Membrane processing of the Brazilian spirit Cachaça

As an alternative technology for the production of cachaça, fermented sugar cane must was clarified by ceramic α‐alumina membranes, followed by water removal by pervaporation using a silk sericin/polyvinylalcohol (PVA) non‐porous membrane. The high solute content in the fermented must resulted in fouling and concentration polarisation in both microfiltration and pervaporation. The hydrophilicity of the sericin/PVA blends was exploited in ethanol and aroma concentration, at an optimal temperature of 20°C, resulting in a separation factor and permeation flux of 3.7 and 958.3 g/m² h. An aroma profile was performed using GC SPME/headspace and GC‐MS, analysing the content of ethanol, 3‐methyl‐1‐butanol, 2‐methyl‐1‐butanol, ethyl lactate, isoamyl acetate, ethyl octanoate and ethyl laurate. The results show that the volatiles present in the fermented sugar cane must were concentrated, with recoveries of 93.9 and 94.3% of the principal aromatic compounds. © 2019 The Institute of Brewing & Distilling     

The effect of distillation conditions and alcohol content in ‘heart’ fractions on the concentration of aroma volatiles and undesirable compounds in plum brandies

This study investigates the effect of double‐ or single‐stage distillation and different alcohol content in ‘hearts’ (middle fractions) on the distribution of aroma volatiles and undesirable compounds (methanol, hydrocyanic acid, ethyl carbamate) during distillation of plum brandies. Irrespective of the distillation method used, the first fractions (‘heads’) included mainly aliphatic aldehydes, acetals and esters as well as higher alcohols (1‐propanol, 2‐methyl‐1‐propanol, 1‐butanol, 2‐methyl‐1‐butanol and 3‐methyl‐1‐butanol). Furfural, 1‐hexanol, benzyl alcohol, 2‐phenylethanol and ethyl carbamate occurred in relatively high concentrations in the ‘tail’ fractions. Increasing the concentration of alcohol in the heart fractions from 70 to 90% v /v resulted in a gradual decrease in the concentration of all detected volatile compounds. Compared with single‐stage distillation, double distillation produced heart fractions with lower concentration of acetaldehyde and benzaldehyde and with higher contents of furfural and esters, such as isobutyl acetate and isoamyl acetate. There was a statistically significant increase in the amounts of methanol and ethyl carbamate obtained from double distillation compared with similar fractions derived from the single‐stage process. However, in all fractions these compounds occurred in concentrations much lower than the limits specified by EU regulations. The heart fraction from the double‐stage process with 83% v /v alcohol content received the best scores for aroma and flavour. Copyright © 2017 The Institute of Brewing & Distilling     

Fermentation temperature and the phenolic and aroma profile of persimmon wine

Persimmon wine may offer nutritional and medicinal value as it contains compounds that may be beneficial to health. Product quality is impacted by fermentation and this study investigated the influence of different fermentation temperatures on the phenolic content, aroma profile and antioxidant activity of persimmon wine. Low ethanol concentration and high residual sugar content were found in wine fermented at low temperature (15°C) leading to sluggish fermentation. The majority of phenolic compounds determined by spectrophotometric and HPLC methods increased as temperature increased from 15 to 25°C, and then decreased at 30°C. However, total tannins, total flavonids and antioxidant activity, including reducing power and radical scavenging with DPPH, hydroxyl and ABTS, were enhanced by elevated temperature. For wine aroma, GC–MS demonstrated increased isoamyl alcohol, phenylethyl alcohol, acetic acid 2‐phenylethyl ester, decanoic acid ethylester and 1‐butanol‐3‐methyl‐acetate. These results provided some basic insights for the quality control and commercial development of persimmon wine. © 2018 The Institute of Brewing & Distilling     

三华李果酒发酵工艺的优化及香气成分分析

以三华李为原料,进行三华李果酒主发酵工艺条件优化并分析鉴定果酒中的香气成分。通过比较不同品牌酵母产酒精能力的大小选择马利干酵母作为三华李果酒主发酵的发酵菌。研究了不同的酵母菌接种量、初始糖度、初始pH值、发酵温度对三华李果酒酒精度（酒精体积分数）的影响;在单因素试验的基础上进行了四因素三水平三华李果酒主发酵工艺条件的响应面优化。结果表明,三华李果酒主发酵的最佳工艺条件为：接种量5%、初始糖度24 °Bx、初始pH 3.70、发酵温度28 ℃、发酵时间5 d,在此条件下得到的酒精度为12.4%。该果酒经22 d后发酵,采用顶空固相微萃取法,利用气相色谱-质谱联用技术对其香气成分进行分析与鉴定,结果表明：从三华李果酒中共鉴定出31 种香气成分,占总峰面积的99.48%;其香气物质主要是异戊醇、异丁醇、乙酸乙酯和辛酸乙酯。     

Effects of Fermentation Temperature on Key Aroma Compounds and Sensory Properties of Apple Wine

Fermentation temperature strongly affects yeast metabolism during apple wine making and thus aromatic and quality profiles. In this study, the temperature effect during apple wine making on both the key aroma compounds and sensory properties of apple wine were investigated. The concentration of nine key aroma compounds (ethyl acetate, isobutyl acetate, isopentylacetate, ethyl caprylate, ethyl 4‐hydroxybutanoate, isobutylalcohol, isopentylalcohol, 3‐methylthio‐1‐propanol, and benzeneethanol) in apple wine significantly increased with the increase of fermentation temperature from 17 to 20 °C, and then eight out of the nine key aroma compounds with an exception of ethyl 4‐hydroxybutanoate, decreased when the temperature goes up 20 to 26 °C. Sensory analysis showed that the apple wine fermented at 20 °C had the highest acceptance for consumers. Fermentation at the temperature of 20 °C was therefore considered to be the most suitable condition using the selected yeast strain (Saccharomyces cerevisiae AP05) for apple wine making. Changes in the fermentation temperature can considerably affect the production of key aroma compounds and sensory profiles of apple wine. These results could help apple wine producers make better quality production for consumers at the optimal fermentation temperature.     

Headspace solid‐phase micro extraction coupled to comprehensive two‐dimensional with time‐of‐flight mass spectrometry applied to the evaluation of Nebbiolo‐based wine volatile aroma during ageing

This study presents the application of a headspace solid‐phase microextraction (HS‐SPME) method on the analysis of Nebbiolo‐based wine volatiles by comprehensive two‐dimensional gas chromatography (GC×GC) and time‐of‐flight mass spectrometry (TOF‐MS). The aroma patterns were established for different samples of Nebbiolo‐based wines, aged in oak wood barrels for 18 months at constant temperature. The methodology allowed for the simultaneous analysis of over 130 different volatile compounds detected in the headspace. The odour activity values (OAVs) were assessed to identify potentially important odorants of Nebbiolo‐based wine during ageing. The highest OAVs were obtained for several compounds such as ethyl octanoate, ethyl hexanoate, isoamyl acetate, β‐damascenone, ethyl cinnamate, ethyl 3‐methylbutanate and acetaldehyde. Ethyl butanoate, octanoic acid, ethyl dihydrocinnamate and γ‐nonalactone were also at concentrations higher than their corresponding threshold. Also vanillin, (E)‐whisky lactone, (Z)‐whisky lactone, guaiacol and 4‐ethyl guaiacol seem to be important odorants after oak wood ageing period.     

A Dynamic Analysis of Higher Alcohol and Ester Release During Winemaking Fermentations

Isobutanol, isoamyl acetate and ethyl hexanoate production during winemaking fermentations was precisely described. Volatile compound concentrations and their rates of change and losses in the exhausted gas were determined throughout the fermentation. Negligible amounts of isobutanol were lost, whatever the fermentation temperature. In contrast, 56 % of the ethyl hexanoate and 34 % of the isoamyl acetate were stripped by CO₂ when the temperature profile simulated red winemaking conditions. Even at a moderate temperature of 20 °C, typical of white wine fermentations, 40 % of the ethyl hexanoate and 21 % of the isoamyl acetate were lost. The effect of temperature on the production of the volatile compounds was assessed by running fermentations at different temperatures, with the same medium and strain. By taking into account the volatile compound losses in the exhausted gas, changes in volatile compound production were found to be smaller than those usually calculated from the concentrations in the wine. These findings highlight the potential importance of knowledge concerning aroma gas–liquid balances for both an understanding of yeast metabolism and the identification of innovative control strategies minimizing aroma losses.     

The Usefulness of Intermediate Products of Plum Processing for Alcoholic Fermentation and Chemical Composition of the Obtained Distillates

In this study, an evaluation of intermediate products of plum processing as potential raw materials for distillates production was performed. Effects of composition of mashes on ethanol yield, chemical composition and taste, and flavor of the obtained spirits were determined. The obtained results showed that spontaneous fermentations of the tested products of plum processing with native microflora of raisins resulted in lower ethanol yields, compared to the ones fermented with wine yeast Saccharomyces bayanus. The supplementation of mashes with 120 g/L of sucrose caused an increase in ethanol contents from 6.2 ± 0.2 ÷ 6.5 ± 0.2% v/v in reference mashes (without sucrose addition, fermented with S. bayanus) to ca. 10.3 ± 0.3% v/v, where its highest yields amounted to 94.7 ± 2.9 ÷ 95.6 ± 2.9% of theoretical capacity, without negative changes in raw material originality of distillates. The concentrations of volatile compounds in the obtained distillates exceeding 2000 mg/L alcohol 100% v/v and low content of methanol and hydrocyanic acid, as well as their good taste and aroma make the examined products of plum processing be very attractive raw materials for the plum distillates production.     

Effect of added sulphur dioxide levels on the fermentation characteristics of strawberry wine

The aim of this study to evaluate the effects of sulphur dioxide (SO₂) on strawberry wine fermentation and on the quality of the final wine product. Major aroma compounds, reducing sugars, ethanol, titratable acid and microflora were analyzed during the fermentation of strawberry wine supplemented with 0–100 mg/L SO₂. As the amount of added SO₂ increased, the consumption of reducing sugars and soluble solids and ethanol production decreased during early fermentation, but increased during late fermentation. During the fermentation process, the concentrations of 2‐phenethanol, isobutanol and isopentanol significantly increased and those of n‐propanol, isoamyl acetate and ethyl lactate decreased with increasing amount of added SO₂. The production of n‐butanol, ethyl acetate and ethyl butyrate was slightly dependent on the amount of added SO₂. Yeast cells were the dominant microbe in the fermenting strawberry pulp, and indigenous bacteria and fungi populations decreased rapidly or disappeared because of their sensitivity to SO₂. It was concluded that 60–80 mg/L SO₂ should be added during strawberry wine fermentations to improve wine quality. Copyright © 2016 The Institute of Brewing & Distilling     

Fermentation Characteristics and Aromatic Profile of Plum Wines Produced with Indigenous Microbiota and Pure Cultures of Selected Yeast

The aim of this study was to assess and compare fermentation characteristics and aromatic profile of plum wines produced with indigenous microbiota and pure cultures of different selected yeast. Experiments were carried out with plum (Prunus domestica L.) varieties of different fruit ripening times (?a?anska rana, ?a?anska lepotica, and Po?ega?a). Wine fermentations were conducted by the activity of indigenous microbiota, commercially available Saccharomyces cerevisiae and Saccharomyces bayanus yeast strains and joint activity of Schizosaccharomyces pombe and S. cerevisiae (sequential inoculation). Statistically significant differences in fermentative characteristics and the content of certain volatile compounds were observed as a result of metabolic activity of various indigenous and/or selected yeasts during fermentation of plum pomace. Minimal duration of fermentation (4 to 5 d) and fastest ethanol production rate (from 12.3 to 15.5 g/L/d) were the characteristics of the studied S. cerevisiae strains. Isobutanol, 3‐methyl‐1‐butanol, 1‐heptanol, and 1‐octanol were the most prevalent higher alcohols in the tested plum wine samples. The predominant ester in plum wines was ethyl acetate, ethyl lactate, amyl acetate, isoamyl acetate, and ethyl palmitate, esters responsible for the floral and fruity olfactory tones, were also present in large amounts. Also, the use of S. cerevisiae strains resulted in the production of plum wines with better sensory characteristics than ones produced with other investigated yeasts. Obtained results are significant since there is limited data on the compounds responsible for the unique flavor of plum wine, as well as on the impact of different yeast starter cultures application on the overall quality of fruit wines.     

A new technological approach proposed for distillate production using immobilized cells

A new technological approach to distillate production using immobilized cells was investigated. The effect of temperature on the main volatile by-products in distillates was determined. Wines produced by delignified cellulose-, gluten- and kissiris-supported biocatalysis were used as starting materials. The produced distillates were analyzed for ethanol, methanol, acetaldehyde, ethyl acetate, propanol-1, isobutanol and amyl alcohol content. The results showed that distillates from delignified cellulosic material (DCM) at 16 degrees C contained smaller amounts of amyl alcohols, 57% of that produced by gluten and 32% of that produced by kissiris. The ethyl acetate content of distillates from DCM improved the aroma of distillates. These results agree with those of sensory evaluation. Subsequently, the scale-up for low-temperature distillate production at 16 degrees C using DCM was further investigated. A new version of an industrial multi-stage fixed bed tower (MFBT) bioreactor with a capacity of 11,000 l proved to be suitable for continuous fermentation by DCM-supported biocatalysis. Economic analysis showed a reduction in the cost of almost 30% for distillate production and 78% for wine production.     

Aroma compounds in barrel aged apple distillates from two different distillation techniques

The major fermentation and maturation related congeners in apple distillates from two different distillation techniques (alembic and column), matured in oak for 18 months, were measured by GC‐MS and HPLC. Together with a higher ethanol content, column distillates had higher ethyl acetate, methanol and n‐propanol levels compared with alembic distillates. A higher content of acetaldehyde was characteristic of the alembic distillates. The concentrations of i‐butanol, n‐butanol, amyl alcohols and n‐hexanol were not affected by the distillation technique used. Increasing the ageing time of distillates in oak resulted in an increase in the contents of acetaldehyde, ethyl acetate and amyl alcohols while the content of methanol decreased during ageing. Throughout ageing, there were no significant changes in the concentrations of n‐propanol, i‐butanol, n‐butanol and n‐hexanol. Among the maturation related compounds, gallic acid, ellagic acid, vanillin and syringaldehyde were determined in apple distillates with ellagic acid being the most abundant. The contents of gallic acid and ellagic acid increased during ageing whereas vanillin and syringaldehyde slightly increased throughout the 18 months of maturation. © 2019 The Institute of Brewing & Distilling     

基于GC-O、OAV及Feller加和模型对酱香型习酒特征香气成分的分析

通过气相色谱-质谱联用仪、气相色谱硫磷检测器研究3种酱香型习酒(习酒蓝、习酒印象贵州、习酒银质)中的挥发性香气成分,分别鉴定出99、96、98种香气成分,其中各包含12种含硫化合物.基于气相色谱嗅闻仪和香气活性值(odor activity value,OAV)方法,表明己酸乙酯(OAV:1720～1992)、丁酸乙酯...     

The effect of increased yeast alcohol acetyltransferase and esterase activity on the flavour profiles of wine and distillates

The fruity odours of wine are largely derived from the synthesis of esters and higher alcohols during yeast fermentation. The ATF1- and ATF2-encoded alcohol acetyltransferases of S. cerevisiae are responsible for the synthesis of ethyl acetate and isoamyl acetate esters, while the EHT1-encoded ethanol hexanoyl transferase is responsible for synthesizing ethyl caproate. However, esters such as these might be degraded by the IAH1-encoded esterase. The objectives of this study were: (a) to overexpress the genes encoding ester-synthesizing and ester-degrading enzymes in wine yeast; (b) to prepare Colombard table wines and base wines for distillation using these modified strains; and (c) to analyse and compare the ester concentrations and aroma profiles of these wines and distillates. The overexpression of ATF1 significantly increased the concentrations of ethyl acetate, isoamyl acetate, 2-phenylethyl acetate and ethyl caproate, while the overexpression of ATF2 affected the concentrations of ethyl acetate and isoamyl acetate to a lesser degree. The overexpression of IAH1 resulted in a significant decrease in ethyl acetate, isoamyl acetate, hexyl acetate and 2-phenylethyl acetate. The overexpression of EHT1 resulted in a marked increase in ethyl caproate, ethyl caprylate and ethyl caprate. The flavour profile of the wines and distillates prepared using the modified strains were also significantly altered as indicated by formal sensory analysis. This study offers prospects for the development of wine yeast starter strains with optimized ester-producing capability that could assist winemakers in their effort to consistently produce wine and distillates such as brandy to definable flavour specifications and styles.     

不同馏分清香型白酒感官质量与风味构成相关性分析

对不同馏分酒进行风味物质变化差异分析发现,乙酸乙酯含量在蒸馏前期较高,随后迅速降低并稳定,而乳酸乙酯、乳酸和乙酸等风味成分含量随着蒸馏的进行不断上升,高级醇类物质呈现下降趋势,二米查酒中醇酯比、酸酯比和乙乳比均大于大米查同段馏分酒。通过感官品评发现,在大米查中第3段馏分酒复合酯香最好,第5段馏分酒绵甜口感最好;二米查中第2段馏分酒复合酯香最好,第4段馏分酒绵甜口感最好。结合主成分分析发现,乙酸乙酯等风味物质对清香型白酒蒸馏前期的馏分酒质量具有较大贡献率,对酒体质量具有较大影响;乳酸乙酯等风味物质对蒸馏后期的馏分酒质量均具有较大贡献率,对酒体质量影响较大。     

蛋白酶对黄酒发酵的影响及挥发性成分分析

为了改善黄酒生产工艺,本文研究风味蛋白酶(Flavorzyme)、中性蛋白酶(Neutrase)、复合蛋白酶(Protamex)对黄酒发酵及风味物质的影响。采用传统摊饭法进行黄酒酿造,糖酵期添加蛋白酶,30℃发酵3 d后,再15 d低温发酵30 d,经压榨、灭菌得成品黄酒。测定了黄酒挥发性成分,筛选32种香气化合物进行主成分分析(Principal Component Analysis,PCA)与聚类热图分析;并通过香气活力值(Odor Activity Value,OAVs)评价香气化合物对黄酒整体香气的贡献。结果表明,风味蛋白酶能促进酵母菌生长,提高酒精度,并促进挥发性成分生成,总酯含量上升了97.6%,与风味蛋白酶相关性高的琥珀酸二乙酯(r=0.992)、己酸乙酯(r=0.990)、乙酸异戊酯(r=0.987)和乙酸乙酯(r=0.982)等香气物质集中分布在第一象限,对第一主成分、第二主成分均有正向作用;风味蛋白酶提高了异戊醇、乙酸乙酯、肉豆蔻酸乙酯等物质对黄酒整体香气的贡献率(OAVs>1),减少了4-乙基愈创木酚辛辣、刺激的气味。发酵过程中风味蛋白酶的添加能改善黄酒风味品质。     

Influence of composition and structure of oil‐in‐water emulsions on retention of aroma compounds

The influence of the composition and structure of oil‐in‐water emulsions on aroma retention was examined for 20 volatile compounds. Compositional and structural parameters included the fraction of emulsifier phase, the fraction of lipid phase and the particle size distribution of the dispersed lipid phase in the emulsion. Air/liquid partition coefficients of dimethyl sulphide, 1‐propanol, diacetyl, 2‐butanone, ethyl acetate, 1‐butanol, 2‐pentanol, propyl acetate, 3‐methyl‐1‐butanol, ethyl butyrate, hexanal, butyl acetate, 1‐hexanol, 2‐heptanone, heptanal, α‐pinene, 2‐octanone, octanal, 2‐nonanol and 2‐decanone were determined by static headspace gas chromatography. The hydrophobicity of the compounds determined the influence of the compositional and structural parameters of the emulsions on air/liquid partitioning. Increase of the emulsifier fraction increased the retention of mainly hydrophilic aroma compounds and decreased the retention of hydrophobic compounds. Higher lipid levels led to increased retention of hydrophobic compounds and release of hydrophilic compounds. Emulsions with larger particles showed increased aroma retention, which was independent of the lipid fraction and the polarity of the aroma compounds. The data demonstrated a profound effect of both composition and structure of oil‐in‐water emulsions on the air/liquid partitioning of the 20 aroma compounds under equilibrium conditions. © 2002 Society of Chemical Industry     

搅拌棒萃取-气相色谱-质谱联用法分析‘媚丽’桃红葡萄酒中的香气成分

采用搅拌棒萃取法-气相色谱-质谱联用技术,对‘媚丽’桃红葡萄酒中的香气成分进行定量检测。结果表 明：‘媚丽’桃红葡萄酒中共检测到55 种香气成分,包括26 种酯类物质、4 种酸类物质、9 种醇类物质、6 种萜烯 类物质、3 种C13-降异戊二烯等。通过计算香气活性值发现,其中12 种香气成分对‘媚丽’桃红葡萄酒的香气有重 要贡献。这些物质是：乙酸乙酯、丁酸乙酯、己酸乙酯、辛酸乙酯、乙酸异戊酯、异丁酸乙酯、异戊酸乙酯、异戊 醇、2-苯乙醇、里哪醇、β-大马士酮和β-紫罗兰酮。感官分析结果表明：‘媚丽’桃红葡萄酒具有玫瑰香、苹果、 草莓、菠萝等香气。     

Effect of short‐term anaerobic conditions on the production of volatiles,activity of alcohol acetyltransferase and other quality traits of ripened bananas

Yellow, ripened (yellow with green tips) bananas were treated with nitrogen gas for 12, 24 and 48 h at 20 °C to study the effects of anaerobic conditions on the fruit quality, including the production of volatile compounds and activity of alcohol acetyltransferase (AAT) during the post‐harvest period. Significantly higher concentrations of acetaldehyde and ethanol were found in the treated fruit than in the untreated bananas after removal from the conditions. The 48‐h treatment showed higher levels of ethanol and acetaldehyde after storage. Immediately after releasing the fruit from the anaerobic atmosphere, the amounts of isobutyl acetate and isoamyl acetate decreased. The production of ethyl acetate increased markedly in each treatment unit 1 day after removing the fruit. Regardless of recovery from the production of isobutyl acetate and isoamyl acetate 1 day after treatment, the banana‐like aroma was denatured because of the production of high levels of ethyl acetate and ethanol. The increase in AAT was slightly lower in nitrogen‐treated fruit than untreated fruit. However, the activity in treated fruit was sufficient for ester production in bananas. The endogenous alcohol levels were increased during nitrogen gas treatment in the fruit due to the inhibition of ester production. Colour development of the bananas was greatly inhibited by the treatments, while the sugar content did not show any differences between the treated and untreated fruit. The results suggest that, even if bananas are removed from the short‐term anaerobic conditions, a loss in quality, except sweetness, easily occurs afterwards, especially the characteristic aroma of the fruit during the post‐harvest period. Copyright © 2006 Society of Chemical Industry