Organic acids and sugars are related to the chemical balance of wines and grape juices, besides exerting a strong influence on the taste balance and sensorial acceptance by consumers. The aim of this study was to validate a method for the simultaneous determination of sugars and organic acids in wines and grape juices by highperformance liquid chromatography (HPLC) with refractive index detection (RID) and diode array detection (DAD) and to characterize commercial products from northeast Brazil. The method provided values for linearity (R > 0.9982), precision (CV% < 1.4), recovery (76-106%) and limits of detection (0.003-0.044 g L −1) and quantification (0.008-0.199 g L −1) which are considered acceptable for application in the characterization of these types of matrices. Principal components analysis (PCA) was used to verify the applicability of the method in the quality control of the products and resulted in the correct separation of the samples according to their type of processing. The results obtained in the characterization of the samples studied showed high levels of glucose and fructose in grape juice and the organic acids content was similar to those found in products originating from other regions around the world.

A method for rapid determination of phenolic compounds by reversed-phase high-performance liquid chromatography (RP-HPLC), using a new column of faster resolution was validated and used to characterize commercial products produced with new grape Brazilian varieties of Northeast of Brazil. The in vitro antioxidant activity was also measured. The method showed linearity (R>0.9995), good precision (CV%<2.78), recovery (91.8-105.1%) and limits of detection (0.04-0.85mgL) and quantification (0.04-1.41mgL) according to other methods previously published with the difference of a run time of only 25min. The results obtained in the characterization of the samples differed for juices and wines from other world regions, mainly because of the high values of (-)-epigallocatechin and trans-caftaric acid. The products analyzed showed high antioxidant activity, especially the wine samples with values higher than those from wines of different regions of the world.

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The aim of this study was to investigate the phenolic composition and antioxidant activity of commercial red wines produced from Vitis vinifera L. grapes grown in the São Francisco Valley (SFV), which is a tropical region in northeastern Brazil. All wines showed phenolic compound contents consistent with those of other traditional wine producing regions and high antioxidant activity. In total, 20 phenolic compounds were quantified by RP‐HPLC‐DAD‐FD and the antioxidant activity was positively correlated with the content of syringic acid > peonidin 3‐O‐glucoside > ρ‐coumaric acid > (+)‐catechin, epigallocatechin gallate > cyanidin‐3‐O‐glucoside > procyanidin A2 > (‐)‐epicatechin, highlighting the contribution of these bioactive compounds to the antioxidant potential of tropical wines. This study shows that it is possible to obtain wines with a good bioactive component and high antioxidant activity in tropical climates such as that of the SFV. The data reported herein contribute to our knowledge of the wine producing potential of new regions worldwide. Practical applications An important difference between the tropical viticulture practiced in the São Francisco Valley (SFV) and that of other traditional regions of the world is that in the SFV each vine can produce two harvests per year. Also, since this is a region with hot weather, high luminosity and abundant water for irrigation, wineries operate according to a particular scheme, according to the best period in which to harvest the grapes and to prune the vines. Also, the “step” system can be applied, where the harvesting is distributed within a certain period (e.g., one month, several months, or the whole year). Thus, it is possible to prepare wines throughout the year. This study contributes to gaining a better enological understanding of the wines produced in an atypical grape production region.

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