Influence of Different Vinification Techniques on Volatile Compounds and the Aromatic Profile of Palomino Fino Wines

Discovering the volatilome fingerprint of selected traditional Cuban wines elaborated with native grapes, tropical fruits, and rice using DHS-TD-GC-MS

Cuban wine is a traditional alcoholic beverage elaborated with a wide variety of raw materials, such as native grapes, tropical fruits, and rice, and different winemaking processes. Research on Cuban wines is almost nonexistent, and therefore, a study of these wines is necessary to improve their quality. Dynamic headspace (DHS)-TD-gas chromatography-mass spectrometry (GC-MS) analysis was carried out to establish the different aroma fingerprints of different Cuban wines. A total of 42 volatile aroma metabolites (VAMs) were identified, including esters, alcohols, aldehydes, acids, volatile phenols, terpenes, and lactones. The odorant activity values (OAV) of each VAM were obtained, and the esters were the most relevant group due to their highest OAV. Ethyl octanoate, hexanoate, and butanoate stand out and are considered key odorants in the aromatic fingerprint. The VAMs were grouped into seven aromatic series. Fruity series showed the highest OAVs due to the contribution of ethyl esters and acetates. Principal component analysis was used to identify the specific parameters most accurately reflecting the differences between the wines. Showing that fruity, spicy, and chemical aromatic series allow distinguishing the wines into three aroma types. These results may provide useful information for the selection of raw materials and optimization of the traditional winemaking processes of Cuban wines. PRACTICAL APPLICATION: This research contributes to knowledge of the aroma and the oenological parameters of traditional and selected Cuban wines (rice wine, tropical fruit wine, and native grape varieties). The establishing of the aroma fingerprint of these wines provides useful information for the industrial development of a quality product that may then be promoted in other areas of the world.

White wine vinification and an expanded insight into pellicular macerations: bibliometric and bibliographic review

BACKGROUND

Pellicular macerations in the vinification of white wines involve the contact of grape skins and seeds with the must before, during or after alcoholic fermentation. Pre-fermentative pellicular maceration aims to enrich the must with volatile compounds and aroma precursors. Fermentative maceration occurs during alcoholic fermentation, whereas post-fermentative maceration is carried out after this process, associated with orange, amber or skin-contact wines, which have experienced a growing global demand in recent years. In this context, this research aimed to conduct a bibliometric review on pellicular macerations in white wines using two search strategies on the specific platform for the period from 2010 to 2023. Additionally, we sought to identify research trends in this segment of the wine industry through a comprehensive literature review of the retrieved documents.

RESULTS

The results emphasized more studies on pre-fermentative pellicular maceration than on long-duration macerations during and after alcoholic fermentation. Alternative maceration techniques, such as grape freezing, were also observed as study subjects, including their effects on final wines. The research identified a wide variety of grapes explored in studies related to pellicular macerations of the Vitis vinifera L. species, with approximately 50 distinct nomenclatures identified. Regarding pre-fermentative macerations, the contact time varied from 2 to 60 h, with the temperature range 1-20 °C.

CONCLUSION

The specific search for extended skin contact white wines revealed a limited number of available documents, indicating that studies related to this product style are promising and necessary, given the growing commercial relevance of this product profile. © 2024 Society of Chemical Industry.

Complexity of the effects of pre-fermentation oxygenation, skin contact and use of pectolytic enzymes in white winemaking as revealed by comprehensive proteomics and volatilomics analysis

Ion exchange chromatography and SDS-PAGE followed by identification by MALDI-TOF/TOF, and two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOF-MS) were used for comprehensive proteomics and volatilomics evaluation of the effects of pre-fermentative oxygenation, skin contact and use of pectolytic enzymes in production of Malvazija istarska white wine, respectively. Many protein species and an unprecedented number of volatiles have been identified and (semi)quantified, revealing high complexity of the observed effects. Compared to a standard control wine, oxygenation treatment modulated the protein composition and resulted with a volatilome characterized by decreased levels of several important volatiles. Skin contact treatments, especially in combination with pectolytic enzymes, significantly increased the levels of a large number of proteins, but were also deprived of particular protein species found in other wines. Wines obtained by skin contact with exogenous enzymes exhibited the most complex volatile composition with increased levels of many key monoterpenoids, alcohols and esters.

Effects of Different Freezing Treatments during the Winemaking of a Varietal White Wine with Regard to Its Phenolic Components

In white wine production, the technique consisting of freezing whole or crushed grapes usually increases the levels of aroma-related compounds in the final wine products. However, this technique may affect phenolic compounds, among other chemical compounds. Phenolic compounds are crucial to white wines because of their susceptibility to oxidation and their role with regard to color stability. In this study, white wines made from Muscat of Alexandria grapes were subjected to two different freezing techniques: whole-bunch freezing and crushed-grape freezing. In addition, a pre-fermentative maceration was applied to each experiment in order to determine if the effects of freezing were comparable to those of maceration. The phenolic compounds studied were gallic acid, protocatechuic acid, caffeic acid, trans-coutaric acid, and epicatechin, which are the key compounds from the point of view of wine stability. The freezing of crushed grapes enhanced the extraction of phenolic compounds in comparison to the freezing of whole bunches of grapes without pre-fermentative maceration. On the other hand, the effect of pre-fermentative maceration was comparable to that resulting from freezing crushed grapes. This step made the must from whole frozen grapes having even larger levels of phenolic compounds. Without pre-fermentative maceration, freezing whole bunches of grapes only allowed a moderate extraction of phenolic compounds and produced wines with lower individual phenolic contents than those obtained through traditional winemaking procedures.

Role of Yeasts on the Sensory Component of Wines

The aromatic complexity of a wine is mainly influenced by the interaction between grapes and fermentation agents. This interaction is very complex and affected by numerous factors, such as cultivars, degree of grape ripeness, climate, mashing techniques, must chemical−physical characteristics, yeasts used in the fermentation process and their interactions with the grape endogenous microbiota, process parameters (including new non-thermal technologies), malolactic fermentation (when desired), and phenomena occurring during aging. However, the role of yeasts in the formation of aroma compounds has been universally recognized. In fact, yeasts (as starters or naturally occurring microbiota) can contribute both with the formation of compounds deriving from the primary metabolism, with the synthesis of specific metabolites, and with the modification of molecules present in the must. Among secondary metabolites, key roles are recognized for esters, higher alcohols, volatile phenols, sulfur molecules, and carbonyl compounds. Moreover, some specific enzymatic activities of yeasts, linked above all to non-Saccharomyces species, can contribute to increasing the sensory profile of the wine thanks to the release of volatile terpenes or other molecules. Therefore, this review will highlight the main aroma compounds produced by Saccharomyces cerevisiae and other yeasts of oenological interest in relation to process conditions, new non-thermal technologies, and microbial interactions.

Improving an Industrial Sherry Base Wine by Yeast Enhancement Strategies

There is growing interest in yeast selection for industrial fermentation applications since it is a factor that protects a wine’s identity. Although it is strenuous evaluating the oenological characteristics of yeasts in selection processes, in many cases the most riveting yeasts produce some undesirable organoleptic characteristics in wine. The aim of the present work is to improve an industrial yeast strain by reducing its hydrogen sulfide (H₂S) production. To accomplish this, two different improvement approaches were used on said yeast: hybridization by mass mating and adaptive laboratory evolution, both performed through spore generation and conjugation, thus increasing genetic variability. Three evolved variants with lower H₂S production were obtained and used as starters to carry out fermentation at an industrial level. Wine quality was analyzed by its principal oenological parameters and volatile aroma compounds, which were both corroborated by sensory evaluations. Significant differences between the produced wines have been obtained and a substantial improvement in aromatic quality has been achieved. Both hybrids were the most different to the control due to terpenes and esters production, while the evolved strain was very similar to the parental strain. Not only have organoleptic defects been reduced at an industrial level, more floral and fruitier wines have been produced.

Validation of a Standard Protocol to Assess the Fermentative and Chemical Properties of Saccharomyces cerevisiae Wine Strains

This paper reports on a common experiment performed by 17 Research Units of the Italian Group of Microbiology of Vine and Wine (GMVV), which belongs to the Scientific Society SIMTREA, with the aim to validate a protocol for the characterization of wine strains of Saccharomyces cerevisiae. For this purpose, two commercial S. cerevisiae strains (EC 1118 and AWRI796) were used to carry out inter-laboratory-scale comparative fermentations using both synthetic medium and grape musts and applying the same protocol to obtain reproducible, replicable, and statistically valid results. Ethanol yield, production of acetic acid, glycerol, higher alcohols, and other volatile compounds were assessed. Moreover, the Fourier transform infrared spectroscopy was also applied to define the metabolomic fingerprint of yeast cells from each experimental trial. Data were standardized as unit of compounds or yield per gram of sugar (glucose and fructose) consumed throughout fermentation, and analyzed through parametric and non-parametric tests, and multivariate approaches (cluster analysis, two-way joining, and principal component analysis). The results of experiments carried out by using synthetic must showed that it was possible to gain comparable results from three different laboratories by using the same strains. Then, the use of the standardized protocol on different grape musts allowed pointing out the goodness and the reproducibility of the method; it showed the main traits of the two yeast strains and allowed reducing variability amongst independent batches (biological replicates) to acceptable levels. In conclusion, the findings of this collaborative study contributed to the validation of a protocol in a specific synthetic medium and in grape must and showed how data should be treated to gain reproducible and robust results, which could allow direct comparison of the experimental data obtained during the characterization of wine yeasts carried out by different research laboratories.

Fast and Reliable Multiresidue Analysis of Aromas in Wine by Means of Gas Chromatography Coupled with Triple Quadrupole Mass Spectrometry

The paper would like to show a direct injection into GC-MS/QqQ for the determination of secondary aromas in white wine samples fermented in two different ways. The procedure has been compared with more traditional methods used in this field, i.e., headspace analysis and liquid–liquid extraction. The application of such direct injection, for the first time in the literature, allows us to analyze Volatile Organic Compounds (VOCs) in the range 0.1–100 µg mL−1, with Limits of Detection (LODs) and Limits of Quantification (LOQs) between 0.01–0.05 µg mL−1 and 0.03–0.09 µg mL−1, respectively, intraday and interday below 5.6% and 8.5%, respectively, and recoveries above 92% at two different fortification levels. The procedure has been applied to real wine samples: it evidences how the fermentation in wood (cherry) barrel yields higher VOC levels than ones in wine fermented in steel tank, causing production of different secondary aromas and different relative flavors.