Harnessing Green Solvents for Extraction of Natural Food Colorants from Plants

Aurelia Bárbara^*
*Correspondence: Aurelia Bárbara, Department of Medicinal Chemistry, Medical University of Lublin, Jaczewskiego 4, 20-090 Lublin, Poland, Email:

Introduction

In recent years, there has been a growing demand for natural food colorants due to increasing consumer awareness of health and environmental concerns associated with synthetic additives. Plants offer a vast array of pigments that can be utilized as natural colorants, ranging from vibrant reds to soothing greens. However, the extraction of these colorants presents challenges, particularly in terms of sustainability and environmental impact. In response to this, researchers have been exploring the use of green solvents for the extraction of natural food colorants from plants. Green solvents, derived from renewable resources and possessing low toxicity, offer a promising alternative to conventional solvents, aligning with the principles of green chemistry [1].

Description

Several extraction techniques are employed for isolating natural colorants from plant sources, including maceration, Soxhlet extraction, ultrasound-assisted extraction (UAE), supercritical fluid extraction (SFE) and subcritical water extraction (SWE). Each method has its advantages and limitations, with the choice often influenced by factors such as efficiency, selectivity, cost and environmental impact.

Green solvents, also known as eco-friendly or bio-based solvents, are characterized by their low environmental impact, renewable nature and reduced toxicity compared to traditional organic solvents. Common examples of green solvents include supercritical carbon dioxide (scCO₂), ethanol, water and ionic liquids. These solvents offer several advantages for the extraction of natural food colorants:

Green solvents are typically derived from renewable resources such as biomass, reducing reliance on fossil fuels and mitigating greenhouse gas emissions. Additionally, many green solvents are biodegradable, minimizing environmental pollution [2].

Unlike conventional solvents such as chloroform or benzene, green solvents pose minimal risks to human health and the environment. They exhibit low toxicity and are safer to handle, reducing occupational hazards for workers involved in the extraction process.

Green solvents can be tailored to optimize selectivity for specific compounds, allowing for the targeted extraction of natural food colorants while minimizing co-extraction of unwanted components. This selectivity enhances the purity and quality of the extracted colorants.

Certain extraction techniques utilizing green solvents, such as SFE and SWE, operate at moderate temperatures and pressures, resulting in lower energy consumption compared to conventional methods. This energy efficiency contributes to overall sustainability [3].

Supercritical carbon dioxide (scCO₂) is widely utilized as a green solvent for extracting natural pigments from plants due to its unique properties. In SFE, CO₂ is pressurized above its critical point, where it exhibits both gas-like and liquid-like properties, enabling efficient extraction of target compounds. Studies have demonstrated the successful extraction of carotenoids, chlorophylls and anthocyanins from various plant sources using SFE with CO₂.

Subcritical water extraction (SWE), also known as hot water extraction, involves the use of water at elevated temperatures and pressures below its critical point. Water acts as a green solvent capable of selectively extracting polar compounds such as polyphenols and flavonoids from plant materials. SWE offers advantages such as reduced solvent usage, shorter extraction times and preservation of thermolabile compounds.

While the use of green solvents for extraction of natural food colorants holds great promise, several challenges remain to be addressed. These include optimizing extraction conditions, scaling up processes for industrial applications and ensuring economic feasibility. Additionally, further research is needed to explore novel green solvents and extraction techniques that offer improved efficiency and sustainability [4,5].

Conclusion

The extraction of natural food colorants from plants using green solvents represents a sustainable and environmentally friendly approach that aligns with the principles of green chemistry. By harnessing the unique properties of green solvents such as supercritical CO₂ and subcritical water, researchers can achieve efficient extraction of vibrant pigments while minimizing environmental impact. Continued advancements in this field promise to provide the food industry with a diverse range of natural colorants that meet consumer demand for clean label products.

Acknowledgement

None.

Conflict of Interest

None.

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