**9. Encapsulation of anthocyanins**

As it has been mentioned throughout the chapter, anthocyanins are potentially used in food and pharmaceutical industries since their practical applications as natural colourants [13, 49, 58, 76, 79, 327] as well as their potential health benefits to humans [13, 56, 90, 110, 114]. Nevertheless, the incorporation of anthocyanins into food and medical products is a challenging task due to their low stability and susceptibility to degradation [292] towards environmental conditions during processing and storage. In order to prevent these limitations, delivery systems have been developed, and among them, encapsulation [328–334] would appear to be an interesting option.

Encapsulation, developed approximately 60 years ago [335], is a rapidly expanding technology to entrap one substance (active agent, solid, liquid or gas) within another substance (a matrix or a polymeric wall) in the form of micro‐ and nanoparticles to protect the 'actives' from environmental conditions and their interactions with other components or to control their release [331, 332]. In addition, once encapsulated bioactive compounds are easier to transportation and handling, masking of undesirable flavour and compartmentalization of two or more reactive species [328, 335].

In general, the three‐stage process during encapsulation is [335] as follows: (i) formation of the wall around the material; (ii) ensuring that undesired leakage does not occur; and (iii) ensuring that undesired materials are kept out. For that end, different techniques have been studied and applied to encapsulate active agents, some of them successfully applied for anthocyanins including spray‐ drying, emulsification, ionotropic gelation or coacervation, and thermal gelation [328, 330].

Among the most important factors to take into account when choosing the microencapsulation technique are particle size, physicochemical properties of the core, the process cost and the selection of wall materials. According to the literature, encapsulation by spray‐drying is the most economical, simplest and the most applied method (80–90% of encapsulates are spray‐

dried) for preservation of anthocyanin pigments [332], being maltodextrins as the most used coating material. The use of other techniques than spray‐drying [331] still remains an unexplored area. This fact could be explained by the hydrophilic nature of anthocyanins [332, 336], so it is, therefore, a promising area of research.

Ghiselli et al. [320] studied three polyphenolic subfractions of red wine, evaluating the capacity to trap hydroxyl and peroxyl radicals, the inhibition in vitro of the oxidation of LDLs and platelet aggregation. The fraction containing the anthocyanins proved to be the most effective in its capacity to trap ROS and to inhibit the oxidation of LDLs and platelet aggregation. Anthocyanins are quantitatively the most abundant phenolic subclass in red wine [321, 322]. The other two fractions, containing the phenolic acids and quercitin 3‐glucuronide, and pro-

Some authors still attribute the antioxidant activity of red wines to all polyphenolic compounds [323–325], not discarding the hypothesis that the different classes of polyphenolic compounds can be more effective and act in a synergistic way. However, according to Fernández‐Pachón et al. [319], no synergistic effects were observed among the isolated fractions of red wines (anthocyanins, flavonols and phenolic acids). Galanakis et al. [326] characterized the phenolic content and antioxidant capacity of Cypriot wines. The higher concentrations of phenols did not always reflect higher antioxidant capacity of wines, probably due to the observed antago-

As it has been mentioned throughout the chapter, anthocyanins are potentially used in food and pharmaceutical industries since their practical applications as natural colourants [13, 49, 58, 76, 79, 327] as well as their potential health benefits to humans [13, 56, 90, 110, 114]. Nevertheless, the incorporation of anthocyanins into food and medical products is a challenging task due to their low stability and susceptibility to degradation [292] towards environmental conditions during processing and storage. In order to prevent these limitations, delivery systems have been developed, and among them, encapsulation [328–334]

Encapsulation, developed approximately 60 years ago [335], is a rapidly expanding technology to entrap one substance (active agent, solid, liquid or gas) within another substance (a matrix or a polymeric wall) in the form of micro‐ and nanoparticles to protect the 'actives' from environmental conditions and their interactions with other components or to control their release [331, 332]. In addition, once encapsulated bioactive compounds are easier to transportation and handling, masking of undesirable flavour and compartmentalization of two or more reac-

In general, the three‐stage process during encapsulation is [335] as follows: (i) formation of the wall around the material; (ii) ensuring that undesired leakage does not occur; and (iii) ensuring that undesired materials are kept out. For that end, different techniques have been studied and applied to encapsulate active agents, some of them successfully applied for anthocyanins including spray‐ drying, emulsification, ionotropic gelation or coacervation, and thermal gelation [328, 330].

Among the most important factors to take into account when choosing the microencapsulation technique are particle size, physicochemical properties of the core, the process cost and the selection of wall materials. According to the literature, encapsulation by spray‐drying is the most economical, simplest and the most applied method (80–90% of encapsulates are spray‐

nistic effect between hydroxycinnamic acid derivatives, flavonols and anthocyanins.

cyanidins, catechins and quercitin 3‐glucoside, are less active.

**9. Encapsulation of anthocyanins**

228 Flavonoids - From Biosynthesis to Human Health

would appear to be an interesting option.

tive species [328, 335].

In order to increase the efficiency and stability by spray‐drying, different biopolymers are used [328, 333], most common are natural gums (gum arabic, alginates, etc.), proteins (dairy proteins, soy proteins, gelatine, etc.), carbohydrates (maltodextrins and cellulose derivatives) and/or lipids (waxes, emulsifiers). Some authors [330, 332] have revealed that a combination of other wall materials and other modifiers (as oxygen scavengers, antioxidants, chelating agents, and surfactants) increases the encapsulation efficiencies.

**Table 8** [131, 328–342] summarizes some selected reviews on anthocyanin, polyphenol and bioactive compounds encapsulation. In last years, the use of biodegradable polymeric nanoparticles has attracted the interest of researches [337] due to their good biocompatibility, easy design and preparation, structure variations and interesting biomimetic characters.


**Table 8.** Selected reviews on encapsulations of anthocyanins, polyphenols and bioactive substances.

#### **10. Final comments**

Anthocyanins [13, 14, 17, 293, 343–346] are members of the flavonoid group of phytochemicals, a group predominant in fruits and vegetables, especially in berries. Recent research raised awareness of the importance [347, 348] of anthocyanins in the diet. Anthocyanin identification is critical in adulteration and profiling [349, 350] studies and in evaluating the quality of crude and processed food. The design of plant products with a high added value allows increasing the synthesis [351] of plant‐derived food antioxidants and in particular anthocyanins. In an effort to expand the palette of natural organic colourants (colour additives of food and beverage products), the food industry has launched a search for new products, for example blue colourants [352, 353]. Food, pharmaceutical and nutraceutical industries are interested in [354] clean recovery of valuable compounds. Thus, exploration of more efficient, cost‐effective and eco‐friendly techniques of polyphenol extraction, that is anthocyanins, from food matrices and waste plant food processing residues (grape fruit, fruits by‐products, winery waste materials, by‐products) is a challenge [355–360]. In any case, in order to ascertain the nutraceutical potential of bioactive compounds, quantification [359, 361] is required, thus obtaining vital information for future food industrial applications.

Apart from their well‐known potential for their practical applications as natural colourants [13, 48, 49, 58, 76, 79, 281, 328], anthocyanins show antioxidant activity and a wide variety of health‐promoting properties for human health [12, 56, 81, 85, 90, 111, 112, 120, 130, 264, 343], ranging from cytoprotective, antimicrobial and antitumor activities to neuroprotective, anti‐ obesity and lipidomic potential. Moreover, epidemiological evidence suggests [12, 111, 112, 362] a direct correlation between anthocyanin intake and a lower incidence of chronic and degenerative diseases.

However, the issue of food antioxidants although important is a controversial topic [11, 64, 72, 363–365]. The plethora of published studies on mechanisms [132] that may mediate therapeutic or chemical chemopreventive effects of dietary constituents contrasts sharply with a scarcity of information on their pharmaceutical and clinical‐pharmacological properties. Most of the evidence supporting a therapeutic effect of anthocyanins is in vitro or mechanical in nature, although the number of studies on bioavailability in humans has increased significantly over the past two decades. Anthocyanins show a complex biochemical (more than other compounds of flavonoids type), and there is still much to discover [94, 95, 366] about the biochemical activity and clinical pharmacology of these compounds (stability, bioavailability and formulation of dietary constituents), which constitutes an obstacle [367] to understand their health benefits. As evidence of their therapeutic effects accumulates, it is important to understand the nature [81, 85, 87, 89, 139] of the absorption and metabolism "in vivo" and that such knowledge will enable the development of new food products, both fresh and manufactured with greater therapeutic efficacy [95, 366]. Progress in this field requires a multidisciplinary research carried out by a wide range of professionals: food science and technology scientists, chemists (analytical chemists), nutritionist, physiologists, pharmacist, pharmacologists, engineers, physicians, biologists, genetics, clinics, etc., being a field in which promising progress will be undoubtedly made in the future.

More complete details of the basics of polyphenols and anthocyanins can be seen in previous reviews [4–7, 346, 368] by the authors.
