Chemical composition and sensory profile of Syrah wines from semiarid tropical Brazil – Rootstock and harvest season effects

Development and Characterization of Powdered Antioxidant Compounds Made from Shiraz (Vitis vinifera L.) Grape Peels and Arrowroot (Maranta arundinacea L.)

Grapevine (Vitis vinifera L.) is a plant containing many phenolic compounds, mostly distributed in the peel, pulp, and seeds. This study evaluates the centesimal composition and bioactive compounds in Shiraz grape (Vitis vinifera) peels using spectrophotometric and UHPLC techniques and develops different formulations of compound powders from the peels and arrowroot using conventional drying technology. The results demonstrate that Shiraz grape skin contains significant amounts of insoluble fiber (15.3%), phenolics (157.09 ± 6.96-149.11 ± 9.27 mg GAE g-1), and flavonoids (0.75 ± 0.50-2.00 ± 0.50 mg QE g-1), with excellent antioxidant capacity observed in the alcoholic extracts. The phenolic content in the developed powdered compounds ranged from 128.32 to 139.70 mg GAE g-1. In general, the compounds showed good antioxidant capacity (IC50 = 0.17 to 0.19 μg mL-1). According to the chromatographic evaluation, it was possible to quantify gallic acid, catechin, and epicatechin, the latter of which was found in the largest quantities in the six formulations. The EV5 formulation was the most efficient in terms of phenolic compounds and protein amounts. This formulation's composition and low cost could make it viable for use in the food industry.

Identification of Tentative Traceability Markers with Direct Implications in Polyphenol Fingerprinting of Red Wines: Application of LC-MS and Chemometrics Methods

This study investigated the potential of using the changes in polyphenol composition of red wine to enable a more comprehensive chemometric differentiation and suitable identification of authentication markers. Based on high performance liquid chromatography-mass spectrometry (HPLC-MS) data collected from Feteasca Neagra, Merlot, and Cabernet Sauvignon finished wines, phenolic profiles of relevant classes were investigated immediately after vinification (Stage 1), after three months (Stage 2) and six months (Stage 3) of storage, respectively. The data were subjected to multivariate analysis, and resulted in an initial vintage differentiation by principal component analysis (PCA), and variety grouping by canonical discriminant analysis (CDA). Based on polyphenol common biosynthesis route and on the PCA correlation matrix, additional descriptors were investigated. We observed that the inclusion of specific compositional ratios into the data matrix allowed for improved sample differentiation. We obtained simultaneous discrimination according to the considered oenological factors (variety, vintage, and geographical origin) as well as the respective clustering applied during the storage period. Subsequently, further discriminatory investigations to assign wine samples to their corresponding classes relied on partial least squares-discriminant analysis (PLS-DA); the classification models confirmed the clustering initially obtained by PCA. The benefits of the presented fingerprinting approach might justify its selection and warrant its potential as an applicable tool with improved authentication capabilities in red wines.

Colonization of Aspergillus carbonarius and accumulation of ochratoxin A in Vitis vinifera, Vitis labrusca, and hybrid grapes - research on the most promising alternatives for organic viticulture

BACKGROUND

Aspergillus carbonarius has been identified as one of the main fungi that produce ochratoxin A (OTA) in grapes. This nephrotoxic mycotoxin has been legislated against in several countries and is a major concern for viticulture. Knowledge of resistance to, or susceptibility to, colonization by A. carbonarius may be useful in selecting the most promising cultivars for organic agriculture and could help in preventing fungal contamination in vineyards. This study aimed to evaluate the colonization potential and the capacity to produce OTA by A. carbonarius in Vitis vinifera, V. labrusca, and hybrid grapes. The correlation between OTA levels and grape berry characteristics was also analyzed.

RESULTS

The OTA content was only strongly correlated with the thickness and hardness of the grape skins. The correlation between OTA levels and these parameters was negative (grapes with the least thickness and hardness had the highest OTA levels). Vitis vinifera grapes were more susceptible to A. carbonarius than V. labrusca and hybrid grapes at both 25 and 4 °C. Chardonnay (V. vinifera) grapes showed the highest levels of OTA, followed by Merlot, Cabernet Sauvignon, Tannat, and Moscato Branco. Italia grapes were the exceptions among V. vinifera cultivars, since they showed similar thickness, hardness, and fungal resistance as the V. labrusca and hybrid grapes.

CONCLUSION

The highest resistance to A. carbonarius was observed in the following grapes: hybrids (BRS Lorena and BRS Violeta), V. labrusca (Isabel and Bordo), and V. vinifera (Italia). These cultivars can be prioritized in the implementation of organic viticulture. © 2020 Society of Chemical Industry.

Production of low-calorie apricot nectar sweetened with stevia: Impact on qualitative, sensory, and nutritional profiles

This study aimed to develop a low-calorie apricot nectar by replacing sucrose with different amount of Stevia rebaudiana bertoni (Rebaudioside A, 98%). Stevia has become very popular as sweetener for the production of low-calorie products but its addition could be a challenge for industry, since it could modify sensory features of the product and consumers' acceptance. To this end, apricot nectars without sugar, with sucrose 10%, and with different amounts of stevia were produced and evaluated for microbiological quality using the pour-plate technique, and physicochemical (pH, TTA, and a w) and nutritional (moisture, fat, protein, carbohydrates, and ash) characteristics. Furthermore, a sensory analysis of the samples was performed by a panel of trained judges using quantitative descriptive analysis. The effect of stevia addiction on the consumers' acceptance was investigated by 102 consumers of fruit juices that evaluated the overall acceptability of the samples using a structured 9-point hedonic scale. Levels of microbial groups in nectars were under the detection limit confirming a good hygienic practice within the production. Nectars produced with stevia resulted in significant reduction in caloric value from 86 kcal (nectar with 10% sucrose) to 49 kcal (nectars with stevia), without altering its typicality. Different sensory profiles among samples were pointed out; all the products are liked, but with a different level of pleasantness. The study highlighted that the apricot nectars with 0.07% stevia are characterized for sweet and liquorice aroma notes and received the same level of consumer acceptability of nectars produced with 10% sucrose.