Reflectance of botanical, production and geographical origin on the unique compositional traits of purple grape juices

Abstract

Grape juices represent one of the most consumed fruit juices because of its sensory properties, availability, reasonable price, and more recently because of their functional properties demonstrated by a vast number of in vitro, in vivo, clinical, and epidemiological studies. Although grape juices have been the target of a high number of studies, it is still not fully known how geographical origin and production management system, affect the chemical profile, quality traits related to flavor, and in vitro antioxidant of grape juices. Therefore, the main objective of this study is to elucidate the reflectance of origin (botanical, geographical, production system) in the unique compositional traits of juices from different botanical origins, with emphasis on purple grape juices. Subsequently, chemometric methods were used to try to authenticate the origin of grape juice based on the grape juice’s quality traits. Results showed that it was possible to note that the instrumental taste profile, chemical composition related to phenolic compounds, and antioxidant activity of juices from distinct botanical origins differ considerably. More specifically, pomegranate and elderberry juices presented the highest phenolic content and antioxidant activity, implying that the botanical origin of juices affected remarkably their unique instrumental taste profile and physicochemical parameters, phenolic composition, and in vitro antioxidant activity. The production managements systems, (organic/biodynamic, ORG/BIO, versus conventional, CONV) is influencing the volatile organic composition (VOC) profiles, some phenolic compounds and copper chelating activity. It is not affecting the instrumental taste profile nor the in vitro antioxidant activity results. ORG and BIO purple grape juices can be differentiated by their VOC profiles but not by the other characteristics studied. More specifically, CONV juices had higher mean levels for all ions compared to ORG and BIO juices. More specifically, in fact, BIO juices presented the lowest mean values for almost all ions measured. When European grape juices were studied, no significant difference (p>0.05) between ORG, BIO, and CONV juices was observed for instrumental richness, umami, saltiness, sourness, astringency, bitterness, total phenolic content, total soluble solids, pH, ortho-diphenols, copper chelating activity, and ferric reducing antioxidant activity. For the Brazilian samples, the contents of chlorogenic acid and myricetin were statistically higher in ORG juices, while the in vitro antioxidant activity measured by three assays (DPPH, CUPRAC, and iron chelating ability) were not different between production management systems. For the European juices, some differences were observed: BIO and ORG juices presented higher contents of (-)-epicatechin, quercetin, (+)-catechin, and myricetin compared to the CONV juices. The VOC profile, instrumental taste parameters, phenolic composition, and in vitro antioxidant activity is highly affected between regions, in which Brazilian juices presented higher ion intensities as compared to the European juices. Brazilian juices, regardless of the production management system adopted, presented higher total phenolic content and flavonoids, total anthocyanins, proanthocyanidins, flavonols, and flavanols, except for trans-resveratrol, malvidin-3-glucoside and pelargonidin-3-glucoside. From this work, we can conclude that the geographical and botanical origins affect significantly the VOC profiles, instrumental taste profile, the phenolic composition, and antioxidant activity of grape juices.