Determination of the Principal Volatile Compounds of Turkish Raki

Turkish Raki is a type of traditional aniseed spirit produced in different areas of Turkey. The amounts and the repartition of the alcoholic fermentation products (fusel alcohols, esters, and aldehydes) are mainly responsible for the flavours and quality of the spirit. Previous studies have been carried out on the quantification of the volatiles of the different aniseed spirits using GC and GC‐MS. In this study of 20 different commercial brands of bottled Raki and 5 homemade Turkish Raki products, the major volatiles and methanol were determined using direct injection with GC‐MS. SPME extraction was also used as a confirmation method for the separation of Raki volatiles. Eight different substances were successfully identified using SPME extraction. The results indicated that some homemade Turkish Raki products from the different regions contained slightly higher concentrations of the most studied compounds. The toxic compound methanol was detected only at a level far below the acceptable legal limit.     

The lack of reproducibility of different distillation techniques and its impact on pear spirit composition

We analysed the impact of operation variability on the composition of pear spirits obtained with a Charentais alembic and a packed distillation column. Lack of reproducibility significantly affected the spirits’ compositions, with batch distillation columns more difficult to operate reproducibly vs. traditional alembics. The composition of column distilled spirits differed more in esters, such as ethyl octanoate, ethyl decanoate and ethyl palmitate. In turn, alembic spirit compositions differed more in acetaldehyde and acetal. Moreover, column distilled spirits contained four times more esters, 20% more higher alcohols, 40% less acetaldehyde and 10% less methanol than alembic spirits. Spirits distilled with a rectification column were more concentrated in ethanol than alembic distilled spirits, although both distillation systems recovered the same amount of ethanol in the heart fraction.     

Methanol and Major Volatile Compounds of Turkish Raki and Effect of Distillate Source

Turkish Raki is the traditional anise flavoured distillate beverage produced mainly from a grape distillate called suma. Two types of Raki are produced in Turkey according to the distillate source. They are Type I — a fresh grape Raki produced only from suma and Type II — a Raki produced from a blended distillate of suma and alcohol of agricultural origin (mainly molasses). In this study the content of ethanol, methanol, distillate based major volatile compounds (aldehydes, esters, higher alcohols), aniseed based anethole and estragole, volatile acid and sugar values in two types of commercial Raki samples (40 samples) was determined and the effect of distillate source on the composition was examined. The distillate and the aniseed based major compounds of the Raki samples were analysed by direct injection with a GC‐MS‐FID according to the European Commission Reference Method. The results of variance analysis and PCA showed that there was a significant difference between the two types of Raki samples. Total volatiles (esters and higher alcohols), methanol, trans‐anethole, estragole and sugar values were higher in the samples made from suma alone. All of the analysed component levels of the Turkish Raki samples were in compliance with Turkish Distilled Beverage Regulations. The methanol levels ranged between 28.00–50.87 g/hL absolute alcohol (AA) in Type I samples and 22.03–41.06 g/hL AA in Type II samples. Distillate based total volatiles levels ranged between 136.12–147.88 g/hL AA, with a mean value of 142.88 g/hL AA, in Type I samples and 102.44–113.45 g/hL, with a mean value of 107.9 g/hL, in the Type II samples. The anise based compound trans‐anethole levels were significantly higher in the Type I samples (1,298–1,570 mg/L) than in the Type II samples (1,014–1,199 mg/L). According to distillate based volatiles, the Turkish Raki has a valuable content of volatile substances compared to other anise flavoured spirits.     

Differentiation of Turkish Rakies through Headspace Solid‐Phase Microextraction and Gas Chromatography‐Mass Spectrometry Analysis

Composition of flavour compounds from several commercial raki samples was determined through headspace solid‐phase microextraction (HS‐SPME) and gas chromatography coupled to mass spectrometry (GC‐MS). The extraction of volatile compounds was performed using a 75 μm CAR/PDMS fibre. Forty three volatile compounds were identified. The major compounds were trans‐anethole (86.47–94.19%), valencene (1.15–6.77%), estragole (2.66–5.46%), and cis‐anethole (0.72–2.33%). Principal component analysis (PCA) enabled the differentiation of the raki samples thanks to compounds arising mainly from aniseed.     

A laboratory yeast strain suitable for spirit production

Yeast strains of the species Saccharomyces cerevisiae currently in use for the production of consumable alcohols such as beer, wine and spirits are genetically largely undefined. This prevents the use of standard genetic manipulations, such as crossings and tetrad analysis, for strain improvement. Furthermore, it complicates the application of the majority of modern methods developed in yeast molecular biology. Here we used two haploid laboratory strains with suitable auxotrophic markers for the construction of a genetically well defined, prototrophic diploid production strain. This strain was tested for its fermentative and sensory performances in comparison to commercially available yeasts. Three different fruit mashes (cherries, plums and pears) were fermented in a 90 kg scale. These were then subjected to distillation and used for the production of spirits with a final ethanol content of 40% (v/v). Fermentation parameters assayed included growth, sugar utilization, ethanol production and generation of volatile compounds, higher alcohols and glycerol. The spirits were also tested for their sensory performances and the data obtained statistically consolidated. Our results clearly demonstrate that this laboratory strain does not display any disadvantage compared with commercial yeasts in spirit production for any of the parameters tested, yet it offers the potential to apply both classical breeding and modern molecular genetic techniques for adjusting yeast physiology to special production schemes.     

Application of Mid-infrared Spectroscopy for the Measurement of Several Quality Parameters of Alcoholic Beverages, Wine and Raki

Mid-infrared (IR) spectroscopy, which is a rapid and relatively small amount of waste producing technique, was used to predict several quality parameters of two types of alcoholic beverages, wine and raki. Mid-infrared spectra of red, rose and white wines and a traditional aniseed alcoholic beverage, raki were collected and relations were established between measured chemical parameters (pH, brix, total phenol content, anthocyanin content, titratable acidity, sugar content, electrical conductivity and some colour parameters) of these beverages and their infrared spectra using chemometric techniques. Partial least square regression provided excellent prediction of total phenol (R ²?=?0.97) and anthocyanin contents (R ²?=?0.98) of wine samples and a good prediction of pH (R ²?=?0.9), brix (R ²?=?0.92) and colour intensity (R ²?=?0.93) values were obtained. Brix, total phenol and sugar content of raki samples were also estimated very successfully (R ²?=?0.99) for raki and good prediction was obtained with pH value. Mid-IR spectroscopy in combination with chemometrics could be a promising technique for determination of several quality parameters of alcoholic beverages simultaneously and rapidly.     

酒醅水分与蒸馏效率的关系

通过传统的甑桶蒸馏方式可实现浓缩和提取发酵酒醅中的乙醇及其他风味成分的目的。酒醅中水分含量的高低直接影响到蒸馏酒产量和质量。通过对酒醅水分含量的控制研究,使甑桶蒸馏效率达到优质、高产。     

Grape brandy production,composition and sensory evaluation

Grape brandy is a spirit drink produced by wine distillation and is matured in wooden casks. According to legislation, it can be characterised by the geographical area where the grapes were produced, the grape variety used and the selected distillation and ageing techniques. Distillation increases ethanol concentration and aromatic constituents which are already present in grapes or are developed during fermentation and distillation. During maturation in wooden casks, compounds that contribute to the aroma and taste are extracted from the wood. Hence the spirit acquires the desired softer mouth feel, aromatic complexity and overall quality. Different methods of analysis are used in order to pursuit this process by analysing volatile and non‐volatile substances and correlate composition with quality. Analysis can also be useful in identification of brandy safety, potential adulterations, provenance and differentiation from other spirits drinks. © 2013 Society of Chemical Industry     

Essential oils of Turkish anise seeds and their use in the aromatization of raki

The objectives of this study were the characterization of Turkish anise seeds, their essential oils, and investigations into the suitability of the direct use of these oils in the production of raki, a traditional Turkish distilled liqueur. The moisture, protein, ash, acid-insoluble ash, nonvolatile ethyl ether and ethanol extracts, and essential oil contents of anise seeds were determined, as were the specific gravity, refractive index, solidification point and chemical composition of anise essential oil. Finally a series of raki samples were produced, on a laboratory scale, using rectified anise essential oils obtained in this study as well as those imported and these were compared with traditionally produced rakis by a specially trained panel. The results of sensory analyses were quite promising for the use of anise essential oil as a direct flavouring additive to Turkish raki.

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Ätherische Öle türkischer Anissamen und deren Eignung für die Herstellung von Raki

Zusammenfassung Arbeitsziele waren die Charakterisierung türkischer Anissamen, ihrer ätherischen Öle und Untersuchungen zu deren Anwendbarkeit bei Herstellung von Raki, einem traditionellen türkischen alkoholischen Getränk. Zu diesem Zweck wurden der Feuchtigkeitsund Proteingehalt, der Anteil an Asche, deren säuereunlöslicher Anteil, die Äthyläther- und Äthanolextrakte und der Gehalt an ätherischen Ölen lokal vorkommender Anissamen, ferner die spezifische Dichte, der Brechungsindex und die chemische Zusammensetzung bestimmt. Die rektifizierten Öle wurden dann im Labormaßstab zur Raki-Herstellung genutzt. Die Produkte wurden auf ihre sensorischen Qualitäten hin untersucht sowie mit traditionell hergestelltem Raki verglichen. Die Ergebnisse sind vielversprechend im Hinblick auf eine kommerzielle Nutzung.

     

底醅串蒸工艺在浓香型白酒生产中的应用

利用窖池长、短发酵周期的底醅,结合酒甑蒸馏提香特点,在浓香型白酒生产中应用双轮底醅、普通底醅结合窖池中、上层酒醅的串蒸工艺,合理配醅串蒸;以充分利用酒醅中的风味物质,提高原酒特优率,同时探究浓香型白酒生产工艺与质量特征。结果表明,双轮底醅串蒸工艺在稳定出酒率的基础上,能有效提高原酒中特征性风味物质的含量,原酒特优率平均提高2.0%左右。     

Volatile aroma composition of distillates produced from fermented sweet and acid whey

Lactose within whey can be fermented and distilled to produce a potable distilled spirit. The aim of this study was to determine if acid and sweet whey types can be fermented and distilled using similar processes and to investigate differences in volatile aroma compounds for the 2 distillates. Fermentation and distillation of the 2 whey types progressed in a similar manner, using Kluyveromyces marxianus for the initial fermentation and a glass still fitted with a Vigreux column for the subsequent distillation. Ethanol content of the wash (fermented whey) varied considerably following each fermentation and ranged from 1.2 and 2.0% (wt/wt) with no clear trend between acid and sweet whey samples. Volatile aroma compounds were extracted using headspace solid-phase microextraction and identified via gas chromatography-mass spectrometry. Acid and sweet whey distillates contained unique volatile aromatic compounds, and significant differences in compound peak areas were observed. These differences may have an effect upon the organoleptic qualities of spirits produced from whey; therefore, whey source may be an important factor when fermenting and distilling whey.     

Ethyl carbamate kinetics in double distillation of sugar cane spirit

The aim of this study was to verify the effect of a double distillation on the reduction of the ethyl carbamate content in sugar cane spirit. Ethyl carbamate is a potentially carcinogenic compound normally present at critical levels in sugar cane spirit, constituting a public health problem and therefore hindering the export of this beverage. The ethanol, copper and ethyl carbamate contents were evaluated, using gas chromatography/mass spectroscopy, during a double distillation of the fermented sugar cane juice. The distillate fraction from the first distillation accumulated 30% of the ethyl carbamate formed. In the second distillation, the ethyl carbamate and the copper content increased during the process as the alcohol content decreased, and only 3% of the ethyl carbamate formed was collected in the spirit. Double distillation decreased the ethyl carbamate content in the sugar cane spirit by 97%. Copyright © 2012 The Institute of Brewing & Distilling     

Characterization of major volatile compounds in whey spirits produced by different distillation stages of fermented lactose-supplemented whey

This research aimed to advance the understanding of acceptable sensory qualities of potable whey-based spirit from nonsupplemented, mid-supplemented, and high-supplemented whey samples by analyzing major volatile compounds during different stages of distillation (head, heart, and tail). The results demonstrated that commercial Saccharomyces cerevisiae strain in lactase-hydrolyzed whey showed rapid and complete sugar hydrolysis and efficient ethanol production in 24, 30, and 36 h on average, producing up to 29.5, 42.1, and 56.4 g/L of ethanol, respectively. The variations in titratable acidity, specific gravity, pH value, residual protein, sugar content, and alcohol yield were investigated during the fermentation. The total amount of volatile compound concentrations significantly decreased from the head (2,087–2,549 mg/L) to the tail whey spirits (890–1,407 mg/L). In the whey spirit, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-1-propanol, 1-propanol, acetaldehyde, and ethyl acetate were the most prevalent dominant compounds, accounting for the largest proportion of total volatile compounds. The volatile compounds detected were far below the acceptable legal limit. The results suggest that high sensory qualities of potable whey-based spirits can be produced by fermentation of lactose-supplemented whey with S. cerevisiae cells.     

Ethyl carbamate kinetics in double distillation of sugar cane spirit. Part 2: influence of type of pot still

This study aimed to assess the influence of the pot still configuration on the reduction of ethyl carbamate content in double‐distilled sugar cane spirit, as well as to describe the effects of double distillation on this reduction. Ethyl carbamate is a potentially carcinogenic compound that may be present in high concentrations in sugar cane spirit, and therefore could become a public health problem, as well as a factor hindering Brazilian exports of this beverage. In sugar cane spirit production in Brazil, neither pot still configuration nor distillate reflux and cooling/condensation systems are standardized. In this study, ethanol, copper and ethyl carbamate contents were assessed (GC‐MS) in sugar cane spirits that were double‐distilled in pot stills with different reflux and cooling systems. Double distillation removed 94–98.5% of ethyl carbamate from sugar cane spirit. Pot stills with high reflux rates (equipped with dephlegmator or rectifying system) were more effective in reducing the ethyl carbamate content in double‐distilled sugar cane spirit. Copyright © 2013 The Institute of Brewing & Distilling     

GC-MS定量分析传统小麦酱中的挥发性成分

采用同时蒸馏萃取和气-质联用技术,对传统小麦酱中的挥发性成分进行提取、定性和定量分析。分析结果通过计算机联机检索,结合计算的保留指数和对照标准品,确定所含化合物的种类,采用面积归一化法确定相对含量,采用内标法确定在传统小麦酱中的含量。共鉴定出113种化合物,占色谱流出组分总量的95.368%,在传统小麦酱中的含量为263.049μg/g,包括醛类10种(11.862μg/g)、酯类25种(6.955μg/g)、酸类20种(140.596μg/g)、烃类14种(1.934μg/g)、醇类9种(5.666μg/g)、杂环类化合物19种(53.938μg/g)、酮类7种(1.406μg/g),其他化合物9种(40.692μg/g)。     

The brewing process and microbial diversity of strong flavour Chinese spirits: a review

Chinese Baijiu (Chinese spirit or Chinese liquor) is one of the six major distilled spirits in the world, and is renowned overseas. Chinese Baijiu has a long history of more than 1000 years when people first begin to brew liquor using distillation. So far, Chinese Baijius have formed 12 types according to their flavour characteristics. The strong flavour Chinese spirit is regarded as one of the typical representatives, and occupies a > 70% market share in China. The liquor brewing process is under an open environment, with grains as the fermentation substrates, as well as Daqu as the saccharifying ferment. The brewing process is complex and impacted by multiple factors. Among the factors, the microorganisms have important influences on the brewing process and product quality of liquors. In the past decades, a series of research achievements have been made with strong flavour Chinese spirits. However, reviews related to this field are relatively few. In this paper, we have reviewed strong flavour Chinese spirits including the introduction, brewing process, microorganism diversity of Daqus , fermented grains and pit muds, and the application of microbes. Copyright © 2017 The Institute of Brewing & Distilling     

THE STIMULATION OF PHENOLICS AND ANTIOXIDANT ACTIVITY IN PEA (PISUM SATIVUM) ELICITED BY GENETICALLY TRANSFORMED ANISE ROOT EXTRACT

A series of dark germination experiments demonstrate the potential of an Agrobacterium rhizogenes‐transformed, high cytokinin root extract of anise (Pimpinella anisum), to stimulate phytophenolic and enhance antioxidant activity in pea (Pisum sativum) seedlings. Average shoot weight increased 40–60% after imbibing seeds for 24 h in a 1.5 to 2.0% extract of the anise root clone AR‐10. Phenolic concentration was positively correlated with shoot weight, suggesting that the total phenolic content was related to seedling vigor. Antioxidant protection factor in pea shoots was also stimulated by AR‐10 extracts. Free proline concentrations were 2–3 times higher in shoots collected from AR‐10 treated peas versus controls. However, proline content also increased as shoot weight declined after being subjected to an overdose of AR‐10 extract in 25% ethanol. G6PDH specific activity, the first committed step of the pentose phosphate pathway, was negatively associated with shoot growth and proline concentrations.     

The analysis of raw spirits – a review of methodology

Agricultural distillates (raw spirits) are alcoholic liquids obtained through distillation (preceded by alcoholic fermentation) of specific agricultural products that do not have the properties of ethyl alcohol or a spirit, but still retain the aroma and taste of the raw ingredients used. This review is a brief overview of agricultural distillates and of some methods commonly used (GC‐MS, GC‐FID, GC‐O, electronic nose) for performing quality assessments and for determining the composition and botanical origins of the raw spirits. Copyright © 2016 The Institute of Brewing & Distilling     

Characterisation of wines and distilled spirits from melon (Cucumis melo L.)

Melon fermentation and distillation was studied with a view to produce melon spirits. Three different substrates were obtained from melon (Cucumis melo L.). Sugar concentration was around 60–70 g L^?1 and the pH between 4.6 and 5.2. The substrates were clarified and then fermented at one of two pH levels at 20 °C. A commercial Saccharomyces cerevisiae starter culture was used to obtain melon wines with an alcohol concentration of 3.8–5.8% (v/v). The melon wines were distilled in a distillation column to yield distillates with an alcohol content of 33–60% (v/v). The major volatiles in the melon wines and in the distillates were analysed by gas chromatography (GC). The results demonstrated that melon could be a good substrate of fermentation and distillation but also yielded significant differences in the volatiles analysed in the different melon wines and distillates obtained from the different substrates in the different conditions of the experiment. Fermentation pH greatly affected the methanol, acetaldehyde, and butanol contents and thus the final quality of the spirits produced.