Influence of yeast strains on the physicochemical characteristics,methanol and acetaldehyde profiles and volatile compounds for Korean rice distilled spirit

The objective of this study was to investigate the influence of yeast strains on the physicochemical characteristics, methanol and acetaldehyde profiles, and volatile compounds of Korean rice distilled spirits. Ten yeast strains were employed for the brewing of distilled spirits and the resulting products were filtered and distilled twice. The amounts of methanol and acetaldehyde for the ten yeasts showed different profiles. Higher amounts of methanol were detected for strains CL, CY, DV, BD, ED and LP, while EC, D2, D4 and RH had <2 mg L^?1 methanol content. Strains D2, BD and ED produced the lowest amounts of acetaldehyde. The head portions of the spirits, which started in the fraction that contained <5 mg L^?1 of acetaldehyde, were between 7.7% (BD) and 18.2% (LP) of the total fractions. Strains D2, CL and CY produced more alcohol in the body fraction than the other yeasts. The major volatile compounds were esters in the form of fatty acid ethyl esters, such as ethyl palmitate, ethyl myristate and ethyl oleate. Isoamyl alcohol, which is an important volatile compound for rice wine, occupied 0.91–2.24% of the relative peak areas. Strain D2, of the strains tested, appeared to be the most appropriate yeast for Korean distilled spirit based on alcohol production and the high relative peak area of volatile compounds, except for ethanol. Strains CL and CY could also be considered for producing high‐quality Korean rice distilled spirits with efficiency and flavour. Copyright © 2015 The Institute of Brewing & Distilling     

Influence of the number of distillations on the composition of organic sugarcane spirit

Sugarcane spirit is the most consumed distilled beverage in Brazil. Currently the manufacturing industries are trying to widen their market and attract new consumers, and thus it has become necessary to elevate the product to national and international quality standards. This study's aim was to determine the influence of subsequent distillations on the composition of organic sugarcane spirit. From mono‐distilled organic sugarcane spirit, bi‐, tri‐, tetra‐ and penta‐distilled sugarcane spirits were obtained, and analysed for the following: relative density, alcoholic degree, volatile acidity, pH, copper, methanol, aldehydes, furfural, esters, ethyl carbamate and higher alcohols. The most relevant results were reductions of 69.57% volatile acidity, 98.4% copper, 40.9% methanol, 71.5% aldehydes, 100% esters, 100% ethyl carbamate and 32.2% higher alcohols in the penta‐distilled sugarcane spirit, as compared with the mono‐distilled. It was concluded that subsequent distillations would put sugarcane spirit in line with the international standards for distilled beverages. Copyright © 2013 The Institute of Brewing & Distilling     

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     

Role of maceration in improving melon spirit

The effect of maceration on increasing and improving aroma intensity in a melon (Cucumis melo L.) spirit was studied. A first distilled spirit (23.5% alcohol v/v) was macerated before undergoing a second distillation, and compared with a double-distilled spirit (56% alcohol v/v). A double-distilled spirit (final spirit) was also macerated. Two different parts of the fruit (sliced melon flesh and seeds+placenta) were used for maceration, for differing maceration times. The volatile content of the macerated spirits was determined using GC-MS, the colour attributes were measured, and the influence of maceration was evaluated by sensory analysis. The results indicated that there were differences between the control (unmacerated) and the macerated spirits and that the double-distilled spirit macerated in contact with the seeds+placenta exhibited the best sensory characteristics.     

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.     

The impact of maturation on concentrations of key odour active compounds which determine the aroma of tequila

Samples of non‐mature and añejo (matured) tequila of the same brand/provenance were analysed using GC–MS and gas chromatography olfactometry (GC‐O)/aroma extract dilution analysis (AEDA) to provide quantitative data on the most odour active compounds that contribute to the aroma of these spirits. Extracts of non‐mature tequila were characterized by 26 odour‐active regions, which included ethyl hexanoate, ethyl octanoate, 2‐phenylethyl acetate, β‐damascenone, isoamyl alcohol and octanoic acid as the most odour‐active compounds (flavour dilution, FD, factor ≥ 6561). In contrast, extracts of the mature spirit showed 36 odour‐active zones, where the compounds with the highest FD factors (6561) were ethyl hexanoate, ethyl octanoate, 2‐phenylethyl acetate, isoamyl alcohol, phenethyl alcohol, guaiacol, 4‐ethyl guaiacol, vanillin, cis/trans whisky lactones, β‐damascenone and octanoic acid. The aromagram of mature tequila was thus differentiated from that of the non‐mature spirit owing to the presence of cask‐extractive compounds and the increased FD factors of certain terpenes, higher alcohols and acetals. This study provides a comprehensive and quantitative understanding of changes in key odourants of tequila as a result of the maturation process and also reveals a further characterization of the likely impact of each compound on overall spirit flavour, in terms of odour activity values. Copyright © 2016 The Institute of Brewing & Distilling     

短波近红外光谱-偏最小二乘法测定白酒中乙醇含量

应用近红外光谱技术结合偏最小二乘法(NIRS-PLS)建立白酒中乙醇含量定量分析数学模型。所建校正模型相关系数(Corr.Coeff.)达到0.99986,校正集均方根误差(RMSEC)为0.00225,预测均方根误差(RMSEP)为0.00137,模型通过交互验证检验,得出PLS因子数为4时预测残差平方和(PRESS)和交互验证均方根误差(RMSECV)最小。用所建模型测定样品与气相色谱分析结果相对误差不大于0.81%。实验结果表明该方法准确性、稳定性好、精密度高。     

Discrimination of Luzhou‐flavoured fresh raw liquor distilled from Zaopei fermented in new,trend to‐be aged and aged pit mud based on their aroma and flavour compounds

Fresh raw liquors distilled from Zaopei fermented in new, trend to‐be aged and aged pit mud, labelled as N1 and N2, T1 and T2, and A1 and A2, respectively, were analysed by sensory evaluation, two‐dimensional gas chromatography/time‐of‐flight mass spectrometry with combined principal component analysis, gas chromatography–flame ionization detection, liquid chromatography–mass spectrometry with combined hierarchical cluster analysis, and partial least square–discrimination analysis. Results showed that samples had the same grouping situations by each method: the N‐group containing N1 and N2; the T‐group containing T1 and T2; and the A‐group containing A1 and A2. The specific markers for the N‐group liquors were 2‐butanol and butanoic acid, and those for the A‐group were 1‐hexanol, ethyl pentanoate and 2‐pentanone. The threshold contents of 1‐hexanol, ethyl pentanoate, and 2‐pentanone for the A‐group liquors were 1207.95 ± 252.59, 469.89 ± 73.08 and 1105.12 ± 141.91 mg L⁻¹, while those of 2‐butanol and butanoic acid for the N‐group liquors were 215.66 ± 179.50 and 430.65 ± 60.47 mg L⁻¹, respectively. The results from modern chromatographic techniques and chemometric analyses verify the correctness of the traditional sensory evaluation used in controlling the quality of Chinese liquor, contribute to further studies related to the aroma and flavour of Chinese Luzhou‐ flavour of fresh raw liquors and may provide significantly helpful thresholds in distinguishing Chinese Luzhou‐ flavour fresh raw liquors distilled from Zaopei fermented in new, trend to‐be aged and aged pit muds. Copyright © 2017 The Institute of Brewing & Distilling     

甲醇内标法测定酒精饮料中乙醇含量的研究

在国产SC－6气相色谱仪上使用FID和GDX－102填充柱,甲醇作内标,用峰高比测定酒精饮料中的乙醇含量。对无水乙醇、两种米酒、1种葡萄酒和1种啤酒分别进行了10次平等测定,其CV依次是0．010、0．021、0．0059和00082。可定量回收添加的乙醇。方法具有简便快速的特点。     

DETERMINATION OF ETHYL CARBAMATE IN DISTILLED SPIRITS USING NITROGEN SPECIFIC AND MASS SPECTROMETRIC DETECTION

Gas chromatographic methods are described for the determination of naturally occurring ethyl carbamate in distilled spirits at levels as low as 5 ppb. Bottled products, such as whisky, gin and brandy, are extracted in the presence of n-propyl carbamate as internal standard and analysed by capillary column gas chromatography with either nitrogen specific or mass spectrometric detection. A shorter extraction procedure is satisfactory when the more sensitive and selective mass spectrometric detection is used. Direct sample injection without extraction may be used for higher alcoholic strength cask and new-make samples. Analysis of 181 blended Scotch whisky samples indicated ethyl carbamate concentrations ranging from 20 to 75 ppb. Concentrations in 48 malt whiskies ranged from 15–100 ppb. Ethyl carbamate was not detected in gin, vodka and rectified neutral alcohol. All concentrations in bottled product fell below the Canadian limit of 150 ppb in distilled spirits.     

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.     

在线质谱法快速检测酒中5种常见乙酯

采用在线质谱法,在无需样品预处理的条件下,建立快速检测酒中乙酸乙酯、丁酸乙酯、乳酸乙酯、戊酸乙酯、己酸乙酯5 种常见乙酯的方法。5 种乙酯在0.5～20 mg/L内线性关系良好（R2＞0.99）,2 个加标水平（0.5、5 mg/L）的回收率为81.1%～99.7%,相对标准偏差为4.7%～9.4%,检出限为24～312 μg/L。对市场上消费的蒸馏酒（中国白酒、白兰地、金酒及威士忌）进行检测分析,同种类蒸馏酒检出的主要成分及其比例基本一致,中国白酒、威士忌和白兰地均不同程度地检出乙酯。同时,结合主成分分析可对不同品种的蒸馏酒进行较好的区分。     

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     

The production of the Chinese baijiu from sorghum and other cereals

Baijiu is a widely consumed spirit usually distilled from fermented sorghum. Here the use of other cereal grains (wheat, corn, rice and barley) is compared with sorghum. The concentration of ethyl acetate in spirit made from sorghum was found to be higher than in the spirits made using other grains, whereas the concentrations of aldehydes and higher alcohols were lower. Based on sensory evaluations, the flavours were more satisfactory when sorghum was used for making Baijiu. Of the other cereals, the flavour from wheat was better than those of corn, rice and barley for making Baijiu. The ester concentration of the spirit made from the rice was low, whereas aldehyde and alcohol contents were high. An abnormal flavour was found in spirits made from corn or barley. Further work with sorghum showed variations in tannin content, and a correlation between the tannin content and brewing performance. When the content of tannin was <1.94%, the ethyl acetate and ethyl octanoate content were positively correlated with tannin content. In contrast, the ethyl lactate and higher fatty acid ethyl esters content were negatively correlated with tannin content. The results of flavour analysis and sensory evaluation indicated that the ideal sorghum tannin content for producing Baijiu was between 1.0 and 2.0%. Copyright © 2017 The Institute of Brewing & Distilling     

Fourier Transform Infrared Spectroscopy with Multivariate Analysis as a Novel Method for Characterizing Alcoholic Strength,Density, and Total Dry Extract in Spirits and Liqueurs

Fourier transform infrared (FTIR) spectroscopy allows fast throughput screening of beverages (less than 2 min per sample). Using partial least squares (PLS) regression, it was demonstrated that relative density and alcohol content, which have previously been calibrated only for extract-free spirits, can also be determined in highly viscous liqueur samples. In addition, total dry extract (TDE) was successfully calibrated for the first time for both spirit and liqueur screening. An inter-laboratory validation showed that the standard errors of prediction, ranging between 0.0006 and 0.0078 (relative density), 0.23 and 0.74 % vol (alcoholic strength), and 0.55 and 7.53 g/l (TDE), were satisfactory for use of the FTIR-PLS method in the context of screening analysis in official food control of alcoholic beverages.     

Measurement of antioxidants in distilled spirits by a silver nanoparticle assay

Ingestion of antioxidants from the diet is associated with improved health. Total antioxidant capacity as gallic acid equivalents (GAE) of distilled spirits was determined using a modified and validated silver nanoparticle (SNaP) assay utilizing silver nanoparticles pre‐capped with starch and microwave technology. GAE concentrations determined by the SNaP assay for the distilled spirits were validated by high‐performance liquid chromatography (HPLC) measurements of key antioxidant components including gallic acid, ellagic acid, caffeic acid, syringic acid, syringaldehyde and 2‐furaldehyde. SNaP assay and HPLC measurements of GAE were compared via statistical and graphical methods to demonstrate comparability. Application of the assay to 33 different distilled spirits demonstrated good agreement with published literature values, with the highest total antioxidant capacity values observed for bourbon samples followed by whisky, tequila and other types of liqueur. This study is novel for demonstrating the utility of a nanoparticle assay for determination of antioxidant capacity in distilled spirits with validation by HPLC. © 2018 The Institute of Brewing & Distilling     

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     

Quantification of soluble solids in reconstituted açaí (Euterpe oleracea Mart.) pulp using near‐infrared spectroscopy

Açaí consumption is increasing worldwide because of the growing recognition of its nutritional and therapeutic properties. This product is classified based on its soluble solids content (SS), but the determination of SS in pulp is time consuming, tedious and not suitable for modern food processing plants. As near‐infrared (NIR) systems have been implemented to measure various quality attributes of food products, the objective of this study was to evaluate the feasibility of NIR diffuse reflectance spectroscopy to quantify the SS content of açaí pulp. Partial least squares (PLS) regression models were constructed to predict the SS. An optimum PLS model required one latent variable [principal component (PC)1 = 97%] with a root‐mean‐square error of calibration (RMSEC) of 1.06% for the calibration data set and the root‐mean‐square error of prediction (RMSEP) of 1.03% for internal cross‐validation. External validation using an independent data set showed good performance (RMSEP = 1.33% and Rp² = 0.82). NIR spectroscopy is a reliable method with which to determine SS in açaí pulp and thereby to classify açaí pulp according to established minimum quality standards.     

前处理方法对蒸馏酒及其配制酒中甲醇测定的影响

目的:研究GB 5009.266-2016《食品安全国家标准食品中甲醇的测定》在颜色深浅不一的蒸馏酒及其配制酒中,采用直接进样法与蒸馏前处理法的前处理方法的适用性。方法:以蒸馏酒及其配制酒为研究对象,按照该国家标准的要求,采用上述两种前处理方法进行检测数据比较。结果:样品颜色的深浅未能影响其中甲醇含量的测定结果,而且测定结果重现性及准确性都符合要求。结论:直接进样法操作简便、经济快速,适用于白酒、伏特加、朗姆酒、威士忌、白兰地这5种无论颜色深浅不一,但非复杂基质样品的蒸馏酒中,甲醇含量的快速测定。但是配制酒属于复杂基质样品,即使颜色很浅,如不进行蒸馏前处理的话,易对气相色谱仪器造成严重的污染,因此建议配制酒应采用蒸馏前处理法。     

黑果腺肋花楸与赤霞珠波特酒中挥发性香气成分分析

以黑果腺肋花楸和赤霞珠葡萄为原料,在二者混合发酵过程中添加无核白、霞多丽、赤霞珠3种葡萄蒸馏酒终止酒精发酵,制备波特酒。采用顶空固相微萃取（HS-SPME）结合全二维气相色谱-飞行时间质谱（GC×GC-TOF MS）技术,对黑果腺肋花楸和赤霞珠波特酒的挥发性香气成分进行分析,并对结果进行主成分分析（PCA）。结果表明,3种波特酒中共检测出68种挥发性香气成分,包括酯类25种、醇类21种、酸类7种、酮类6种、醛类4种、其他类5种。对3种波特酒的共有挥发性物质和挥发性化合物进行主成分分析,发现醇类和醛类物质是影响波特酒香气的主要因素。香气品质评价模型结果表明,添加赤霞珠蒸馏酒的波特酒香气品质最佳,添加霞多丽蒸馏酒的波特酒次之,添加无核白蒸馏酒的波特酒最差。