Optimization of Ultrasound-Assisted Obtention of Bluish Anthocyanin Extracts from Butterfly Pea (Clitoria ternatea) Petal Powders Using Natural Deep Eutectic Solvents

What if the secret to vibrant blue colors and antioxidant power lies in a simple flower, extracted with a solvent as natural as the petal itself?

Butterfly pea flowers are more than just a pretty sight—they're packed with anthocyanins, the pigments behind their striking blue hue. But extracting these fragile molecules has always been a challenge. Traditional methods often rely on harsh solvents, which can degrade the very compounds we want to preserve. Enter natural deep eutectic solvents (NADES): a greener, gentler alternative that's turning heads in the food, pharmaceutical, and cosmetic industries.

In this study, researchers optimized the ultrasound-assisted extraction of anthocyanins from butterfly pea petal powders. They tested different times (15–50 min), temperatures (40–80°C), and petal-to-solvent ratios (2.5–7%), using a choline chloride:glycerol (ChCl:Gly) NADES. The best results came from 80°C, 50 minutes, and a 7% petal ratio—conditions that yielded a striking 374.65 mg DGE/L of anthocyanins, compared to just 211.63 mg/L with water.

But the real win was stability. When stored at 5°C, the ChCl:Gly extract lost only 16% of its anthocyanins over 21 days, while the water extract lost 38%. The NADES extract also boasted superior antioxidant capacity (156.43 µmol/mL) and showed less noticeable color changes, especially when refrigerated. This suggests that NADES not only extracts more but also better preserves the bioactive goodness.

The implications are huge: a sustainable, effective method to produce stable, bioactive extracts that could color our foods, fortify our supplements, and enhance our cosmetics—all from a humble flower and a natural solvent.

Key Points

• NADES (ChCl:Gly) outperforms water in anthocyanin extraction.
• Optimal extraction: 80°C, 50 min, 7% petal ratio.
• NADES extract loses only 16% anthocyanins after 21 days at 5°C.