Search Results (20)

This study evaluates the impact of two non-Saccharomyces yeasts, Lachancea thermotolerans and Metschnikowia pulcherrima, on the oenological and sensory characteristics of Pedro Ximénez (PX) white wines produced in warm regions of southern Spain. PX wines are particularly affected by climate change, often exhibiting low acidity and limited aromatic complexity. Fermentations were performed using pure and sequential cultures of these yeasts and compared to a control inoculated with Saccharomyces cerevisiae. Wines fermented with L. thermotolerans showed increased titratable acidity (up to 6.83 g/L), reduced pH (down to 3.02), and higher lactic acid concentrations, contributing to improved freshness and microbial stability. The use of M. pulcherrima led to a significant rise in ester production, enhancing fruity and floral aromatic notes. Sequential fermentation using both yeasts produced wines with the highest overall aromatic complexity and superior performance in sensory evaluations. These findings support the use of L. thermotolerans and M. pulcherrima as a promising biotechnological strategy to improve white wine quality under climate change conditions. Full article

This study investigated young white wines produced during the 2021 and 2022 vintages from Pedro Ximénez grapes cultivated in three different terroirs within a high-quality production zone. The general oenological parameters were significantly influenced by vintage and terroir (p ≤ 0.001), with ethanol and reducing sugars specifically affected by the terroir and its interaction with the vintage. Multivariate analysis of major and minor volatile compounds enabled the characterization of terroir-specific volatile profiles. However, principal component analysis (PCA) grouped samples by vintage rather than terroir. Ethyl esters of medium- and long-chain fatty acids and certain acetates of higher alcohols were the most discriminant volatiles and were proposed as key compounds for differentiating wines by terroir and vintage. These findings underscore the influence of the terroir on the volatilome and support its relevance in defining wine typicity and quality. Full article

Wine vinegar and wine are traditional Spanish products, obtained from grape must by alcoholic fermentation (wine) and subsequent acetification (vinegar). Although these are established products, there is great interest in the development of new products, particularly new vinegars, and among these, the possibility of vinegars containing gluconic acid stands out. Gluconic acid in vinegar, mainly produced by acetic acid bacteria (AAB), is positively valued by consumers. Its content depends on the availability of glucose in the base wine; however, this hexose is preferentially consumed by the indigenous yeast population which conducts the previous alcoholic fermentation. For this reason, the use of non-conventional fructophilic yeasts, which consume fructose rather than glucose, is required. In this work, we isolated, screened, and identified osmophilic and fructophilic non-Saccharomyces yeasts from sun-dried grape must and tested them under different fermentation conditions in synthetic and natural grape musts, in order to obtain a base wine with ethanol and glucose content for the development of new vinegars containing gluconic acid. The isolate of the species Starmerella lactis-condensi was found to be an ideal candidate due to its fructophilic and osmophilic features, which allowed for the production of a base wine with high ethanol (11% v/v) and glucose (up to 200 g/L) content from a natural concentrated must. In fresh must, inoculation with Starmerella lactis-condensi resulted in faster and preferential fructose consumption over glucose compared to the control. However, both sugars were completely consumed at the end of the alcoholic fermentation; therefore, new fermentation strategies should be tested in this type of must. Furthermore, this strain could be of interest in oenology due to its high glycerol yield and low volatile acid production during alcoholic fermentation. The use of this strain could allow for the production of new wines with unique metabolic profiles suitable for further vinegar production. Full article

Non-Saccharomyces yeasts play a significant role in winemaking, offering unique benefits and contributing to wine complexity and varied and desirable aromatic profiles. This work focuses on the sensory improvement of Pedro Ximénez white wines using selected strains of Wickerhamomyces anomalus isolated from biologically aged wines. Chemical and microbiological analyses confirmed the implantation of W. anomalus; these yeast strains appear to displace indigenous non-Saccharomyces species in the must and produce large amounts of ethyl acetate and lower ethanol content. Wines made with W. anomalus strains were judged negatively by the tasting panel due to a nail polish/varnish odor and a strong, bitter taste; however, when these wines were blended with wine normally produced by spontaneous fermentation, the judges rated them positively, highlighting fruity aromas not detected under other conditions. These results conclude that W. anomalus strains isolated from biologically aged wines could be useful for modulating the sensory profile of white wines. Moreover, their use in combination with other yeasts or in immobilized form could improve the results obtained and avoid the blending process. The high yield of ethyl acetate produced by these strains could be of interest as an alternative to current methods of producing this compound, including the use of these wines for the production of quality vinegar. Full article

This research aims to identify aroma compounds, their combinations, and statistical relationships to classify and characterize wines produced in small, defined areas known as “terroirs”, which share edaphoclimatic characteristics grape varieties, viticultural practices, harvest timing, and winemaking processes. The goal is to deepen the understanding of the relationship between the terroir and wine typicity. This study analyzed the contents based on enological parameters, the major and minor volatile compounds of the young wines produced in three wineries across two vintages, using the Pedro Ximenez white grape variety cultivated in different terroirs within the same quality zone. Statistical tools, such as Multiple Variable Analysis (MVA) and Principal Component Analysis (PCA), were employed to identify significant differences in the volatilomes of wines. PCA effectively differentiated wines from each terroir and vintage using scores from the first two principal components, calculated based on the absolute concentrations of 12 major volatile compounds and 3 polyols. Conversely, PCA based on the concentrations of 52 minor volatile compounds showed a strong ability to classify wines by vintage year. The minor volatile contents of wines from 2 vintages, grouped into 9 chemical families, provide distinct fingerprints that enable wines to be distinguished by terroir. The results underscore the chemical basis underlying terroir typicity in a production zone within a warm Protected Denomination of Origin (PDO). Full article

This work focuses on the production of a white wine with a specific organoleptic profile by means of sequential fermentation using immobilized yeast in a system known as “microbial biocapsules”. Three fermentation conditions were created: sequential fermentation with immobilized yeast (SqFMB) employing a matrix composed by Aspergillus oryzae (pellet-forming fungus recognized as GRAS), sequential fermentations with non-immobilized yeast cells (SqF), and a control of spontaneous fermentation (SpF). To carry out these fermentations, Pedro Ximénez grape must was used and two non-Saccharomyces yeast strains, Debaryomyces hansenii LR1 and Metschnikowia pulcherimma Primaflora, and the Saccharomyces cerevisiae X5 strain were used. The wines produced were subjected to microbiological and chemical analyses in which metabolites that positively influence the wine profile, such as 1,1-diethoxyethane and decanal, are only produced in the SqFMB condition, and others, like nonanal, were detected in higher concentrations than in SqF and SpF. Microbiological analyses show that less non-Saccharomyces yeasts were isolated in the SqFMB condition than in SqF, which indicates an efficiency in the inoculation and removal method proposed. These results conclude that microbial biocapsules seem to be a good yeast carrier for wine elaboration; however, modulation of some variables like yeast concentration inocula, the employment of preadaptation methods or the use of yeast species with higher fermentative power need to be tested to improve the novel methodology. Full article

This work focuses on the establishment of analytical and sensory differences between young wines obtained from the same grape must fermented using different strategies. The main purpose is to provide winemakers with objective criteria to help them to choose the best fermentation method to obtain the desired wine characteristics. The effects of four strategies were tested: a spontaneous fermentation with wild yeasts (WYs) and the addition of starter cultures of Lachancea thermotolerans (LT), Metschnikowia pulcherrima (MP), and a Saccharomyces cerevisiae strain that is an overproducer of glutathione (SC) in different batches of the same must of the Pedro Ximénez white grape. The analytical results obtained show as the LT wine has the highest glutathione content, while the lowest ethanol concentrations. The use of chemometric tools applied to the volatile compounds allowed to differentiate the four wines by a principal component analysis (PCA) and the identification of 27 key compounds. The four wines did not show statistical differences in their smell or taste attributes and only the LT wine was visually differentiated from the rest. Full article

Due to global warming and the effects associated with it, the wine industry is facing important challenges during the winemaking process and the production of high-quality wines. In this study, mistelas and naturally sweet wines were produced with the ‘Pedro Ximénez’ grapevine cultivar, overripened by sun drying and fermented with and without the presence of grape skins. Some oenological parameters related to alcoholic fermentation and low-molecular-weight polyphenols and furans were considered. Naturally sweet wines with skins presence showed a higher value of viable biomass than those with grape skins absence. However, in terms of density and ethanol production, sweet wines with grape skins absence presented lower and higher values, respectively, than the other elaborations. No significant differences in the organic acids and low-molecular-weight polyphenols and furans contents, with respect to the presence or absence of grape skins, were observed. In this sense, this research proves that the production of sweet wines from sun-dried grapes with the presence/absence of grape skins during alcoholic fermentation could be a possible choice in areas where agro-climatic conditions make it possible. Full article

One of the challenges that European agriculture will have to face will be to adapt conventional agriculture to procedures of the new European agricultural policies. In this way, organic farming will have more importance in the coming years. One of the most important crops worldwide is grapevine. The main objective of this research work focuses on the physiological, agronomic, and enological characterization of Pedro Ximénez with the purpose of knowing the viability of the organic cultivation of this cultivar in a warm climate zone. Two experimental plots were selected with two different types of management, organic and conventional. In both plots, photosynthetic capacity (A_N), stomatal conductance (g_s), and intrinsic water-use efficiency (WUE_i) were measured, and physicochemical composition of grape must was analyzed during ripening. In addition, bunch and pruning weight were measured as agronomic parameters. Physiological results were not significantly different between management at a general level in g_s and WUE_i, being possible to identify a difference in A_N just before the harvest. At the level of fruit ripening, significant differences were found between the two managements. At harvest, grape must had a higher sugar concentration, amine nitrogen (α-NH₂), and yeast assimilable nitrogen (YAN) in the organic management than in conventional, where higher values of pH and l-malic acid were observed. Taking into account the preliminary results obtained it could be concluded the viability of the organic management for Pedro Ximénez crop in a warm climate zone. Full article

Pedro Ximénez is a naturally sweet sherry wine produced in southern Spain from raisined Pedro Ximénez grape must and aged using a traditional Criaderas y Solera system. Complete analytical characterization has been useful in determining which parameters are the most influential in the aging of this wine. The organic acids, volatile compounds (higher alcohols, esters, aldehydes, and acetals), and phenolic compounds of this wine evolve during its aging, mainly through physico-chemical reactions and the contributions of wood compounds. During their aging, Pedro Ximénez sherry wines develop their organoleptic profiles, as tasting sessions have confirmed. A strong correlation between the aging of a wine and the parameters analyzed has also been corroborated through an MLR analysis. This allowed for the development of a model that, by using just 8 of the variables considered in the study, led to the determination of wine samples’ ages at over 97% confidence. This constitutes a rather useful tool for wineries to control Pedro Ximénez sherry wine aging processes. Full article

Viticulture around the world is currently affected by climate change, which is causing an increasing scarcity of water resources necessary for the maintenance of vineyards. Despite the drought hardiness of grapevine (Vitis vinifera L.), this threat seriously compromises its cultivation in the near future, particularly in wine-growing areas with a semi-arid climate. Identifying varieties capable of producing suitable yields and good-quality grapes under drought conditions is integral to ensuring the sustainability of the wine sector. This study focuses on vines from both minority and widely grown varieties, which were supplied only with the water intended to ensure their survival. The carbon and oxygen isotope ratios, yield, and quality parameters were evaluated on the vines and musts during the period of 2018–2020. The results revealed that not all varieties responded equally well to drought. Albillo Real, Coloraillo, Macabeo, and Verdejo adapted well to drought conditions, simultaneously maintaining high yields and must quality. By contrast, Pedro Ximénez can be considered poorly adapted. This variety was the one that produced the lowest yield and had low acidity levels in the must. Full article

In this work, we study the effect of bentonite addition to the grape must before alcoholic fermentation on the chemical composition and sensorial profile of the obtained wines. Fermentations were carried out with two Saccharomyces cerevisiae commercial active dry yeasts treated or not with bentonite and were compared with a control wine obtained by spontaneous fermentation (using the grape must microbiota). Several significant effects on the chemical and sensorial attributes were established by statistical treatments. The selection by multiple variable analysis of seven volatile molecules (ethyl acetate; methanol; 1-propanol; isobutanol; 2-methyl-1-butanol; 3-metyl-1-butanol and 2-phenylethanol) provided several footprints that provide an easy visualization of bentonite effects on wine volatile compounds. A Principal Component Analysis carried out with all the compounds quantified by Gas-Chromatography revealed that the first two Principal Components explain 60.15 and 25.91%, respectively, of the total variance and established five groups that match with the five wines analyzed. Lastly, predictive models at p ≤ 0.05 level for the attributes sight, smell and taste were obtained by Partial Least Squared regression analysis of selected chemical variables. Full article

Grape pomace and seeds are important winemaking by-products. Their oils are rich in bioactive compounds such as fatty acids and tocopherols. We have characterized oils from both by-products from five Spanish grape varieties (Palomino Fino, Pedro Ximénez, Muscat of Alexandria, Tempranillo and Tintilla de Rota). A high content of UFAs was found in all the analyzed samples. Grape pomace oils generally had the same oleic acid (PUFA_ω-6) content as seed oils, and lower PUFA contents; they also had a markedly higher linolenic acid (PUFA_ω-3) content, improving the PUFA_ω-6/PUFA_ω-3 ratio. All the oil studied show good indicators of nutritional quality: low values of the atherogenicity (0.112–0.157 for pomace, 0.097–0.112 for seed) and thrombogenicity indices (0.30–0.35 for pomace, 0.28–0.31 for seed) and high values of the relationship between hypo- and hypercholesterolemic fatty acids (6.93–9.45 for pomace, 9.11–10.54 for seed). Three tocopherols were determined: α-, γ- and δ-tocopherol. Pomace oils have higher relative contents of α- and δ-tocopherol, whereas seed oils have higher relative contents of γ-tocopherol. A significantly higher content of total tocopherols has been found in pomace oil; it is higher in the oils from red varieties of pomace (628.2 and 706.6 mg/kg by-product), and in the oils from pomace containing stems (1686.4 mg/kg by-product). All the oils obtained can be considered as a source of vitamin E, and their consumption is beneficial for health. Full article

This study aims to evaluate the epidemiological and molecular features associated with HAV transmission in adults in Rio de Janeiro during a period of increased registered cases of HAV (2017–2018). Socio-epidemiological data and serum samples from anti-HAV IgM+ individuals were obtained. HAV RNA was RT-PCR amplified and sequenced for further phylogenetic and phylogeographic analyses. From fifty-two HAV IgM+ individuals, most were men (78.85%; p = 0.024), aged 20–30 years old (84.61%; p < 0.001), resided in the Rio de Janeiro north zone (31/52; 59.62%; p = 0.001), and are men who have sex with men (MSM) (57.69%; p = 0.002). Sexual practices were more frequent (96%) than others risk factors (food-borne (44%), water-borne (42.31%), and parenteral (34.62%)). Individuals who traveled to endemic regions had a 7.19-fold (1.93–36.04; p < 0.01) increased risk of HAV. Phylogenetic analysis revealed four distinct clades of subgenotype IA, three of them comprised sequences from European/Asian MSM outbreaks and one from Brazilian endemic strains. Bayesian Inference showed that the imported strains were introduced to Brazil during large mass sportive events. Sexual orientation and sexual practices may play a role in acquiring HAV infection. Public policies targeting key populations must be implemented to prevent further dissemination of HAV and other STIs. Full article

Transfusion transmissible infections (TTIs), caused by hepatitis B virus (HBV), human immunode-ficiency virus (HIV), hepatitis C virus (HCV), and syphilis, have a high global impact, especially in sub-Saharan Africa. We evaluated the trend of these infections over time in blood donors in Angola. A retrospective cross-sectional study was conducted among blood donors in Angola from 2005 to 2020. Additionally, frozen samples obtained from blood donors in 2007 were investigated to identify chronic HCV carriers and possible occult HBV infection (OBI). The overall prevalence of HBV, HCV, HIV, and syphilis was 8.5, 3, 2.1, and 4.4%, respectively, among 57,979 blood donors. HBV was predominant among male donors, while the remaining TTIs were predominant among women. Donors >50 years had a significantly high prevalence for all TTIs. Chronic HCV infection was ab-sent in 500 samples tested and OBI was present in 3%. Our results show the continued high prev-alence of TTIs among blood donors in Angola. Most infections showed a significantly low preva-lence in years with campaigns seeking voluntary blood donors, thus, reinforcing the importance of this type of donor to ensure safe blood. Africa, with a high prevalence of diverse pathogens, should consider cost-effective pathogen reduction technologies, once they are commercially accessible, to increase the availability of safe blood. Full article