**1. Introduction**

The types of foods the consumers consume have taken greater relevance during the last decade [1, 2]. The preference for consuming natural, fresh, and uncrossed food products is not new. Particularly when the term "functional food" appeared in the foods and nutritional areas. Functional foods claimed to provide health benefits or cure some diseases after the incorporation to a food or modification of the food [3]. The food industry has taken this into account and is interested in increasing the consumption of natural compounds through natural ingredients in the food matrix. Due to this, researchers have investigated different compounds such as polyphenols, mainly colored polyphenols of vegetables, and their residues [4–6] in terms of extraction, stability, conservation.

Colored polyphenols include anthocyanins, betalains, and some flavonoids [7, 8]. Their molecular structure poses double bonds and acts as antioxidants [9, 10] against cardiovascular illness, cancer, diabetes, and heart and neurological ailments; also, some have exhibited anti-inflammatory and antimicrobial effects [11–13].

Anthocyanins are unstable to some factors such as pH, temperature, heat, enzymes, oxygen, and other compounds (co-pigments or metals) [14–16]. One or more of these factors could be involved during the anthocyanins extraction. Therefore, extraction type and process conditions play an important role in the recovery and further stability of anthocyanins. There exist different types of extraction methods; they are divided into physical (shearing force, ultrasound, microwaves, pulsed electric fields), chemical (decoction, maceration), and biological methods (enzymatic). Another way of classification is as conventional and non-conventional technologies [17, 18]. However, most of them require the use of at least one type of solvent. Mohd Fuad et al. [19] have mentioned that the selection of the solvent is crucial to recover the compound of interest due to the coexistence of many compounds with different chemical characteristics, polarities, wherein each compound has its own solubility in a solvent. The main solvents used for anthocyanin extraction are polar solvents (water, ethanol, acetone, acetic acid) [17]. However, these solvents present the disadvantage of being highly volatile, flammable, and corrosive as well as toxic, carcinogenic, and non-biodegradable [19]. In some cases, the use of solvents is excessive, expensive, requires filtering, multiple extractions, and techniques to remove the solvent using pressurized evaporation [17].

Recently, the deep eutectic solvents (DES), a new green alternative for organic solvents, are under research since they exhibit a promising capacity for extracting anthocyanins. DES consists of a mixture of two or more organic compounds which in combination present a reducing melting point, lower than each individual component, and exist as liquid form at room temperature [20, 21]. DES shows the advantage of being easily synthesized, inexpensive, biodegradable, and with low toxicity [22]. In addition, they have the capacity of being modified to improve extraction yields and be selective [23]. DES have been used to extract bioactive compounds such as flavonoids, polyphenols, and pigments [21].
