crocin is a glycosyl ester of crocetin acid and is classified as a water-soluble carotenoid. It is abundant in Gardenia jasminoides (Ellis GJE.) GJE is a natural ingredient widely used to impart an orange-yellow hue to traditional Vietnamese products such as cakes, jelly, and fish sauce. Crocin, a key bioactive compound in Gardenia, has been used in medicine for its antioxidant, anticancer, and memory-enhancing properties. In this study, we introduced an effective strategy for the extraction of crocin pigments derived from Gardenia. The pretreatment of Gardenia is crucial in the extraction process, with the most effective method involving freeze-drying Gardenia followed by grinding with liquid nitrogen to enhance the extraction efficiency. Second, this study focused on optimizing crocin extraction using ultrasound-assisted methods by evaluating key parameters, including ultrasonic amplitude, extraction time, materialto- solvent ratio, and solvent concentration. The crocin content reached 95.04±0.81 mg ․ g–1dw. Finally, the optimal ultrasound-assisted extraction conditions were determined using response surface methodology, ensuring the maximum extraction efficiency of crocin (ultrasonic amplitude (60.41%), extraction time (5.95 min), solvent concentration (41.48%), and material/solvent ratio (2.7 g/100 mL). The maximum concentration of crocin from Gardenia was determined to be 97.05±1.00 mg ․ g–1dw.

Abstract
Introduction
Materials and Methods
    Raw materials
    Extraction procedures for crocin using theultrasound-assisted method
Results and Discussion
    Effect of different raw material pretreatmentmethods on crocin extraction yield
    Effect of extraction conditions on crocin yield
    Optimization of crocin extraction using responsesurface methodology (RSM)
    Response surface methodology
Conclusion
ORCID
References

• Trang Nguyen Huu Phuoc(Department of Chemical Engineering – Environment, University of Technology and Education, University of Da Nang, Vietnam) Corresponding author
• Hong Tran Thi Kim(Department of Chemical Engineering – Environment, University of Technology and Education, University of Da Nang, Vietnam)
• Linh Tran Thi Ngoc(Department of Chemical Engineering – Environment, University of Technology and Education, University of Da Nang, Vietnam)
• Chi Mai Thi Phuong(Department of Chemical Engineering – Environment, University of Technology and Education, University of Da Nang, Vietnam)