Emerging biotechnologies and non-thermal technologies for winemaking in a context of global warming

In the current situation, wine areas are affected by several problems in a context of global warming: asymmetric maturities, pH increasing, high alcohol degree and flat wines with low freshness and poor aroma profile. The use of emerging biotechnologies allows to control or manage such problems. Emerging non-Saccharomyces as Lachancea thermotolerans are very useful for controlling pH by the formation of stable lactic acid from sugars with a slight concomitant alcohol reduction. Lower pH improves freshness increasing simultaneously microbiological stability. The use of Hanseniaspora spp. (specially H. vineae and H. opuntiae) or Metschnikowia pulcherrima promotes a better aroma complexity and improves wine sensory profile by the expression of a more complex metabolic pattern and the release of extracellular enzymes. Some of them are also compatible or synergic with the acidification by L. thermotolerans, and M. pulcherrima is an interesting biotool for reductive winemaking and bioprotection. The use of bioprotection is a powerful tool in this context, allowing oxidation control by oxygen depletion, the inhibition of some wild microorganisms, improving the implantation of some starters and limiting SO2. This can be complemented with the use of reductive yeast derivatives with high contents of reducing peptides and relevant compounds such as glutathione that also are interesting to reduce SO2. Finally, the use of emerging non-thermal technologies as Ultra High-Pressure Homogenization (UHPH) and Pulsed Light (PL) increases wine stability by microbial control and inactivation of oxidative enzymes, improving the implantation of emerging non-Saccharomyces and lowering SO2 additions

Effect of HHP and UHPH High-Pressure Techniques on the Extraction and Stability of Grape and Other Fruit Anthocyanins

Altres ajuts: MALTA CONSOLIDER TEAM Research Network RED2022-134388-TThe use of high-pressure technologies is a hot topic in food science because of the potential for a gentle process in which spoilage and pathogenic microorganisms can be eliminated; these technologies also have effects on the extraction, preservation, and modification of some constituents. Whole grapes or bunches can be processed by High Hydrostatic Pressure (HHP), which causes poration of the skin cell walls and rapid diffusion of the anthocyanins into the pulp and seeds in a short treatment time (2-10 min), improving maceration. Grape juice with colloidal skin particles of less than 500 µm processed by Ultra-High Pressure Homogenization (UHPH) is nano-fragmented with high anthocyanin release. Anthocyanins can be rapidly extracted from skins using HHP and cell fragments using UHPH, releasing them and facilitating their diffusion into the liquid quickly. HHP and UHPH techniques are gentle and protective of sensitive molecules such as phenols, terpenes, and vitamins. Both techniques are non-thermal technologies with mild temperatures and residence times. Moreover, UHPH produces an intense inactivation of oxidative enzymes (PPOs), thus preserving the antioxidant activity of grape juices. Both technologies can be applied to juices or concentrates; in addition, HHP can be applied to grapes or bunches. This review provides detailed information on the main features of these novel techniques, their current status in anthocyanin extraction, and their effects on stability and process sustainability

Yield and sugar accumulating capacities of Airén cultivar. A preliminary study

Airén is the most worldwide spread white grape cultivar, high yielding, well adapted to hot, dry conditions, and not very sensitive to fungal diseases. Its largest growing region is La Mancha, where Airén has been traditionally bush trained, spur pruned and grown with no irrigation. However, grape growing has evolved to meet the need for higher yields and harvest mechanization; and modern cultural practices train grape vines to simple multi-wire trellis systems, cane pruned, and usually irrigated. The aim of the present study was to evaluate the yield and sugar accumulating capacities of Airén cultivar with regard to leaf area, and to assess the influence that different yield components have on yield. In 2014, five commercial irrigated vineyards, located in La Mancha, of different ages, and grafted onto different rootstocks were selected for this study. Canopy surface area (SA) was measured at maturity. Berry weight and sugar concentration were measured during ripening on a weekly basis. Yield and yield components were determined at harvest. Values for shoot density ranged 2.3-5.1 shoots/m2; SA, 0.6-1.1 m2/m2; yield, 20-40 t/ha; fertility, 1.1-1.7 bunches/shoot; bunch weight, 450-650 g; berry weight, 2.5-2.9 g; and sugar concentration, 17-21 ºBrix. The number of bunches per shoot was the yield component that had the greatest influence on yield. The number of berries was the main contributing factor to bunch weight. A lineal relationship between SA/yield and sugar concentration was observed, with values of SA/yield ranging from 0.20 to 0.45 m2/kg. A ratio SA/yield of approximately 0.4 m2/kg was needed to reach a value of 20 ºBrix. Hence it would be necessary a SA of 12000 m2/ha, under the conditions of this study, to achieve a 30 t/ha yield, and a sugar concentration of 20 ºBrix. These results are a step forward in the study of the Airén cultivar, being of help for grape growers in the center area of Spain in order to maximize crop yield and sugar accumulation

Acceleration of ageing on lees in red wines by application of ultrasounds

A transfer of parietal polysaccharides and mannoproteins is produced during aging on lees [1]. This transfer of compounds to wine is carried out after cell death. It comes to breakdown of polysaccharides from cell wall (yeast autolysis). This technique increases the density in wines [2] and gives more body and structure. Interactions between yeast polysaccharides and wine tannins will result in decrease of tannic perception (decrease of astringency). Increase of varietal characteristics is produced. The main disadvantage of the ageing on lees is the time that the process requires. Usually, nine months are necessary at least for obtaining a noticeable effect in wines. The objective of this work is the acceleration of this process using ultrasounds to lyse the yeast cell wall. In addition, the influence of this technique in different red wine quality parameters was studied

Use of Hanseniaspora spp. in sequential fermentation with Saccharomyces cerevisiae to improve the aromatic complexity of Albillo Mayor white wines

Hanseniaspora spp apiculate yeasts can be found on ripe grape skins and during the first six days of the alcoholic fermentation. Generally, these yeasts have poor characteristics for its industrial application in winery as they are related with low fermentative power, low resistance to SO2 and even high volatile acidity production. However, some species have a better fermentative capacity and are producers of certain floral and fruity volatiles. This is the case of the two strains used in this study. Hanseniaspora vineae (HV) has a fermentative power around 8-10% v/v, low volatile acidity production and produces high levels of 2-phenylethyl acetate. Similarly, Hanseniaspora opuntiae (HO) also produces a low volatile acidity providing sweet and floral aromas, but has a fermentative power around 6% v/v, which means that it must be used in sequential fermentation with Saccharomyces cerevisiae (SC). In addition, several studies indicate that both species can increase the mouthfeel and wine body. The aim of this study was to evaluate the use of HV and HO in sequential fermentation with SC to improve the sensory profile of high quality white wines from the neutral grape variety Albillo Mayor. Fermentations were performed in triplicate in 150 L stainless steel barrels with grapes from the 2021 vintage. Pure SC fermentations were used as controls. After the fermentation, the polysaccharide content and the colour was measured, and an intensive study of the aromatic profile was done

Polymeric pigments formed in sequential fermentation of red fresh musts by adding flavan-3-ols

Red wine pigments are susceptible to degradation by light, SO2 and changes in pH and temperature1,2. The formation of pyranoanthocyanins and polymeric pigments during fermentation and wine aging promote the stability of such pigments3. Glycolytic metabolites (e.g. acetaldehyde and pyruvic acid) may interact with anthocyanins and flavan-3-ols to form more stable molecules4 without a drastic change in hue values. Procyanidins are molecules from the flavanoids family that may condense with anthocyanins5. The contribution of non-Saccharomyces yeasts (e.g. L. thermotolerans, M. pulcherrima and T. delbrueckii), in sequential fermentation with S. cerevisiae and S. pombe, to the production of stable pigments was assessed in this project. with the use of HPLC-DAD/MS-ESI. The red musts have been enriched with flavanols prior fermentation. Fermentative volatiles and sensorial analysis were also performed to characterize experimental wines produced

Strategies to Improve the Freshness in Wines from Warm Areas

Trends in wine consumption are continuously changing. The latest in style is fresh wine with moderate alcohol content, high acidity, and primary aromas reminiscent of grapes, whereas certain fermentative volatiles may also influence the freshness of the wine. In addition, the effects of climate change on the composition of the grapes (high sugar content and low acidity) are adverse for the quality of the wine, also considering the microbiological stability. Herein, different strategies aiming at improving wine freshness are presented, and their performance in winemaking is discussed: among them, the addition of organic acids able to inhibit malolactic fermentation such as fumaric acid; the use of acidifying yeasts for alcoholic fermentation, such as Lachancea thermotolerans; and the selection of non-Saccharomyces yeasts with β-glucosidase activity in order to release terpene glycosides present in the must

Cluster microclimate, canopy management and its influence on the berry (size and composition) quality

Sunlight and microclimate inside the clusters’ zone are key factors in berry development and must composition. Plant geometry and training system should be joined with a proper sunlight and temperature cluster microclimate and, also in the rest of the plant. Berry temperature can vary between 2 and 10 ºC or even more in inner clusters, depending on their exposure (Spayd et al., 2002). Sunlight, air ventilation within the canopy, temperature cluster and microclimate are affected by the exposure and radiation percentage received by grapes during its growth and maturation period (Deloire and Hunter 2005). In Mediterranean conditions (warm and dry climate), the use of porous systems may help plants establish a better leaf distribution inside this area (de la Fuente et al., 2015), providing more space and enhancing certain physiological processes, both in leaves (photosynthesis, ventilation, transpiration) and berries (growth and maturation). Grapes exposed to direct radiation are more sensitive to ripening and they can even suffer a dehydration process in the Mediterranean regions, where the temperature during the ripening after midday is frequently between 30-35 ºC or higher than 40 ºC (de la Fuente et al., 2015). A key point for well microclimate management inside the canopy is heat flux control, which is usually generated by three factors: surface area (SA) to PAR (direct or indirect) radiation; intensity or thermal value (related to the temperature) and time of exposure (de la Fuente, 2009; de la Fuente et al., 2013). Sprawl systems are non-positioned systems where vegetation is in multidirectional directions. Therefore, as sun position changes along the day, some leaves are first shaded and then others, so the sun leaf exposure decreases (Gutiérrez et al., 2021). The study was conducted in D.O. Uclés vineyards (lat. 39º50’8” N; long. 3º09’48.6” W; elevation 746 m above sea level) during the 2020 season, in cv. Tempranillo. The trial was designed with two training system: Vertical Shoot Positioned (VSP) and Sprawl (SP). Berry sampling was done every three days within the final 15 days before the estimated harvest date. A single sample comprised 100 berries collected from the clusters of the 10 selected vines in each block. Weight, size, must composition (reducing sugar, pH, acidity, volatile acidity, etc.) and skin composition (total and acylated monomeric pigments, TPI) were analysed. Regarding the berry composition, SP accumulated larger concentration of reducing sugars (+7.4%). No statistical differences were observed in the remaining oenological parameters measured in the berries between treatments. Nevertheless, inside total pigments and color parameters, TPI values reached significantly higher (+40%) in the SP vs VSP treatments. In the total concentration of pigments (including the acylated fraction) and pH, no differences were founded. Berry's weight and size showed some relevant differences between treatments. During the end maturity-harvest period, the berry weight (12-11%) and berry size (6-9%) were higher in SP treatment compared to VSP. These results suggest that the SP systems can induce an increment of reducing sugars, and TPI and also, can modulate the berry weight and size, helping to control overripening and berry dehydration processes. Therefore, sprawl systems (SP) represent an alternative to VSP systems in warm areas for achieving an increment of pigments, as well as for better control of the accumulation of reducing sugars, without compromising the harvest yield (higher berry weight and size)

Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO₂

This chapter reviews the main non-thermal technologies with application in enology and their impact in: the extraction of phenolic compounds from grapes, the elimination of indigenous microorganisms, and the subsequent effect in SO2 reduction. The technologies are physical processes with null or low repercussion in temperature and therefore gentle with sensory quality of grapes. High hydrostatic pressure (HHP), ultra high pressure homogenization (UHPH), pulsed electric fields (PEFs), electron-beam irradiation (eBeam), ultrasound (US), and pulsed light (PL) have interesting advantages and some drawbacks that are extensively reviewed highlighting the potential applications in current technology

Optical and AFM microscopy of grape juices treated with UHPH: Effects of microstructure and nanostructure

UHPH treatment of Vitis vinifera must for winemaking leads to fragmentation of colloidal particles into smaller structures. The shear and fracture forces experienced by grape juice during valve pressurization are sufficient to reduce the particle size of grape juice to below 500 nm. As a result, the applied force can disrupt bacterial and yeast cell structures, altering or breaking down proteins, polysaccharides and enzymes. This effect is not observed for low molecular weight compounds such as monomeric pigments and phenolic structures, varietal aroma precursors, fermentable sugars, etc. Treated and untreated samples can be compared using optical and atomic force microscopy. Optical microscopy images show reduction or elimination of bacteria and yeast and changes in microstructure. On the other hand, in addition to describing topography in the nanometer range, AFM can also measure particles in comparison to other techniques such as laser diffraction (LD). This work contributes to the characterization and better understanding of the effects of UHPH on grape juice for winemaking