Beneficial effects of bunch-zone late defoliations and shoot positioning on berry composition and colour components of wines undergoing aging in an organically-managed and rainfed Sangiovese vineyard

n the context of climate change, where high temperatures are frequent in the first phases of ripening, protecting grapevine bunches from solar radiation is essential for preserving berry composition and wine colour. The effects of bunch-zone late defoliations (DEFs) and “semi-ballerina” shoot positioning (SB) on vine physiology and grape and wine quality of organic cv. Sangiovese wines during storage were assessed in two contrasting seasons (2013 and 2014). The treatments altered neither vine physiology (leaf photosynthetic activity and stomatal conductance, stem water potential) nor vine phenology, yield, budburst and fruitfulness. Defoliations imposed at post-veraison (DEF I) and pre-harvest (DEF II), but not shoot positioning imposed at post-veraison, enhanced the concentration of berry skin flavonols at harvest, compared to an untreated control. Late defoliations and SB did not change berry weight, anthocyanins, soluble solids, pH or titratable acidity at harvest. The severity of Botrytis bunch rot was assessed in both seasons. In 2013, it was negligible regardless of the treatment. In 2014 (characterised by higher rainfall and lower average temperatures than in 2013), late defoliations (DEF I and DEF II), especially DEF I, and SB to a minor extent, limited the severity of Botrytis bunch rot. The oenological benefits of late defoliations and shoot positioning were observed during wine storage. These canopy management practices positively influenced wine components (polymeric pigments; namely short polymeric pigments) that might have a marked effect on the final colour intensity, without altering the basic chemical characteristics of the wine. When choosing the timing for carrying out defoliation in order to improve grape quality and bunch rot containment, the meteorological conditions should be properly considered. Our results may contribute to providing further recommendations for canopy management for grape growers who produce organic Sangiovese wines that undergo aging

Leuconostoc oenos and malolactic fermentation in wine: a review

This review article summarizes the state of the art on Leuconostoc oenos, the bacteria responsible for malolactic fermentation in wine. Both basic and practical aspects related to the metabolism of this microorganism and malolactic fermentation in general are critically reviewed. The former examines the role of genetics for the identification and classification of L. oenos and energetic mechanisms on solute transport (malic and lactic acid). The latter includes practical information on biomass production, optimal growth conditions and stress factors, which are important in growth optimization of malolactic starter cultures. Extensive data and references on the effect of malolactic fermentation on wine composition and sensory analysis are also included

Evaluation of Plant-Based Byproducts as Green Fining Agents for Precision Winemaking

Consumers are increasingly looking for foods, including wine, that are free of animal-derived proteins. This study seeks to evaluate patatin, a new, plant-based and allergen-free fining agent, by comparing it with the fining agents polyvinipolypyrrolidone, bovine serum albumin, and methylcellulose. Specifically, its effects on the phenolic profile of enological tannins were analyzed with four spectrophotometric assays: OD 280 nm, Folin–Ciocâlteu, Adams–Harbertson, and methylcellulose. In addition, changes in the polyphenol composition of Sangiovese red wine were determined by UV-Vis spectrophotometry and HPLC with adsorption trials, and the solid–liquid interaction in a wine solution was modeled by both Langmuir and Freundlich equations. Our findings highlight the occurrence of systematic proportional error between the selected spectrophotometric assays. As a result, direct comparisons of protein precipitation assays can be made only among results obtained with the same spectrophotometric method. However, it is clear that patatin has an impact on the phenolic profile of Sangiovese red wine: it removes simple phenolics (gallic acid, (+)-catechin, (–)-epicatechin, epicatechin gallate, syringic acid, fertaric acid, coutaric acid, and rutin) as well as both oligomeric and polymeric tannins to different extents. In concentrations of less than 1 g/L, the patatin isotherm showed a linear relation between the equilibrium concentration and the quantity absorbed, obeying the Freundlich model reasonably well (KF 1.46; 1/n 1.07; R2 0.996 with 1/n > 1). Thus, the adsorption process is strongly dependent on the fining dosage

Effect of Interspecific Yeast Hybrids for Secondary In-Bottle Alcoholic Fermentation of English Sparkling Wines

In sparkling winemaking, only a few yeast strains are regularly used for the secondary in-bottle alcoholic fermentation (SiBAF). Recently, advances in yeast development programs have yielded new breeds of interspecific wine yeast hybrids that ferment efficiently while producing novel flavors and aromas. In this work, the chemical and sensorial impacts of the use of interspecific yeast hybrids for SiBAF were studied using three commercial English base wines prepared for SiBAF using two commercial and four novel interspecific hybrids. After 12 months of lees aging, the chemical and macromolecular composition, phenolic profile, foaming, viscosity and sensory properties of the resulting 13 wines were assessed. Chemically, the yeast strains did not result in significant differences in the main wine parameters, while some differences in their macromolecular contents and sensory characteristics were noticeable. The foamability was mostly unaffected by the strain used; however, some effect on the foam stability was noticeable, likely due to the differences in polysaccharides released into the wines by the yeast strains. The wines exhibited different sensory characteristics in terms of aroma and bouquet, balance, finish, overall liking and preference, but these were mostly attributable to the differences in the base wines rather than the strain used for SiBAF. Novel interspecific yeast hybrids can be used for the elaboration of sparkling wines, as they provided wines with chemical characteristics, flavor and aroma attributes similar to those of commonly used commercial Saccharomyces cerevisiae strains

Astringency sub-qualities of red wines and the influence of wine–saliva aggregates

Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivary–proteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and Carménère, and tannin–protein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication

Membrane-based Operations for the Fractionation of Polyphenols and Polysaccharides From Winery Sludges

The present work investigated the impact of ultrafiltration (UF) and nanofiltration (NF) membranes on the recovery and fractionation of polyphenolic compounds and polysaccharides from Sangiovese and Cabernet Sauvignon wine lees. A laboratory-made flat-sheet membrane in cellulose acetate (CA400-38) was used in the UF treatment of Sangiovese wine lees; three laboratory-made flat-sheet membranes in cellulose acetate (CA316, CA316-70, CA400-22) and a polyamide commercial membrane (NF90) were used in the NF treatment of Cabernet Sauvignon wine lees. All membranes were characterized in terms of hydraulic permeability and rejection toward references solutes; the performances of the membranes were measured in terms of productivity, fouling index, cleaning efficiency and retention toward target compounds. Experimental results indicated that all UF and NF membranes were effective in separating target compounds rejecting more than 92% of polysaccharides with polyphenols preferentially permeating through the membrane. The UF membrane rejected more than 40% of total polyphenols; rejections toward non-flavonoids and flavonoids were less than 25% and 12.5%, respectively. The laboratory-made NF membranes exhibited higher permeate flux values (of the order of 11–12 L/m2h) in comparison with the commercial NF membrane, despite the observed differences in the retention of specific solutes. Among the prepared membranes the CA316 showed a total rejection toward most part of non-flavonoids and flavonoids. The experimental results support the use of UF and NF processes in a sequential design to fractionate and refine phenolic compounds from winery sludge for the production of concentrated fractions with high antioxidant activities