Influence of the fermentation pH on the final quality of Blanquilla pear spirits

Blanquilla pear concentrate was diluted, fermented and distilled to produce the pear spirits. The fermentations were held at the native pH and at an acidified pH of 3.2. Two sets of experiments were performed using a different fermentation yeast and a different distillation equipment. The heart fractions from each distillation (which form the pear spirits) were analysed by gas chromatography. The results showed, in both experimental sets, that reducing the fermentation pH significantly increased the concentration of most of the higher alcohols and decreased the concentration of ethyl acetate in the spirits. Moreover, pear distillates obtained in the first experimental set showed significantly higher concentrations of most of the long‐chain ethyl esters (C₆–C₁₂) compared to those obtained in the second experimental set.     

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 evaluation of grape pomace distillates from selected red grape varieties

This report describes the composition of the volatiles from grape pomace distillated that are commercially available in Greece. These spirits, which are a valuable by‐product of the winemaking industry, were obtained by distillation of grape pomace after fermentation under anaerobic conditions. The volatiles were distilled twice. Each distillate was separated in to 4 equal (by volume) fractions and the changes in volatile concentration during distillation were measured. Assays were done by gas/liquid chromatography (for alcohols, carboxylic acids, esters and aldehydes). The average values for volatile concentrations obtained for Greek grape pomace distillates were compared with the corresponding values for grape pomace manufactured in other Mediterranean countries.     

Physicochemical and sensory quality of wines from red sorrel/roselle (Hibiscus sabdariffa L.) calyces: effects of pretreatments of pectolase and temperature/time

The effects of pretreating red sorrel (Hibiscus sabdariffa L.) calyces on the physicochemical and sensory quality of wines were investigated. Sorrel calyces were processed at 60 °C for 3.5 h or 90 °C for 30 min at 0%, 0.5% and 1.0% w/w pectolase addition in fermentation of wines. Significant changes (P < 0.01) in all physicochemical parameters of sorrel wines were found during fermentation, but not (P > 0.05) because of temperature/time effects. Colour (P < 0.01) became redder with pectolase and on storage at 23 °C for 2 months. Significant differences (P < 0.01) were noted in sensory quality for taste and flavour, balance, duration and overall quality. Higher (P < 0.01) overall sensory quality scores were obtained for wines by pretreatment at 90 °C for 30 min (10.44–11.06/20) when compared with wines at 60 °C for 3.5 h (6.88–9.06/20). Colour of wines from 90 °C/30 min was most saturated and red than all wines and had pH 2.57 ± 0.01, 0.43 ± 0.07% citric acid, 10.53 ± 0.53 °Bx and 15.29 ± 0.71% alcohol.     

Effects of cofermentation and sequential inoculation of Saccharomyces bayanus and Torulaspora delbruckii on durian wine composition

This work investigated the effects of cofermentation and sequential inoculation of Torulaspora delbrueckiiBiodiva and Saccharomyces bayanusEC‐1118 on chemical and volatile components of durian wines. Cofermentation and sequential inoculation resulted in higher production of ethanol (6.2% and 7.7% v/v, respectively) relative to the control (5.3% for S. bayanus and 5.8% for T. delbrueckii). Further, cofermentation and sequential inoculation produced higher amounts of acetyl esters and higher alcohols especially isoamyl alcohol and 2‐phenylethyl alcohol than monoculture fermentation. Most endogenous sulphur volatiles, especially disulphides that impart a character‐impact durian odour, declined to trace levels, but new ones such as thioesters were formed. Sulphur volatiles in the durian wines fermented by cofermentation and sequential inoculation accounted for 0.03% and 0.05% of total peak area. The study suggests that the use of S. bayanus in conjunction with non‐Saccharomyces such as T. delbrueckii may improve the aromatic intensity and complexity of durian wine.     

Effect of terroir on the volatiles of Vitis vinifera cv. Albariño

The effect of terroir on volatiles of Vitis vinifera cv Albariño was studied. Twelve commercial Albariño wines from Galicia, Spain, were analysed. The content of varietals and fermentative volatile compounds was determined by gas chromatography. The numerous significant differences found for most of the aromatic compounds studied show the influence of the terroir. The Albariño wines from northern Galicia showed the highest total concentration of volatiles analysed. The volatile components showing the greatest differences in Albariño wines from different areas were terpenes and higher alcohols. Among the terpenes found, geraniol was markedly abundant in the north, while nerol and linalool were most abundant in the south. Among the alcohols, 2‐phenyl ethanol and benzyl alcohol showed the highest concentrations in the south and in the north, respectively. Cluster analysis and principal component analysis revealed two clearly defined main groups of Albariño wines from different terroirs. Albariño wines from the south were more heterogenic than those of the north. Copyright © 2007 Society of Chemical Industry     

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     

Preparation of novel distinct highly aromatic liquors using fruit distillates

This work describes the preparation of aromatised liquors using deodorised and concentrated fruit distillates. The raw spirits were improved by making a partial deodorisation, using activated charcoal, followed by concentration, using a distiller. The liquors were prepared by a maceration process. The procedure is exemplified using fig distillates to prepare myrtle berry liquors. The acidity, copper, polyphenol and anthocyanin indexes and volatile and anthocyanin profiles were monitored in each preparation step. The concentration process increased the ethanol proof to 75% v/v and decreased the acidity and the copper content. The partial deodorisation decreased the levels of high molecular weight volatiles, while the content of lower molecular weight compounds that contribute to flavour was maintained. Delphinidin‐3‐O‐glucoside, cyanidin‐3‐O‐glucoside, petunidin‐3‐O‐glucoside and malvidin‐3‐O‐glucoside were the major anthocyanins.     

Contribution by Saccharomyces cerevisiae Yeasts to Fermentation and Flavour Compounds in Wines from cv. Kalecik karasi Grape

The effect of indigenous and commercial S. cerevisiae yeasts on fermentation and flavour compounds of wines was examined in pasteurised grape juice. The flavour compounds were analysed and identified by GC‐FID and GC‐MS, respectively and in general, the amounts of these volatiles were increased by the use of both indigenous and commercial yeasts. The levels of isoamyl alcohol, isoamyl acetate, ethyl octanoate and ethyl deconoate exceeded flavour thresholds. All grape juices were fermented to dryness. Selected yeasts produced higher ethanol concentrations compared to spontaneous fermentations.     

The Production of Low-Alcohol Wines by Aerobic Yeasts

Aerobic yeasts of the genera Pichia and Williopis are commonly regarded as spoilage yeasts of beer and wine by causing turbidity, a surface film of yeast growth and often an excessive estery flavour. However, their ability to utilise sugars oxidatively for cell growth with the production of estery and other flavours of wine with only minimal production of ethanol suggests a method for the production of low-alcohol wines of pleasant “fermented” flavour without the need for additional equipment to remove alcohol by dialysis, reverse osmosis or distillation, or without the excessive sweetness remaining from arrested fermentation. Three strains of Pichia and one of Williopsis were examined for their ability to produce approximately 3%(v/v) ethanol and a good estery and fruity flavour. With normal anaerobic fermentation conditions, or with gentle stirring to prevent formation of a surface film, excessive amounts of alcohol were produced from grape juice of 15% or 20% (w/v) initial sugar concentration. However, an acceptably flavoured wine of alcohol content < 3% was produced by agitation and aeration during fermentation. The ethanol formed in the early stages of culture was oxidised to a final level < 3%, with the production of cell mass and an acceptable flavour.     

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.     

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     

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     

ETHANOL FERMENTATION OF VARIOUS RED RICES WITHOUT COOKING

With various red rices as raw material, fermentation without cooking was allowed to proceed at pH 4.0 and 30°C for 4 d for production of novel alcoholic beverages. Ethanol fermentation was achieved with various rice grains. In particular, uncooked wild-rice (Zizania aquatica) is reported now for the first time as being used for ethanol fermentation. The final concentration of ethanol achieved during fermentation was 8.8–9.3% (v/v). Rice wine made from aromatic red rice (Oryza sativa var. Indica, Tapol) had a wine-like red color. It was rich in a fruity aroma and had a characteristic sour taste, as revealed by organoleptic testing. Volatile substances formed have been analysed by gas chromatography. Rice wine made from black rice (Oryza sativa var. Indica) also had a wine-like red color and a sour taste. By contrast, rice wines made from red rice (Oryza sativa var. Japonica) and wild-rice were faintly yellow in color and had a sake-like and a somewhat green tea-like flavor, respectively. Although the red pigments of the aromatic red rice and black rice were solubilized during uncooked ethanol fermentation, the pigments of red rice and wild-rice were insoluble and not available as material for brewing of red-colored alcoholic beverages. Aromatic red rice appears to be a suitable material for the production of a wine-like alcoholic beverage.     

Development of a novel solid-phase extraction,LC-MS/MS method for the analysis of ethyl carbamate in alcoholic beverages: application to South African wine and spirits

Ethyl carbamate (EC) is a known genotoxic carcinogen that is frequently present in alcoholic beverages and is therefore a public health concern. As a consequence, maximum concentration levels for EC in these commodities are legislated in several countries. Quantitative analytical methods are therefore essential to monitor EC levels in beverages. Most published analytical methods for the determination of EC in alcoholic beverages utilise elaborate sample pre-treatment procedures to obtain injectable samples, or yield low sensitivity, for example where direct injection is used. In addition, these procedures often require large volumes of toxic solvents and are not generally applicable to diverse alcoholic beverages. This paper describes a novel procedure for the determination of EC in wines, fortified wines and spirits. The procedure is based on reversed-phase solid-phase extraction (SPE) sample clean-up combined with normal-phase liquid chromatography-atmospheric pressure chemical ionisation tandem mass spectrometric (NP-LC-APCI-MS/MS) analysis. This method provides a rapid, robust and simple analytical procedure suitable for the analysis of a diverse range of alcoholic beverages. The accuracy of the method (expressed as average recovery from diverse matrices) is 94.5%, with limits of detection (LODs) ranging between 0.25 and 0.63?µg?l^?1 for different matrices. Benefits such as simplified sample preparation, low detection limits, low solvent consumption and good selectivity render the methodology ideally suited to study the occurrence of EC in diverse commodities. The method was applied to study the occurrence of EC in South African wines, fortified wines and spirits. South African wines, aged 1–9 years, contained 1.8–31?µg?l^?1 EC (RSD?=?69%, n?=?106), fortified wines aged 2–34 years contained 2.8–79?µg?l^?1 EC (RSD?=?89%, n?=?21), and brandies aged 3–20 years contained 4.4–95?µg?l^?1 EC (RSD?=?105%, n?=?26). Factors affecting the formation of EC in these commodities were investigated and storage temperature, alcohol content and pH were found to affect the rate of EC formation. Of these variables storage temperature has by far the greatest effect.     

Pear distillates: influence of the raw material used on final quality

Pear juice from concentrated and natural juices of Blanquilla variety was fermented using Saccharomyces cerevisiae. The pear wines obtained were distilled at two different conditions: distillation in the presence and in the absence of fermented juice lees. The distillates from natural pear juice have a higher amount of most of the volatile compounds compared to the ones from concentrated pear juice. In addition, the distillation of the fermented juice from natural pear juice in the absence of the lees significantly increased the concentration of some of these compounds compared to distillation in the presence of lees. However, most of the compounds whose concentration was higher in the distillates from natural pear juices are negative (furfural, methanol) or become negative in high concentrations (acetaldehyde, ethyl lactate, methyl acetate). Therefore, in terms of the compounds tested, it can be said from our results that using natural pear juice does not offer any benefit when compared to using concentrated pear juice from Blanquilla variety pears.     

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.     

Influence of pH and ethanol on malolactic fermentation and volatile aroma compound composition in white wines

The present study investigated the influences of pH and ethanol on malolactic fermentation (MLF) and the volatile aroma profile of the subsequent white wines from Riesling and Chardonnay inoculated with two different Oenococcus oeni strains. In all cases MLF was induced after completion of alcoholic fermentation (AF). Partial MLF occurred under low pH 3.2 and high alcohol (118.3 g/L) conditions. In the cases with complete MLF, the time required for each strain varied from 13 to 61 days and was dependent on bacterial culture, cultivar and wine parameter. Chemical properties of each wine were determined after AF, complete and partial MLF. The wines showed significant differences in total higher alcohols, esters and acids that are important for the sensory profile and quality of wine. This work demonstrated that the wine matrix as well as the pH and alcohol concentration affects MLF and the final volatile aroma profile. Results indicate that changes in volatile aroma composition are not necessarily related to complete MLF and that partial MLF already has distinct influences on the wine aroma profile of white wines.