Green extraction of carotenoids from pumpkin with ultrasound-assisted method; optimization using response surface methodology

Abstract

Pumpkin is a rich source of carotenoids with antioxidant activity. The objective here was to extract carotenoids from pumpkin through ultrasound and sunflower oil as a green solvent. The effects of solid-solvent ratio (0.01–0.1 g/mL), temperature (20–60 °C), and ultrasonic time (10–70 min) were assessed by applying response surface methodology (RSM). Interactive effects of solid-solvent ratio, temperature, and ultrasonic time increased the carotenoid, phenolic content, and antioxidant activity of enriched oil types, where, at the highest levels of independent variables, a decreasing trend was observed. The solid-solvent ratio at 0.06 g/mL and the ultrasonic time of 100 min increased the extraction of carotenoid and phenolic compounds. L* and a* values increased by an increase in the solid-solvent ratio and decreased at high temperatures. The b* value and chroma decreased by an increase in the solid/solvent and time. An increase in the solid-solvent ratio and temperature and ultrasonic time increased the b* value and chroma. The peroxide, acid, and anisidine values were not considerably different between groups (p˃0.05). The optimal conditions for the highest carotenoid content extracted from pumpkin with ultrasound and sunflower oil included 0.08 g/mL solid/solvent, at 30 °C, and an extraction time of 55 min. ConclusionThe optimum extraction condition yielded the expected highest volume of carotenoid content (13.93 mg/100 g), β-carotene (13.30 mg/kg), phenolic content (219.6 mg GAE/g), antioxidant activity (83.66%), L* (12.85), a* (2.39), b* (7.12), and chroma (7.50). The enriched oil type with pumpkin carotenoid is a proper natural colorant for the food industry.