Efficient Anthocyanin Recovery from Black Bean Hulls Using Eutectic Mixtures: A Sustainable Approach for Natural Dye...

Area of Science:

• Food Science
• Natural Product Chemistry
• Green Chemistry

Background:

• Growing demand for natural colorants.
• Need for stable and efficient extraction methods for anthocyanins.
• Potential of agricultural byproducts like black bean hulls as a source.

Purpose of the Study:

• To extract anthocyanins from black bean hulls using a eutectic mixture (choline chloride:citric acid).
• To optimize ultrasound-assisted extraction (UAE) parameters.
• To evaluate the stability and concentration of extracted anthocyanins and their potential application.

Main Methods:

• Ultrasound-assisted extraction (UAE) optimized for temperature, power, and eutectic mixture concentration.
• Analysis of major anthocyanins (delphinidin-3-O-glycoside, petunidin-3-O-glycoside, malvidin-3-O-glycoside).
• Assessment of anthocyanin stability (heat and light) and concentration via cryoconcentration.
• Evaluation of color change at different pH levels.

Main Results:

• Optimal extraction achieved at 66 °C, 420 W, and 8.2% (w/v) eutectic mixture.
• Anthocyanin half-life increased significantly (12-fold for heat, 10-fold for light) in the eutectic mixture.
• Centrifuge-assisted cryoconcentration effectively concentrated the extracts, improving green metrics.
• Extracts demonstrated vibrant colors and potential as pH indicators.

Conclusions:

• Eutectic mixtures and cryoconcentration offer an efficient, green method for extracting and stabilizing anthocyanins.
• The technology shows promise for developing anthocyanin-based smart packaging indicators.
• Broken black bean hulls are a viable source for high-quality natural colorants.