Determination and identification of organic acids in wine samples. Problems and challenges

Screening of fermentation resources of Actinidia arguta wine based on principal component analysis combined with a fuzzy mathematical sensory evaluation method

Actinidia arguta is a nutritious fruit with several health benefits. Recently, A. arguta wine has gained popularity among consumers. However, limited research is available on the effect of different cultivars and yeast strains on fruit wine quality. Therefore, in this study, we aimed to analyze the physicochemical indicators and ester aroma compositions of 16 wines derived from four A. arguta cultivars and fermented using four yeast strains to identify the most favorable combinations. The results showed significant differences in nutritional composition and flavor among the 16 wines. Principal component analysis (PCA) indicated that wines produced from the Changjiang No. 1 (CJ No. 1) and Liaofeng No. 1 (LF No. 1) cultivars, as well as those fermented with the LA-FR and LA-BA yeast strains, received higher scores. Furthermore, a fuzzy mathematical sensory evaluation (fuzzy logic model) confirmed the reliability of the PCA results, with the highest comprehensive sensory score (1.812) being awarded to CJ No. 1 wine fermented with LA-BA yeast. In this study, we identified the optimal combination of A. arguta cultivars and yeast strains to provide a theoretical reference for the quality control and development of A. arguta wine production.

Vineyard Location Impact on the Composition and Quality of Wines from International and Native Varieties Grown in Drama, Greece

The objective of this work was to investigate the effect of location on the composition and quality of wines from the viticultural zone PGI Drama. Grapes from two white (Sauvignon blanc, Assyrtiko) and three red varieties (Merlot, Cabernet Sauvignon, Agiorgitiko) were collected from nine locations within the zone during 2022. The vineyards span distances ranging from several hundred meters to 100 km, and their altitudes vary from 90 to nearly 820 m. Vinification was performed following the same protocol according to the type of wine. Wines were analyzed for quality parameters such as pH, total acidity, alcohol, and residual sugar content. In addition, elemental composition, phenolic content, antioxidant capacity, and sensory attributes of the wines were assessed. The obtained results suggested that besides the type of wine and variety, the location significantly affects the quality parameters of the wine. PCA analysis revealed that location is an important factor affecting the wine quality. The areas north and northwest proved more suitable for specific varieties, as they produce wines with more distinct organoleptic characteristics. The results provide insights into the behavior of international and native varieties in the face of global warming and assist in decisions concerning the most suitable plant material.

Correlation analysis between quality characteristics and rhizosphere microorganisms of different wine grape varieties during their ripening phase

Wine grapes are the raw material used in wine brewing. The soil microenvironment is regulated by plant rhizosphere microorganisms, which can have a direct or indirect impact on plant growth and development. The population distribution of rhizosphere soil and endophytic microorganisms of Cabernet Sauvignon, Merlot, and Pinot Noir was investigated in this study utilizing high-throughput sequencing technology in relation to the characteristics of wine quality during the ripening phase. The results showed that the community composition of dominant fungi and bacteria in the rhizospheric soil of the three wine grapes varieties was similar at the phylum level. The microbial richness of Cabernet Sauvignon rhizosphere soil was higher than that of Merlot and Pinot Noir, and the bacterial community structure of various wine grape rhizosphere soil varied at the genus level. There were more differential microorganisms in rhizosphere soil than endophytic microorganisms. At the phylum level, malic acid correlated favorably with Mortierellomycota, while flavonol in the fruit peel and flesh of wine grapes correlated favorably with Aphelidiomyceta and Calcarisporiellomycota in rhizosphere soil fungi; The fruit peel's malic acid showed a negative correlation with the soil bacterial community's verrucomicrobiota, while the fruit flesh's succinic and oxalate acids showed a favorable correlation. Proanthocyanidin in wine grape fruit flesh positively correlated with several fungal genera in rhizosphere soil at the genus level, including Hydnocystis, Schizothecium. Additionally, there was more negative correlation than positive correlation between wine grape quality and soil bacterial community. Several endophytic fungal communities showed good correlations with the proanthocyanidin in wine grapefruit flesh. The fruit peel's ascorbic acid, phenolics, and tannins showed a favorable correlation with rhizosphere endophytic bacteria that were highly abundant at the genus level. However, some endophytic bacteria negatively correlated with malic acid in the fruit flesh. This study provides new ideas and theoretical support for improving the quality of grapes for winemaking.

Enhancing blueberry wine quality and antioxidant capacity through mixed fermentation with S. cerevisiae and O. oeni

This study investigates the impact of O. oeni on the quality of blueberry wine, employing various analytical methods to determine parameters such as alcohol content, antioxidant capacity, organic acids, amino acids, and volatile components. The results demonstrated that co-inoculation with O. oeni significantly decreased the titratable acidity of blueberry wine. Among the organic acids, the malic acid content of ST and SE groups decreased by (26.24 ± 1.24)% and (35.75 ± 4.02)%, respectively. The main consumed amino acids were aspartate, lysine, and arginine after co-inoculation with O. oeni. Additionally, co-inoculation with O. oeni significantly increased the content of medium-chain fatty acid ethyl esters, especially isoamyl acetate content. The antioxidant capacity of blueberry wine was significantly enhanced by co-inoculation with O. oeni, particularly in terms of measurement of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) clearance. The findings of this study provide a solid basis for improving the quality of blueberry wine and promoting the growth of blueberry wine industry.

Effects of Mountain-Basin System on Chemical Composition, Antioxidant Activity and Volatile Flavor Substances of Cabernet Sauvignon Wines in Xinjiang Region, China

To investigate the effect of mountain-basin system on wine quality, four different regions were selected according to altitude and latitude. This work analyzed the differences in physicochemical properties, organic acids, monomeric phenols, antioxidant activity and volatile compounds of Cabernet Sauvignon wine between four regions. Comparative analysis revealed that there were significant differences in alcohol content and pH, respectively. Malic acid in organic acids was the main acid to distinguish the four regions. Correlation analysis showed that there was a significant correlation between physicochemical properties and climatic conditions in the four regions. There were significant differences in most of the monomeric phenols, and the antioxidant capacity was also significantly different. A total of 60 volatile compounds were detected, including 11 key volatile compounds, and there were significant differences in the composition of wines in the four regions. Methyl salicylate, ethyl caprate and ethyl hexanoate were the characteristic aromas in mountain front (MF) and intermontane basin (IB) regions, decanal was the characteristic aroma in sloping field (SF) region, and ethyl butyrate was the characteristic aroma in near desert (ND) region. This study further clarified the influence of climate and terrain on wine quality, and provided a better theoretical basis for the fine management of small producing areas.

Organic acids from ice wine ameliorate fructose-induced disorders of glycolipid metabolism in C57BL/6J mice

Excessive intake of fructose has been widely reported to cause glycolipid metabolism disorders, and it is unclear whether long-term consumption of ice wine, a sweet wine with high sugar content, is beneficial for health. In this study, 6-week-old male C57BL/6J mice were divided into pure water, ice wine, fructose, fructose + succinic acid, fructose + malic acid and fructose + alcohol groups to study the effects and mechanisms of organic acids on glycolipid metabolism. The results indicated that long-term consumption of ice wine did not lead to disorders of glycolipid metabolism, and organic acids inhibited the negative effects of fructose and reduced hepatic fat synthesis by decreasing the mRNA expression of hepatic ACC1, SREBP-1c, and ChREBP-β, as well as controlling the protein expression of KHK-C. These findings provide a theoretical basis for the healthy consumption of ice wine, helping consumers enjoy wine more scientifically and promoting the high-quality development of the industry.

A novel Co/Zn-ferrite molecularly imprinted polymer-based electrochemical assay for sensing of gallic acid in plant extracts, wine, and herbal supplement

In this study, a new molecularly imprinted polymer (MIP)-based sensor platform was developed for the electrochemical determination of gallic acid (GAL) in plant extracts, wine, and herbal supplements. Gallic acid is known for its natural antioxidant properties, which play an important role in preventing cell deterioration that can lead to various diseases. In addition, gallic acid has therapeutic potential due to its anticancer, antiinflammatory, antimicrobial, and neuroprotective properties. Accurate analysis of gallic acid in complex matrices, in mixed samples where different components coexist, is necessary to evaluate the efficacy and safety of this compound. Cobalt ferrite-zinc-dihydro caffeic acid (CFO_Zn_DHCA) nanoparticles, sphere-like in shape and 5 ± 1 nm in size, were incorporated into the MIP-based electrochemical sensor design to enhance the active surface area and porosity of the glassy carbon electrode (GCE) surface. The functional monomer chosen for this study was aminophenyl boronic acid (3-APBA). In the GAL/CFO_Zn_DHCA/3-APBA@MIP-GCE sensor, which was developed using photopolymerization (PP), 3-APBA as a functional monomer was designed, and obtained in the presence of basic monomer (HEMA), cross-linker (EGDMA), and initiator (2-hydroxy-2-methyl propiophenone) by keeping it under a UV lamp at 365 nm. It aims to detect GAL in real samples such as Punica granatum (pomegranate) peel, Camellia sinensis (green and black tea leaves), wine, and herbal supplements. Morphological and electrochemical characterizations of the designed GAL/CFO_Zn_DHCA/3-APBA@MIP-GCE sensor were carried out using scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The linear range for the determination of GAL using the indirect method (5.0 mM [Fe(CN)6]-3/-4) was found to be 1.0 × 10-13 M-1.0 × 10-12 M, and the limit of detection (LOD) and limit of quantification (LOQ) for standard solutions were calculated as 1.29 × 10-14 and 4.29 × 10-14 M, respectively. As a result of the study, the developed MIP-based electrochemical sensor was suitable for detecting GAL with high specificity, selectivity, and sensitivity. Recovery studies were performed to determine the practical applicability of the sensor, and the results were satisfactory. This innovative sensor platform stands out as a reliable and sensitive analytical tool for determining GAL.

Evaluating the Potential of Gamma-Glutamylcysteine and Glutathione as Substitutes for SO2 in White Wine

Sulfur dioxide (SO2) is the most common additive used in winemaking with its antimicrobial and antioxidant properties. However, in recent years, there has been an increasing tendency to reduce the use of excessive SO2 in wine due to its negative effects on human health and organoleptic characteristics. Therefore, the aim of this study was to evaluate the potential use of glutathione (GSH) and its precursor, gamma-glutamyl-cysteine (gGC), which are known as strong antioxidants, for substituting SO2 in white wines. The Turkish indigenous white grape cultivar, Narince (Vitis vinifera), was used to produce white wine. The wines with additions (SO2, gGC, and GSH) and those without (control) were matured for 2 months. As a result, the protective effects of gGC and GSH additions on phenolic compounds, as well as their ability to reduce browning in white wine, were demonstrated. The addition of gGC and GSH enhanced the amount of esters and higher alcohols, improving the wine's aroma. In conclusion, gGC and GSH-particularly gGC-showed great potential as SO2 replacements in wine.

On-vine drying (passérillage) improves the quality of "Hutai No. 8" table grape wine: Focusing on phenolics, aromas, color and sensory attributes

On-vine drying (passérillage) was employed for Hutai No.8 table grapes with different water loss rates and that are used for winemaking to alter the qualities of wine. Results showed that on-vine drying increased sugar content, thereby elevating alcohol and glycerol contents in the resulting wine. A moderate drying treatment (D2, 18 % water loss) produced wine with optimal red color characteristics. The D2 wine contained abundant individual phenolics such as caffeic acid, salicylic acid, resveratrol, p-coumaric acid, and proanthocyanidin B1, which exhibited strong positive correlations with color parameters (a⁎, C*ab and △E*ab). Similar trends were observed in aroma compounds, with ethyl acetate, ethyl caproate, diethyl succinate, geraniol, linalool, 4-terpinenol, α-terpineol, and β-ionone contents showing significant increment in D2, aligning with enhanced sensory evaluations of wines. Thus, improvement of wine quality can be achieved through moderate on-vine drying (18 % water loss)，serving as a valuable reference for table grape winemaking.

Revealing differences in flavor compounds during plum wine fermentation using single and mixed yeast strains through metabolomic analysis

Mixed fermentation can enhance the flavor and aroma of fruit wine, but the mechanisms driving this enhancement remain unclear. This study used non-targeted metabolomics to analyze the effects of mixed versus single fermentation on plum wine flavor. The results showed that compared with single fermentation, mixed fermentation reduced ethanol content and the ability to consume reducing sugars. In single fermentation, volatile compounds increased over time, while in mixed fermentation, they first increased and then declined. Mixed fermentation notably increased esters and reduced higher alcohols, with key differentiators including phenethyl acetate, hexyl acetate, isoamyl acetate, ethyl acetate, isoamyl alcohol, phenethyl alcohol, ethyl caproate, and isobutanol. Furthermore, 40 differential non-volatile flavor compounds were identified, with amino acids emerging as the predominant differentiators. The annotation analysis of these compounds revealed 11 important metabolic pathways for proline, aspartate, glutamate, and β-alanine metabolism. These findings provide insight about producing plum wines with distinct flavor profiles.

The insights into sour flavor and organic acids in alcoholic beverages

Alcoholic beverages have developed unique flavors over millennia, with sourness playing a vital role in their sensory perception and quality. Organic acids, as crucial flavor compounds, significantly impact flavor. This paper reviews the sensory attribute of sour flavor and key organic acids in alcoholic beverages. Regarding sour flavor, research methods include both static and dynamic sensory approaches and summarize the interaction of sour flavor with aroma, taste, and mouthfeel. In addition, this review focuses on identifying key organic acids, including sample extraction, chromatography, olfactometry/taste, and mass spectrometry. The key organic acids in alcoholic beverages, such as wine, Baijiu, beer, and Huangjiu, and their primary regulatory methods are discussed. Finally, future avenues for the exploration of sour flavor and organic acids by coupling machine learning, database, sensory interactions and electroencephalography are suggested. This systematic review aims to enhance understanding and serve as a reference for further in-depth studies on alcoholic beverages.

The flavour of wheat gluten hydrolysate after Corynebacterium Glutamicum fermentation: Effect of degrees of hydrolysis and fermentation time

Corynebacterium glutamicum was used to ferment wheat gluten hydrolysates (WGHs) to prepare flavour base. This study investigated the effect of hydrolysis degrees (DHs) and fermentation time on flavour of WGHs. During fermentation, the contents of amino nitrogen, total acid and small peptides increased, while the protein and pH value decreased. Succinic acid, GMP, and Glu were the prominent umami substances in fermented WGHs. The aromas of WGHs with different DHs could be distinguished by electronic nose and GC-IMS. Based on OAV of GC-MS, hexanal was the main compound in WGHs, while phenylethyl alcohol and acetoin were dominant after fermentation. WGHs with high DHs accumulated more flavour metabolites. Correlation analysis showed that small peptides (<1 kDa) could promote the formation of flavour substances, and Asp was potentially relevant flavour precursor. This study indicated that fermented WGHs with different DHs can potentially be used in different food applications based on flavour profiles.

Metabolic Profiling and Stable Isotope Analysis of Wines: Pilot Study for Cross-Border Authentication

Globalization and free market dynamics have significantly impacted state economies, particularly in the wine industry. These forces have introduced greater diversity in wine products but have also heightened the risk of food fraud, especially in high-value commodities like wine. Due to its market value and the premium placed on quality, wine is frequently subject to adulteration. This issue is often addressed through regulatory trademarks on wine labels, such as Protected Designation of Origin (PDO) and Protected Geographic Indication (PGI). In this context, the metabolic profiles (organic acids, carbohydrates, and phenols) and stable isotope signatures (δ13C, δ18O, D/HI, and D/HII) of red and white wines from four agroclimatically similar regions were examined. The study explored how factors such as grape variety, harvest year, and geographical origin affect wine composition, with a particular focus on distinguishing samples from cross-border areas. Multivariate statistical analysis was used to assess the variability in wine composition and to identify distinct groups of samples. Preliminary results revealed that organic acids and volatile compounds were found in lower concentrations than carbohydrates but were significantly higher than phenols, with levels ranging between 1617 mg/L and 6258 mg/L. Carbohydrate content in the wines varied from 8285 mg/L to 14662 mg/L. Principal Component Analysis (PCA) indicated certain separation trends based on the variance in carbohydrates (e.g., fructose, glucose, galactose) and isotopic composition. However, Discriminant Analysis (DA) provided clear distinctions based on harvest year, variety, and geographical origin.

Antimicrobial Compounds in Wine

Ipsum vinum est potestas et possession (wine itself is power and possession). Wine is a complex system that triggers multisensory cognitive stimuli. Wine and its consumption are thoroughly intertwined with the development of human society. The beverage was appreciated in many ancient mythologies and plays an essential part in Christianity and rituals to this day. Wine has been said to enlighten and inspire artists and has even been prohibited by law and some religions, but has nevertheless played a role in human civilizations since the beginning. Winemaking is also a prospering and economically important industry and a longtime symbol of status and luxury. In winemaking, the formation of the final product is influenced by several factors that contribute to the chemical and sensory complexity often associated with quality vintages. Factors such as terroir, climatic conditions, variety of the grape, all aspects of the winemaking process to the smallest details, including metabolic processes carried out by yeast and malolactic bacteria, and the conditions for the maturation and storage of the final product, up to, and even beyond the point of deciding to open the bottle and enjoy the wine. In conjunction with the empiric and scientific process of winemaking, different molecules with antibacterial activity can be identified in wine during the production process, and several of them are clearly present in the final product. Some of these antibacterial components are phytochemicals, such as flavonoids and phenolic compounds, that may be delivered to the final product (wine) as a part of the grape, a variety of potential additive compounds, or from the oak barrels or clay amphoras used during the maturation process. Others are produced by yeasts and malolactic bacteria and play a role not only in the moderation of the fermentation process but contributing to the microbiological safety and beneficial properties spectra of the final product. Lactic acid bacteria, responsible for conducting malolactic fermentation, contribute to the final balance of the wine but are also directly involved in the production of different compounds exhibiting antibacterial activity. Some examples of these compounds include bacteriocins (antibacterial peptides), diacetyl, organic acids, reuterin, hydrogen peroxide, and carbon dioxide. Major aspects of these different beneficial metabolites are the subject of discussion in this review with the aim of highlighting their beneficial functions.

Effect of short-term moderate intake of ice wine on hepatic glycolipid metabolism in C57BL/6J mice

As the correlation between high fructose intake and metabolism-related diseases (e.g., obesity, fatty liver, and type 2 diabetes) has been increasingly reported, the health benefits of consuming ice wine high in fructose have been called into question. In this study, 6-week-old male C57BL/6J mice were divided into control (pure water), fructose (130 g L-1 fructose solution), alcohol (11% alcohol solution), low-dose (50% diluted ice wine) and high-dose ice wine (100% ice wine) groups to investigate the effects and mechanisms of short-term (4 weeks) ice wine intake on hepatic glycolipid metabolism in mice. The results showed that short-term consumption of ice wine suppressed the elevation of low-density lipoprotein cholesterol content and did not cause hepatic lipid accumulation compared with those of the fructose group. Meanwhile, ice wine had no significant effect on lipogenesis although it inhibited fatty acid oxidation via the PPARα/CPT-1α pathway. Compared with the control group, ice wine interfered with the elevation of fasting glucose and the insulin resistance index in a dose-dependent manner, and led to an increase in plasma uric acid levels, which may further contribute to the disruption of glucolipid metabolism. Overall, short-term moderate intake of ice wine over a 4-week period may not significantly affect hepatic glycolipid metabolism in C57BL/6J mice for the time being.

Preliminary characterization of chemical and sensory attributes for grapes and wines of different cultivars from the Weibei Plateau region in China

Chemical and sensory attributes play a vital role in evaluating the quality of grapes and wines. This study compared basic physicochemical parameters, organic acids, phenolic compounds, and aroma profiles of grapes and wines of six cultivars using chemometrics. The results showed that the reducing sugar contents of Beibinghong, Gongniang, and Granoir grapes were significantly higher than those of others cultivars, whereas their juice yields were significantly lower. The phenolic compound contents in Moldova, Beibinghong, and Gongniang grape skins and wines were higher than those in others cultivars. The organic acid contents in Beibinghong grape and Dunkelfelder wine were highest. Beibinghong and Gongniang grapes and wines showed richer aldehyde and ester concentrations. Beibinghong wine obtained the highest sensory scores. Ethyl decanoate, coumaric acid, and methyl dodecanoate were characteristic variables distinguishing wine cultivars, exhibiting important contributions to their sensory characteristics. These findings were useful for viticulturists and winemakers to select grape varieties.

Simultaneous Analysis of Organic Acids, Glycerol and Phenolic Acids in Wines Using Gas Chromatography-Mass Spectrometry

Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. However, chromatographic analyses face limitations due to the high sugar content in the grape must. Meanwhile, phenolic acids, found in higher quantities in red wines than in white wines, are typically analyzed using HPLC. This study presents a novel method for the quantification of organic acids (OAs), glycerol, and phenolic acids in grape musts and wines. The approach involves liquid-liquid extraction with ethyl acetate, followed by sample derivatization and analysis using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) detection mode. The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. The approach of this proposed method involves (i) methoximation of wine compounds in a basic medium, (ii) acidification with HCl, (iii) liquid-liquid extraction with ethyl acetate, and (iv) silyl derivatization to analyze samples with gas chromatography-mass spectrometry (GC-MS) in ion monitoring detection mode (SIM). The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. In other words, the proposed method may be suitable for profiling (targeted) or fingerprinting (untargeted) strategies to quantify wine metabolites or to classify wines according to the type of winemaking process, grape, or fermentation.

Investigating the Role of Odorant-Polymer Interactions in the Aroma Perception of Red Wine: A Density Functional Theory-Based Approach

The aroma of red wine results from the intricate interplay between aroma compounds (odorants) and complex polymers generated during fermentation. This study combines density functional theory (DFT), human sensory experiments, and nuclear magnetic resonance to investigate the impact of odorant-polymer interactions on wine aroma. Molecular aggregation patterns of odorants with polymer segments are identified, indicating the crucial role of intermolecular noncovalent interactions, such as hydrogen bonds and van der Waals interactions, in stabilizing odorant-polymer conformations. Certain odorants, including 3-isobutyl-2-methoxypyrazine and cis-whisky lactone, exhibit high binding affinity to specific polymer segments, such as (+)-catechin and p-coumaric acid, resulting in substantial changes in the perceived aroma. Their strong binding affinities correlate with changes in sensory experiments for binary mixtures. The results provide insights into the molecular mechanisms of odorant-polymer interactions in red wine with the potential of DFT calculations as a tool for predicting and tailoring red wine aroma.

Comprehensive Evaluation of Ten Actinidia arguta Wines Based on Color, Organic Acids, Volatile Compounds, and Quantitative Descriptive Analysis

Actinidia arguta wine is a low-alcoholic beverage brewed from A. arguta with a unique flavor and sweet taste. In this study, the basic physicochemical indicators, color, organic acid, and volatile aroma components of wines made from the A. arguta varieties 'Kuilv', 'Fenglv', 'Jialv', 'Wanlv', 'Xinlv', 'Pinglv', 'Lvbao', 'Cuiyu', 'Tianxinbao', and 'Longcheng No.2' were determined, and a sensory evaluation was performed. The findings show that 'Tianxinbao' produced the driest extract (49.59 g/L), 'Kuilv' produced the most Vitamin C (913.46 mg/L) and total phenols (816.10 mg/L), 'Jialv' produced the most total flavonoids (477.12 mg/L), and 'Cuiyu' produced the most tannins (4.63 g/L). We analyzed the color of the A. arguta wines based on CIEL*a*b* parameters and found that the 'Kuilv' and 'Longcheng No.2' wines had the largest L* value (31.65), the 'Pinglv' wines had the greatest a* value (2.88), and the 'Kuilv' wines had the largest b* value (5.08) and C*ab value (5.66) of the ten samples. A total of eight organic acids were tested in ten samples via high-performance liquid chromatography (HPLC), and we found that there were marked differences in the organic acid contents in different samples (p < 0.05). The main organic acids were citric acid, quinic acid, and malic acid. The aroma description of a wine is one of the keys to its quality. A total of 51 volatile compounds were identified and characterized in ten samples with headspace gas chromatography-ion mobility spectrometry, including 24 esters, 12 alcohols, 9 aldehydes, 3 aldehydes, 2 terpenes, and 1 acid, with the highest total volatile compound content in 'Fenglv'. There were no significant differences in the types of volatile compounds, but there were significant differences in the contents (p < 0.05). An orthogonal partial least squares discriminant analysis (OPLS-DA) based on the odor activity value (OAV) showed that ethyl butanoate, ethyl pentanoate, ethyl crotonate, ethyl isobutyrate, butyl butanoate, 2-methylbutanal, ethyl isovalerate, and ethyl hexanoate were the main odorant markers responsible for flavor differences between all the A. arguta wines. Sensory evaluation is the most subjective and effective way for consumers to judge A. arguta wine quality. A quantitative descriptive analysis (QDA) of the aroma profiles of ten grapes revealed that the 'fruity' and 'floral' descriptors are the main and most essential parts of the overall flavor of A. arguta wines. 'Tianxinbao' had the highest total aroma score. The flavor and quality of A. arguta wines greatly depend on the type and quality of the A. arguta raw material. Therefore, high-quality raw materials can improve the quality of A. arguta wines. The results of the study provide a theoretical basis for improving the quality of A. arguta wines and demonstrate the application prospects of HS-GC-IMS in detecting A. arguta wine flavors.

An enzyme-centric approach for constructing an amperometric l-malate biosensor with a long and programmable linear range

l-Malate is a key flavor enhancer and acidulant in the food and beverage industry, particularly winemaking. Enzyme-based amperometric biosensors offer convenience for monitoring its concentration. However, only a small number of off-the-shelf malate-oxidizing enzymes have been used in previous devices. These typically have linear ranges poorly suited for the l-malate concentrations found in fruit processing and winemaking, making it necessary to use precisely diluted samples. Here, we describe a pipeline of database-mining, gene synthesis, recombinant expression, and spectrophotometric assays to characterize previously untested enzymes for their suitability in biosensors. The pipeline yielded a bespoke biocatalyst-the Ascaris suum malic enzyme carrying mutation R181Q [AsME(R181Q)]. Our first prototype with AsME(R181Q) had an ultra-wide linear range of 50-200 mM l-malate, corresponding to concentrations found in undiluted fruit juices (including grape). Changing the dication from Mg2+ to Mn2+ increased sensitivity five-fold and adding citrate (100 mM) increased it another six-fold, albeit decreasing the linear range to 1-10 mM. To our knowledge, this is the first time an l-malate biosensor with a tuneable combination of sensitivity and linear range has been described. The sensor response was also tested in the presence of various molecules abundant in juices and wines, with ascorbate shown to be a potent interferent. Interference was mitigated by the addition of ascorbate oxidase, allowing for differential measurements on an undiluted, untreated wine sample that corresponded well with commercial l-malate testing kits. Overall, this work demonstrates the power of an enzyme-centric approach for designing electrochemical biosensors with improved operational parameters and novel functionality.

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.

Comparison Study of the Physicochemical Properties, Amino Acids, and Volatile Metabolites of Guangdong Hakka Huangjiu

The physicochemical properties, amino acids, and volatile metabolites of 20 types of Guangdong Hakka Huangjiu were systematically compared in this study. Lower sugar contents were detected in LPSH, ZJHL-1, and GDSY-1, but the total sugar contents of the other types of Guangdong Hakka Huangjiu were more than 100 g/L (which belonged to the sweet type). Among them, a lower alcohol content was found in GDSY-1 (8.36 %vol). There was a significant difference in the organic acid and amino acid composition among the 20 Guangdong Hakka Huangjiu samples, especially the amino acid composition. However, bitter amino acids as the major amino acids accounted for more than 50% of the total amino acids. A substantial variation in volatile profiles was also observed among all types of Guangzhou Hakka Huangjiu. Interestingly, MZSK-1 had different volatile profiles from other Guangzhou Hakka Huangjiu samples. According to gas chromatography olfactometry (GC-O), most of the aroma-active ingredients identified in Guangdong Hakka Huangjiu were endowed with a pleasant aroma of "fruity".

Chemometric analysis for authentication of 'Syrah' and 'Tempranillo' red wines of San Francisco Valley-Brazil compared to wines from other world regions by the molecular profile in HPLC

The aim of this study was to evaluate the phenolic composition, sugars, and organic acids by HPLC-DAD/RID, and the antioxidant capacity of 100% commercial 'Syrah' and 'Tempranillo' red wines from the San Francisco Valley-SFV wineries, and to compare them with commercial monovarietal wines of the same cultivars from countries such as South Africa, Spain, Chile, and Australia. In total, 25 phenolic compounds were quantified and classified into chemical groups in all wines (phenolics acids, flavanones, flavan-3-ols, flavonols, anthocyanins, and stilbenes). Among these, catechin, procyanidins B1 and B2, lactic acid, and antioxidant capacity were highlighted as the markers responsible for the typification of SFV wines when compared to wines from temperate regions. The data reported here contribute to the knowledge of the potential for producing quality wines in tropical climate regions. The wines of cultivars 'Syrah' and 'Tempranillo' are consolidated among the wineries in the SFV region, Brazil, due to their excellent adaptation to the semi-arid tropical climate. The SFV recently applied for a wine geographical indication as its wines are young with tropical climate typicity. This study shows that it is possible to differentiate SFV Syrah and Tempranillo wines from other world regions by HPLC molecular profile using chemometric techniques.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05739-7.

Comparison of microbial communities and volatile profiles of wines made from mulberry and grape

In this study, three kinds of wines separately made from mulberry (MW), grape (GW), or mulberry/grape (MGW) were developed and their enological parameters, sensory scores, volatile components, and microbiota were investigated and compared. Contrary to the order of residual sugar and acidity of the three kinds of wines, the order of alcohol content from high to low is GW, MW, and MGW. A total of 60 volatile components (VCs), including esters (17), alcohols (12), acids (6), aldehydes (7), ketones (3), alkenes (3), amines (3), alkanes (4), pyrazines (2), benzene (1), sulfide (1), and thiazole (1), were identified by gas chromatography-ion mobility spectrometer (GC-IMS). The fingerprint of VCs and principal component analysis revealed that the volatile profiles of MGW and GW were more similar in comparison to that of MW and were significantly correlated with the mass ratio of mulberry to grape. Lactobacillus, Weissella, Pantoea, Leuconostoc, Lactococcus, Paenibacillus, Pediococcus, and Saccharomyces were identified as the main microflora at the genus level shared by the MW, MGW, and GW, suggesting that the heterolactic bacteria may contribute more to the high content of volatile acids in MW and MGW. The heatmap of core microbiota and main VCs of MW, MGW, and GW suggested the complicated and significant correlation between them. The above data implied that the volatile profiles were more closely related to the raw materials of winemaking and markedly affected by the fermentation microorganisms. This study provides references for evaluation and characterization of MGW and MW and improvement of MGW and MW winemaking process. KEY POINTS: • Fruit wine enological parameters, volatile profile, and microbiota were compared. • Sixty volatile compounds were identified by GC-IMS in three types of fruit wines. • Winemaking materials and microbiota affect volatile profiles of the fruit wines.

Analysis of the formation mechanism of volatile and non-volatile flavor substances in corn wine fermentation based on high-throughput sequencing and metabolomics

The purpose of this study was to reveal the relationship between core microorganisms and flavor substances in the fermentation process of corn wine. Microbial diversity, volatile and non-volatile flavor substances were detected by high-throughput sequencing (HTS), headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) and gas chromatography time of flight mass spectrometry (GC-TOF-MS). High performance liquid chromatography (HPLC) was used to detect organic acids in corn wine fermentation, and its physiochemical properties were tracked. The results showed that physiochemical factors changed obviously with fermentation time. Bacillus, Prevotella_9, Acinetobacter and Gluconobacter were the predominant bacterial. Rhizopus and Saccharomyces were the dominant fungi. Acetic acid and succinic acid were important organic acids in corn wine. According to variable importance of projection (VIP) > 1 and P < 0.05, 24 volatile flavor substances with significant difference were screened out from 52 volatile flavor substances. Similarly, 25 non-volatile flavor substances with significant differences were screened out from the 97 reliable metabolites identified by 223 chromatographic peaks. Eight key metabolic pathways were enriched from 25 non-volatile flavor substances according to path influence values > 0.1 and P < 0.05. Based on Two-way Orthogonal Partial Least Squares (O2PLS) model and Pearson correlation coefficient, Saccharomyces, Rhizopus, uncultured_bacterium, Aneurinibacillus, Wickerhamomyces and Gluconobacter may be the potential volatile flavor-contributing microorganism genus in corn wine. The Pearson correlation coefficient showed that Saccharomyces was significantly positively correlated with malic acid, oxalic acid, valine and isoleucine, and Rhizopus was positively correlated with glucose-1-phosphate and alanine. These findings enhanced our understanding of the formation mechanism of flavor substances in corn wine and provided the theoretical basis for stabilizing flavor quality of corn wine.

Application of ultrasounds to improve oak aging of white wines

Increasing the efficiency of the release for certain compounds during the maturation of some wines in the presence of oak chips is an important topic for oenology research. This study followed the influence of the use of ultrasound waves with a frequency of 35 kHz on the physicochemical and sensory characteristics of some white wines from Iasi, Romania. Oak chips (1 g/L and 2 g/L, fresh, light, and medium toasted) were added to the Fetească regală and Sauvignon blanc stabilized wines. The samples were kept at a constant temperature of 15oC for 10 and 15 days, respectively. For comparison, 15 mins. ultrasound-treated samples were used. It has been observed that this technique in addition to reducing the aging time, significantly influences the organoleptic characteristics of the treated wines. New ways to continue research to clarify, optimize and streamline the methods of artificial aging of wines have also been identified.

Molecular identification of wines using in situ liquid SIMS and PCA analysis

Composition analysis in wine is gaining increasing attention because it can provide information about the wine quality, source, and nutrition. In this work, in situ liquid secondary ion mass spectrometry (SIMS) was applied to 14 representative wines, including six wines manufactured by a manufacturer in Washington State, United States, four Cabernet Sauvignon wines, and four Chardonnay wines from other different manufacturers and locations. In situ liquid SIMS has the unique advantage of simultaneously examining both organic and inorganic compositions from liquid samples. Principal component analysis (PCA) of SIMS spectra showed that red and white wines can be clearly differentiated according to their aromatic and oxygen-contained organic species. Furthermore, the identities of different wines, especially the same variety of wines, can be enforced with a combination of both organic and inorganic species. Meanwhile, in situ liquid SIMS is sample-friendly, so liquid samples can be directly analyzed without any prior sample dilution or separation. Taken together, we demonstrate the great potential of in situ liquid SIMS in applications related to the molecular investigation of various liquid samples in food science.

[Determination of 10 organic acids in alcoholic products by ion chromatography-tandem mass spectrometry]

A method was developed for the determination of 10 organic acids in liquor, yellow rice wine, and dry red wine by ion chromatography-triple quadrupole mass spectrometry (IC-MS/MS). First, the liquor samples were diluted with deionized water, degassed with nitrogen, and analyzed by IC-MS/MS. Then, the yellow rice wine and dry red wine samples were purified with different solid-phase extraction cartridges. Finally, the GCB solid-phase extraction cartridge was selected for purification, diluted with deionized water, and analyzed by IC-MS/MS. The samples were separated using a Dionex IonPac AS11-HC anion analysis column with high capacity and strong hydrophilicity, with an KOH aqueous solution as the eluent, which was produced by an automatic generator for gradient elution. After being suppressed using a suppressor, the eluent was injected directly into the electrospray ionization tandem mass spectrometry (ESI-MS/MS), ionized in negative ion mode, detected in multiple reaction monitoring (MRM) mode, and quantified using an external standard method. Oxalic acid, fumaric acid, maleic acid, malic acid, tartaric acid, citric acid, quinic acid, and aconitic acid showed good linear relationships in the range of 0.05-2 mg/L. Succinic acid and lactic acid showed good linearities in the range of 0.05-5 mg/L and 0.05-10 mg/L, respectively. The correlation coefficients (r²) were >0.99. The limits of detection (LODs) and limits of quantification (LOQs) were 1.0-8.0 μg/L and 3.5-26.5 μg/L, respectively. The average recoveries ranged from 83.0% to 112.1%, and the relative standard deviations (RSDs) were <9.1% in spiked samples at three levels. The proposed method allowed easy pretreatment without using organic solvents or derivatization processing. Overall, the proposed method is accurate, rapid, sensitive, and it is suitable for the qualitative and quantitative analyses of the 10 organic acids in three wine samples. Moreover, it can be used for the determination of flavor and quality of alcoholic products.

Effect of Hanseniaspora uvarum-Saccharomyces cerevisiae Mixed Fermentation on Aroma Characteristics of Rosa roxburghii Tratt, Blueberry, and Plum Wines

Hanseniaspora uvarum, a non-Saccharomyces cerevisiae species, has a crucial effect on the aroma characteristics of fruit wines, thus, attracting significant research interest in recent years. In this study, H. uvarum-Saccharomyces cerevisiae mixed fermentation was used to ferment Rosa roxburghii Tratt, blueberry fruit wine, and plum fruit wines using either a co-inoculated or a sequentially inoculated approach. The three fruit wines' volatile aroma characteristics were analyzed by headspace-solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results showed that the mixed inoculation of H. uvarum and S. cerevisiae reduced the alcoholic content of Kongxinli fruit wine. Moreover, H. uvarum-S. cerevisiae fermented Rosa roxburghii Tratt, blueberry, and plum fruit wines and further enriched their flavor compounds. The overall flavor characteristics of sequentially inoculated fruit wines differed significantly from those fermented with S. cerevisiae alone, although several similarities were also observed. Sequential inoculation of H. uvarum and S. cerevisiae positively affected the mellowness of the wine and achieved a better harmony of the overall wine flavors. Therefore, H. uvarum-Saccharomyces cerevisiae mixed fermentation can improve the complexity of the wines' aromatic composition and empower them with a unique identity. In particular, H. uvarum-Saccharomyces cerevisiae blueberry wine produced by mixed fermentation had the widest variety and content of aroma compounds among the fermented wines. Therefore, H. uvarum-Saccharomyces cerevisiae mixed-fermentation inoculation in the three fermented fruit wines significantly increased the aroma compound variety and content, thus, enriching their aroma richness and complexity. This study is the first comparative evaluation of the aroma characteristics of different fruit wines fermented with a mixed inoculation of H. uvarum and S. cerevisiae and provides a preliminary guide for these fruit wines produced with non-Saccharomyces yeast.

Influence of the Processing Parameters on the Aroma Profile and Chemical Composition of Conventional and Ecological Cabernet Sauvignon Red Wines during Concentration by Reverse Osmosis

Wine aroma represents one of the most important quality parameters and it is influenced by various factors, such as climate conditions, viticulture and vinification techniques, storage conditions, etc. Wines produced from conventionally and ecologically grown grapes of the same variety have different chemical compositions and aroma profiles. The composition of wine can also be influenced by the additional treatment of wine, such as the concentration of wine by reverse osmosis (RO). The aim of this study was to investigate the influence of four different pressures (2.5, 3.5, 4.5 and 5.5 MPa) and two temperature regimes (with and without cooling) on the aroma profile and chemical composition of conventional and ecological Cabernet Sauvignon red wine during concentration by reverse osmosis. The results showed that different processing parameters influenced the permeate flux, the retentate temperature and the compounds retention. Higher working pressures (4.5 and 5.5 MPa) and the regime, with cooling, resulted in a higher retention of the total aroma compounds than the opposite processing parameters. The retention of individual compounds depended also on their chemical properties and their interactions with the membrane surface. The reverse osmosis membranes proved to be permeable for ethanol, acetic acid or undesirable 4-ethylphenol and 4-ethylguaiacol that made them applicable for their correction or removal.

Multivariate Statistical Analysis for Mutual Dependence Assessment of Selected Polyphenols, Organic Acids and Metals in Cool-Climate Wines

Polyphenols, organic acids and metal ions are an important group of compounds that affect the human health and quality of food and beverage products, including wines. It is known that a specific correlation between these groups exist. While wines coming from the New World and the Old World countries are extensively studied, wines coming from cool-climate countries are rarely discussed in the literature. One of the goals of this study was to determine the elemental composition of the wine samples, which later on, together as polyphenols and organic acids content, was used as input data for chemometric analysis. The multivariate statistical approach was applied in order to find specific correlations between the selected group of compounds in the cool-climate wines and the features that distinguish the most and differ between red and white wines and rosé wines. Moreover, special attention was paid to resveratrol and its correlation with selected wine constituents.

Functional Verification of the Citrate Transporter Gene in a Wine Lactic Acid Bacterium, Lactiplantibacillus plantarum

Organic acid metabolism by lactic acid bacteria plays a significant role in improving wine quality. During this process, the uptake of extracellular organic acids by the transporters is the first rate-limiting step. However, up to now, there is very little published research on the functional verification of organic acid transporter genes in wine lactic acid bacteria. In this study, a predicted citrate transporter gene JKL54_04345 (citP) by protein homology analysis was knocked out using a CRISPR/Cas9-based gene-editing system, and then complemented using the modified pMG36e vectors in a major wine lactic acid bacterium, Lactiplantibacillus plantarum XJ25, to verify its function in citrate metabolism for the first time. The results showed that the gene knockout mutant XJ25-ΔcitP lost the ability to utilize citric acid, while the gene complement mutant XJ25-ΔcitP-pMG36ek11-citP fully recovered the ability of citric acid utilization. Meanwhile, citP knockout and complement barely affected the utilization of l-malic acid. These indicated that citP in L. plantarum functioned as a citrate transporter and was the only gene responsible for citrate transporter. In addition, two modified plasmid vectors used for gene supplement in L. plantarum showed distinct transcription efficiency. The transcription efficiency of citP in XJ25-ΔcitP-pMG36ek11-citP mutant was 4.01 times higher than that in XJ25-ΔcitP-pMG36ek-citP mutant, and the utilization rate of citric acid in the former was 3.95 times higher than that in the latter, indicating that pMG36ek11 can be used as a high-level expression vector in lactic acid bacteria.

New Isolated Autochthonous Strains of S. cerevisiae for Fermentation of Two Grape Varieties Grown in Poland

Many commercial strains of the Saccharomyces cerevisiae species are used around the world in the wine industry, while the use of native yeast strains is highly recommended for their role in shaping specific, terroir-associated wine characteristics. In recent years, in Poland, an increase in the number of registered vineyards has been observed, and Polish wines are becoming more recognizable among consumers. In the fermentation process, apart from ethyl alcohol, numerous microbial metabolites are formed. These compounds shape the wine bouquet or become precursors for the creation of new products that affect the sensory characteristics and quality of the wine. The aim of this work was to study the effect of the grapevine varieties and newly isolated native S. cerevisiae yeast strains on the content of selected wine fermentation metabolites. Two vine varieties—Regent and Seyval blanc were used. A total of 16 different yeast strains of the S. cerevisiae species were used for fermentation: nine newly isolated from vine fruit and seven commercial cultures. The obtained wines differed in terms of the content of analyzed oenological characteristics and the differences depended both on the raw material (vine variety) as well as the source of isolation and origin of the yeast strain used (commercial vs. native). Generally, red wines characterized a higher content of tested analytes than white wines, regardless of the yeast strain used. The red wines are produced with the use of native yeast strains characterized by higher content of amyl alcohols and esters.

Nitrite-Free Implications on Consumer Acceptance and the Behavior of Pathogens in Cured Pork Loins

Cured pork loins are valued products due to their particular sensory characteristics. These products are usually prepared with nitrite to guarantee adequate color and pathogen control. The use of nitrite in meat products has been criticized due to its potential contribution to carcinogenic N-nitroso-compound formation. The present work aimed to evaluate the effect of eliminating nitrite from the manufacturing of cured loins made with wine- and water-based marinades on the color evaluation of consumers and on the behavior of Clostridium sporogenes, Listeria monocytogenes, and Salmonella. The use of nitrite in processing cured loins resulted in a color considered adequate by more than 50% of the consumers. When nitrite was not used, the color was described mainly as weak. The hedonic evaluation of cured loins did not reflect the color evaluation. The samples with a weak and an adequate color had similar hedonic evaluations. The present work did not allow us to infer the potential interest in injecting S. xylosus into meat to prepare cured loins. The use of nitrite did not affect the survival of Cl. sporogenes, L. monocytogenes, or Salmonella. The reduction in the aw was the primary determinant influencing pathogen survival. The production of nitrite-free cured loins seems possible once the control of pathogens can be achieved. However, the product will have a weaker color. Consumers appreciate sensory aspects other than color, which, combined with the positive impact of the “additive-free” claim, can support the possibility of producing cured loins without nitrite.

Determination of home-made wine selected parameters and study of honey addition impact on pro-healthy components content

The chemical characteristic of home-made wine, based on the vinification process of Maréchal Foch grapes with minimal intervention, was discussed. The addition of honey in the vinification process has been studied to improve the parameters of the pro-health properties of wine. Assays of antioxidant capacity, pH, colour intensity, total acidity, histamine, tyramine, tryptamine and phenylethylamine contents were carried out during the fermentation, maturation and storage processes. Moreover, the discussed above and selected oenological and quality parameters (organic acids, metals, total and free sulphur dioxide, alcohol content) of obtained wines were compared with commercial wines. Obtained results of allergenic compounds (SO2 and histamine) showed a significantly lower level for home-made wines. The presence of honey during the fermentation process significantly improved the antioxidant parameters, titratable acidity, and influenced the final product colour intensity and colour brilliance. The obtained data show that home-produced wine seems to be a valuable alternative to traditional commercial production due to the lack of chemical additives and potentially allergenic substances in the presence of compounds that enhance human health. Moreover, minimal intervention during fermentation, no filtering step, no chemical additives, processing aids and clarifying substances suggest that home-made wine can be considered natural.

Application of natural and synthetic zeolites in the oenological field

Zeolites are crystalline hydrated aluminosilicates, of natural or synthetic origin, characterized by a microporous structure and high adsorption properties. They are employed as soil amendments and fertilizer carriers in agriculture, as catalysts, detergents, adsorbents and molecular sieves in many chemical processes, as well as in water and soil decontamination, and in food processing. They have been also tested in the oenological field for several potential applications; yet an overview on such topic is not still available. The present review summarizes the recent and innovative applications of zeolites in winemaking and supplies a critical discussion about their potential to prevent protein haze, tartrate instability or the appearance of certain defects, like light-struck off-flavour and earthy off-flavours. Further applications of these minerals in the management of winery wastes and in the analytical field are also reviewed. The outcomes of this work evidenced the need of further research on the use of zeolites in oenology for better exploiting their peculiar sorption and exchange properties, selecting the most efficient natural types and improving the performances of the synthetic ones, without disregarding the potential secondary effects of these treatments on wine quality.

Effect of Different Winemaking Conditions on Organic Acids Compounds of White Wines

Organic acids represent naturally occurring compounds that are found in many types of food and beverages, with important functions in defining products' final quality. Their proportions in wine are dependent on grape composition and winemaking conditions (temperature, pH levels, oxygen, and carbon dioxide concentration). Therefore, this article studied the influence of different fermentation conditions (200 hL tanks vs. 50 L glass demijohns) and various yeasts on the evolution of the main organic acids during alcoholic fermentation of "Aligoté" wines. The fermentation lasted 22 days and samples were collected daily. Laboratory analyses were quantified according to the International Organization of Vine and Wine recommendations. High-performance liquid chromatography for the identification and quantification of organic acids was used. The data showed the important effect of winemaking conditions on sugar consumption, density or acidity values, and sensory characteristics. Significant differences in organic acid concentrations (especially for tartaric acid) were obtained for all variants, depending on the fermentation conditions, inoculated yeast and the sampling moment. The quantities of most of the identified organic acids were generally significantly increased when glass vessels were used, compared to those fermented in tanks. Most organic acids concentrations were favored by lower pH and showed higher values at lower temperatures.

Comparison between Mid-Infrared (ATR-FTIR) Spectroscopy and Official Analysis Methods for Determination of the Concentrations of Alcohol, SO2, and Total Acids in Wine

The determination of alcohol, SO2, and total acids in wine through conventional laboratory techniques have some limitations related to the amount of the samples, analytical preparation of laboratory staff, and time to carry out the analysis. In recent years, spectroscopic and chromatographic methods have been proposed to determinate simultaneously multiple analytical parameters. The new methods claim the speed of analysis and easy execution. However, they need a validation process that guarantees the reliability of the results to be used in official determinations. This study aimed to evaluate the usefulness of FT-infrared reflectance (FT-IR) to quantify total acid, alcohol, and SO2 concentration in the wines. For this purpose, 156 DOC Italian wines were tested with IR technology, and results were compared to those obtained by official analysis methods. The comparison was performed using two non-parametric statistical methods: the Bland & Altman test and Passing & Bablok regression. Our results showed that the spectrophotometric methods make errors due to interfering contaminants in the sample that can be corrected by blank determination. Therefore, the spectrophotometric methods that use the infrared region of the electromagnetic spectrum can be used by the wine industry and regulators for the wine routine as an alternative to official methodologies.

Development of Microchip Isotachophoresis Coupled with Ion Mobility Spectrometry and Evaluation of Its Potential for the Analysis of Food, Biological and Pharmaceutical Samples

An online coupling of microchip isotachophoresis (µITP) with ion mobility spectrometry (IMS) using thermal evaporation interface is reported for the first time. This combination integrates preconcentration power of the µITP followed by unambiguous identification of trace compounds in complex samples by IMS. Short-chain carboxylic acids, chosen as model analytes, were first separated by the µITP in a discontinuous electrolyte system at pH 5–6, and subsequently evaporated at 130 °C during their transfer to the IMS analyzer. Various parameters, affecting the transfer of the separated sample components through the evaporation system, were optimized to minimize dispersion and loss of the analytes as well as to improve sensitivity. The following analytical attributes were obtained for carboxylic acids in the standard solutions: 0.1–0.3 mg L⁻¹ detection limits, 0.4–0.9 mg L⁻¹ quantitation limits, linear calibration range from the quantitation limit to 75 mg L⁻¹, 0.2–0.3% RSD of the IMS response and 98–102% accuracy. The analytical potential of the developed µITP-IMS combination was demonstrated on the analysis of various food, pharmaceutical and biological samples, in which the studied acids are naturally present. These include: apple vinegar, wine, fish sauce, saliva and ear drops. In the real samples, 0.3–0.6% RSD of the IMS response and 93–109% accuracy were obtained.

Use of Lachancea thermotolerans for Biological vs. Chemical Acidification at Pilot-Scale in White Wines from Warm Areas

Climate change is affecting vineyards, resulting in grapes with a low acidity a high pH and sugar at harvest time. The most common procedure so far to improve the acidity and reduce the final pH of wines is to use tartaric acid, but wine can also be acidified microbiologically using Lachancea thermotolerans yeasts, a natural bio-tool that acidifies gradually during the first stage/days of fermentation. Two strains of L. thermotolerans were compared with one Saccharomyces cerevisiae at a pilot-scale under similar fermentation conditions and in duplicate. A sequential inoculation was performed on the third day for the non-Saccharomyces, producing only about 1 g/L of lactic acid, which was suitable for comparison with the Saccharomyces, to which 1.5 g/L of tartaric acid had been added to lower the final pH. The three fermentations ended with a total acidity without significant differences. A significant and normal feature of the L. thermotolerans yeasts is their higher propane-1,2,3-triol production, which was observed in the Laktia yeast, and the acetic acid was <0.3 g/L. The amount of volatile metabolites was generally higher for non-Saccharomyces and the increase was seen in carbonyl compounds, organic acids, lactones, fumaric compounds, and phenols. Finally, the sensory analysis showed that there were hardly any significant differences, even though the non-Saccharomyces had a higher quantity of volatile metabolites, which could lead to a good acceptance of the product, since biological acidification was used, generating a more natural product.

Analysis of chemical compounds’ content in different varieties of carrots, including qualification and quantification of sugars, organic acids, minerals, and bioactive compounds by UPLC

Twelve carrot varieties in different colours and sizes were investigated for chemical properties (dry matter, ash, pectins, titratable acidity, and pH), contents of vitamin C, sugar, organic acids, mineral (sodium, potassium, calcium, iron, and magnesium), and anti-oxidant activities (ABTS, FRAP, and ORAC). Moreover, total polyphenolics and total tetraterpenoids of colourful carrot varieties were presented. According to the study, sucrose was the dominant sugar and isocitric acid was the most common organic acid in carrot samples. In the case of mineral content, potassium, sodium, calcium, magnesium, and iron were identified, while copper was not identified in carrots. Additionally, most of the analyzed carrots were a good source of pectins (average—1.3%), except for mini-orange carrot. Purple-coloured carrot samples demonstrated the highest results for total sugar (11.2 g/100 g fm), total organic acid (2.8 g/100 g fm), total polyphenolic contents (224.4 mg/100 g fm), and anti-oxidant activities (17.1 mmol Trolox equivalents/100 g dm). In turn, the lowest results were observed in normal yellow carrot for total polyphenols (7.3 mg/100 g fm), and anti-oxidant activities (2.5 mmol Trolox equivalents/100 g dm); besides, the lowest total tetraterpenoids were determined in micro-white carrot—0.2 mg/100 g fm.

Determination of Antioxidant Activity by Oxygen Radical Absorbance Capacity (ORAC-FL), Cellular Antioxidant Activity (CAA), Electrochemical and Microbiological Analyses of Silver Nanoparticles Using the Aqueous Leaf Extract of Solanum mammosum L

PURPOSE

The importance of studying polyphenolic compounds as natural antioxidants has encouraged the search for new methods of analysis that are quick and simple. The synthesis of silver nanoparticles (AgNPs) using plant extracts has been presented as an alternative to determine the total polyphenolic content and its antioxidant activity.

METHODS

In this study, aqueous leaf extract of Solanum mammosum, a species of plant endemic to South America, was used to produce AgNPs. The technique of oxygen radical absorption capacity using fluorescein (ORAC-FL) was used to measure antioxidant activity. The oxidation of the 2´,7´-dichlorodihydrofluorescein diacetate (DCFH2-DA) as fluorescent probe was used to measure cellular antioxidant activity (CAA). Electrochemical behavior was also examined using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Total polyphenolic content (TPH) was analyzed using the Folin-Ciocalteu method, and the major polyphenolic compound was analyzed by high performance liquid chromatography with diode array detector (HPLC/DAD). Finally, a microbial analysis was conducted using Escherichia coli and Bacillus sp.

RESULTS

The average size of nanoparticles was 5.2 ± 2.3 nm measured by high-resolution transmission electron microscopy (HR-TEM). The antioxidant activity measured by ORAC-FL in the extract and nanoparticles were 3944 ± 112 and 637.5 ± 14.8 µM ET/g of sample, respectively. Cellular antioxidant activity was 14.7 ± 0.2 for the aqueous extract and 12.5 ± 0.2 for the nanoparticles. The electrochemical index (EI) was 402 μA/V for the extract and 324 μA/V for the nanoparticles. Total polyphenolic content was 826.6 ± 20.9 and 139.7 ± 20.9 mg EGA/100 g of sample. Gallic acid was the main polyphenolic compound present in the leaf extract. Microbiological analysis revealed that although leaf extract was not toxic for Escherichia coli and Bacillus sp., minor toxic activity for AgNPs was detected for both strains.

CONCLUSION

It is concluded that the aqueous extract of the leaves of S. mammosum contains nontoxic antioxidant compounds capable of producing AgNPs. The methods using AgNPs can be used as a fast analytical tool to monitor the presence of water-soluble polyphenolic compounds from plant origin. Analysis and detection of new antioxidants from plant extracts may be potentially applicable in biomedicine.