**2. Phenolic composition of red/dark‐colored fruits**

### **2.1. Phenolic composition of wine grapes and table grapes**

Grapevine (*Vitis vinifera* L.) is the most important Mediterranean fruit crop, used to pro‐ duce wine, table grapes, and raisins. The phenolic compounds in grapes include two classes of phenolic compounds: non‐flavonoids and flavonoids. The major C<sup>6</sup> ‐C3 ‐C<sup>6</sup> flavonoids in grapes include conjugates of flavonols, quercetin, and myricetin; flavan‐3‐ols (+)‐catechin and (‐)‐epicatechin; and malvidin‐3‐*O*‐glucoside and other anthocyanins. Non‐flavonoids include C<sup>6</sup> ‐C<sup>1</sup> hydroxybenzoic acids, and gallic acid, C<sup>6</sup> ‐C3 hydroxycinnamates caffeic, caf‐ taric, and *p*‐coumaric acids; and C<sup>6</sup> ‐C3 ‐C<sup>6</sup> stilbenes *trans*‐resveratrol, *cis*‐resveratrol, and *trans*‐ resveratrol glucoside. Polyphenols are a diverse group of secondary metabolites, which exist in different grape bunch fraction, such as stems, skins, pulp, and seeds [4–8]. According to Pastrana‐Bonilla et al. [6], the average concentration of total phenolic compounds in wine grapes is around 2178.8 mg/g gallic acid equivalent, in seeds, 374.6 mg/g gallic acid equiva‐ lent, in skins, and 23.8 mg/g gallic acid equivalent, in pulps. In addition, for table grapes, several authors also reported high levels of global and individual phenolic compounds [9]. Also for grape raisins, several works reported high levels of phenolic compounds [10, 11]. Thus, Sério et al. [12] reported levels of total phenolic compounds from several commercial red raisins (namely from Cardinal and Moscatel of Alexandria grape varieties) that ranged from 110.8 to 406.9 mg/100 g raisin. Phenolic compounds play an important role in wine quality and also in sensorial characteristics of table grapes, such as color, astringency, bit‐ terness, and aroma. However, it is important to note that the phenolic composition of grape berries depends on grape variety, environmental factors, and viticultural practices [8, 13–15]. Consequently, all these isolated or combined factors will be critical for the composition of grape phenolic compounds, grape variety being one of the most important [16, 17]. Thus, genotypic differences among different varieties have a great influence in grape phenolic syn‐ thesis and accumulation during grape fruit maturation and development [18]. However, the interaction between the genotype, environment, and management practices heavily influ‐ ences the overall phenolic composition. Recently, Costa et al. [8] analyzed the phenolic com‐ position of several grape varieties cultivated at the same time in two Portuguese regions with distinct climatic conditions and reported that in general significantly higher global phenolic composition was obtained in the grapes collected in one of the regions. In addition, other work recently published [15] analyzed the adaptability of several red grape varieties from French origin to the other specific "terroirs" and compare their characteristics with native grape varieties. These authors reported that French grape varieties studied showed a higher degree of adaptation of the climate and soil conditions from the Portuguese vineyards, espe‐ cially for phenolic composition. Thus, grape phenolic characteristics are strongly influenced by environmental conditions specific from each place and consequently each grape variety produced in a specific terroir reflects the locality in its chemical composition, including in phenolic composition. According to several works, the geological and soil conditions [19], vineyard altitude [20], sunlight exposition [21], climate [21, 22], and solar radiation [23] of a region are important environmental factors that determine grape phenolic composition. Finally, there are also other factors that directly or indirectly may determine the grape pheno‐ lic composition, namely cultivation practices [22], exposure to diseases [24], and the degree of grape ripeness [4, 17].

### **2.2. Phenolic composition of sweet cherry**

**1. Introduction**

262 Phenolic Compounds - Natural Sources, Importance and Applications

processing techniques [3].

taric, and *p*‐coumaric acids; and C<sup>6</sup>

include C<sup>6</sup>

**2. Phenolic composition of red/dark‐colored fruits**

of phenolic compounds: non‐flavonoids and flavonoids. The major C<sup>6</sup>

‐C3 ‐C<sup>6</sup>

‐C<sup>1</sup> hydroxybenzoic acids, and gallic acid, C<sup>6</sup>

**2.1. Phenolic composition of wine grapes and table grapes**

Phenolic compounds (phenolic acids, flavonoids, and stilbenes) are today among the most important classes of phytochemicals, since they are responsible for disease protection con‐ ferred from diets rich in these compounds [1]. Some fruits with high content of phenolic com‐ pounds, including flavonols, flavones, anthocyanins, and phenolic acids are grapes, sweet cherries, and blueberries. Polyphenolic compounds form complexes with salivary proteins, playing a role in the sensation of astringency, due to delubrication of oral surfaces. For astrin‐ gency, the tannin molecular weight seems to be important for its perception and to the inter‐ actions with salivary proteins. Flavor and color are also important factors for the selection of fruit by consumers. Sweetness and bitterness are mutually suppressed in mixtures, but astringency and bitterness tend to be perceived as negative attributes. Polyphenols' sensory properties are related to molecules specific structures, including pigments correlated to fruit color [2]. This richness in phenolic compounds is also directly related with the positive effects on human health. However, the phenolic composition of the red/dark‐colored fruits depends on cultivar, maturity, growing environment, cultural practices, postharvest conditions, and

Grapevine (*Vitis vinifera* L.) is the most important Mediterranean fruit crop, used to pro‐ duce wine, table grapes, and raisins. The phenolic compounds in grapes include two classes

grapes include conjugates of flavonols, quercetin, and myricetin; flavan‐3‐ols (+)‐catechin and (‐)‐epicatechin; and malvidin‐3‐*O*‐glucoside and other anthocyanins. Non‐flavonoids

resveratrol glucoside. Polyphenols are a diverse group of secondary metabolites, which exist in different grape bunch fraction, such as stems, skins, pulp, and seeds [4–8]. According to Pastrana‐Bonilla et al. [6], the average concentration of total phenolic compounds in wine grapes is around 2178.8 mg/g gallic acid equivalent, in seeds, 374.6 mg/g gallic acid equiva‐ lent, in skins, and 23.8 mg/g gallic acid equivalent, in pulps. In addition, for table grapes, several authors also reported high levels of global and individual phenolic compounds [9]. Also for grape raisins, several works reported high levels of phenolic compounds [10, 11]. Thus, Sério et al. [12] reported levels of total phenolic compounds from several commercial red raisins (namely from Cardinal and Moscatel of Alexandria grape varieties) that ranged from 110.8 to 406.9 mg/100 g raisin. Phenolic compounds play an important role in wine quality and also in sensorial characteristics of table grapes, such as color, astringency, bit‐ terness, and aroma. However, it is important to note that the phenolic composition of grape berries depends on grape variety, environmental factors, and viticultural practices [8, 13–15]. Consequently, all these isolated or combined factors will be critical for the composition of

‐C3

stilbenes *trans*‐resveratrol, *cis*‐resveratrol, and *trans*‐

‐C3 ‐C<sup>6</sup>

hydroxycinnamates caffeic, caf‐

flavonoids in

Cherries are an excellent source of antioxidants, particularly phenolics, such as flavonoids, fla‐ van‐3‐ols, and flavonols in addition to non‐flavonoid compounds such as hydroxycinnamic and hydroxybenzoic acids, which are concentrated in the epicarp and mesocarp of the fruit [25, 26]. The most abundant phenolic compounds are anthocyanins such as cyanidin‐3‐*O*‐rutinoside, cyanidin‐3‐*O*‐glucoside, peonidin‐3‐*O*‐rutinoside and glucoside, as well as pelargonidin‐3‐*O*‐ rutinoside are the most important anthocyanins in cherries [27]. The total anthocyanin content ranged from 6.21 to 94.20 mg cyanidin‐3‐*O*‐glucoside equivalents/100 g fresh weight in 24 sweet cherry cultivars grown on the mountain sides of the Etna volcano (Sicily, Italy) [28]. Other phe‐ nolics in cherries include neochlorogenic acid, *p*‐coumaroylquinic acid, and chlorogenic acid as the main hydroxycinnamic acids [26, 29, 30], the flavonol rutin and the flavan‐3‐ols (+)‐catechin and (‐)‐epicatechin (**Figure 1**) [26, 31]. The total phenol content ranged from 84.96 to 162.21 mg gallic acid equivalents/100 g fresh weight in 24 sweet cherry cultivars grown in Italy [28]. Moreover, several studies reported higher phenolic content [26, 32] and antioxidant activity [32] in ripe cherries than in partially ripe. However, other pre‐ and postharvest factors, such as rootstock, cultivar, climate, soil type, storage conditions, and processing can significantly alter the amounts of bioactive compounds. In fact, levels of chlorogenic acid, neochlorogenic acid, *p*‐coumaric acid, and quercetin‐3‐rutinoside were higher in fruits grown on Weiroot 13 and PiKu 1 rootstocks compared to MaxMa 14, Weiroot 158, F12/1 and Gisela 5 rootstocks [31]. According to Gonçalves et al. [26], the cherry cultivars have the same phenolic pattern, how‐ ever, with large variation on content as presented in **Table 1**. The climatic conditions have great influence on phenolic levels. Indeed, Gonçalves et al. [26] stated that higher temperature and solar irradiation favored the biosynthesis of phenolic acids and decreased the content of antho‐ cyanins. However, the phenolic content tends to reach highest levels in the late stage of final maturity as refereed by Stöhr et al. [33]. In recent research, the preharvest application of several products to improve cherry quality, such as the oxalic acid (2 mM), has been studied, which increased anthocyanins, flavonols, neochlorogenic, and chlorogenic acids [34]. All the pheno‐ lic compounds and the antioxidant activity increased in several sweet cherry cultivars during cold storage [26, 27, 32, 35]. Also, the level of phenolics in "Canada Giant" and "Ferrovia" cherries increased during 8 days of shelf life [36]. Nevertheless, Esti et al. [37] detected a total anthocyanin content decrease of 41–52% in two sweet cherry cultivars after 15 days at 1°C and 95% RH. The use of edible coatings has been used to extend the postharvest storage of cher‐ ries. Petriccione et al. [38] specified that chitosan‐coated sweet cherries presented higher total phenolic, flavonoid, and anthocyanin levels. Moreover, increasing health‐promoting properties of cherry fruit can be achieved with the addition of methyl salicylate treatment to cherry trees. This compound also delays the fruit postharvest senescence process by increasing the activity of the enzymes involved in ROS scavenging [39].

**Figure 1.** HPLC chromatogram of the Van sweet cherry cultivar extracts recorded at 280 nm. Adapted from Gonçalves et al. [26].


NcAc, neochlorogenic acid; *p*CqAC, *p*‐coumaroylquinic acid; CAc, chlorogenic acid; Cat, catechin; Epi, epicatechin; Rut, Rutin; cy‐3‐glu, cyanidin‐3‐*O*‐glucoside; cy‐3‐rut, cyanidin‐3‐*O*‐rutinoside; pn‐3‐glu, peonidin‐3‐*O*‐glucoside; plg‐3‐rut, pelargonidin‐3‐*O*‐rutinoside; pn‐3‐rut, peonidin‐3‐*O*‐rutinoside; n.d., not detected. Adapted from Gonçalves et al. [26].

**Table 1.** Content of several phenolic compounds in four sweet cherry cultivars (mg /100g fresh weight).

Almost all phenolic compounds in sweet cherry show strong antioxidant activity [35, 40, 41]. Adequate consumption of phenolic compounds may offer health benefits that include inhibi‐ tion of tumor cells growth [41], inhibition of inflammation [42], and protection against neu‐ rodegenerative diseases [43]. According to Matias et al. [44], a phenolic‐rich extract derived from sweet cherries could be an attractive candidate to formulate an agent for the prevention of oxidative stress‐induced disorders such as intestinal inflammation disorders. In spite of the large variations in the phenolic compounds content observed among several cherry cultivars, the levels of health‐promoting compounds are relevant to human health. Sweet cherries might therefore be considered as a functional food [41]. In fact, cyanidin‐3‐*O*‐rutinoside can slow down the absorption of carbohydrates by the inhibition of α‐glucosidase which may there‐ fore be useful as inhibitor to prevent or treat diabetes mellitus [45]. Cyanidin‐3‐*O*‐glucoside showed cardioprotective effects by reducing blood lipid levels in rats [46]. The oxygen radical absorbance capacity (ORAC) assay indicated that the fruit of all genotypes possessed consid‐ erable antioxidant activity [28]. Moreover, several cherry cultivars were effective in inhibiting human cancer cells derived from colon (HT29) and stomach (MKN45) [41]. Finally, cherry phenolic, mainly anthocyanins, also protects neuronal PC 12 cells from cell‐damaging oxida‐ tive stress (antineurodegenerative activity). However, this protection is dose‐dependent [43].
