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Phenolic Compounds in Plants
The main categories of bioactive compounds found in plants are anthocyanins, flavanols, flavan-3-ols (catechin monomers), curcumin, proanthocyanidins, and phenolic acid derivatives (Cote et al. 2010). Table 2 illustrates encapsulation of bioactive
compounds in protein matrices.
Anthocyanins
Anthocyanins as water-soluble bioactive compounds are widely present in flowers,
fruits, and vegetables (Flores et al. 2014a, b). Cyanidin, delphinidin, and peonidin
are the most common anthocyanin molecules which bind to one or more sugar molecules. In anthocyanidin molecule, glycosylation almost always occurs at the C3
position (Cote et al. 2010). The high amount of anthocyanins contributes to the
color of the plants (Blumberg et al. 2013). Their color depends on the pH: anthocyanins exist as red-colored flavylium cationat pH below 3 which is the stable form and
they convert to quinoidal base (blue color)at pH ranging from 6 to 8 which is an
unstable state and therefore, anthocyanins bioavailability is reduced (Oidtmann
et al. 2012). In plants, anthocyanins are stable as the pH of the cells is acidic.
However after extraction, anthocyanins tend to be unstable at high pH and in the
presence of oxygen, therefore, susceptible to degradation (Betz et al. 2012; Flores
et al. 2014a, b). Anthocyanins can also degraded by heat treatment, UV light exposure, and presence of specific enzymes or some metallic ions (Betz et al. 2012;
Frank et al. 2011). Anthocyanins are absorbed by the stomach and the intestine after
digestion (Zhang et al. 2014). However, the bioavailability of anthocyanins is very
low as the environmental conditions trigger the degradation of anthocyanins in the
gastrointestinal tract (Betz and Kulozik 2011). Hence, introducing a protective
method to preserve them has acquired a lot of interest recently. Microencapsulation
is the most promising approach for improving anthocyanins stability which aims at
ensures the quality and physicochemical stability of heat- or photosensitive components (Vicente et al. 2017).
Oanceaa et al. (2018) investigated microencapsulation of the sour cherries anthocyanins within whey proteins isolate and gum acacia via freeze-drying method. In
vitro digestibility tests revealed that the whey proteins isolate had the ability to
protect the anthocyanins from the gastric digestion, their release being facilitated
into the intestine. Similarly, Shaddel et al. (2018) encapsulated black raspberry
anthocyanins followed by GE–GA (gelatine:gumacacia) complex coacervate matrix
by double emulsion system, and results revealed that this treatment ismore efficient
as it confers high loadingcapacity, good morphological features, high retention of
anthocyanins, aswell as more color retention and greater stability during storage.
F. Jhan et al.
Phenolic Compounds in Plants
The main categories of bioactive compounds found in plants are anthocyanins, flavanols, flavan-3-ols (catechin monomers), curcumin, proanthocyanidins, and phenolic acid derivatives (Cote et al. 2010). Table 2 illustrates encapsulation of bioactive
compounds in protein matrices.
Anthocyanins
Anthocyanins as water-soluble bioactive compounds are widely present in flowers,
fruits, and vegetables (Flores et al. 2014a, b). Cyanidin, delphinidin, and peonidin
are the most common anthocyanin molecules which bind to one or more sugar molecules. In anthocyanidin molecule, glycosylation almost always occurs at the C3
position (Cote et al. 2010). The high amount of anthocyanins contributes to the
color of the plants (Blumberg et al. 2013). Their color depends on the pH: anthocyanins exist as red-colored flavylium cationat pH below 3 which is the stable form and
they convert to quinoidal base (blue color)at pH ranging from 6 to 8 which is an
unstable state and therefore, anthocyanins bioavailability is reduced (Oidtmann
et al. 2012). In plants, anthocyanins are stable as the pH of the cells is acidic.
However after extraction, anthocyanins tend to be unstable at high pH and in the
presence of oxygen, therefore, susceptible to degradation (Betz et al. 2012; Flores
et al. 2014a, b). Anthocyanins can also degraded by heat treatment, UV light exposure, and presence of specific enzymes or some metallic ions (Betz et al. 2012;
Frank et al. 2011). Anthocyanins are absorbed by the stomach and the intestine after
digestion (Zhang et al. 2014). However, the bioavailability of anthocyanins is very
low as the environmental conditions trigger the degradation of anthocyanins in the
gastrointestinal tract (Betz and Kulozik 2011). Hence, introducing a protective
method to preserve them has acquired a lot of interest recently. Microencapsulation
is the most promising approach for improving anthocyanins stability which aims at
ensures the quality and physicochemical stability of heat- or photosensitive components (Vicente et al. 2017).
Oanceaa et al. (2018) investigated microencapsulation of the sour cherries anthocyanins within whey proteins isolate and gum acacia via freeze-drying method. In
vitro digestibility tests revealed that the whey proteins isolate had the ability to
protect the anthocyanins from the gastric digestion, their release being facilitated
into the intestine. Similarly, Shaddel et al. (2018) encapsulated black raspberry
anthocyanins followed by GE–GA (gelatine:gumacacia) complex coacervate matrix
by double emulsion system, and results revealed that this treatment ismore efficient
as it confers high loadingcapacity, good morphological features, high retention of
anthocyanins, aswell as more color retention and greater stability during storage.
F. Jhan et al.