2(A)–(C), respectively. The concentration of monomeric anthocyanins (Table 2) ranged from 57.6 ± 9.4 to 86.2 ± 1.0 mg/L in Concord juices, 95.2 ± 4.4 to 250.2 ± 7.2 mg/L in Isabel juices, and 411.8 ± 1.1 to 436.1 ± 15.7 mg/L in Bordo juices. The addition of grape seeds showed no significant effect on the

anthocyanins content of the Bordo juices. In the Isabel juices, the anthocyanin content was significantly different among treatments, with concentration of monomeric anthocyanins up to 250.2 ± 7.2 mg/L in the selleck juice with seed concentration of 100 g/kg. However, the addition of seeds was poorly correlated with the total anthocyanins content of these juices (r = 0.51). For Concord and Bordo juices, no correlation was verified between seed addition and total monomeric anthocyanins. The inclusion of grape seeds from V. labrusca L. during juice production increased the overall bioactive content, which was confirmed by the total phenolic content in the juice samples. Also, a positive correlation between the total phenolics and the antioxidant capacity was verified in all varietal juices. An improvement selleck screening library in the bioactive content of juices can be associated with a high amount of oligomeric and polymeric polyphenols in grape seeds. These findings are consistent with previous reports of the high content

of polyphenols in grape seeds and grape seed extracts, mainly flavan-3-ols catechin, epicatechin, epicatechin gallate, and proanthocyanidins, in concentrations higher than those in grape peel ( Chamorro, Viveros, Alvarez, Vega, & Brenes, 2012; Gibis & Weiss, 2012; Montealegre, Peces, Vozmediano, Gascuena, & Romero, Casein kinase 1 2006; Rockenbach, Gonzaga, et al., 2011). Moreover, the increase in the antioxidant

capacity in juice samples can also be explained by the high amount of phenolic compounds in grape seeds, particularly the galloylated flavanols which are present at higher concentrations in seeds than in grape peel and pomace. These compounds have a higher antioxidant activity in aqueous medium than their non-galloylated homologues ( González-Paramás, Esteban-Ruano, Santos-Buelga, Pacual-Teresa, & Rivas-Gonzalo, 2004; Rockenbach, Gonzaga, et al., 2011). The temperatures used in the juice elaborating process in this work (50 °C/80 °C) possibly enhanced the extraction of polyphenols from the seeds and, therefore, the bioactive content of the grape juices. These findings are consistent with a previous study reporting a yield increase on total phenolic compounds in grape seed extracts through increasing temperature (Bucić-Kojić, Sovová, Planinić, & Tomas, 2013). On the other hand, the extraction of seed polyphenols during juice processing can affect taste of grape juices, due to the high amounts of flavan-3-ols and polymeric proanthocyanidins contained in the grape seeds.