Advances in Wine Aging Technologies for Enhancing Wine Quality and Accelerating Wine Aging Process

Ultrasound and its coupled oak blocks treatment based on absorbed energy density for comprehensive insight and scale-up consideration of phenolic and astringency profiles in red wines

Ultrasound and ultrasound-coupled oak blocks techniques on the phenolic and astringency profiles of Petit Verdot wines were discussed in this study. The relationship between techniques at varying absorbed energy density (AED) gradients and astringency was revealed, elucidating potential molecular mechanisms regarding compound interactions. Ultrasound was found to promote phenolics degradation and condensed tannins maturation, while oak blocks improved ellagitannins release into wines, facilitating polycondensation reactions to form larger complexes. Phenolics binding to salivary proteins decreased at low AED values (0-33.07 J/mL), enhanced at high AED values (66.14-165.34 J/mL), and reduced salivary proteins' precipitation ability. Treated samples significantly altered astringency's global terminology and sensory attributes across oral regions, with oak blocks enriching the astringency hierarchy. Multivariate analysis identified an optimal ultrasound AED of 0 to 33.07 J/mL, and an effective PLS-DA model was developed for industrial scale-up considerations, aiming to cost-effectively enhance the organoleptic quality of wines.

Variation and fractionation of δ2H, δ18O, and δ17O stable isotopes from irrigation water to soil, grapes, and wine for the traceability of geographical origins

To investigate the variation and fractionation of stable isotopes from irrigation water to soil, grapes, and wine, δ2H, δ18O, and δ17O in different samples from 10 regions in China were determined using a water isotope analyser. The values were significantly different among regions according to the chemometric analysis. All isotopes were significantly and positively correlated with irrigation water-soil and grape-wine. A significant water isotopic fractionation effect was observed from the irrigation water to the soil, grapes, and wine. Stable isotope distribution characteristics correlated with longitude, latitude, altitude, temperature, precipitation, station pressure and wind speed. The linear discriminant analysis (LDA), random forest (RF), support vector machine (SVM), and feed-forward neural network (FNN) models 58.33-100 %, 80-100 %, 53.33-100 %, and 73.33-100 % accurate for distinguishing the geographical origins of all samples from training and test data, respectively. These findings provide a theoretical basis for authenticating the geographic origin of Chinese wines using stable isotope analysis.

Research advances in technologies and mechanisms to regulate vinegar flavor

New vinegar needs a long maturing time to improve its poor flavor before sale, which greatly increases its production cost. Therefore, it is urgent to explore regulation technologies to accelerate vinegar flavor maturation. Based on literature and our research, this review introduces the latest advances in flavor regulation technologies of vinegar including microbial fortification/multi starters fermentation, key production processes optimization and novel physical processing technologies. Microbial fortification or multi starters fermentation accelerates vinegar flavor maturation via enhancing total acids, esters and aroma precursors content in vinegar. Adjusting raw materials composition, fermentation temperature, and oxygen flow reasonably increase alcohols, organic acids, polyphenols and esters levels via generating more corresponding precursors in vinegar, thereby improving its flavor. Furthermore, novel processing technologies greatly promote conversion of alcohols into acids and esters in vinegar, shortening flavor maturation time for over six months. Meanwhile, the corresponding mechanisms are discussed and future research directions are addressed.

Characterization of volatile compounds and sensory properties of spine grape (Vitis davidii Foex) brandies aged with different toasted wood chips

Aging is an important process for improving wine and brandy quality. In this study, the chemical characterization and sensory properties of spine grape brandies were compared after aging with various species of wood chips, including French oak (FO), American oak (AO), Mongolian oak (MO), Japanese blue oak (JO), chestnut, catalpa, and cherry. The results showed that high color intensity and significant concentrations of tannins and polyphenols were observed in the brandies aged with FO, AO, and chestnut chips. The volatile compounds, such as ethyl decanoate, ethyl 2-methylbutanoate, ethyl octanoate, methyl salicylate, (Z)-2-hexenol, and furfural, contributed to the floral, fruity, and roasted/smoky attributes of the brandies aged with FO, AO, and chestnut chips. The 1-butanol, 1-propanol, phenylethanol, phenylethyl acetate, isoamyl acetate, and linalool contributed to the fruity, honey, and floral attributes of the brandies aged with JO and cherry chips. These findings are extremely useful for the production of differentiated and high-quality spine grape brandies.

UHPLC-Q-Orbitrap metabolomics of Syrah red wines during bottle ageing: Molecular markers of evolution and cork permeability

An experiment involving the ageing of Syrah red wine was conducted over a period of 24 months, during which the impact of four different micro-agglomerated corks was examined. An untargeted UHPLC-Q-Orbitrap metabolomics analysis was performed and provided valuable insights into the chemical dynamics of red wine evolution. Forty-three specific discriminating compounds were found for non-aged wines, including various CHO and CHON-types molecules. Thirteen specific discriminating compounds were found for 24-months-aged wines including CHO, CHNOS and CHOS compounds. Among them, sulfonated flavanols and pyranoanthocyanins were identified and emerged as key molecular markers of wine ageing. This metabolomics analysis also enabled us to identify specific chemical markers of cork oxygen transfer rate (OTR) influence. Analysis revealed specific molecules linked to corks with low and high OTR such as anthocyanins and proanthocyanins respectively. This research enhances our comprehension of intricate chemical changes during red wine ageing and underscores the potential impact of cork OTR on wine composition.

Detailed three-dimensional analyses of tyloses in oak used for bourbon and wine barrels through X-ray computed tomography

American white (Quercus alba L.) oak casks have been used for liquid storage for centuries. Their use in aged spirits is critical to imparting flavor and mouthfeel to the final product. The reason that barrels retain liquid has been hypothesized to be the result of abundant physiological structures called tyloses in parenchyma tissues and medullary rays in white oak. Using non-destructive X-ray computed tomography (XRCT) imaging, we reveal an unprecedented view of tylose structure and quantify the pore-filling capacity of tyloses in white oak that underscores the liquid retention we observe in casks. We show that pores of white oaks are filled with sevenfold higher tylose volume compared to northern red oak (Q. rubra), consistent with prior literature that casks made from white oak retain liquid while red oak fails to do so. We propose that XRCT represents a methodological standard for observing these complex structures and should be employed to understand the many questions related to liquid losses from casks, cultural treatment of casks, and the influence of climate change on oak tyloses in the future.

Analysis of targeted phenolic ageing markers in Syrah red wines during bottle ageing: Influence of cork oxygen transfer rate

A Syrah red wine ageing experiment was set up during 24-months and the influence of four micro-agglomerated corks were investigated. Specific phenolic ageing markers were selected and hemi-synthesized: vitisin B, malvidin-ethyl-catechin, and epicatechin-sulfonate. A targeted quantification method of these markers was then developed and validated by using ultra-high performance liquid chromatography - triple quadrupole mass spectrometry (UHPLC-QqQ-MS) operating in MRM (Multiple Reaction Monitoring). Results showed a significant decline in native grape polyphenol levels (anthocyanins, flavanols) as ageing progresses while pyranoanthocyanins, ethyl-linked pigments, and flavanol-sulfonates content increased. The cork oxygen transfer rate emerged as a pivotal factor and had significant effects on polyphenolic concentration evolution but had no significant impact on flavanol-sulfonate formation. These results provide valuable insights into the chemical evolution ongoing during wine ageing, accentuating the pivotal role of cork stopper selection in preserving wine quality over time.

A quality comparison for Xiecun Huangjiu with different aging stages based on chemical profile, aroma composition and microbial succession

The Xiecun Huangjiu (XCHJ), an exemplary representation of North Huangjiu, exhibits a distinct and invigorating aroma predominantly formed during its aging period. In this study, we observed dynamic changes in 16 key aroma compounds by gas chromatography-mass spectrometry (GC-MS) during the aging of XCHJ, with compounds such as phenethylalcohol, isoamylalcohol, benzaldehyde, and ethylbenzoate initially increasing and then decreasing. Ultra-Performance Liquid Chromatography (UPLC) detected nineteen amino acids, with total content ranging from 1901.45 to 3764.45 mg/L. High-throughput sequencing indicated that Pseudomonas, Ochrobactrum, Moesziomyces and Aspergillus et al. were abundant in aged XCHJ. Totally, 4 bacteria and 8 fungi exhibited strong associations with aroma compounds production. Physicochemical properties were primarily interacted with Pseudomonas, Aspergillus, Pseudeurotium, Thermomyces, Bacteroides and Blautia. Furthermore, co-occurrence network analysis highlighted significant interactions between Pantoea, Rhodotorula, Monascus, and amino acids. These findings provide valuable insights for the regulation of aroma in aged XCHJ.

Flavor characteristics of Shanlan rice wines fermented for different time based on HS-SPME-GC-MS-O, HS-GC-IMS, and electronic sensory analyses

Flavor characteristics of Shanlan rice wines with different fermentation time were analyzed. Results suggested that 3-methyl-1-butanol, phenylethyl alcohol, ethyl acetate, and diethyl succinate were the characteristic volatiles of Shanlan rice wine by using headspace solid-phase microextraction-gas chromatography-mass spectrometry-olfactometry. The most varieties (38) of volatiles appeared at a 3-year-fermentation time, contributing a unique and harmonious aroma to the Shanlan rice wine fermented for 3 years, but only 19 types were observed at 45-days and 1-year fermentation times. A similar trend was intuitively visible in the headspace-gas chromatography-ion mobility spectrometry analysis. The Shanlan rice wine fermented for 3 years had a similar taste profile to that fermented for 45 days, but with distinguishing contents of free amino acids (1352.80 mg/L and 2261.50 mg/L, respectively) and organic acids (9.58 g/L and 49.88 g/L, respectively). The Shanlan rice wine fermented for 1 year had a strong taste with more intensity of most taste attributes.

Integrated characterization of filler tobacco leaves: HS-SPME-GC-MS, E-nose, and microbiome analysis across different origins

This study delves into the aroma characteristics and microbial composition of filler tobacco leaves (FTLs) sourced from six distinct cigar-growing regions within Yunnan, China, following standardized fermentation. An integrated approach using gas chromatography-mass spectrometry (GC-MS), electronic nose (E-nose), and microbiome analysis was employed for comprehensive profiling. Results derived from Linear Discriminant Analysis (LDA) using E-nose data confirmed the presence of notable variability in flavor substance profiles among the FTLs from six regions. Additionally, GC-MS was used to discern disparities in volatile organic compound (VOC) distribution across FTLs from these regions, identifying 92, 81, 79, 58, 69, and 92 VOCs within each respective sample set. Significantly, 24 VOCs emerged as pivotal determinants contributing to the heterogeneity of flavor profiles among FTLs from diverse origins, as indicated by Variable Importance for the Projection (VIP) analysis. Furthermore, distinctions in free amino acid content and chemical constituents were observed across FTLs. Of noteworthy significance, solanone, isophorone, durene, (-)-alpha-terpineol, and 2,3'-bipyridine exhibited the strongest correlations with microbiome data, with fungal microorganisms exerting a more pronounced influence on metabolites, as elucidated through two-way orthogonal partial least-squares (O2PLS) modeling. These findings provide a theoretical and technical basis for accurately evaluating the synchronization of FTLs in aromas and fermentation processes, and they will enhance the quality of fermented FTLs and foster the growth of the domestic cigar tobacco industry ultimately.

Aroma Profile of Merlot Red Wine Stored in Stainless-Steel Tanks and Wooden Barrels with Different Toasting Methods

Stainless-steel tanks and wooden barrels are the most common wine ageing and storage vessels. Wooden barrels are often toasted to improve their chemical composition and influence on wine. The aim of this study was to investigate the changes in Merlot red wine aroma from the 2020 and 2021 vintages during 12-month storage (with sampling every 3 months) in a stainless-steel tank (SST), Excellence oak barrels with medium (EMT), medium plus (EMT+) and medium long (EMLT) toasting and a Premium oak barrel with medium toasting (PMT). The results showed that even slight differences in the time and temperature of medium toasting influenced the extraction of aroma compounds from wood to wine. The changes in individual aroma compounds depended on the vessel type, toasting level, initial wine composition and storage time. An increase in the total concentration of compounds with smoky, spicy and woody notes occurred in both wine vintages stored in wooden barrels, especially during longer storage. In samples from SST, floral, fruity and herbal aromas were more pronounced, according to the gas chromatography and sensory evaluators. Sensory evaluators rated the samples according to the 100-point test, and after 12 months of storage, 2020 and 2021 vintage Merlot stored in PMT obtained the highest points.

Effects of sediment and temperature on the long-term aging process of rice wine: Microbial and metabolic insights

Rice wine is low in alcohol content (6 %), rich in nutrients, and contains live microorganisms; therefore, it is generally produced without an aging process during manufacturing. In this study, we investigated the microbial and metabolic changes that occur during the long-term aging of undiluted rice wine with different amount of sediment and aging temperatures. Rice wine samples with higher amounts of sediment had higher yeast counts and alcohol content, indicating a crucial role of sediment in providing nutrients for yeast survival during aging. Furthermore, the rice wine samples that were aged at 12 °C exhibited a notable increase in the relative abundance of Lactobacillus after 100 days of aging. Metabolic profiling revealed that the production of metabolites during rice wine aging was greatly influenced by the amount of sediment and aging temperature, with most metabolites showing a strong correlation with these factors. This study provides valuable insights into the impact of sediment and temperature on the microbial and metabolic changes that occur during the long-term aging of rice wine.

Quality Characteristics and Antioxidant Activities of Six Types of Korean White Wine

The cultivation of European grape cultivars suitable for winemaking in Korea presents challenges due to factors such as climate, soil conditions, precipitation, and sunlight. Consequently, Korea has traditionally resorted to adding sugar to its wine production to counteract the low sugar content in Korean grapes, yielding lower-quality wines. However, recent success in the cultivation of five European grape cultivars and the development of the domestic grape cultivar Cheongsoo have increased the possibility of achieving high-quality Korean wines. This study aimed to explore the potential of European grape cultivars and Cheongsoo as wine grapes in Korea. This study also conducted sensory evaluation and analyzed the physicochemical properties of the grapes and wines, including antioxidant capacity and color. Despite originating from the same vineyard, the composition of grapes and wines, including volatile aromatic compounds, significantly differed among the grape cultivars. In particular, Vidal wine exhibited superior antioxidant capacity compared with other wines. Moreover, Cheongsoo wine showed higher levels of essential volatile aromatic compounds, such as monoterpenes, than other wines. Sensory evaluation of these two wines also revealed excellent results. In conclusion, these findings hold promise for enhancing the diversity of Korean white wine and fostering growth in the wine industry.

Selected Maillard Reaction Products and Their Yeast Metabolites in Commercial Wines

During beer and wine production, Maillard reaction products (MRPs) are formed, which have a particular influence on the taste and aroma of the fermented beverages. Compared to beer, less is known about individual Maillard compounds and especially corresponding yeast metabolites in wine. In this study, 36 selected wines (Amarone, Ripasso, red, and white wines) were analyzed by HPLC-UV and GC-MS concerning the amounts of 3-deoxyglucosone (3-DG), 3-deoxygalactosone (3-DGal), methylglyoxal (MGO), glyoxal (GO), 5-hydroxymethylfurfural (HMF), and furfural (FF). 3-DG was found to be the dominant compound with values from 3.3 to 35.1 mg/L. The contents of 3-DGal, MGO, GO, HMF, and FF were in a single digit range. In addition to MRPs, the yeast metabolites originating from 3-DG, namely, 3-deoxyfructose and 3-deoxy-2-ketogluconic acid, 2,5-bis(hydroxymethyl)furan and 5-formyl-2-furancarboxylic acid, both formed from HMF, and the FF metabolites furfuryl alcohol and furan-2-carboxylic acid were detected and quantitated in wines for the first time. The amounts were between 0.1 and 53.5 mg/L with especially high contents of the oxidation products. Differences between red and white wines indicate that enological parameters like grape variety, production method, and aging may have an influence on the MRP contents in wines.

Impact of phenolic composition and antioxidant parameters on the ageing potential of Syrah red wines measured by accelerated ageing tests

Fourteen Syrah red wines with different initial composition and antioxidant properties (polyphenols, antioxidant capacity, voltammetric behaviour, colour parameters and SO₂) were selected. Three different accelerated ageing tests (AATs) were then performed on these wines: thermal test at 60 °C (60 °C-ATT), enzymatic test with laccase (Laccase-ATT) and chemical test with H₂O₂ (H₂O₂-ATT). The results showed high correlations between the initial phenolic composition and antioxidant properties of the samples. Partial least squares (PLS) regressions were used in order to establish some models that can predict the AATs test results based on their different initial composition and antioxidant properties. The PLS regression models had overall very good accuracy and involved different explaining variables for each test. The models taking into account all the measured parameters and the phenolic composition alone showed good predictive capacities with correlation coefficients (r²) > 0.89.

The state-of-the-art research of the application of ultrasound to winemaking: A critical review

As a promising non-thermal physical technology, ultrasound has attracted extensive attention in recent years, and has been applied to many food processing operation units, such as involving filtration, freezing, thawing, sterilization, cutting, extraction, aging, etc. It is also widely used in the processing of meat products, fruits and vegetables, and dairy products. With regard to its application in winemaking, most of the studies available in the literature are focused on the impact of ultrasound on a certain characteristic of wine, lacking of systematic sorting of these literatures. This review systematically summarizes and explores the current achievements and problems of the application of ultrasound to the different stages of winemaking, including extraction, fermentation, aging and sterilization. Summarizing the advantages and disadvantages of ultrasound application in winemaking and its development in future development.

Identification of Oak-Barrel and Stainless Steel Tanks with Oak Chips Aged Wines in Ningxia Based on Three-Dimensional Fluorescence Spectroscopy Combined with Chemometrics

With the increased incidence of wine fraud, a fast and reliable method for wine certification has become a necessary prerequisite for the vigorous development of the global wine industry. In this study, a classification strategy based on three-dimensional fluorescence spectroscopy combined with chemometrics was proposed for oak-barrel and stainless steel tanks with oak chips aged wines. Principal component analysis (PCA), partial least squares analysis (PLS-DA), and Fisher discriminant analysis (FDA) were used to distinguish and evaluate the data matrix of the three-dimensional fluorescence spectra of wines. The results showed that FDA was superior to PCA and PLS-DA in classifying oak-barrel and stainless steel tanks with oak chips aged wines. As a general conclusion, three-dimensional fluorescence spectroscopy can provide valuable fingerprint information for the identification of oak-barrel and stainless steel tanks with oak chips aged wines, while the study will provide some theoretical references and standards for the quality control and quality assessment of oak-barrel aged wines.

The Application of Non-Thermal Technologies for Wine Processing, Preservation, and Quality Enhancement

Recently, non-thermal wine processing technologies have been proposed as alternatives to conventional winemaking processes, mostly with the aims to improve wine quality, safety, and shelf-life. Winemakers typically rely on sulfites (SO2) to prevent wine oxidation and microbial spoilage, as these processes can negatively affect wine quality and aging potential. However, SO2 can trigger allergic reactions, asthma, and headaches in sensitive consumers, so limitations on their use are needed. In red winemaking, prolonged maceration on skins is required to extract enough phenolic compounds from the wine, which is time-consuming. Consequently, the wine industry is looking for new ways to lower SO2 levels, shorten maceration times, and extend shelf life while retaining wine quality. This review aggregates the information about the novel processing techniques proposed for winemaking, such as high-pressure processing, pulsed electric field, ultrasound, microwave, and irradiation. In general, non-thermal processing techniques have been shown to lead to improvements in wine color characteristics (phenolic and anthocyanin content), wine stability, and wine sensory properties while reducing the need for SO2 additions, shortening the maceration time, and lowering the microbial load, thereby improving the overall quality, safety, and shelf life of the wines.

Aroma characteristics of volatile compounds brought by variations in microbes in winemaking

Wine is a highly complex mixture of components with different chemical natures. These components largely define wine's appearance, aroma, taste, and mouthfeel properties. Among them, aroma is among the most important indicators of wine's sensory characteristics. The essence of winemaking ecosystem is the process of metabolic activities of diverse microbes including yeasts, lactic acid bacteria, and molds, which result in wines with complicated and diversified aromas. A better understanding of how these microbes affect wine's aroma is a crucial step to producing premium quality wine. This study illustrates existing knowledge on the diversity and classification of wine aroma compounds and their microbial origin. Their contributions to wine characteristics are discussed, as well. Furthermore, we review the relationship between these microbes and wine aroma characteristics. This review broadens the discussion of wine aroma compounds to include more modern microbiological concepts, and it provides relevant background and suggests new directions for future research.

Aging acceleration of balsamic vinegar applying micro-oxygenation technique

The effect of micro-oxygenation (MOX) technique on quality and sensorial characteristics of balsamic vinegar was investigated, aiming to aging acceleration. Aging experiments were conducted using a multiple diffuser micro-oxygenator for up to 6 months with an oxygen flow of 30 mg/L/month, including oak chips (1 g/L) or not. Barrel maturation was simultaneously carried out. Quality, nutritional, sensorial characteristics and the aromatic profile of all aged vinegars were evaluated throughout aging. MOX accelerated the alteration of aging indices. Volatile compounds of fruity aroma and wine were decreased, while the fatty/buttery and caramel aroma compounds were increased. Similar compounds of 1.5-year barrel maturation were developed within 6 and 5 months applying MOX without or with oak chips, respectively. MOX resulted in reduction of the aging time to 1/3 compared to the corresponding one in barrels, considered as an attractive approach for vinegar-producing industries, mimicking and accelerating the long and costly barrel aging.

Distilled beverage aging: A review on aroma characteristics, maturation mechanisms, and artificial aging techniques

The market value of distilled beverage relies on its quality with a major contribution of distinctive and fascinating aromas. The aroma of distilled beverage is built on the basis of chemical components and can be modified through a series of physical and chemical processes such as aging. Revealing the hidden knowledge behind the evolution of numerous chemical components during these physicochemical processes in distilled beverages is not only significant but also challenging due to its complex system. In this review, the trends in the changes of associated aroma compounds over aging are proposed on the basis of understanding the relationship between chemical components and aroma profiles of numerous typical distilled beverages. The different aging systems, both classical platforms from Eastern countries (pottery jars) to Western countries (wood barrels), and modern platforms such as artificial aging technologies are outlined and compared with their respective applications. Optimizing aging processes is a challenging but imperative step, which warrants further fundamental knowledge from targeting aging-related molecules to the exploration of multitude physicochemical reaction mechanisms that occur during this process, such as the formation of potent odorant compounds in specific containers and environments, as well as mass transfer processes between solid and liquid interfaces. Understanding these maturation mechanisms of distilled beverages expressed by chemosensory signature holds promise for major improvements in future aging technologies that can efficiently yield stable and high-quality products.

Ultrasound-assisted production of alcoholic beverages: From fermentation and sterilization to extraction and aging

Ultrasound is sound waves above 20 kHz that can be used as a nonthermal ''green'' technology for agri-food processing. It has a cavitation effect, causing bubbles to form and collapse rapidly as they travel through the medium during ultrasonication. Therefore, it inactivates microorganisms and enzymes through cell membrane disruption with physicochemical and sterilization effects on foods or beverages. This emerging technology has been explored in wineries to improve wine color, taste, aroma, and phenolic profile. This paper aims to comprehensively review the research on ultrasound applications in the winery and alcoholic beverages industry, discuss the impacts of this process on the physicochemical properties of liquors, the benefits involved, and the research needed in this area. Studies have shown that ultrasonic technology enhances wine maturation, improves wine fermentation, accelerates wine aging, and deactivates microbes while enhancing quality, as observed with better critical aging markers such as phenolic compounds and color intensity. Besides, ultrasound enhances phytochemical, physicochemical, biological, and organoleptic properties of alcoholic beverages. For example, this technology increased anthocyanin in red wine by 50%. It also enhanced the production rate by decreasing the aging time by more than 90%. Ultrasound can be considered an economically viable technology that may contribute to wineries' waste valorization, resource efficiency improvement, and industry profit enhancement. Despite numerous publications and successful industrial applications discussed in this paper, ultrasound up-scaling and applications for other types of liquors need further efforts.

Characterization of the Key Aroma Volatile Compounds in Nine Different Grape Varieties Wine by Headspace Gas Chromatography-Ion Mobility Spectrometry (HS-GC-IMS), Odor Activity Values (OAV) and Sensory Analysis

During this study, the physicochemical properties, color, and volatile aroma compounds of the original wines produced from the grape varieties ‘Hassan’, ‘Zuoshaner’, ‘Beibinghong’, ‘Zuoyouhong’, ‘Beta’, ‘Shuanghong’, ‘Zijingganlu’, ‘Cabernet Sauvignon’, and ‘Syrah’ were determined and sensory evaluation was performed. Results indicated that ‘Hassan’ contained the most solids, ‘Zuoshaner’ produced the most total acid, residual sugar, total anthocyanin, and total phenol, and ‘Shuanghong’ produced the most tannin. Calculation of the chroma and hue of the wines according to the CIEL*a*b* parameters revealed that the ‘Cabernet Sauvignon’ wines were the brightest of the nine varieties and that the ‘Zuoshaner’ wines had the greatest red hue and yellow hue and the greatest saturation’. A total of 52 volatile compounds were identified and quantified in nine wine samples by HS-GC-IMS analysis, with the most significant number of species detected being 20 esters, followed by 16 alcohols, 8 aldehydes, four ketones, one terpene, and one furan, with the highest total volatile compound content being ‘Beta’. A total of 14 volatile components with OAV (odor activity value) >1 were calculated using the odor activity value (OAV) of the threshold of the aromatic compound, and the OPLS-DA analysis was performed by orthogonal partial least squares discriminant analysis (OPLS-DA) using the OAV values of the compounds with OAV values >1 as the Y variable. The VIP (Variable Importance in Projection) values of six compounds, ethyl isobutyrate, ethyl hexanoate-D, 2-methylpropanal, ethyl octanoate, ethyl butanoate-D, and Isoamyl acetate-D, were calculated to be higher than one between groups, indicating that these six compounds may influence aroma differences. It is essential to recognize that the results of this study have implications for understanding the quality differences between different varieties of wines and for developing wines that have the characteristics of those varieties.

Color Stability Enhancement and Antioxidation Improvement of Sanhua Plum Wine under Circulating Ultrasound

Anthocyanins contribute to the attractive color of fruit wine, and their excessive degradation is deleterious to quality, especially for wine with an inherently low anthocyanin content, such as Sanhua plum wine. Ultrasonic treatment is well recognized for wine color maintenance. In the present study, fresh Sanhua plum wine was ultrasonic-treated and aged in barrels for three months. Our results demonstrate that ultrasonic treatment at 28 and 40 kHz improves color performance, as expressed by an increase in a*, b*, and C* values and color intensity, which is highly related to copigmentation. This successful conservation was attributed to the inactivation of polyphenol oxidase and the corresponding reduction in anthocyanin degradation. Finally, the increased antioxidative ability was verified due to the hydrogen donating ability of the surviving anthocyanins. This study indicates the reliability of ultrasonic treatment for providing superior colorfastness during Sanhua plum wine aging, which is also of great potential in processing different fruit wines.

Flavor compounds with high odor activity values (OAV > 1) dominate the aroma of aged Chinese rice wine (Huangjiu) by molecular association

Aging is an essential operation to perfect the flavor quality of Hungjiu. In this study, formation mechanism of flavor compounds responsible for the characteristic flavor of aged Huangjiu was investigated. The contents of umami and bitter free amino acids (FAA) increased with the storage period prolonged, while that of sweet FAA showed downward trend. Gas chromatograph-mass spectrometry and principal component analysis indicated that the volatile flavor compounds with OAV exceed 1, especially middle-chain fatty-acid-ethyl-esters and aromatic compounds, dominated the characteristic flavor of aged Huangjiu. Low field-NMR was firstly applied to characterize the molecular association between water and dissolved flavor compounds in aged Huangjiu. The results showed that basic amino acids contributed greatly to the flavor formation of aged Huangjiu via molecular association. In addition, the molecular association significantly promoted the accumulation of flavor compounds with OAV > 1, especially ethyl esters.

Monitoring of the Rioja red wine production process by 1 H-NMR spectroscopy

BACKGROUND

As an inherently quantitative and unbiased analytical technique, proton nuclear magnetic resonance (¹ H-NMR) provides an excellent method to monitor the quality of food and beverages, and a sensitive and informative tool to study the winemaking process.

RESULTS

By using NMR, it is possible to monitor quantitative changes in wine metabolites (amino acids, organic acids and some phenolic compounds) during the winemaking process, including wine ageing. This study shows an increase in the concentration of the phenols at the beginning of alcoholic fermentation, as well as a stabilization and slight increase in gallic acid and a slight decrease in resveratrol during the oak barrel ageing step.

CONCLUSION

This study demonstrates the potential of NMR as a process analytical technology (PAT) tool in the wine industry, by monitoring amino acids, organic acids and three polyphenols - gallic acid, catechin and resveratrol - during the winemaking process. This study of the time course evolution of wine has been conducted in a commercial winery rather than an experimental laboratory, demonstrating the capacity of this technique in commercial winemaking production. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Microwave Irradiation: Effects on the Change of Colour Characteristics and Main Phenolic Compounds of Cabernet Gernischt Dry Red Wine during Storage

Wine colour is an essential organoleptic property considered by consumers. In this paper, the potential effects on colour characteristics and the content of main phenolic compounds in red wine under microwave irradiation were investigated during wine storage. The results showed that the changing trend of colour characteristics of microwave-treated and untreated wines was very similar. Moreover, total phenolic compounds, total monomeric anthocyanins, main anthocyanins, main flavonoids, and main phenolic acids (gallic acid; caffeic acid; syringic acid; (+)-catechin; Cy-3-glu; Mv-3-glu) also showed similar change trends during storage. In other words, microwave irradiation had a long-term effect on the colour properties and main phenolic compounds of red wine, changes that require long-time aging in traditional processing. In terms of the studied parameters, the changes in microwave-treated wine were faster than those in untreated wine. These results showed that microwave technology, as a promising artificial aging technology, could in a short time produce red wine of similar quality to traditional aging.

The Application of Wood Species in Enology: Chemical Wood Composition and Effect on Wine Quality

Aging wine is a usual practice in winemaking, as the wine quality improves due to the compounds extracted from wood barrels or chips, cubes, blocks, or staves used. The wood species used are traditionally oak, namely from Quercus petraea, Q. alba, or Q. robur species. In the last years, the increasing request for oak wood has caused a significant increase in environmental and production costs. Therefore, heartwood from several alternative species has been considered a potential wood source for winemaking and aging. Thus, the main purpose of this review is the application of these alternative wood species on wine production and to discuss the advantages and disadvantages of its use compared with the traditional wood species, namely oak wood. In addition, a brief chemical characterization of several wood species with possible application in enology is also discussed in this review.

Different approaches to enhance resveratrol content in wine

Resveratrol is a polyphenol with antioxidant properties and possible beneficial effects on human health. Grapes, peanuts, berries, cacao beans and red wine contain resveratrol. Resveratrol attracts attention due to its bioactive properties, however, the concentration of this compound is not high in grape and wine. Therefore, different studies have been carried out to increase resveratrol level in these products. Several factors such as the grapevine variety, the climatic conditions and the viticultural practices used to create stress on the vine affect the level of resveratrol. Winemaking technologies applied during pre-fermentation, fermentation and post–fermentation stages could also have an effect on the concentration of this stilbene. In addition, recent studies have evaluated biotechnological approaches through the use of different bacteria and yeast strains to produce wine with increased resveratrol content. In this review, the most important factors contributing to increase the resveratrol concentration in grapes and wines are examined. Besides, analytical methods to determine resveratrol content in wine are addressed.

Effect of Graphene vs. Reduced Graphene Oxide in Gold Nanoparticles for Optical Biosensors-A Comparative Study

Aiming to develop a nanoparticle-based optical biosensor using gold nanoparticles (AuNPs) synthesized using green methods and supported by carbon-based nanomaterials, we studied the role of carbon derivatives in promoting AuNPs localized surface plasmon resonance (LSPR), as well as their morphology, dispersion, and stability. Carbon derivatives are expected to work as immobilization platforms for AuNPs, improving their analytical performance. Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4·3H2O using phytochemicals (from tea) which act as both reducing and capping agents. UV-Vis spectroscopy, transmission electron microscopy (TEM), zeta potential (ζ-potential), and X-ray photoelectron spectroscopy (XPS) were used to characterize the AuNPs and nanocomposites. The addition of reduced graphene oxide (rGO) resulted in greater dispersion of AuNPs on the rGO surface compared with carbon-based nanomaterials used as a support. Differences in morphology due to the nature of the carbon support were observed and are discussed here. AuNPs/rGO seem to be the most promising candidates for the development of LSPR biosensors among the three composites we studied (AuNPs/G, AuNPs/GO, and AuNPs/rGO). Simulations based on the Mie scattering theory have been used to outline the effect of the phytochemicals on LSPR, showing that when the presence of the residuals is limited to the formation of a thin capping layer, the quality of the plasmonic resonance is not affected. A further discussion of the application framework is presented.

Alternative Woods in Oenology: Volatile Compounds Characterisation of Woods with Respect to Traditional Oak and Effect on Aroma in Wine, a Review

The interest of winemakers to find new woods that can give their wines a special personality and the need for cooperage wood have led to the use of other woods than traditional oak. The aroma of wines is undoubtedly one of the quality factors most valued by consumers. Volatile compounds from wood are transferred to wines during ageing. The type and quantity of aromas in wood depend on several factors, with the species, origin and cooperage treatments, particularly toasting, being very important. The transfer of volatile compounds to the wine depends not only on the wood but also on the wine itself and the type of ageing. This review therefore aims to recapitulate the volatile composition of alternative oenological woods at different cooperage stages and to compare them with traditional woods. It also summarises studies on the effect of wine aromas during ageing both in barrels and with fragments of alternative woods. In summary, it is observed that both woods and wines aged with alternative species of the Quercus genus present the same volatile compounds as traditional ones, but differ quantitatively; however, non-Quercus woods also differ qualitatively.

Roles of free radical on the formation of acetaldehyde in model wine solutions under different ultrasound parameters: A key bridge-link compound for red wine coloration during ageing

In order to explore the effects of ultrasound on the formation of acetaldehyde and its mechanism in model wine solutions, ultrasound conditions and free radicals were investigated by response surface methodology and electron paramagnetic resonance spectroscopy (EPR), respectively. The results indicate that ultrasound does induce the production of acetaldehyde with the maximum amount under the conditions of ultrasound power density 0.2 W/cm², 48 min and 32 °C. The hydroxyl radicals and the 1-hydroxyethyl free radicals are the main initiator and precursor for acetaldehyde, respectively. Furthermore, the stronger the 1-hydroxyethyl free radicals captured by EPR, the lower the formation of acetaldehyde. In addition, the content of Fe²⁺and ethanol also exerted a certain influence on the acetaldehyde formation. In conclusion, ultrasound does promote the production of acetaldehyde in the model wine solutions, which is beneficial for well understanding the mechanism of ultrasound in modifying the wine color and accelerating ageing.

Wineinformatics: Can Wine Reviews in Bordeaux Reveal Wine Aging Capability?

Wineinformatics is a new and emerging data science that uses wine as domain knowledge and integrates data systems and wine-related data sets. Wine reviews from Wine Spectator usually include the aging information, at the end of the review, in the form of “Best from YearA through YearB”; with the vintage of the wine included, the suggested holding year (YearA—vintage), shelf-life (YearB—vintage) and aging capacity (YearB—YearA) can be calculated and provide crucial information in the study of wineinformatics. The goal of this paper is to test whether wine reviews describing olfactory and gustatory information reveal wines’ suggested holding-year information. Wine reviews from Wine Spectator are extracted and processed by a natural language processing tool named the Computational Wine Wheel for categorizing and mapping various wine terminologies from wine reviews into a consolidated set of descriptors. The suggested aging capability is also calculated from the review and served as a label for classification problems. The study uses different learning algorithms, analyzing their performances and using the best-performing algorithm(s) to build a model for the prediction of a wine’s aging properties. The results of the study suggest that both support vector machine (SVM) and the K-nearest neighbor (KNN) algorithms achieved more than 70% accuracy. These results suggest that the algorithms are able of capturing a hidden informational relationship between a wine’s reviews and its aging capability.

Accelerating vinegar aging by combination of ultrasonic and magnetic field assistance

Most fermented foods need a natural aging process to enrich desired flavours. This process is normally the bottleneck for cost-effective production. Therefore, it is desirable to accelerate the process and obtain products with the same flavour profile. Here, we used physical interventions (ultrasonic field, alternating magnetic field, or combination of both) to assist the aging process with naturally brewed vinegar as a case example. Flavour profiles of different physical-assisted aging process were compared with that of the naturally aged vinegar by using gas-chromatography mass-spectrometry (GC-MS) and electronic nose. Principal component analysis (PCA) and Pearson correlation analyses show that ultrasonic and alternating magnetic fields treatment could accelerate the aging process of vinegar. The highest accelerating aging effect was combination of ultrasonic and magnetic field followed by individual ultrasonic or magnetic field and natural process (combination of ultrasonic and magnetic field > ultrasonic or magnetic field individual > natural process). These results suggest that physical field intervention could potentially be used for acceleration of aging of fermented products without affecting flavour quality.

Age Discrimination of Chinese Baijiu Based on Midinfrared Spectroscopy and Chemometrics

Baijiu is a traditional and popular Chinese liquor which is affected by the storage time. The longer the storage time of Baijiu is, the better its quality is. In this paper, the raw and mellow Baijiu samples from different storage time are discriminated accurately throughout midinfrared (MIR) spectroscopy and chemometrics. Firstly, changing regularities of the substances in Chinese Baijiu are discussed by gas chromatography-mass spectrometry (GC-MS) during the aging process. Then, infrared spectrums of Baijiu samples are processed by smoothing, multivariate baseline correction, and the first and second derivative processing, but no significant variation can be observed. Next, the spectral date pretreatment methods are constructively introduced, and principal component analysis (PCA) and discriminant analysis (DA) are developed for data analyses. The results show that the accuracy rates of samples by the DA method in calibration and validation sets are 91.7% and 100%, respectively. Consequently, an identification model based on support vector machine (SVM) and PCA is established combined with the grid search strategy and cross-validation methods to discriminate the age of Chinese Baijiu validly, where 100% classification accuracy rate is obtained in both training and test sets.

Application of nonthermal processing technologies in extracting and modifying polysaccharides: A critical review

Polysaccharides are natural polymer compounds widely distributed in plants, animals, and microorganisms, most of which have a broad spectrum of biological activities to promote human health. They could also be used as texture modifiers in food industry due to their excellent rheological and mechanical properties. Many researchers have shown that nonthermal processing technologies have numerous advantages, such as high extraction efficiency, short extraction time, and environmental friendliness, in the extraction of polysaccharides compared with the traditional extraction methods. Moreover, nonthermal technologies could effectively change the physicochemical properties and structural characteristics of polysaccharides to improve their biological activities or processing properties. Therefore, a comprehensive summary about the extraction and modification of polysaccharides by nonthermal technologies, including ultrasound, high hydrostatic pressure, pulsed electric fields, and cold plasma, was provided in this review. In particular, the underlying mechanisms, processing operations, and current application status of these technologies were discussed. In addition, the applications of combining nonthermal techniques with other technological methods in polysaccharide extraction and modification were briefly introduced.

The Potential of Flos sophorae immaturus as a Pigment-Stabilizer to Improve the Monascus Pigments Preservation, Flavor Profiles, and Sensory Characteristic of Hong Qu Huangjiu

Hong Qu Huangjiu (HQW) is distinguished by its inclusion of Monascus pigments, meaning that photosensitivity strongly affects the sensory quality of the wine. In this study, the effects of Flos sophorae immaturus (FSI) on the stability of Monascus pigments, the flavor profiles, and the sensory characteristics of HQW were investigated. After sterilization, the addition of FSI increased the preservation rate of Monascus pigments in HQW by up to 93.20%, which could be accounted for by the synergy of rutin and quercetin in FSI. The total content of the volatile flavor compounds in HQW increased significantly as the added amounts of FSI were increased, especially 3-methyl-1-butanol, 2-methyl-1-propanol, and short-chain fatty acid ethyl esters (SCFAEE). Sensory evaluation and partial least-squares regression revealed that the concentration of FSI significantly affected the aroma characteristics of HQW but had little effect on the mouthfeel. The addition of 0.9 mg/mL FSI yielded a satisfactory HQW with high scores in terms of mouthfeel and aroma. The strong correlation between fruit-aroma, full-body, and SCFAEE suggests that FSI might alter the aroma of HQW by enhancing the synthesis of SCFAEE. Summarily, treatment with FSI represents a new strategy for improving the stability of photosensitive pigments and thus adjusting the aroma of HQW or similar beverages.

Impact of High-Power Ultrasound for Barrel Regeneration on the Extraction of Wood Volatile and Non-Volatile Compounds

High-power ultrasound (HPU) is an innovative cleaning method used in wineries for oak barrel sanitation and regeneration. The process is associated with hot water (HPUhw) to ensure microbial stabilization and has been proved to be highly effective in recent years. This study thus examines the impact of different cleaning treatments on the subsequent extraction of wood compounds in wine and their impact on organoleptic properties. Red wines aging in barrels treated (HPUhw and steam) in different years (1, 2, and 3 years) were examined during the first 12 months for chemical exchange from wood to wine. Specific analyses were realized on ellagitannins, the physicochemical composition, and oak wood volatile compounds. Only a small increase in some wood volatile compounds occurred in the case of HPUhw, including furfural, 5-methylfurfural, trans-whisky lactone, vanillin, and syringaldehyde. The sensory analysis carried out by a panel of experts showed that the impact on the organoleptic properties of wines is similar with both processes (HPUhw and steam). However, since HPUhw treatment requires lower energy for the same efficiency, it could be an interesting alternative to steam treatment, given the promising prior microbial results.

Relationship between anthocyanins, proanthocyanidins, and cell wall polysaccharides in grapes and red wines. A current state-of-art review

Numerous research studies have evaluated factors influencing the nature and levels of phenolics and polysaccharides in food matrices. However, in grape and wines most of these works have approach these classes of compounds individually. In recent years, the number of publications interconnecting classes have increased dramatically. The present review relates the last decade's findings on the relationship between phenolics and polysaccharides from grapes, throughout the entire winemaking process up to evaluating the impact of their relationship on the red wine sensory perception. The combination and interconnection of the most recent research studies, from single interactions in model wines to the investigation of the formation of complex macromolecules, brings the perfect story line to relate the relationship between phenolics and polysaccharides from the vineyard to the glass. Grape pectin is highly reactive toward grape and grape derived phenolics. Differences between grape cultivars or changes during grape ripeness will affect the extractability of these compounds into the wines. Therefore, the nature of the grape components will be crucial to understand the subsequent reactions occurring between phenolics and polysaccharide of the corresponding wines. It has been demonstrated that they can form very complex macromolecules which affect wine color, stability and sensory properties.

Profiling the key metabolites produced during the modern brewing process of Chinese rice wine

The study quantitatively profiled 83 low-molecular-weight metabolites in the categories of alcohols, aldehydes, amino acids, esters, fatty acids, organic acids, and reducing sugars produced during the advanced brewing process of Chinese rice wine, using multiply chromatography and mass spectrum. In the primary fermentation, vigorous metabolisms were demonstrated by the production of ethanol at the level of 14% by volume, and the consumption of reducing sugars from the maximum level of 100 g/L to 20 g/L. Meantime, more than 70% of the contents of organic acids, fatty acids, higher alcohols, and aldehydes were formed. The metabolisms slowed down in the secondary fermentation, whereas 60% of the contents of amino acids and esters were accumulated in this stage. The nutrients, such as amino acids, organic acids, and reducing sugars reached 10 g/L, 5 g/L, and 3 g/L at the end of brewing, respectively. In terms of flavor and taste attributes to the brewed rice wine, the organoleptic activity value (i.e. the ratio of content to threshold value) was above 1 for 17 compounds, including six organic acids, namely acetic acid, citric acid, lactic acid, malic acid, succinic acid, and tartaric acid, four amino acids, namely cysteine, aspartic acid, glutamic acid, and lysine, three higher alcohols namely isoamyl alcohol, isobutanol, and phenethyl alcohol, three esters, namely ethyl acetate, ethyl butyrate, and ethyl hexanoate, and an aldehyde, namely benzaldehyde.

Bottle Aging and Storage of Wines: A Review

Wine is perhaps the most ancient and popular alcoholic beverage worldwide. Winemaking practices involve careful vineyard management alongside controlled alcoholic fermentation and potential aging of the wine in barrels. Afterwards, the wine is placed in bottles and stored or distributed in retail. Yet, it is considered that wine achieves its optimum properties after a certain storage time in the bottle. The main outcome of bottle storage is a decrease of astringency and bitterness, improvement of aroma and a lighter and more stable color. This is due to a series of complex chemical changes of its components revolving around the minimized and controlled passage of oxygen into the bottle. For this matter, antioxidants like sulfur oxide are added to avoid excessive oxidation and consequent degradation of the wine. In the same sense, bottles must be closed with appropriate stoppers and stored in adequate, stable conditions, as the wine may develop unappealing color, aromas and flavors otherwise. In this review, features of bottle aging, relevance of stoppers, involved chemical reactions and storage conditions affecting wine quality will be addressed.