Grape brandy production, composition and sensory evaluation

Evaluation of the effect of Torulaspora delbrueckii on important volatile compounds in navel orange original brandy using E-nose combined with HS-SPME-GC-MS

Simultaneous inoculation of non-Saccharomyces cerevisiae during the alcoholic fermentation process has been found to be an effective strategy for enhancing wine flavor. This study aimed to investigate the effect of Torulaspora delbrueckii NCUF305.2 on the flavor of navel orange original brandy (NOOB) using E-nose combined with HS-SPME-GC-MS. The results showed a significant increase (p < 0.05) in the sensitivity of NOOB to W5C, W3C, W1S, and W3S sensors by mixed fermentation (MF). Esters in NOOB increased by 4.13%, while higher alcohols increased by 21.93% (p < 0.001), terpenes and others increased by 52.07% and 40.99% (p < 0.01), respectively. Notably, several important volatile compounds with relative odor activity values above 10 showed an increase. Sensory analysis revealed that a more pronounced citrus-like flavor and higher overall appearance scores were found in MF than in pure fermentation (PF). These findings offer valuable theoretical guidance for enhancing the quality of fruit brandies.

Preliminary Investigation of Fruit Mash Inoculation with Pure Yeast Cultures: A Case of Volatile Profile of Industrial-Scale Plum Distillates

This study investigates the effect of pure yeast culture fermentation versus spontaneous fermentation on the volatile compound profile of industrially produced plum brandy. Using traditional distillation methods, the evolution of key volatile compounds is monitored at seven different moments during the distillation process. By integrating advanced analytical techniques such as GC-MS and sensory evaluation, significant differences in the composition of the distillates are highlighted, particularly in terms of ethyl esters and higher alcohols which are key to the sensory properties of the final product. Distillates produced with the addition of pure cultures gave higher concentrations of esters than those obtained by wild fermentation. The results of our industrial research show that the most critical step is to limit the storage of the input raw material, thereby reducing the subsequent risk of producing higher concentrations of 1-propanol. Furthermore, our results indicate that the heart of the distillate can only be removed up to an ethanol content of approximately 450 g/L and that the removal of additional ethanol results in only a 10% increase in the total volume of the distillate, which in turn results in an increase in boiler heating costs of approximately 30%.

Investigating the Effects of Distillation System, Geographical Origin, and Aging Time on Aroma Characteristics in Brandy Using an Untargeted Metabonomic Approach

In this study, the influence of the distillation system, geographical origin, and aging time on the volatiles of brandy was investigated. An untargeted metabolomics approach was used to classify the volatile profiles of brandies based on the presence of different distillation systems and geographical origins. Through the predictive ability of PLS-DA models, it was found that higher alcohols, C13-norisopenoids, and furans could serve as key markers to discriminate between continuous stills and pot stills, and the contents of C6/C9 compounds, C13-norisoprenoids, and sesquiterpenoids were significantly affected by brandy origin. A network analysis illustrated that straight-chain fatty acid ethyl esters gradually accumulated during aging, and several higher alcohols, furfural, 5-methylfurfural, 4-ethylphenol, TDN, β-damascenone, naphthalene, styrene, and decanal were also positively correlated with aging time. This study provides effective methods for distinguishing brandies collected from different distillation systems and geographical origins and summarizes an overview of the changes in volatile compounds during the aging process.

Charentaise distillation of cognac. Part II: Process simulation and impact of recycling practices on the aroma composition of freshly distilled spirit

A growing number of studies over the years has successfully employed computer simulation tools to understand, optimize and design spirit distillations. Amongst distilled spirits, cognac is a reputed wine spirit resulting from a double batch distillation process known as Charentaise distillation. This complex operation comprises the wine distillation (WD) and the brouillis distillation (BD), which are carried out in copper alembics. The distillate produced in each batch is fractionated and some of those fractions are recycled in subsequent batches. To improve the current understanding of the behavior of aroma compounds during the process, computer simulation modules were built in this work for a WD and a BD and the results were compared with experimental data. Of the 62 aroma compounds detected in the samples over time, 52 could be represented in the simulations, including 37 using the NRTL thermodynamic model to calculate vapor-liquid equilibria and another 15 with the UNIFAC model. Half of those had their concentration profiles and their partitioning accurately described by the simulation, most of which were modeled with NRTL. This highlights the need for reliable vapor-liquid equilibrium data for aroma compounds that were poorly represented or absent from the simulation as well as kinetic data for chemical reactions occurring during distillation. Furthermore, the impact of the recycling operation on the composition in aroma compounds of freshly distilled cognac was investigated. To represent a steady state, a mathematical model was employed to implement the recycling of distillate fractions during 8 successive Charentaise distillation cycles. The operation was shown to improve the extraction of ethanol and of all volatile compounds in the heart, reaching a pseudo steady state after 3 to 5 cycles. The recycling of the second fraction had a higher influence on the extraction of alcohols and terpenes, while for most esters and norisoprenoids the recycled head fractions played a bigger role.

Influence of Oak Species, Toasting Degree, and Aging Time on the Differentiation of Brandies Using a Chemometrics Approach Based on Phenolic Compound UHPLC Fingerprints

Oak wood is the main material used by coopers to manufacture casks for the aging of spirits or wines. Phenolic compounds are the main components extracted from the wood during spirit aging. In the present study, a chemometric approach based on unsupervised (PCA) and supervised (PLS-DA) pattern recognition techniques has been applied to the chromatographic instrumental fingerprints, obtained by ultra-high-performance liquid chromatography (UHPLC) at 280 nm, of the phenolic profiles of brandies aged in casks made of different oak wood species. The resulting natural data groupings and the PLS-DA models have revealed that the oak wood species, the toasting level, and the aging time are the most influential factors on the phenolic profile of the final products. Fingerprinting should be considered as a very useful feature, as it represents a considerable advantage, in terms of internal and quality control, for brandy producers.

Separation techniques for manufacturing fruit spirits: From traditional distillation to advanced pervaporation process

Separation process is one of the key processes in the production of fruit spirits, including the traditional distillation method and the new pervaporation membrane method. The separation process significantly determines the constituents and proportions of compounds in the fruit spirit, which has a significant impact on the spirit quality and consumer acceptance. Therefore, it is important and complex to reveal the changing rules of chemical substances and the principles behind them during the separation process of fruit spirits. This review summarized the traditional separation methods commonly used in fruit spirits, covering the types, principles, and corresponding equipment of distillation methods, focused on the enrichment or removal of aroma compounds and harmful factors in fruit spirits by distillation methods, and tried to explain the mechanism behind it. It also proposed a new separation technology for the production of fruit spirits, pervaporation membrane technology, summarized its working principle, operation, working parameters, and application in the production of fruit spirits, and outlined the impact of the separation method on the production of fruit spirits based on existing research, focusing on the separation of flavor compounds, sensory qualities, and hazard factors in fruit spirits, along with a preliminary comparison with distillation. Finally, according to the current researches of the separation methods and the development requirement of the separation process of fruit spirits, the prospect of corresponding research is put forward, in order to propose new ideas and development directions for the research in this field.

Effects of cold atmospheric plasma pre-treatment on maintaining the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) stored at chilled conditions

This present study investigated the effect of cold atmospheric plasma (CAP) pre-treatment on the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) during chilled storage. The shrimp were pre-treated with the CAP at 40 kV and 36 kH for 100 s in a plasma generating equipment before the drunken treatment and compared with an untreated control sample. The results showed that the CAP pre-treatment significantly inhibited the total viable count (TVC) values, total volatile basic nitrogen (TVB-N) content, and polyphenol oxidase (PPO) activity of the drunken shrimp compared to the control treatment. Furthermore, the CAP pre-treatment also significantly maintained the myofibrillar protein (MP) content, texture properties, and a more stable histological structure of muscle fibers compared to the control. High-throughput sequencing results confirmed that the CAP pre-treatment significantly reduced the diversity and abundance of several bacteria in the shrimp. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis detected that the CAP pre-treatment effectively maintained the stability of volatile organic compounds (VOCs). These findings provide valuable theoretical support for the processing and storage of drunken shrimp.

Chemosensory Characteristics of Brandies from Chinese Core Production Area and First Insights into Their Differences from Cognac

This work aimed to compare the aroma characteristics of representative brandies with different grades from Yantai (one of the Chinese core production areas) and Cognac and to establish relationships between sensory descriptors and chemical composition. Descriptive analysis was performed with a trained panel to obtain the sensory profiles. Forty-three aroma-active compounds were quantified by four different methodologies. A prediction model on the basis of partial least squares analysis was performed to identify candidate compounds that were unique to a certain group of brandies. The result showed that brandies from Yantai could be distinguished from Cognac brandies on the basis of spicy, dried fruit, floral, and fruity-like aromas, which were associated with an aromatic balance between concentrations of a set of compounds such as 5-methylfurfural, γ-nonalactone, and γ-dodecalactone. Meanwhile, brandy with different grades could be distinguished on the basis of compounds derived mostly during the aging process.

Alcoholic Fermentation as a Source of Congeners in Fruit Spirits

Fermentation is a crucial process in the production of alcoholic beverages such as spirits, which produces a number of volatile compounds due to the metabolic activities of yeast. These volatile compounds, together with the volatile components of the raw materials and the volatile compounds produced during the distillation and aging process, play a crucial role in determining the final flavor and aroma of spirits. In this manuscript, we provide a comprehensive overview of yeast fermentation and the volatile compounds produced during alcoholic fermentation. We will establish a link between the microbiome and volatile compounds during alcoholic fermentation and describe the various factors that influence volatile compound production, including yeast strain, temperature, pH, and nutrient availability. We will also discuss the effects of these volatile compounds on the sensory properties of spirits and describe the major aroma compounds in these alcoholic beverages.

Pattern Recognition of GC-FID Profiles of Volatile Compounds in Brandy de Jerez Using a Chemometric Approach Based on Their Instrumental Fingerprints

Brandy de Jerez is a unique spirit produced in Southern Spain under Protected Geographical Indication “Brandy de Jerez” (PGI). Two key factors for the production of quality brandies are the original wine spirit and its aging process. They are significantly conditioned by specific variables related to the base wine and the distillation method employed to produce the wine spirit used to obtain a finally aged brandy. This final beverage is therefore strongly influenced by its production process. The chromatographic instrumental fingerprints (obtained by GC FID) of the major volatile fraction of a series of brandies have been examined by applying a chemometric approach based on unsupervised (hierarchical cluster analysis and principal component analysis) and supervised pattern recognition tools (partial least squares–discriminant analysis and support vector machine). This approach was able to identify the fermentation conditions of the original wine, the distillation method used to produce the wine spirit, and the aging process as the most influential factors on the volatile profile.

Influence of the use of sulfur dioxide, the distillation method, the oak wood type and the aging time on the production of brandies

Brandies are spirits produced from wine spirit and wine distillates. The original wines selected to be distilled to produce the wine spirits as well as the distillation method used determine, to a large extent, the organoleptic characteristics of the final products. The young wine spirits evolve during their aging in oak casks, this being another key stage that affects the chemical and sensorial characteristics of the final brandy. In this work, seven different brandies have been studied. They were obtained from wine produced with and without the addition of sulfur dioxide, during their fermentation, using different distillation methods (single, double or serial distillation using pot stills and continuous column distillation) and aged for 14 or 28 months in three different types of oak wood (Quercus alba, Quercus robur and Quercus petraea) previously toasted to two different grades (medium or light). The use of unsupervised pattern recognition methods (HCA and FA) determined that the addition of sulfur dioxide during the fermentation of the base wine has a major influence on the aromatic and phenolic profile of the aged distillates. On the other hand, by means of supervised pattern recognition methods such as LDA and ANNs, the most significant variables that would allow to discriminate between the classes of brandies identified in the study were evaluated. Thus, the results obtained should cast some light on the most significant variables to be taken into account regarding Brandy production processes if a better control over these production processes is to be achieved, so that more exclusive and better quality products are obtained.

A Study on the Influence of the Use of Sulphur Dioxide, the Distillation System and the Aging Conditions on the Final Sensory Characteristics of Brandy

Brandy is a unique alcoholic beverage obtained from wine distillates. Numerous studies have been published on its physicochemical traits and the effect of certain elaboration variables on them, but not many studies have been carried out from a sensory point of view or that have followed standardized methods applicable to this discipline. This study intends to determine the effect that certain production variables have on the sensory characteristics of brandy. These variables are the following: The use of sulphur dioxide during the fermentation of the base wine, the subsequent distillation system, the alcohol content during aging, the botanical origin of the aging casks, and their toasting degree. For this purpose, the guidelines provided by the ISO standards for sensory analysis have been followed, and chromatic parameters have also been determined. Heavy extractions from Quercus petraea casks resulted in brandies with widely varying colors, although these were hard to distinguish using the olfactory and gustatory properties associated with the factors under study. Conversely, those brandies aged in Quercus alba casks presented very consistent greenish shades that are not traditionally associated with aged brandy. This lower extraction could explain why the aromatic traits that are found in the fresh spirit are better preserved when this type of oak is used. The spirit obtained through the distillation of SO2-free wines aged in Quercus robur presented average sensory characteristics: Good color, smooth in the mouth, and medium-intensity oak notes. The distillates that were aged at 55% ABV were later perceived as more aromatically intense with a greater oak note on the palate. On the other hand, the brandies obtained from wines without SO2 added were perceived as less alcoholic, sweeter, and more balanced, with a softer oak note.

An Exploration of Pepino (Solanum muricatum) Flavor Compounds Using Machine Learning Combined with Metabolomics and Sensory Evaluation

Flavor is one of the most important characteristics that directly determines the popularity of a food. Moreover, the flavor of fruits is determined by the interaction of multiple metabolic components. Pepino, an emerging horticultural crop, is popular for its unique melon-like flavor. We analyzed metabolomics data from three different pepino growing regions in Haidong, Wuwei, and Jiuquan and counted the status of sweetness, acidity, flavor, and overall liking ratings of pepino fruit in these three regions by sensory panels. The metabolomics and flavor ratings were also integrated and analyzed using statistical and machine learning models, which in turn predicted the sensory panel ratings of consumers based on the chemical composition of the fruit. The results showed that pepino fruit produced in the Jiuquan region received the highest ratings in sweetness, flavor intensity, and liking, and the results with the highest contribution based on sensory evaluation showed that nucleotides and derivatives, phenolic acids, amino acids and derivatives, saccharides, and alcohols were rated in sweetness (74.40%), acidity (51.57%), flavor (56.41%), and likability (33.73%) dominated. We employed 14 machine learning strategies trained on the discovery samples to accurately predict the outcome of sweetness, sourness, flavor, and liking in the replication samples. The Radial Sigma SVM model predicted with better accuracy than the other machine learning models. Then we used the machine learning models to determine which metabolites influenced both pepino flavor and consumer preference. A total of 27 metabolites most important for pepino flavor attributes to distinguish pepino originating from three regions were screened. Substances such as N-acetylhistamine, arginine, and caffeic acid can enhance pepino‘s flavor intensity, and metabolites such as glycerol 3-phosphate, aconitic acid, and sucrose all acted as important variables in explaining the liking preference. While glycolic acid and orthophosphate inhibit sweetness and enhance sourness, sucrose has the opposite effect. Machine learning can identify the types of metabolites that influence fruit flavor by linking metabolomics of fruit with sensory evaluation among consumers, which conduces breeders to incorporate fruit flavor as a trait earlier in the breeding process, making it possible to select and release fruit with more flavor.

Characterization of Key Aroma-Active Compounds in Two Types of Peach Spirits Produced by Distillation and Pervaporation by Means of the Sensomics Approach

As a deep-processed product of peach, the aroma characteristics of peach spirit have not been systematically studied, and there has been no research on improving the aroma quality through process improvement. Pervaporation technology was used for the first time in the production of peach spirit instead of distillation, and its critical aroma compounds were analyzed compared with distilled peach spirit. Compared to the distilled peach spirit, pervaporation produced peach spirit presented stronger fruity, honey, and acidic aromas, and lighter cooked-apple aroma. Sixty-two and 65 aroma-active regions were identified in the distilled and pervaporation produced peach spirits, and 40 and 43 of them were quantified. The concentrations of esters, lactones, and acids were significantly higher in the pervaporation produced peach spirit than those in the distilled peach spirit, while terpenoids showed opposite tendency. Both of the overall aromas of distilled and pervaporation produced peach spirits were reconstituted successfully by the compounds with OAV ≥ 1. The omission tests identified 10 and 18 compounds as important aroma compounds for distilled and pervaporation-produced peach spirits, respectively. The differences in the key aroma compounds between the two types of peach spirits explained the differences in the aroma profiles.

Changes in Volatile Compounds during Grape Brandy Production from ‘Cabernet Sauvignon’ and ‘Syrah’ Grape Varieties

Grape-based brandies are one of the most popular alcoholic beverages in the world. The most popular one, Cognac, comes from the Charentes region of Southwest France, and it is mostly produced from the grape variety ‘Ugni Blanc’. However, wines destined for the elaboration of wine spirits also come from different white grape varieties; ‘Colombard’, ‘Folle Blanche’, ‘Montils’, and ‘Semillon’. In this study, the possibility of using the red grape varieties ‘Cabernet Sauvignon’ and ‘Syrah’ was investigated with an emphasis on the change of volatile compounds during the production process. During production, some specific volatile compounds such as 2-hexenal, 3-octanone, isopropyl myristate, ethyl palmitate, ethyl oleate, phenethyl acetate, 1-hexanol, and β-damascenone could be attributed to the primary aroma generated from the grape varieties. During the vinification and fermentation process, the development of ethyl hexanoate, ethyl octanoate, 3-methylbutanol, acetic acid, and octanoic acid occurred. Finally, 3-methylbutanol and predominant esters, ethyl hexanoate, ethyl octanoate, ethyl decanoate, and ethyl laurate, were generated during the distillation and maturation process. The composition and concentration of determined predominant esters in produced brandies suggest that both brandies have volatile profiles comparable to some of the world’s most popular brandies.

The Impact of Type of Brandy on the Volatile Aroma Compounds and Sensory Properties of Grape Brandy in Montenegro

This paper presents the results of a study that examined the impact of grape variety on the volatile aroma compounds and sensory properties of standard and Muscat grape brandy produced in the Podgorica sub-region (Montenegro) in vintages 2011, 2012, and 2013. The brandies were prepared by the distillation of crushed grapes, from the autochthonous varieties of Vranac and Kratošija, and Muscat grapes, in a traditional copper alembic, under the same conditions. The gas chromatographic-mass spectrometric (GC/MS) method of 82 volatile aroma compounds that belong to the group (alcohols, volatile acids, volatile esters, terpenes, volatile aldehydes, acetals, ethers, ketones, and alkanes) and an evaluation of the sensory properties of brandies were carried out to determine the typical characteristics of the examined brandies. Alcohols, fatty acid esters, and terpene compound contents were significantly more abundant in all Muscat grape brandies compared to the brandies from the Vranac and Kratošija wine varieties (Standard brandy). Research results revealed that variety had a significant impact on the volatile aroma compound and sensory properties of brandy. The varietal effect was also confirmed, by multivariate analysis, based on the aroma volatile composition, which showed a grouping by type of grape brandy (varietal origin). Sensory analyses showed that all the brandies belonged to the category of high-quality brandies.

PLS-R Calibration Models for Wine Spirit Volatile Phenols Prediction by Near-Infrared Spectroscopy

Near-infrared spectroscopic (NIR) technique was used, for the first time, to predict volatile phenols content, namely guaiacol, 4-methyl-guaiacol, eugenol, syringol, 4-methyl-syringol and 4-allyl-syringol, of aged wine spirits (AWS). This study aimed to develop calibration models for the volatile phenol’s quantification in AWS, by NIR, faster and without sample preparation. Partial least square regression (PLS-R) models were developed with NIR spectra in the near-IR region (12,500–4000 cm⁻¹) and those obtained from GC-FID quantification after liquid-liquid extraction. In the PLS-R developed method, cross-validation with 50% of the samples along a validation test set with 50% of the remaining samples. The final calibration was performed with 100% of the data. PLS-R models with a good accuracy were obtained for guaiacol (r² = 96.34; RPD = 5.23), 4-methyl-guaiacol (r² = 96.1; RPD = 5.07), eugenol (r² = 96.06; RPD = 5.04), syringol (r² = 97.32; RPD = 6.11), 4-methyl-syringol (r² = 95.79; RPD = 4.88) and 4-allyl-syringol (r² = 95.97; RPD = 4.98). These results reveal that NIR is a valuable technique for the quality control of wine spirits and to predict the volatile phenols content, which contributes to the sensory quality of the spirit beverages.

Effect of organic compounds on cognac sensory profile

Introduction. The present research featured the effect of carbonyls, phenols, furans, fatty alcohols, ethers, and other chemical compounds on the sensory properties of cognac distillates of different ages. The research objective was to identify additional criteria of sensory evaluation by measuring the effect of various compounds on perception intensity. Study objects and methods. The study featured cognac samples of different ages. The experiment involved standard methods, including high-performance liquid and gas chromatography and a mathematical analysis based on Microsoft software. Results and discussion. The content of fatty alcohols, ethers, and carbonyl compounds that formed as a result of fermentation demonstrated little change during the aging period in oak casks. A longer extraction increased the content of phenolic and furan compounds and sugars. The content of terpene compounds decreased due to their high lability. The study revealed the effect of organic compounds on taste descriptors. The article introduces multivariate equations that calculate the dependences of the descriptor intensity on the content of organic compounds. A correlation and regression analysis revealed that phenolic compounds had a significant effect on the taste formation of cognac samples, depending on the aging time. Conclusion. Organic compounds proved to affect the taste profiles of cognac samples of different ages, as well as sensory evaluation descriptors.

Non-Invasive Monitoring of Ethanol and Methanol Levels in Grape-Derived Pisco Distillate by Vibrational Spectroscopy

Handheld Raman and portable FT-IR spectroscopy devices were evaluated for fast and non-invasive determination of methanol and ethanol levels in Peruvian Pisco. Commercial Peruvian Pisco (n = 171) samples were kindly provided by the UNALM Alliance for Research in Alcohol and its Derivatives (Lima, Peru) and supplemented by purchases at grocery and online stores. Pisco spectra were collected on handheld Raman spectrometers equipped with either a 1064 nm or a 785 nm excitation laser and a portable infrared unit operating in transmission mode. The alcohol levels were determined by GC-MS. Calibration models used partial least-squares regression (PLSR) to develop prediction algorithms. GC-MS data revealed that 10% of Pisco samples had ethanol levels lower than 38%, indicating possible water dilution. Methanol levels ranged from 10 to 130 mg/100 mL, well below the maximum levels allowed for fruit brandies. Handheld Raman equipped with a 1064 nm excitation laser gave the best results for determining ethanol (SEP = 1.2%; RPre = 0.95) and methanol (SEP = 1.8 mg/100 mL; RPre = 0.93). Randomly selected Pisco samples were spiked with methanol (75 to 2800 mg/100 mL), and their Raman spectra were collected through their genuine commercial bottles. The prediction models gave an excellent performance (SEP = 98 mg/100 mL; RPre = 0.97), allowing for the non-destructive and non-contact determination of methanol and ethanol concentrations without opening the bottles.

Sensory Lexicon and Major Volatiles of Rakı Using Descriptive Analysis and GC-FID/MS

Rakı is a traditional and Protected Designation of Origin (PDO) alcoholic beverage that is distilled from grape distillate with Pimpinella anisum L. in copper pot stills in Turkey. This study focused on the development of a sensory lexicon, a sensory wheel, using a consensus approach and the determination of major volatiles by GC-FID/MS for Rakı. A total of 37 Rakı samples representing all producers were used for volatile and sensory evaluation. The experts identified 78 attributes and references for the lexicon. The main attributes were spicy, anise, sweet, resinous, fruity, dry fruit, floral, head&tail aroma and white colour. The Rakı sensory wheel was created to provide a graphical display of its sensory attributes. For validation of the lexicon, 18 samples were evaluated using descriptive analysis. The results were subjected to PCA to examine the relationship of the samples with the defined sensory attributes. The PCA results show that there is a significant relationship between the Rakı categories and sensory terms and flavour intensities. The GC-MS analyses depicted the following major volatile compounds n-propanol, 2-methyl-1-propanol, 2 and 3-methyl-1-butanol, ethyl-acetate, acetal, acetaldehyde, trans-anethol and estragole. The characterization of the product using its most distinctive sensory descriptors are important tool and can be used for the industry, marketing, consumer education and scientists.

Differences between retort distillation and double distillation in cherry spirits with double-kettle equipment

The effects of retort distillation (RD) and double distillation (DD) for producing cherry spirits using unique double-kettle equipment were compared, for the first time. RD improved distillation efficiency and kept methanol at a safe level. Compared with DD, the contents of higher alcohols increased with RD: isobutanol, propanol, and benzyl alcohol increased by 15.5, 32.9, and 37.9%, respectively, with the content of ethyl esters being reduced. In contrast, isoamyl formate, with its cherry aroma, was not detected in DD spirits, but was present at up to 10.71 mgL−1 in RD spirits. Six terpenoids were detected in RD spirits, but only four in DD spirits. These changes were also reflected in the sensory scores. Although the purity and elegance of the RD spirits decreased, their complication, richness, and honey aroma increased. These changes are very important for guaranteeing spirits quality, providing a reference for research and production of cherry distilled spirits.

Microbial Community Succession and Its Environment Driving Factors During Initial Fermentation of Maotai-Flavor Baijiu

The microbial composition and environmental factors can take a great influence on community succession during the solid-state fermentation (SSF) of Maotai-flavor Baijiu. In this paper, high-throughput sequencing was used to reveal the dominant microorganisms and the evolution process of microbial community structure in the initial fermentation of Maotai-flavor Baijiu. The correlation analysis was carried out for the relationship between physicochemical factors and fermented microbes. The results showed that microorganisms were obviously enriched and the diversity of bacteria and fungi showed a downward trend during the heap fermentation process of Maotai-flavor Baijiu. However, the diversity of fungi in the pit fermentation process increased. Generally, Lactobacillus, Pichia, and Saccharomyces were the dominant microorganisms in the initial fermentation of Maotai-flavor Baijiu. According to the redundancy analysis, we found that reducing sugar was the key driving factor for microbial succession in the heap fermentation, while acidity, alcohol, and temperature were the main driving forces in pit fermentation. This study revealed the microbial succession and its related environmental factors in the initial fermentation of Maotai-flavor Baijiu, which will enrich our knowledge of the mechanism of solid-state liquor fermentation.

Wine Spirit Ageing with Chestnut Staves under Different Micro-Oxygenation Strategies: Effects on the Volatile Compounds and Sensory Profile

The purpose of this work is to evaluate the wine spirit aged by an alternative process (staves combined with different micro-oxygenation levels) and its comparison with the traditional process (wooden barrels). This evaluation was made by analyzing the volatile compounds and sensory profile of the spirits during 365 days of ageing. The findings confirmed the role played by oxygen in the volatile profile of aged wine spirits. Samples of alternative ageing modalities were well distinguished from those of wooden barrels based on the volatile profile, namely on the concentrations of several volatile phenols. From a sensory point of view, the results are promising with high overall consistency scores obtained from samples of alternative ageing process modalities.

GC-FID-MS Based Metabolomics to Access Plum Brandy Quality

Plum brandy (Slivovitz (en); Šljivovica(sr)) is an alcoholic beverage that is increasingly consumed all over the world. Its quality assessment has become of great importance. In our study, the main volatiles and aroma compounds of 108 non-aged plum brandies originating from three plum cultivars, and fermented using different conditions, were investigated. The chemical profiles obtained after two-step GC-FID-MS analysis were subjected to multivariate data analysis to reveal the peculiarity in different cultivars and fermentation process. Correlation of plum brandy chemical composition with its sensory characteristics obtained by expert commission was also performed. The utilization of PCA and OPLS-DA multivariate analysis methods on GC-FID-MS, enabled discrimination of brandy samples based on differences in plum varieties, pH of plum mash, and addition of selected yeast or enzymes during fermentation. The correlation of brandy GC-FID-MS profiles with their sensory properties was achieved by OPLS multivariate analysis. Proposed workflow confirmed the potential of GC-FID-MS in combination with multivariate data analysis that can be applied to assess the plum brandy quality.

Comparative Evaluation of Brandy de Jerez Aged in American Oak Barrels with Different Times of Use

Brandy de Jerez is a European Geographical Indication for grape-derived spirits aged in oak casks that have previously contained any kind of Sherry wine and, therefore, are known as Sherry Casks^®. Wood compounds have a substantial influence in the quality of the brandies that are aged in the barrels. In the cellar, the barrels that have been used for many years to keep Sherry wine or other wine spirits are often used for this purpose. When wooden barrels are used for the first time, they release a large amount of compounds into the liquid contained in them. Such amount decreases over time but casks life cycle has remained unexplored until now. The present work has the aim to study the brandies obtained from the same wine spirit after two years ageing in three differently oak casks: namely new, 7 years of use (4 years containing Oloroso wine and 3 years containing wine spirits) and 32 years of use (8 years containing Oloroso wine and 24 years containing wine spirits). According to the results from our experiments, even after 32 years of use, the wood barrels still contribute to modify the organoleptic characteristics of brandy. Moreover, the brandies aged in used barrels were judged more balanced than those aged in new barrels.

Sensorial and Volatile Analysis of Wines Made from Partially Dehydrated Grapes: An Ontario Case Study

Winemaking in cool climate viticultural areas can pose challenges due to difficulties in achieving optimal ripeness from climatic conditions that tend to vary vintage-to-vintage. To stabilize quality, the use of partially dehydrated grapes has been indicated as beneficial to the production of high-quality wine (“appassimento” style) despite climatic variation. Postharvest wine grape dehydration is a complex process that involves the concentration or formation of sugars, aromas, and flavours. One of the quality challenges facing appassimento style winemaking is elevated levels of undesirable oxidation compounds. The aim of this study was to characterize wines made from a local yeast isolate, Saccharomyces uvarum CN1, which demonstrates limited osmotolerance and may have application to this wine style, as it is a known lower producer of such compounds. Wines made with CN1 were compared to wines made with the accepted commercial standard, S. cerevisiae, EC1118. Fermentations (n = 24) were established at three target starting sugar concentrations from dehydrated Cabernet franc grapes (24.5, 26.0, and 27.5°Brix) and a control (21.5°Brix) and were assessed for volatile organic compound (VOC) composition via gas chromatography-mass spectrometry (GC-MS). Wines also underwent quantitative descriptive analysis to identify and quantify sensory attributes by a trained panel (n = 11). Results show that the wines fermented with the yeast isolate contain significant differences in the concentrations of VOCs in the wines. Sensorially, the wines differed in intensity for a number of attributes, including red fruit aroma, black fruit flavour, and length of finish both within Brix treatments and amongst yeast strains. The most important differentiating factor amongst these wines was the combination of yeast strain at the highest starting sugar concentration (27.5°Brix). These findings may assist winemakers by informing the yeast strain choice for optimizing appassimento style wine quality in cool climates.

Characterization of odor-active compounds in the head, heart, and tail fractions of freshly distilled spirit from Spine grape (Vitis davidii Foex) wine by gas chromatography-olfactometry and gas chromatography-mass spectrometry

Differences in key odor-active volatile compounds among the head, heart, and tail fractions of freshly distilled spirits from Spine grape (Vitis davidii Foex) wine were identified for the first time by gas chromatography-olfactometry and gas chromatography-mass spectrometry. Results from aroma extract dilution analysis (AEDA) showed that there were 34, 45, and 37 odor-active compounds in the head, heart and tail fractions, respectively. Besides, 20, 22, and 17 quantified compounds, respectively, showed odor activity values (OAVs) > 1. The head fraction was characterized by fruity, fusel/solvent notes owing to higher concentrations of higher alcohols and esters, while the tail fraction had more intense smoky/animal, sweaty/fatty attributes due to higher concentrations of volatile phenols and fatty acids. Finally, the heart fraction was characterized by ethyl octanoate, ethyl hexanoate, ethyl 3-phenylpropanoate, ethyl cinnamate, isoamyl alcohol, guaiacol, 4-ethylguaiacol, 4-vinylguaiacol, 2,3-butanedione, and (E)-β-damascenone. Furthermore, observation of the distillation progress indicated that different volatiles with various boiling points and solubilities followed diverse distillation patterns: concentrations of most esters, higher alcohols, terpenes and C13-norisoprenoids decreased, while concentrations of volatile phenols, fatty acids and some aromatic compounds increased during distillation. As a result, their final concentrations in the three distillate fractions varied significantly.

Development of the Method for Determination of Volatile Sulfur Compounds (VSCs) in Fruit Brandy with the Use of HS-SPME/GC-MS

Volatile sulfur compounds (VSCs) play an important role in the aroma profile of fermented beverages. However, because of their low concentration in samples, their analysis is difficult. The headspace solid-phase microextraction (HS–SPME) technique coupled with gas chromatography and mass spectrometry (GC–MS) is one of the methods successfully used to identify VSCs in wine and beer samples. However, this method encounters more obstacles when spirit beverages are analyzed, as the ethanol content of the matrix decreases the method sensitivity. In this work, different conditions applied during HS–SPME/GC–MS analysis, namely: ethanol concentration, salt addition, time and temperature of extraction, as well as fiber coating, were evaluated in regard to 19 sulfur compounds. The best results were obtained when 50/30 μm Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS) was used to preconcentrate the analytes from the sample at 35 °C for 30 min. The dilution of samples to 2.5% v/v ethanol and the addition of 20% w/v NaCl along with 1% EDTA significantly improves the sensitivity of extraction. The optimized method was applied to three fruit brandy samples (plum, pear, and apple) and quantification of VSCs was performed. A total of 10 compounds were identified in brandy samples and their concentration varied greatly depending on the raw material used from production. The highest concentration of identified VSCs was found in apple brandy (82 µg/L).

Use of Alternative Wood for the Ageing of Brandy de Jerez

The use of alternative types of wood has arisen for the aging of the Brandy de Jerez, on a pilot plant level. In particular, besides the use of American oak, two more types of oak have been studied, French oak and Spanish oak, allowed by the Technical File for the ID Brandy de Jerez, and chestnut, which, though it is not officially allowed, is a type of wood which had been traditionally used in the area for the aging of wines and distillates. All of them have been studied with different toasting levels: Intense toasting and medium toasting. The study of the total phenolic composition (TPI), chromatic characteristics, organic acids, and sensory analysis have proven that chestnut leads to distillates with a higher amount of phenolic compounds and coloring intensity than oak. This behavior is the opposite as regards the toasting of the wood. Among the different types of oak, Spanish oak produces aged distillates with a higher phenolic composition and a higher color intensity. Regarding tasting, the best-assessed samples were those aged with chestnut, French oak, and American oak, and the assessors preferred those who had used a medium toasting level to those with an intense level.

Resurgence of minority and autochthonous grapevine varieties in South America: a review of their oenological potential

In contrast with the general trend of producing wine from the most famous grapevine varieties, associated with the French paradigm, such as Cabernet-Sauvignon, Merlot, Pinot Noir, Syrah, Sauvignon Blanc, and Chardonnay, there is a tendency to revalorize and preserve minority or autochthonous grapevine varieties worldwide. The South American wine region, where most of the varieties derived from varieties brought after European colonization, is not exempt from this. This has allowed new wines to be provided with distinctive identities that are markedly different from the current homogeneous wine production. Moreover, varietal homogenization increases vineyard genetic vulnerability in relation to the emergence of grapevine diseases, to which the commonly cultivated varieties are not resistant. This review summarizes the oenological potential of minority or autochthonous grapevine varieties cultivated within the South American wine region, focusing on Argentina, Chile, and Bolivia. © 2019 Society of Chemical Industry.

Freeze-Dried Immobilized Kefir Culture in Low Alcohol Winemaking

Low alcohol wines represent a rising trend in the global market. Since for ethanol removal, certain physicochemical methods that negatively affect wine quality are applied, the aim of this present study was to evaluate the efficiency of freeze-dried, immobilized kefir culture on natural supports (apple pieces, grape skins and delignified cellulosic material) in low alcohol winemaking at various temperatures (5–30 °C). Initially, genetic analysis of kefir culture was performed by Next Generation Sequencing. There was an immobilization of kefir culture on grape skins-enhanced cell survival during freeze-drying in most cases, even when no cryoprotectant was used. Simultaneous alcoholic and malolactic fermentations were performed in repeated batch fermentations for >12 months, using freeze-dried free or immobilized cells produced with no cryoprotectant, suggesting the high operational stability of the systems. Values of great industrial interest for daily ethanol productivity and malic acid conversion [up to 39.5 g/(Ld) and 67.3%, respectively] were recorded. Principal Component Analysis (PCA) showed that freeze-drying rather than the fermentation temperature affected significantly minor volatiles. All low alcohol wines produced were accepted during the preliminary sensory evaluation.

Volatile Aroma Compounds of Brandy 'Lozovača' Produced from Muscat Table Grapevine Cultivars (Vitis vinifera L.)

Grape brandy, known as ‘Lozovača’, is one of the most produced alcoholic beverages in the Republic of Serbia. Muscat cultivars are highly priced in grape brandy manufacturing. Among the numerous factors, cultivar-specific characteristics have a significant influence on its quality and aroma profile. Pectolytic enzymes play a part in increasing intensity of the prefermentative aroma by hydrolysis of terpenic glycosides, from which the compounds that contribute to the aroma of brandy are released. In this study, grape brandy samples were produced from five Muscat table grapevine cultivars (Vitis vinifera L.) namely, Early Muscat, Radmilovac Muscat, Banat Muscat, Italia Muscat, and Muscat Hamburg, with the addition of pectolytic enzyme in two different concentrations or without it (control). A total of 58 volatile aroma compounds were detected by means of combined gas chromatographic-mass spectrometric (GC/MS) method. Ethyl esters of C₈–C₁₈ fatty acids (21) and terpene (16) compounds were considerably more abundant in all grape brandy samples compared to the other volatile compounds identified. Pectolytic enzyme, positively affected terpenes content in the brandy of all studied cultivars. The similarities between brandy samples produced from Muscat Hamburg (MH) and other Muscat cultivars may be attributed to the parentage of MH to those cultivars.

Discriminant ability of phenolic compounds and short chain organic acids profiles in the determination of quality parameters of Brandy de Jerez

Brandy de Jerez is the most produced spirit in Spain. The rules of its Regulatory Council require the spirit to age in American oak casks that have previously contained any kind of sherry wine. This use, called seasoning, releases wine compounds into the spirit. Because of the differences among sherries, the organoleptic features of a brandy will be significantly different from any other depending on the seasoning. In addition, its specific features make it different from any other spirit. The chromatographic profiles of Brandy de Jerez are reported to be different depending on the seasonings through their ageing process. Different types of Brandy de Jerez have been characterised, regarding their seasoning, using chromatographic techniques. Applying statistical analysis, correlations between the chromatographic profiles and the seasonings have risen up. In addition, the profiles have demonstrated to possess a high degree of correlation with the ageing time of the samples.

Volatile Composition, Colour, and Sensory Quality of Spirit-Based Beverages Enriched with Medicinal Fungus Ganoderma lucidum and Herbal Extract

The multicomponent mixtures consisting of herbs and fungi are commonly used for the production of alcoholic beverages with potential health-promoting effects in many Asian countries. The medicinal fungus Ganoderma lucidum is one of the most important fungi used for spirit production. Although this fungus affects the aromatic complexity of spirits, only a small number of studies have focused on investigating the influence of G. lucidum on the aromatic profile and colour of spirits. The aim of the research is to evaluate the influence of adding G. lucidum and herbal extract on final concentrations of volatile compounds and sensory quality of several distillates. In this study, distillates (grain, plum, grape and wine) were used to produce new spirit-based beverages with the fungus G. lucidum only, or with the fungus and herbal extract. Fifty-nine aroma compounds were identified by GC-MS. The aromatic profiles were strongly influenced by the primary aromas of the distillates, but the addition of G. lucidum and herbal extract enriched the volatile fraction of distillates with a range of ethyl esters, with a fruity and floral fragrance. Higher alcohols, 1-propanol, 2-isobutanol and isoamyl alcohol, were the most abundant volatile compounds in the analyzed distillates and spirits. The lightness of distillates was from 60.7 to 63.6, and with the addition of Ganoderma it significantly decreased to the range from 43.6 to 50.5. The addition of the fungus also increased the intensity of red and yellow colours. The Ganoderma spirits scored very highly in sensory evaluation (17.6-18.3), significantly better than the spirits without any additions (16.1-16.9).

Compositional Differences and Similarities between Typical Chinese Baijiu and Western Liquor as Revealed by Mass Spectrometry-Based Metabolomics

Distilled liquors are important products, both culturally and economically. Chemically, as a complex mixture, distilled liquor comprises various chemical compounds in addition to ethanol. However, the chemical components of distilled liquors are still insufficiently understood and compositional differences and similarities of distilled liquors from different cultures have never been compared. For the first time, both volatile organic compounds (VOCs) and non-VOCs in distilled liquors were profiled using mass spectrometry-based metabolomic approaches. A total of 879 VOCs and 268 non-VOCs were detected in 24 distilled liquors including six typical Chinese baijiu and 18 typical Western liquors. Principal component analysis and a correlation network revealed important insights into the compositional differences and similarities of the distilled liquors that were assessed. Ethyl esters, a few benzene derivatives, and alcohols were shared by most distilled liquors assessed, suggesting their important contribution to the common flavor and mouthfeel of distilled liquors. Sugars and esters formed by fatty alcohol differ significantly between the assessed Chinese baijiu and Western liquors, and are potential marker compounds that could be used for their discrimination. Factors contributing to the differences in chemical composition are proposed. Our results improve our understanding of the chemical components of distilled liquors, which may contribute to more rigorous quality control of alcoholic beverages.

Detecting Counterfeit Brandies

A hypothesis-free sensor array (optoelectronic tongue) composed of an anionic, a cationic and two neutral poly(para-aryleneethynylene)s (PAE) at pH 3, 7 and 13 discriminate more than 30 spirits (including brandy, Branntwein, Cognac, Spirituose, and Weinbrand). Counterfeits (made by mixing of low-quality spirits and caramel colour) and different batches of identical brands of brandies are discriminated. The sensor array works without sample preparation or great instrumental cost, and is superior to conventional methods with respect to sample need (10-20 μL), time and effort. The discrimination stems from differential fluorescence quenching of the PAE-array by the complex mixture of the beverages' colourants, from the oak barrels or added caramel colour. The collected quenching data were analysed by linear discriminant analysis (LDA) and principal component analysis (PCA) to achieve successful discrimination.

Development of blueberry liquor: influence of distillate, sweetener and fruit quantity

BACKGROUND

In this work different formulations of blueberry liquor were tested and characterised based on their physico-chemical and sensory characteristics.

RESULTS

Three factors were evaluated: the distillate used to produce the liquor (wine spirit or grape marc spirit); the sweetener (white sugar or honey) and the fruit quantity (two doses). For each liquor, pH, total acidity, dry soluble solids content, dry extract, alcoholic strength, reducing sugars, colour intensity, methanol content, acetaldehyde and fusel alcohols were determined. Sensory tests were carried out with a trained panel.

CONCLUSION

The three factors studied significantly influenced the physico-chemical features of the liquors, being the quantity of fruit the most discriminating factor, except for the volatile compounds which were mainly influenced by the distillate. As regards the sensory analysis, it was found that the most appreciated liquor was that prepared with wine spirit, sugar and a lower dose of blueberry, and the less appreciated formulation was the one made with grape marc spirit, honey and a lower quantity of blueberry. © 2017 Society of Chemical Industry.

Exploring the microbiota of the red-brown defect in smear-ripened cheese by 454-pyrosequencing and its prevention using different cleaning systems

Red-brown pigmentation can occasionally form in smeared-ripened cheese such as Fontina during the ripening process. This reaction is due to over-development of the typical microbiota present on the rind. Previous studies have demonstrated the relationship between red-brown pigmentation and the traditional utilization of wooden shelves during cheese ripening. The first part of the paper focuses on the characterisation of yeast and bacterial microbiota: plate counts and 454-pyrosequencing were performed in spoiled (n = 6) and non-spoiled cheeses (n = 6) and on the wooden shelves used during ripening. The second part shows different systems tested for cleaning the wooden shelves and avoiding the development of the red-brown defect in cheese: washing with hot water and ozone treatment. Actinobacteria, dominated on the wooden shelves, suggesting to be responsible for the red-brown pigmentation; they were also found in traces in the defected cheese samples. Galactomyces and Debaryomyces were the main species characterizing the yeast population, with Debaryomyces being the most dominant species on the shelves used during ripening of the red-brown defective cheese. Hot water treatment reduced the microbial contamination of shelves, whereas only the ozone treatment ensured complete elimination of both yeast and bacteria, resulting in the cheese rind not having the red-brown defect.