What Is The Chemical Makeup Of Liquor

iii.i. General aspects

Ethanol and h2o are the primary components of most alcoholic beverages, although in some very sweet liqueurs the sugar content can exist higher than the ethanol content. Ethanol (CAS Reg. No. 64–17–v) is nowadays in alcoholic beverages every bit a result of the fermentation of carbohydrates with yeast. It can as well be manufactured from ethylene obtained from cracked petroleum hydrocarbons. The alcoholic beverage manufacture has generally agreed non to utilise synthetic ethanol manufactured from ethylene for the production of alcoholic beverages, due to the presence of impurities. In gild to determine whether constructed ethanol has been used to fortify products, the low ¹⁴C content of synthetic ethanol, as compared to fermentation ethanol produced from carbohydrates, can exist used as a marker in control analyses (McWeeny & Bates, 1980).

Some concrete and chemic characteristics of anhydrous ethanol are as follows (Windholz, 1983):

• Description: Clear, colourless liquid

• Humid-bespeak: 78.5°C

• Melting-point: −114.1 °C

• Density: 0.789

It is widely used in the laboratory and in industry as a solvent for resins, fats and oils. It also finds utilise in the industry of denatured alcohol, in pharmaceuticals and cosmetics (lotions, perfumes), as a chemical intermediate and equally a fuel, either lonely or in mixtures with gasoline.

Beer, wine and spirits likewise incorporate volatile and nonvolatile season compounds. Although the term 'volatile chemical compound' is rather diffuse, most of the compounds that occur in alcoholic beverages tin exist grouped co-ordinate to whether they are distilled with alcohol and steam, or not. Volatile compounds include aliphatic carbonyl compounds, alcohols, monocarboxylic acids and their esters, nitrogen- and sulphur-containing compounds, hydrocarbons, terpenic compounds, and heterocyclic and aromatic compounds. Nonvolatile extracts of alcoholic beverages incorporate unfermented sugars, di- and tribasic carboxylic acids, colouring substances, tannic and polyphenolic substances, and inorganic salts. The flavour composition of alcoholic beverages has been described in detail in several reviews (Suomalainen & Nykänen, 1970; Amerine et al., 1972; Nykänen & Suomalainen, 1983), and a recent review on the compounds occurring in distilled alcoholic beverages is available (ter Heide, 1986). The volatile compounds of alcoholic beverages and distillates more often than not originate from iii sources: raw materials, fermentation and the wooden casks in which they are matured (Jouret & Puech, 1975).

During maturation, unpleasant flavours, probably acquired by volatile sulphur compounds, disappear. Extensive investigations on the maturation of distillates in oak casks have shown that many compounds are liberated by alcohol from the walls of the casks (Jouret & Puech, 1975; Reazin, 1983; Nykänen, 50., 1984; Nykänen et al., 1984). Lignin plays an important role and is responsible for the occurrence of some aromatic aldehydes and phenolic compounds (Jouret & Puech, 1975; Nykänen et al., 1984). These compounds are liberated from oak during the maturation procedure, together with monosaccharides (pentoses, quercitol), carboxylic acids and 'whisky lactone' (v-butyl-4-methyldihydro-2(3H)-furanone) (Nykänen, L., 1984; Nykänen et al., 1984). The occurrence of aromatic compounds has been considered a manifestation of the degradation (oxidation) of oak lignin (Jouret & Puech, 1975).

The distillation procedure influences the occurrence and concentration of volatile flavour compounds in the distillate. Particularly in the manufacture of strong spirits, it is customary to better the flavour of the distillate by stripping information technology of low-boiling and high-boiling compounds to a greater or bottom caste.

Certain flavoured alcoholic beverages may incorporate, in addition to the natural compounds of the beverages, added synthetic substances and ingredients isolated from herbs and spices. For instance, the flavour of vermouths, aperitifs, bitters, liqueurs and some flavoured vodkas is oftentimes composed of dissimilar essential oils or their mixtures; synthetic products and colouring substances, such as caramel (Ministry of Agriculture, Fisheries and Food, 1987), may besides be added to improve the perceived flavour.

The exact compositions of many alcoholic beverages are trade secrets; however, there is extensive literature on the aroma components which are usually present at low levels, more than 1300 of which accept been identified (Nykänen & Suomalainen, 1983). Information about nonaroma compounds is less extensive. A list of compounds identified in alcoholic beverages is given in Appendix ane to this volume.

Definitions of the traditional terms for production processes and types of beverage are given by Lord (1979), Jackson (1982) and Johnson (1985). A useful glossary has been drawn upwards by Keller et al (1982).

3.two. Compounds in beer

(a) Carbonyl compounds

Carbonyl compounds are amid the most volatile substances in alcoholic beverages. The levels of some aldehydes establish in pasteurized and unpasteurized beers are given in Table 25. Acetaldehyde (meet besides IARC, 1985,1987a) is the principal carbonyl compound in beer and has been constitute at similar ranges (0.i–16.four mg/l) in U.s., German and Norwegian beers; levels as high as 37.2 mg/1 were plant in an unspecified beer (Nykänen & Suomalainen, 1983).

Table 25

Content (mg/fifty) of some aldehydes in pasteurized and unpasteurized beers.

Of the minor carbonyls identified in beer, formaldehyde (encounter IARC, 1982a, 1987a has been found at level of 0.17–0.28 mg/l in a Swiss beer (Steiner et al., 1969); a fresh beer was reported to contain 0.009 mg/l formaldehyde and a stale beer, 0.002 mg/l (Lau & Lindsay, 1972). Some unsaturated aldehydes have also been identified in beer. Particular attention has been paid to the occurrence of trans-2-nonenal, which has been shown to exist responsible for the oxidized or 'cardboard' flavour of stale beer, and to that of trans,cis-2,six-nonadienal, which gives rise to cucumber- or melon-like odours in beer (Visser & Lindsay, 1971 ; Wohleb et al., 1972; Withycombe & Lindsay, 1973).

Beer too contains some aliphatic ketones. Postel et al. (1972a) found 0.three–ane.7 mg/l acetone in German beer, and Tressl et al. (1978) determined the post-obit ketones: 3-hydroxy-2-butanone (0.42 mg/l), 2-pentanone (0.02 mg/fifty), 3-hydroxy-two-pentanone (0.05 mg/l), iii-methyl-2-pentanone (0.06 mg/l), iv-methyl-2-pentanone (0.12 mg/l), 2-heptanone (0.11 mg/l), 6-methyl-v-hepten-2-ane (0.05 mg/50), 2-octanone (0.01 mg/fifty), 2-nonanone (0.03 mg/50) and ii-undecanone (0.001 mg/l).

The occurrence of 2,3-butanedione (diacetyl), 2,3-pentanedione and 3-hydroxy-ii-butanone in beer has been investigated. The 2,iii-butanedione content of beer mostly varies from 0.01 to 0.2 mg/l (Nykänen & Suomalainen, 1983), merely concentrations as high as 0.63 mg/l have been determined in British beer. Slightly smaller amounts (0.01–0.xvi mg/l) of ii,3-pentanedione were found in British beers (White & Wainwright, 1975).

(b) Alcohols

The glycerol content of beer varies little — generally from 1100 to 2100 mg/l (Nykänen & Suomalainen, 1983), although Drawert et al. (1976) institute average glycerol contents ranging up to 3170 mg/l in some German beers.

According to a review (Nykänen & Suomalainen, 1983), beers produced in different countries do not differ greatly in their content of aliphatic fusel booze (college alcohols formed during yeast fermentation of carbohydrates), although the amounts vary to some extent between the unlike beer types because their formation depends on the yeast used and, in detail, on fermentation conditions. Thus, beers have been found to incorporate 4–60 mg/l 1-propanol, half dozen–72 mg/l 2-methyl-l-propanol (isobutanol), 3–41 mg/l 2-methyl-l-butanol and 35–52 mg/l 3-methyl-fifty-butanol.

Phenethyl booze (2-phenylethyl alcohol), an aromatic fusel alcohol, has a relatively strong rose-like odor, and therefore its determination in different beers has been a central subject of many studies; concentrations in beers vary from 4 to 102 mg/l. Benzyl alcohol occurs as a minor component in beer. Tyrosol and tryptophol, which are formed during fermentation, take been found in many beers, the tyrosol content varying from 1 to 29 mg/l and the tryptophol content from 0.2 to 12 mg/l (Nykänen & Suomalainen, 1983).

(c) Volatile acids

Most of the monocarboxylic acids — from formic acid to C₁₈-acids — are nowadays in beer simply, in general, as pocket-sized components. The acidity due to volatile compounds has been found to exist greater in beer than in wort, indicating that the acids are formed during fermentation. Acetic acid is the most abundant, occurring at 12–155 mg/l in ales, 22–107 mg/l in lagers and 30–35 mg/l in stouts. The levels of other short-chain acids, upward to hexanoic acrid, vary from 0.three to 3.4 mg/l. The main volatile acids in beer accept been reported to be hexanoic acrid (1–25 mg/l), octanoic acid (two–15.4 mg/l) and decanoic acid (0.1–v.2 mg/l) (Nykänen & Suomalainen, 1983).

(d) Hydroxy and oxo acids

The occurrence of the L(+) and D(−) forms of lactic acid, which is a major hydroxy acrid in beer, indicates bacterial activity during fermentation. Mändl et al. (1971a,b, 1973,1975) found levels as high as 360 mg/l L-lactic acid in a French beer and 430 mg/l D-lactic acid in an Irish gaelic porter stout; most of the beers examined independent ii–twoscore mg/l L-lactic acrid and 25–100 mg/fifty D-lactic acid. Beer also contains minor amounts of other brusque-chain hydroxy acids (see Appendix 1). Some trihydroxy acids accept as well been detected: German language, Austrian and American beers were reported to comprise 5–9 mg/l 9,12,thirteen-trihydroxy-ten-trans-octadecenoic acid, 1–2.iv mg/l 9,10,13-trihydroxy-xi-trans-octadecenoic acid, and 0.4–0.7 mg/50 ix,10,13-trihydroxy-12-trans-octadecenoic acid (Nykänen & Suomalainen, 1983).

Of the oxo acids that occur in beer, pyruvic acid is present in fairly high amounts; Mändl et al. (1971b, 1973) determined concentrations of 53–89 mg/l in American beers and 17–138 mg/50 in European beers.

(due east) Nonvolatile (fixed) acids

The occurrence of sure nonvolatile (fixed) acids in beer is well established. The oxalic acid content is small, but information technology is of considerable involvement because the formation of calcium oxalate may contribute to the advent of hazes and sediments in beer. Bernstein and Khan (1973) reported 9–fifteen mg/l oxalic acrid in ales and lager beers; Fournet and Montreuil (1975) constitute 2–11 mg/l in French beers; and German beers were found to incorporate 14–28 mg/l (Drawert et al., 1975, 1976).

Succinic acid has been reported to occur at concentrations of 12–166 mg/fifty, malic acrid at 0–213 mg/l and citric acid at 5–252 mg/l (Nykänen & Suomalainen, 1983). Numerous acids that occur at concentrations of only a few milligrams per litre are listed in Appendix 1.

(f) Esters

Beer contains a slap-up number of esters of aliphatic fatty acids. Ethyl acetate is the primary one, occurring at ten–thirty mg/fifty (with values upwards to 69 mg/l), while isopentyl acetate has been establish at 1–7.8 mg/l. Of the high-boiling esters, ethyl hexanoate and ethyl octanoate occur at 0.1–0.v mg/l and 0.1–1.five mg/fifty, respectively, although some beers have been shown to incorporate two.four–4 mg/l ethyl octanoate. The corporeality of phenethyl acetate varies between 0.03 and 1.v mg/fifty (Nykänen & Suomalainen, 1983).

(1000) Nitrogen compounds

(i) Amines and amides

Amines occur in beer due to the biochemical degradation of amino acids, which may begin during malting and then continues during fermentation. They are listed in Appendix i. The post-obit acetamides have been found in German dark beer: N, N-dimethyl-formamide, 0.015 mg/fifty; N, N-dimethylacetamide, 0.01 mg/l; N-methylacetamide, traces; N-ethylacetamide, 0.02 mg/l; N-(2-methylbutyl)acetamide, 0.01 mg/l; Due north-(three-methylbutyl)-acetamide, 0.025 mg/l; N-(2-phenylethyl)acetamide, 0.015 mg/l; and N-furfurylacetamide, 0.12 mg/l (Tressl et al., 1977). The occurrence of several primary, secondary and tertiary amines in unlike beers is summarized in Table 26. Aminoacetophenone may exist responsible in office for the feature scent of beers.

Table 26

Content (mg/l) of some amines in beer.

(ii) N-Heterocyclic compounds

Northward-Heterocyclic compounds present in malt tin be detected at depression levels in some beers. The amounts of pyrazines in dark Bavarian beer are given in Table 27. Tressl et al (1977) assumed that the pyrroles occurring in some beers are responsible for the smoky odour resembling that of pastry and staff of life. A number of compounds with such an scent were establish, iv of which were identified equally nicotinic acid esters. The pyrroles and thiazoles found in dark Bavarian beer are listed in Table 28.

Table 27

Content (mg/l) of pyrazines in dark Bavarian beer.

Table 28

Content (mg/l) of pyrroles, thiazoles and some other cyclic compounds determined in nighttime Bavarian beer.

(iii) Histamine and other nonvolatile N-heterocyclic compounds

Granerus et al. (1969) showed that the level of histamine was 0.03–0.05 mg/l in Swedish beer and 0.03–0.xv mg/fifty in Danish beer. Chen and Van Gheluwe (1979) plant ways of 0.22 mg/l in Canadian ale, 0.twenty mg/l in Canadian lager, 0.38 mg/l in Canadian malt liquor, 0.41 mg/l in Canadian porter, 0.13 mg/l in Canadian calorie-free beer, 0.thirteen mg/l in American lager and 0.xx mg/l in European beers. A high histamine content, one.9 mg/50, was found in a Belgian Gueuze produced by 'spontaneous' fermentation with microorganisms other than brewer'due south yeast.

The purine and pyrimidine contents of beer have been investigated in several studies (Saha et al., 1971; Buday et al., 1972; Charalambous et al., 1974; Kieninger et al., 1976; Ziegler & Piendl, 1976; ; Boeck & Kieninger, 1979). In most beers the amounts of uracil, cytosine, hypoxanthine, xanthine, adenine, guanine, thymine, thymidine, adenosine and inosine were found to range from 0.ane to xl mg/50, whereas higher amounts of guanosine (30–160 mg/l), cytidine (eighteen–70 mg/l) and uridine (15–200 mg/l) were detected.

(h) Aromatic compounds

(i) Phenols

Special attending has been paid to the occurrence of phenols in beer due to their potential influence on the flavour (Nykänen & Suomalainen, 1983). Wackerbauer et al. (1977) investigated the sources of the phenolic flavour of beer and found cresol (0.012 mg/l), 4-vinylphenol (0.17 mg/l), 2-methoxy-4-vinylphenol (4-vinylguaiacol; 0.074 mg/fifty) and 4-hydroxybenzaldehyde (0.018 mg/l) in a flawed beer. Many different phenols accept been found in beers (Tressl et al., 1975a, 1976; see also Appendix ane).

(ii) Aromatic acids

Beer contains numerous effluvious acids (Appendix 1); their occurrence in beer is summarized in Tabular array 29.

Table 29

Content (mg/l) of aromatic acids in beer.

3.iii. Compounds in vino

(a) Carbonyl compounds

Acetaldehyde constitutes more 90% of the total aldehyde content of wines, occurring at 50–100 mg/fifty (Nykänen & Suomalainen, 1983). Wucherpfennig and Semmler (1972, 1973) institute 74–118 mg/l acetaldehyde in wines produced from different grapes in diverse vineyards in dissimilar countries, and Postel et al (1972b) found 11–160 mg/l in German language 'Spätlesen', 'Auslesen' and 'Beerenauslesen' white wines and in red wines; white and red wines had similar aldehyde contents. The aldehyde content is, however, depression, and this may be explained by the fact that the sulphur dioxide added to vino reacts with aldehydes to form α-hydroxysulphonic acids, which reduce the gratuitous aldehyde content. Furthermore, aldehydes can be chemically bound to ethanol and higher alcohols as acetals.

Pocket-sized amounts of other aliphatic aldehydes and ketones are also nowadays in wine (Appendix 1). Baumes et al. (1986) found iii-hydroxy-2-butanone (0.002–0.3 mg/l) and 3-hydroxy-two-pentanone in French white and red wines. The volatile flavour of Chardonnay and Riesling wines has been reported to include pocket-size amounts of 2-methylbutanal, three-methylbutanal, hexanal and 2-heptanone (Simpson & Miller, 1983,1984). Benzaldehyde has been found in detectable amounts (0.002–0.504 mg/50) in different French wines (Baumes et al., 1986), in Chardonnay and Riesling wines (Simpson & Miller, 1983,1984) and in Pinot Noir wine (Brander et al., 1980).

Two vicinal diketones, 2,3-butanedione and 2,3-pentanedione, may be of importance to the season nuances, although they occur at low levels. two,3-Butanedione has been constitute in white wines at 0.05–3.4 mg/l and in red wines at 0.02–5.4 mg/50, whereas lower values have been reported for 2,3-pentanedione (0.007–0.4 mg/l in white wines and 0.01–0.88 mg/l in ruddy wines; Leppänen et al., 1979; Nykänen & Suomalainen, 1983).

(b) Acetals

In contrast to beers, wines contain acetal (1,i-diethoxyethane) as a major component of the volatiles. It is generally assumed that the reaction of acetaldehyde with ethanol to yield acetal may 'round' the scent of wines, which is of bang-up importance. In the French wines investigated by Baumes et al (1986), the total amounts of acetal and 2,4-dimethyl-1,three-dioxane were reported to vary from 0.18 to ix.3 mg/l in white wines and from 0.09 to 0.52 mg/l in scarlet wines. Other acetals found at low concentrations were 2,4,five-trimethyl-1,three-dioxolane (previously identified past Brander et al (1980) in Pinot Noir wine), 1,3-dimethyl-4-ethyl-1,three-dioxolane, 1-ethoxy-1-(ii′-methylpropoxy)ethane, 1 -ethoxy-1 -(3′-methylbutoxy)ethane, 1-(iii′-methylbutoxy)-1-(2′-methylbutoxy)ethane, 1,i -di-(iii′-methylbutoxy)-ethane, 1 -ethoxy-1 -(2′-phenethoxy)ethane, 1-(3′-methylbutoxy)-1-(two′-phenethoxy) ethane, cis-2-methyl-four-hydroxymethyl-fifty, iii-dioxolane and trans-2-methyl-4-hydroxymethyl-l, 3-dioxolane (Baumes et al., 1986).

An ether possibly related to the acetals, 3-ethoxypropanol, has been identifed in Pinot Noir wine (Brander et al., 1980).

(c) Alcohols

(i) Di- and trihydric alcohols

Apart from ethanol, glycerol and 2,iii-butanediol are the principal alcohols in wine. The glycerol content has been reported to range between 2000 and 36 000 mg/50 in audio wines (Nykänen & Suomalainen, 1983). The contents of numerous European and American wines accept been found to vary from 400 to 1100 mg/l; exceptionally high amounts of 2,3-butanediol were constitute in a Romanian 'Trockenbeerenauslese' (2700 mg/fifty) and in an 'Edelauslese'(3300 mg/l; Patschky, 1973).

(two) Fusel alcohols and long-concatenation alcohols

Numerous investigations on the volatile components of different wines have shown that higher alcohols are ubiquitous. White and red wines produced in various countries contain i-propanol (11–125 mg/l), ii-methyl-l-propanol (15–174 mg/50), 2-methyl-50-butanol (12–311 mg/l) and iii-methyl-l-butanol(isopentanol; 49–180 mg/l). In add-on, wines contain 5–138 mg/50 phenethyl alcohol. The occurrence of the effluvious alcohols, tyrosol (4-hydroxy-phenethyl alcohol) and tryptophol (3-indolethanol), which are formed by biochemical mechanisms similar to those proposed for the formation of phenethyl alcohol and aliphatic fusel alcohols, has as well been established; white and red wines take been reported to contain 5–45 mg/l tyrosol and 0.three–3.1 mg/l tryptophol (Nykänen & Suomalainen, 1983).

A number of long-chain alcohols, such as i-pentanol, four-methyl-fifty-pentanol, 3-methyl-50-pentanol, Z-two-penten-l-ol, fifty-hexanol, the Eastward- and Z-isomers of 2-hexen-l-ol and 3-hexen-l-ol, 1-heptanol, 1-octanol, 1-nonanol and i-decanol, accept been identified in wines (Brander et al., 1980; Nykänen & Suomalainen, 1983; Simpson & Miller, 1983, 1984). Of these, 3-methyl-l-pentanol, i-hexanol and E-iii-hexen-l-ol seem to exist fairly important components (Baumes et al., 1986).

(d) Volatile acids

Acetic acid is the most arable of the volatile acidic constituents of wine, although yeast is known to produce only minor amounts of acetic acid in fermentation nether anaerobic weather condition. Whatsoever substantial increase in the volatile acidity in wines thus seems to be due to the activity of spoilage microorganisms. Acerb acid bacteria can oxidize ethanol, first forming acetaldehyde, followed by oxidation of aldehyde to acetic acid, thus restricting volatile acerbity to, for instance, the permissible values of under 900 mg/l in French wines and in German white wines, nether 1200 mg/fifty in German scarlet wines, under 1100 mg/l in Californian white table wines and under 1200 mg/fifty in Californian carmine wines (Nykänen & Suomalainen, 1983). The volatile acidity of German wines, for instance, has been reported to be about 300 mg/l (Schmitt, 1972).

(e) Hydroxy acids

Wines incorporate adequately big amounts of L(+)- and D(−)-lactic acid. The total concentration of lactic acid in French wines that accept undergone malolactic fermentation has been found to vary from 900 to 2600 mg/50, and total lactic acrid contents of 100–5600 mg/l and 200–3100 mg/l take been reported. Other monohydroxy acids occur as small-scale components: ii,3-dihydroxy-two-methylbutyric acid has been establish at 60–523 mg/l in a large number of wines, at 34–205 mg/l in Italian wines and at 70–550 mg/l in Bordeaux wines (Nykänen & Suomalainen, 1983).

(f) 'Stock-still'acids

The acerbity of wines depends mainly on the presence of nonvolatile acids from the grapes. Tartaric, malic, citric and succinic acids are usually the most abundant and are of great importance, not only because they regulate the acidity of the vino merely likewise because their acidity protects sound vino from spoilage and increases the stability of coloured substances. Their total amount is determined by a titrimetric method (Nykänen & Suomalainen, 1983).

de Smedt et al. (1981) found malic acrid (3380 mg/l), tartaric acid (2120 mg/l), succinic acid (500 mg/l), citric acrid (270 mg/fifty) and phosphoric acid (240 mg/l). Of the minor components, they determined shikimic acid (70 mg/l) and citramalic acid (20 mg/l) quantitatively.

(one thousand) Esters

The largest group of flavour compounds in wines consists of esters of the aliphatic monocarboxylic acids. Ethyl acetate and many of the long-chain esters in vino are formed by yeast principally by enzymic reactions during fermentation and non in chemical reactions betwixt ethanol and corresponding acids (Nykänen & Suomalainen, 1983). The acid-catalysed esterification and hydrolysis of the esters, however, may exist of importance during prolonged ageing, even though the reactions go along slowly and equilibrium concentrations are reached only after a long time.

Ethyl acetate is the principal ester component. Postel et al. (1972b) found 44–122 mg/l ethyl acetate in white wines and 78–257 mg/50 in reddish wines. Higher levels were establish in sound white wines produced in different countries (11–261 mg/l), and similar concentrations were found in reddish wines (22–232 mg/l; Shinohara & Watanabe, 1976). Late harvest wines, such as 'Spätlese', 'Auslese' and 'Beerenauslese', were found to contain 52–99 mg/l, 92–108 mg/l and 191–285 mg/l ethyl acetate, respectively (Postel et al., 1972b).

Ethyl esters of short-chain acids too every bit acetate esters of fusel alcohols are frequently institute in white and ruby wines. The ethyl esters of decanoic and dodecanoic acids are normally the longest chain esters found (Nykänen & Nykänen, 1977; Nykänen et al., 1977).

In addition, a number of esters originating in grapes have been identified in wines, such as methyl anthranilate, of which the odor has been reported to be feature of the grape diversity Vitis labrusca and may exist responsible for the 'foxy' ('rosé'.) character of some American wines (Nelson et al., 1978; Nykänen, 1986). The circadian ester, 2,6,6-trimethyl-ii-vinyl-four-acetoxytetrahydropyran, together with a tetrahydrofuran derivative, linalool oxide, potentially contributes to flavour in wine (Schreier & Drawert, 1974).

A number of esters of di- and tricarboxylic acids have also been identified in wine, of which diethyl succinate is ubiquitous. Baumes et al. (1986) found 2,3-butanediol monoacetate, methylethyl succinate, diethyl malonate, diethyl malate, diethyl ii-ketoglutarate and diethyl 2-hydroxyglutarate in French wines. DiStefano (1983) identified ethyl esters of 2-hydroxyglutaric acrid and 2-hydroxyglutaric acid γ-lactone in Italian wine. Diethyl succinate has been found in Australian Chardonnay wines and ethyl iii-methylbutyl succinate in Riesling wines (Simpson & Miller, 1983,1984). The occurrence of mono- and diethyl esters of tartaric acid in wine has been confirmed in several studies (Shimizu & Watanabe, 1978; Sponholz, 1979; Edwards et al., 1985).

(h) Nitrogen compounds

(i) Amines and some N-heterocyclic compounds

Amines are probably formed mainly past bacterial decarboxylation of amino acids, but minor amounts may besides occur equally the upshot of enzymic reactions of yeast. Schreier et al. (1975) showed that the yeast Saccharomyces cerevisiae can produce the corresponding North-acetylamines from 2-methylbutylamine, iii-methylbutylamine and 2-phenethylamine in a fermentation solution. Consequently, some amides detected in vino may exist formed by yeast from amines during wine fermentation. Desser and Bandion (1985) showed that certain technological treatments and the storage of bottled wine may decrease the concentrations of biogenic amines such as ane,three-propanediamine, putrescine (one,iv-butanediamine), histamine (2-(4-imidazolyl)ethylamine), cadaverine (one,5-pentanediamine), spermidine (North-(3-aminopropyl)-1,four-butanediamine) and spermine (Due north,N'-bis(three-aminopropyl)- i,four-butanediamine) in vino. Puputti and Suomalainen (1969) determined the concentrations of a number of volatile and nonvolatile compounds in white and red wines (Table 30).

Tabular array 30

Content (mg/50) of amines in white and red wines.

The amounts of amines in different wines vary widely. Spettoli (1971) found ethylamine (traces-0.36 mg/l), isobutylamine (traces-0.7 mg/50), isopentylamine (isoamylamine; 0.04–0.vii mg/50), hexylamine (0.one–0.9 mg/fifty), ethanolamine (0.05–0.9 mg/l) and para-(2-aminoethyl) phenol (tyramine; 0.06–0.7 mg/l) in Italian white and red wines. The diamines, i,4-butanediamine (putrescine), 1,5-pentanediamine (cadaverine) and tyramine are metabolic products of bacteria; diamines are found in greater amounts in ruby-red wines. Concentrations of 1,4-butanediamine accept been reported to reach 24 mg/l in Swiss white wines and 45 mg/l in Swiss blood-red wines, whereas the concentrations of 1,v-pentanediamine reached two mg/fifty in white wines and four mg/l in red wines (Mayer & Pause, 1973). Woidich et al (1980) establish the amines reported in Table 31 in several Austrian wines.

Table 31

Content (mg/l) of some biogenic amines in Austrian wines.

Other amines and N-heterocyclic compounds take been identified in wine (Table 32). Bosin et al. (1986) determined 1,2,3,four-tetrahydro-β-carboline-3-carboxylic acid and l-methyl-one,ii,iii,4-tetrahydro-β-carboline-3-carboxylic acid at 0.8–1.7 and i.three–nine.1 mg/l, respectively. Some of the pyrroles, thiazoles and piperazines that occur in other beverages have too been identified in wine; these are 50-ethyl-two-formylpyrrole, N-methylpyrrole.

Tabular array 32

Content (mg/l) of amines and N-heterocyclic compounds in wine.

Northward-ethylpyrrole, N-propylpyrrole, benzothiazole, North-methylpiperazine, 2-methylpiperazine, trans-two,5-dimethylpiperazine and Due north,N-dimethylpiperazine (Ough, 1984). The occurrence of 2-methoxypyrazines in wine has been confirmed (Heymann et al., 1986). Serotonin [3-(2- aminoethyl)-1 H-indol-v-ol] and octopamine [(4-hydroxyphenyl)ethanolamine] have been adamant by a high-pressure liquid chromatographic method among the nonvolatile compounds in wine (Lehtonen, 1986).

(ii) Amides

Numerous acetamides have been identified in wines (Ough, 1984). These include N,N- dimethylformamide, N-3-methylbutylacetamide, Due north-northward-pentylacetamide, Northward-ethylacetamide, North-n-hexylacetamide, Due north-northward-propylacetamide, N-cyclohexylacetamide, Northward-isopropylacetamide, N-(3-(methylthio)propylacetamide, N-n-butylacetamide, N-2-phenethylacetamide, N-isobutylacetamide, Due north-tert-butylacetamide, N-piperidylacetamide, N-two-methylbutylacetamide and North,Due north-diethylacetamide. Only a few quantitative results have been reported; for example, N-2-methylbutylacetamide at 0.002–0.02 mg/l and N-three-methylbutylacetamide at 0.002 mg/l.

(i) Terpenic compounds

Vino contains numerous terpene hydrocarbons, terpene aldehydes and ketones, terpene alcohols, esters of terpene alcohols, and their oxidation products (see Appendix 1). The quantities of individual terpenes vary widely according to the vino. Terpene limerick depends, in office, on grape varieties; varieties of white Vitis vinifera grapes and wines have been classified co-ordinate to their terpene profiles (Schreier et al., 1976a,b; Rapp et al., 1984), although whether this tin exist generally used for classifying different grape varieties or wines produced from these grapes is non established. Since complimentary and glycosidic derivatives of monoterpenes are uniformly distributed among the peel, lurid and juice (Wilson et al., 1984; Williams et al, 1985; Wilson, B. et al., 1986), a fairly large proportion of terpenes are present bound to glycosides in young wine; however, when the glycosidic compounds are hydrolysed during ageing, the terpene profile changes (Rapp et al., 1985).

The amounts of terpene compounds in wine have non been reported, but it has been suggested that they contribute markedly to the specific characteristics of wine flavor (Williams, 1982; Rapp et al., 1984; Schreier, 1984; Strauss et al., 1984; Williams et al., 1985; Rapp & Mandery, 1986).

(j) Phenolic compounds

Besides phenolic alcohols, aldehydes and acids, cherry-red wines contain small amounts of phenol, yard-cresol, guaiacol, iv-ethylphenol, 4-vinylphenol, 4-ethylguaiacol, four-vinylguaiacol, eugenol and ii,6-dimethoxyphenol. Corbières vino has been reported to contain 0.001–0.1 mg/fifty phenol, ortho-cresol, meta-cresol, para-cresol, two-ethylphenol, 4-ethylphenol, 4-vinyl-phenol, 2-methoxyphenol (guaiacol), ii-methoxy-4-ethylphenol, 2-methoxy-iv-vinylphenol, acetovanillone and propiovanillone (Etiévant, 1981). The following volatile phenolic compounds were adamant in sherry: 4-ethylphenol (0.35 mg/l), 2-methoxy-4-ethyl-phenol (4-ethylguaiacol; 0.08 mg/l), 2-ethylphenol (0.05 mg/l), 2-methoxy-4-vinylphenol (iv-vinylguaiacol; 0.05 mg/l), 2,vi-dimethoxy-4-ethylphenol (ethyl syringol; 0.04 mg/l), 4-vinylphenol (0.02 mg/l), meta-cresol (0.01 mg/l), para-cresol (0.01 mg/50) and 2-methoxy-four-allylphenol (eugenol; 0.01 mg/l). Phenol, ortho-cresol, 2-methoxy-4-methylphenol (four-methylguaiacol) and two,half dozen-dimethoxy-4-isopropylphenol (isopropyl syringol) were detected at trace levels (Tressl et al., 1976).

Cinnamic acid derivatives, anthocyanins, flavonols and condensed tannins also occur in vino. Anthocyanins and tannins originating in grapes are the principal pigments in red wine, and their presence influences the color and organoleptic characteristics of the vino. Color stability increases with the degree of methylation, glycosylation and acylation of the basic anthocyanin moiety (Van Buren et al., 1970). Anthocyanins are water soluble and have a 4′-hydroxyflavylium structure. The individual anthocyanins differ in the number of hydroxyl and methoxyl groups in the molecule, as well equally in the nature and number of glycosidically bound sugars. Furthermore, aliphatic and aromatic acids may attach to the skeleton of the aglycone; in the acylated anthocyanins, cinnamic acid and, more generally, para-coumaric acrid is esterified with the hydroxyl group in the 6th position of a glucose molecule attached glycosidically to the aglycone (Windholz, 1983).

Five anthocyanins — delphinidin, petunidin, malvidin, cyanidin and peonidin — and their 3-monoglucosides and 3,5-diglucosides are found commonly in grapes and wines. Malvidin 3,5-diglucoside is apparently the primary pigment in wines produced from hybrid grapes, whereas malvidin monoglucoside predominates in wines made from Vitis vinifera grapes (Van Buren et al., 1970). Quercetin-3-glucoside, quercetin-3-glucuronide and myricetin-3-glucoside (the principal flavonols), kaempferol-three-glucoside, kaempferol-3-galactoside and isorhamnetin-3-glucoside (minor compounds) and caffeoyl tartaric acrid and para-coumaroyl tartaric acrid all contribute to the pigment of grapes and wines.

Kaempferol- and myricetin-3-glucuronides and three diglycosides were also identified tentatively (Cheynier & Rigaud, 1986).

three.4. Compounds in spirits

(a) Carbonyl compounds

(i) Aliphatic aldehydes

Acetaldehyde (see IARC, 1985, 1987a) is frequently the major carbonyl component and generally constitutes more 90% of the total aldehyde content. It is hands distilled together with h2o and booze and is therefore institute in all spirits.

Acetal formation is a reversible reaction, with an equilibrium coefficient of about 0.9 (Misselhorn, 1975); thus, if the alcohol content is between 40% and 50% by volume, as is the instance for many stiff spirits, but 15–xx% of the full amount of acetaldehyde combines with ethanol. Hence, acetal germination does not reduce the free aldehyde content of strong spirits markedly, even after prolonged maturation.

The full aldehyde content in alcoholic beverages has been found to vary widely; some levels are summarized in Tabular array 33. In Scotch whisky and cognac, a number of other aldehydes are present at levels similar to that of acetaldehyde (Tabular array 34).

Table 33

Total aldehydes (mg/l ethanol), determined as acetaldehyde, in some brands of distilled beverages.

Tabular array 34

Content (mg/l) of some low-boiling aldehydes in Scotch whisky and cognac.

Co-ordinate to an investigation by Marché et al. (1975), vino distillate and brandy contain the saturated aliphatic aldehydes from formaldehyde (C_ane; see IARC, 1982a, 1987a) to dodecanal (C₁₂). Liebich et al. (1970) investigated the flavour compounds in Jamaican rum and establish propionaldehyde (0.01 mg/l), isobutyraldehyde (0.25 mg/50), 2-methylbutyraldehyde (1.5 mg/l) and isovaleraldehyde (1.8 mg/l). Kirsch has been reported to contain the following aldehydes, calculated as mg/l ethanol: formaldehyde, 10–twenty; propionaldehyde, 10–xxx; valeraldehyde, ⩽10; northward-heptanal, ⩽10; octanal, ⩽x; and n-nonanal, ⩽10 (Tuttas & Beye, 1977).

(ii) Unsaturated aldehydes

Of the unsaturated aldehydes, but acrolein (run across IARC, 1985, 1987a) has been found in new, unaged whisky distillates. Propenal reacts with high concentrations of ethanol to form ane,1,3-triethoxypropane via fifty,l-diethoxyprop-2-ene and three-ethoxypropionaldehyde as intermediate products (Kahn et al., 1968).

A number of unsaturated aldehydes have been identified in cognac and brandy. The occurrence of ii-buten-50-al and 2-hexen-l-al was reported in cognac past Marché et al. (1975). ter Heide et al. (1978) detected two-methyl-two-propen-l-al in headspace and (Z)-two-methyl-2-buten-1-al, 3-methyl-2-buten-fifty-al, (E)-two-penten-l-al, (E)-2-methyl-2-penten-l-al, the (East)-isomers of two-C_{half dozen}, ii-C₇, ii-C_viii, ii-C₉-enals and (E,E)-hepta-two,four-dien-50-al, nona-2,4-dien-l-al and deca-2,4-dien-l-al in extracts of cognac.

Some unsaturated aldehydes take besides been found in rum. Postel and Adam (1982) detected acrolein at 11 mg/l ethanol; ter Heide et al. (1981) found (E)-2-octen-l-al, (Due east)-2-nonen-ane-al, (E,Eastward)two,iv-decadien-fifty-al, β-cyclocitral, α-phellandral and geranial.

(iii) Aliphatic ketones

A large number of aliphatic ketones, from acetone to tetradecanone, have been identified in spirits; most are monoketones. In general, little attending has been paid to the determination of monoketones in spirits because of their relatively high sensory thresholds. In contrast, the occurrence of 2,three-butanedione (diacetyl) and 2,iii-pentanedione in alcoholic beverages has been investigated (ter Heide, 1986).

The acetone content of spirits varies widely, and concentrations of 3–10 mg/fifty in whiskies, 0.25 mg/l in rums and <3–x mg/fifty ethanol in cognacs and brandies have been reported (Nykänen & Suomalainen, 1983). Schreier et al. (1979) adamant the contents of some monoketones in German language and French brandies and French cognacs and establish two-pentanone (0.012–0.274 mg/l), 2-methylcyclopentanone (0.004–0.043 mg/l), 2-hexanone (0.009–0.117 mg/l), 2-heptanone (0.017–0.628 mg/l) and 2-nonanone (<0.001–0.107 mg/fifty). Liebich et al (1970) found that a Jamaican rum contained ii-butanone (0.03 mg/l), iii-penten-2-one (7 mg/l), 2-pentanone (1.two mg/l), 4-ethoxy-ii-butanone (five mg/50) and iv-ethoxy-2-pentanone (7.5 mg/l). Tuttas and Beye (1977) plant ii-butanone and 2-heptanone at concentrations of ten mg/50 ethanol in kirsch.

(4) Unsaturated monoketones

In an investigation of flavour constituents in Japanese whisky, Nishimura and Masuda (1984) identified 3 unsaturated ketones — tri-6-decen-two-1, penta-6-decen-2-one and hepta-6-decen-2-i. The unsaturated ketones three-penten-two-1 (Liebich et al., 1970) and (Due east)-6-nonen-2-one (ter Heide et al., 1981) have been identified in rum. Schreier et al (1978) detected 0.05 mg/l6-methyl-5-hepten-two-i in raw apple brandy. The unsaturated ketones (E)-iii-penten-2-one, (E)-iii-nonen-2-ane, 6-methyl-five-hepten-2-1, (East)- and (Z)-6-methyl-hepta-3,v-diene-ii-one, (Due east)-2-nonen-4-one and (E)-2-undecen-4-one have been plant in cognac (ter Heide et al., 1978).

(five) Diketones

The butterscotch aroma of 2,3-butanedione can be recognized at very depression concentrations.

Diketones are marked flavour compounds in alcoholic beverages, many of which contain 2,3-butanedione and ii,iii-pentanedione in detectable amounts (Nykänen & Suomalainen, 1983). 2,3-Butanedione (<0.01–4.iv mg/l) and 2,3-pentanedione (<0.003–0.57 mg/fifty) have been found in whisky, vodka, brandy and rum (Leppänen et al., 1979).

(vi) Aromatic aldehydes

The simplest effluvious aldehyde, benzaldehyde, can be found in many distilled beverages. It has been detected in large amounts in brandies produced from stone fruits (Nykänen & Suomalainen, 1983). According to Bandion et al (1976), the benzaldehyde content of cherry brandies is 33–75 mg/l; the highest amount, 129 mg/l, was constitute in an apricot brandy.

The appearance of aromatic aldehydes in spirits matured in wooden casks is associated with the deposition of wood lignin. During the maturation of whisky distillates, the amounts of effluvious aldehydes liberated depend on the blazon of cask; alcoholysis of lignin and extraction of the compounds with spirit requite unlike yields when new or old charred or uncharred casks are used. Information technology has been suggested that effluvious aldehydes produced in the gratis form by charring are extracted direct by the spirits. Moreover, ethanol reacts with lignin to form ethanol lignin, some of which breaks down to yield coniferyl and sinapic alcohols, which tin then be oxidized into coniferaldehyde (4-hydroxy-three-methoxycinnamaIdehyde) and sinapaldehyde (three,5-dimethoxy-4-hydroxycinnamaldehyde). Aldehydes with a double bail in the side chain, such every bit coniferaldehyde and sinapaldehyde, are further oxidized to yield vanillin (4-hydroxy-three-methoxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde; Baldwin et al., 1967; Baldwin & Andreasen, 1974; Reazin et al., 1976; Nishimura et al., 1983; Reazin, 1983). Concentrations of vanillin and syringaldehyde in different commercial brands of distilled beverages are given in Tabular array 35. Coniferaldehyde and sinapaldehyde were found in whisky and cognac, whereas salicylaldehyde was plant only in whisky (Lehtonen, 1984).

Table 35

Content (mg/l) of vanillin and syringaldehyde in some brands of spirits.

(b) Alcohols

Some spirits, such as vodka, incorporate few flavour compounds and consist essentially of ethanol and water. In dissimilarity, whiskies, cognacs, brandies and rums frequently contain big numbers of dissimilar volatile compounds.

(i) Methanol

Methanol is non a by-product of yeast fermentation but originates from pectins in the must and juice when grapes and fruits are macerated. In general, the methanol content of commercial alcoholic beverages is adequately small, except in those produced from grapes in prolonged contact with pectinesterase and in some brandies produced from stone fruits, such as cherries and plums. Apricot brandies have been constitute to comprise up to ten 810 mg, plum brandies, up to 8850 mg, and cherry brandies, upwards to 5290 mg methanol/1 pure booze. Cognac and grape brandies incorporate 103–835 mg/l and Scotch whisky lxxx–260 mg/50 methanol (Nykänen & Suomalainen, 1983).

(ii) Higher alcohols

Higher alcohols and fusel alcohols (i-propanol, two-methylpropanol, 2-methylbutanol, 3-methylbutanol and phenylethyl alcohol) are formed in biochemical reactions by yeast on amino acids and carbohydrates. The amounts in different beverages vary considerably. Scotch whisky has been reported to comprise one-propanol (70–255 mg/l), 2-methyl-1-propanol (170–410 mg/50), 2-methyl-l-butanol (74–124 mg/l) and 3-methyl-1-butanol (215–352 mg/l). Irish gaelic whiskey, Canadian whisky and Japanese whisky exercise non differ considerably from Scotch whiskies in concentrations of fusel alcohols, whereas American bourbon whiskeys tin can comprise up to 1390 mg/l2-methyl-50-butanol and upward to 1465 mg/l3-methyl-1-butanol. Brandies and cognacs contain slightly more than fusel alcohols than Scotch whiskies: 1-propanol (53–895 mg/l), 2-methyl-50-propanol (7–688 mg/l), 2-methyl-l-butanol (21–396 mg/l) and 3-methyl-50-butanol (98–2108 mg/l). The total amounts of fusel alcohols in rums correlate with the total congener content. Exceptionally high values have been reported for i-propanol in some heavily flavoured Jamaican rums, in which the concentration of congeners was more than than 9000 mg/l pure booze; the 1-propanol content ranged from 23 840 to 31 300 mg/50 pure alcohol (Horak et al., 1974a,b; Mesley et al., 1975; Nykänen & Suomalainen, 1983).

The rose-like odour of phenethyl alcohol can be recognized in some whiskies, which unremarkably contain 1–30 mg/l (ter Heide, 1986). In brandies and rums, the concentration is much lower. A very high content, 131 mg/fifty, was plant in an American bourbon whiskey (Kahn & Conner, 1972).

A number of long-concatenation alcohols, upwardly to C₁₈, have been found in distilled alcoholic beverages, but the concentrations are very pocket-sized (Nykänen & Suomalainen, 1983).

(c) Acids

(i) Aliphatic acids

All the direct-chain monocarboxylic acids from C₂ to C₁₈ and a large number of branched-concatenation acids accept been identified in distilled alcoholic beverages (ter Heide, 1986); most are produced by yeast during fermentation. Recently, the presence of formic acrid in cognac and rum has been confirmed, and it is i of the major acids in whisky (ter Heide, 1984, 1986). Saturated C₃-C_xviii straight-chain acids predominate, and acerb acid is generally the primary component (ter Heide, 1986). Its relative proportion in Scotch whiskies is approximately fifty% of total volatile acids, and that in other whiskies, 60–95%; cognacs and rums contain quantities of acetic acid amounting to 50–75% and 75–90% of the full volatile acids, respectively (Nykänen et al., 1968).

The 2d largest acid component in distilled beverages is decanoic acrid, followed by octanoic acid and dodecanoic acrid or lauric acid. The concentration of palmitic acid and (Z)-hexadec-ix-enoic acid (palmitoleic acid) is relatively high in Scotch whisky in detail. Of the short-chain acids, propionic, 2-methylpropionic, butyric, iii-methylbutyric and pentanoic acids are present in affluence. The concentrations of brusk-chain acids in rums were: acerb acrid (4.5–11.7 mg/l), propionic acid (0.5–iv.2 mg/fifty), butyric acid (0.iv–two.6 mg/l), 2-ethyl-3-methylbutyric acid (0.one–2.ii mg/fifty) and hexanoic acrid (0.three–1.3 mg/fifty; Nykänen & Nykänen, 1983); Westward Indian and Martinique rums contained 2-propenoic acid (0.one–0.2 mg/l) and nighttime rums, trans-2-butenoic acid, among others (ter Heide, 1986).

(two) Aromatic acids

Modest amounts of aromatic acids tin be found in distilled alcoholic beverages (Nykänen & Suomalainen, 1983). Near are phenolic acids and probably originate in wooden casks used for maturation. In investigations of the nonvolatile compounds liberated by alcohol from oak chips, Nykänen, L. (1984) and Nykänen et al. (1984) plant benzoic acid, phenylacetic acid, cinnamic acid, 2-hydroxybenzoic acrid and benzenetricarboxylic acrid in extracts. iii-Phenylpropanoic acid, salicylic acrid and homovanillic acid ((4-hydroxy-three-methoxyphenyl)acetic acid) were identified in night rum, and 4-hydroxybenzoic acid was identified in cognac matured for l years. In addition, coumaric acid (4-hydroxycinnamic acid) has been constitute in whisky, and gallic acid (3,4,5-trihydroxybenzoic acid), vanillic acid (4-hydroxy-3-methoxybenzoic acid), syringic acrid (3,v-dimethoxy-4-hydroxybenzoic acid) and ferulic acid (iv-hydroxy-three-methoxycinnamic acrid) in rum (ter Heide, 1986). A prolonged maturation may increase the content of some aromatic acids, although, in armagnac, concentrations of cinnamic acrid, benzoic acid, syringic acid, vanillic acrid, ferulic acid, 4-hydroxybenzoic acrid and 4-hydroxycinnamic acid reached their highest values after 15 years; in 30-yr-old armagnac, the full amounts of these acids had decreased to approxi-mately thirty% of the maximal value (Puech, 1978).

(d) Esters

(i) Esters of aliphatic acids

Numerically, the largest group of season compounds in whisky, cognac and rum consists of esters (Nykänen & Suomalainen, 1983; ter Heide, 1986), near of which are ethyl esters of monocarboxylic acids. The straight-chain ethyl esters from C₂ upwardly to C₁₈ acids, and some ethyl esters of branched-concatenation acids, are present in whisky, cognac and heavily flavoured rum. The number of esters increases farther past esterification of acids with fusel alcohols and with long-concatenation fat alcohols likewise as by the appearance of aromatic esters formed during maturation.

The full ester content varies widely in strong spirits. Esters have been plant in anile Scotch malt whiskies (360 mg/50), in Scotch whiskies (550 mg/l), Irish whiskeys (1010 mg/l), Canadian whiskies (645 mg/l) and American whiskeys (269–785 mg/l). The ester contents of rums (44–643 mg/l) and brandies (300–6000 mg/l) are like (Schoeneman et al., 1971; Schoeneman & Dyer, 1973; Reazin et al., 1976; Reinhard, 1977; Nykänen & Suomalainen, 1983).

Ethyl formate is a common component of spirits. Its concentration varies between four and 27 mg/fifty in whiskies and 13 and 33 mg/fifty in cognacs (Carroll, 1970; Nykänen & Suomalainen, 1983). Postel et al. (1975) reported 5–35 mg ethyl formate/ane in rums. Ethyl acetate is quantitatively the most of import component of the ester fraction, unremarkably bookkeeping for over 50%. Many brusk-concatenation esters, such as isobutyl acetate, ethyl isobutyrate, ethyl northward-butyrate, ethyl isovalerate, ii-methylbutyl acetate and 3-methylbutyl acetate, accept adequately strong odours; therefore, their occurrence in whisky, cognac and rum has been investigated extensively (Nykänen & Suomalainen, 1983).

In whisky, the concentrations of long-chain carboxylic acid esters increase from ethyl hexanoate up to ethyl decanoate and and so decrease, and so that C_l8 ethyl esters are usually the last components to be detected. In Scotch whisky, the ethyl esters of hexadec-9-enoic acid and hexadecanoic acid ofttimes occur in nearly equal amounts. In cognac, brandy and rum, the concentrations of the ethyl esters of C₁₄-C₁₈ acids, and particularly of ethyl hexadec-9-enoate, are smaller than those in whisky (Suomalainen & Nykänen, 1970; ter Heide, 1986).

(ii) Esters of aromatic acids

The effluvious acids that occur in whisky, cognac and rum are as well present every bit ethyl esters, although in very pocket-sized amounts (Nykänen & Suomalainen, 1983). College amounts of ethyl benzoate have been found in plum brandies (ter Heide, 1986). Postel et al. (1975) found 8 mg ethyl benzoate / 1 alcohol in plum brandy, 10 mg/50 in mirabelle brandy and half dozen mg/l in kirsch. Beaud and Ramuz (1978) found 15–18 and 12–13 mg ethyl benzoate/1 alcohol in kirsch and Morello scarlet brandy, respectively. Schreier et al. (1978) reported that apple brandy contains 0.32 mg/50 ethyl benzoate. Minor amounts of ethyl phenylacetate accept been detected in cognac, German language and French brandies and apple brandy (Schreier et al., 1978, 1979).

(e) Phenolic compounds

Small-scale amounts of phenols, probably originating from raw materials, accept been institute in spirits. The phenolic compounds determined in whisky by Nishimura and Masuda (1971) and by Lehtonen and Suomalainen (1979) are listed in Table 36.

Table 36

Content (mg/50) of phenols in commercial whiskies.

The phenolic compounds plant in cognac are 2-methoxy-4-ethylphenol (0.29 mg/l), two-methoxy-iv-allylphenol (0.fourteen mg/50), phenol (0.03 mg/l), 4-ethylphenol (0.03 mg/l) and 2-methoxyphenol (0.03 mg/l). In addition, ortho-cresol, meta-cresol and para-cresol were detected every bit trace components. In a commercial dark Martinique rum, 4-ethylphenol (1.8 mg/l), 2-methoxy-four-ethylphenol (ane.1 mg/l), 2-methoxy-4-allylphenol (0.eight mg/fifty), ii-methoxy-phenol (0.7 mg/50), phenol (0.2 mg/50), para-cresol (0.08 mg/l),.ortho-cresol (0.06 mg/50) and meta-cresol (0.04 mg/50) were found (Jounela-Eriksson & Lehtonen, 1981). Schreier et al. (1979) reported the occurrence of four-ethylphenol and 2-methoxy-four-ethylphenol in grape brandy.

Tannins are present in spirits matured in wooden caskes. Brandies were reported to contain epicatechin, gallocatechin, catechin, flavonones and a number of other phenolic compounds (Marché et al., 1975). The concentration of tannins in brandy aged for four to x years in oak barrels ranged between 240 and 1120 mg/l (Guymon & Crowell, 1972). Bourbon whiskeys matured in charred barrels for up to 12 years contained 230–670 mg/50 tannins (Baldwin & Andreasen, 1974).

3.5. Additives and contaminants

(a) Flavouring additives

Hops and hop extracts are used by breweries to improve the flavour of beers. The presence of nonvolatile, bitter and other substances — hop acids and volatile terpenes — in hops has been reviewed (Verzele, 1986) and the chemical limerick of hops is summarized in Table 37.

Various found extracts and essential oils are used in the manufacture of alcoholic beverages, in addition to synthetic products, to flavour liqueurs, aperitif beverages like vermouth and some vodkas. For instance, the strongly flavoured Russian vodka subrowka contains a blade of sugariness, or holy, grass (Hierochloe odorata), beloved of the European bison, from which colouring matter and flavouring compounds are extracted past alcohol during storage. Many terpenic compounds, a number of ketones, alcohols, aldehydes, esters, lactones, phenols and phenol ethers, and acids have been identified as the flavor components of H. odorata. The principal component of the grass is coumarin, which represents about threescore% of the full content of the volatile compounds (Nykänen, L., 1984).

Anethole, which has a strong aniseed-like aroma, is some other natural substance encountered in many beverages, and particularly in liqueurs. Natural anethole is obtained from plant materials, merely information technology is also produced synthetically. A large number of other natural and synthetic flavourings with the same odour are used (Liddle & Bossard, 1984, 1985).

(b) Other additives

Preservatives are often added to beers and wines to prevent the activity of bacteria and moulds. In the UK, breweries are permitted to utilize sulphur dioxide as an antibacterial and antioxidant agent at a statutory limit of 70 mg/l. Many yeasts tin can class small quantities of sulphur clioxide during fermentation. However, the sulphur dioxide formed in beers is jump to naturally occurring compounds, and merely small amounts tin be detected. The sulphur dioxide content of German, Belgian and Dutch beers varies from none to 2.three mg/l every bit gratuitous sulphur dioxide and from 0.eight to 2.iv mg/fifty equally full sulphur dioxide (Nykänen & Suomalainen, 1983).

Sulphur dioxide is also one of the most of import additives in wine making. Information technology is added in aqueous solution or as potassium metabisulphite water solution; most is jump to aldehydes (Ough, 1987), pigments and polyphenols. In many countries, the permitted amount of free sulphur dioxide in commercial wines is 35–100 mg/50; the concentrations reported depend on the analytical method used. Most wines contain like amounts of full sulphur dioxide (>100 mg/l; Nykänen & Suomalainen, 1983). Sulphur dioxide reacts slowly with free oxygen in wine and is therefore a poor antioxidant, unless it is added to wine at much college levels than those generally accepted for inhibiting bacterial activeness. Addition of ascorbic acid to vino merely earlier bottling maintains a moderate level of sulphur dioxide. In the presence of oxygen, ascorbic acid reacts apace to yield hydrogen peroxide and dehydroascorbic acid. Sulphur dioxide so reacts with hydrogen peroxide to course sulphate ions (Ough, 1987).

The use of sorbic acid (hexa-two,4-dienoic acid) is permitted to protect wine against the activity of bacteria and moulds. At concentrations of 180–200 mg/l, it inhibits yeast growth but does not affect bacteria. Certain genera of malolactic bacteria catechumen sorbic acrid to two-ethoxy-3,5-hexadiene (Ough, 1987).

A number of spirits comprise added colouring agents on which fiddling data have been published. Sunset yellow FCF (FD & C yellow 6; meet IARC, 1975, 1987a) has been reported to be nowadays in cocktails and liqueurs (Anon., 1987).

(c) Trace elements

Most of the published literature on trace elements in alcoholic beverages concerns vino.

Concentrations of trace elements establish in wines and some other alcoholic beverages are presented in Table 38.

Table 38

Content (mg/l) of trace elements in some alcoholic beverages.

Trace elements from grapes are transferred during crushing into the must and eventually into wine (Eschnauer, 1982). The total concentration of mineral constituents in wine may be as high as 1000 mg/fifty and more than (Eschnauer, 1967). The principal trace elements are potassium, magnesium, calcium and sodium (run across Table 38), but atomic number 26, copper, manganese and zinc are as well present. In most wines, the fe content varies from 1 to 5 mg/l and copper from 0.ane to 1 mg/50.

A concentration of 0.0002–0.003 mg/l cadmium has been reported in European wines, the majority of levels being in the range 0.0002–0.0015 mg/l (Golimowski et al., 1979a,b). The natural lead content of High german wines has been reported to be 0.01–0.03 mg/l, and the boilerplate chromium content is 0.065 mg/50. It has been suggested that in younger wines the chromium content may be slightly college (0.18 mg/l) than in quondam wines because they are more frequently in contact with stainless steel (Eschnauer, 1982). Interesse et al. (1984) determined 14 trace elements in 51 southern Italian wines; the chromium content was found to range from 0.01 to 0.81 mg/50 and that of nickel from <0.01 to 0.09 mg/50.

In the 1960s, an epidemic of cardiomyopathy in Québec was seen later the introduction of cobalt to heighten the 'head' of foam on commercially produced beer (Morin & Daniel, 1967; Milon et al., 1968; Dölle, 1969).

(d) Contaminants

For the purposes of this section of the monograph, the term 'contaminants' refers to those minor constituents sometimes present in alcoholic beverages which are not essential to the season and backdrop of the product. Some of these contaminants have known toxicological and, in some cases, carcinogenic effects.

(i) N-Nitrosamines

The occurrence of nitrosamines (see IARC, 1978) in alcoholic beverages has been well established in many investigations despite belittling difficulties (McGlashan et al., 1968, 1970; Collis et al., 1971; Bassir & Maduagwu, 1978). Reviews on the chemical science of formation of nitrosamines, with special reference to malting, are bachelor, which report that the almost important source of N-nitrosodimethylamine (NDMA) in beer is malt kilning by reactions involving nitrogen oxides (Wainwright, 1986a,b); a number of other kilning practices have been tested to reduce the quantities of N-nitrosamines in malt. The mechanism of formation suggests that minor amounts of NDMA may occur in whisky (Klein, 1981). The concen-trations plant in various alcoholic beverages are given in Table 39. Leppänen and Ronkainen (1982) reported NDMA levels in Scotch whisky of 0.six–1.1 μg/fifty an average of 0.three μg/l in Irish whisky, of <0.one μg/50 in Bourbon whiskey and <0.05–1.7 μthousand/1 in beer. Of 158 samples of beer, 70% were found to incorporate NDMA; the mean concentration in all samples was 2.seven μg/l; the highest value, 68 μ1000/l, was found in a so-called 'Rauchbier' which is made from smoked malt to give a smokey taste (Spiegelhalder et al., 1979).

Table 39

Average amounts of N-nitrosamines in alcoholic beverages.

Other nitrosamines that have been identified in beer include N-nitrosopyrrolidine (Klein, 1981) and N-nitrosoproline (Massey et al., 1982).

(2) Mycotoxins

A wide diversity of moulds is plant on grapes; Aspergillus flavus may be among them, and hence aflatoxins may occur exceptionally in wines. In an investigation by Schuller et al. (1967), aflatoxin B₁ was establish to be present in two (Ruländer 1964 and Gewürztraminer1964) of 33 German wines analysed at amounts of <one μg/l. Lehtonen (1973) investigated the occurrence of aflatoxins in 22 wines from different countries by a sparse-layer chromatographic method and reported <1 μg/ane in xi samples and ane.2–2.6 μchiliad/1 in five samples; six samples were aflatoxin-free. Takahashi (1974) increased the sensitivity of the method and was able to determine aflatoxins B₁, B₂, Chiliad₁ and Chiliad₂ at concentrations of 0.25 μthou/1 wine; aflatoxins were not determined in 11 samples of French red vino, Castilian sherry, madeira and port wine. French wines and German wines investigated using improved methods have also been found to exist costless of aflatoxins (Drawert & Barton, 1973, 1974; Lemperle et al., 1975).

Aflatoxins were plant by Peers and Linsell (1973) in 16 of 304 Kenyan beer samples at concentrations of 1–2.v μgrand/l. The probable source was rejected maize, which is oft used in the production of local beers. In a study in the Philippines, 47% of 55 samples of [unspecified] alcoholic beverages contained aflatoxins at an average concentration of ane.9 μ1000/1 (Bulatao-Jayme et al., 1982).

Two other mycotoxins, ochratoxin A (see IARC, 1983a, 1987a) and zearalenone (see IARC, 1983a), have been plant in beer fabricated from contaminated barley. Krogh et al. (1974) reported that the malting process degraded ochratoxin A in moderately contaminated (830 μone thousand/ kg and 420 μg/ kg) barley lots; however, modest amounts of ochratoxin A (11 μg/i and 20 μyard/l) were left in beer produced from heavily contaminated barley (2060 μthousand/ kg and 27 500 μg/ kg). Commercial and abode-fabricated Zambian beer brewed from maize contained zearale-none at concentrations ranging from no detectable amount to 2470 μg/i. The concentration of zearalenone in 12% of 140 beer samples in Kingdom of lesotho was 300–2000 μg/ane (Food and Agricultural Arrangement, 1979).

(three) Ethyl carbamate (urethane)

Urethane (see IARC, 1974,1987a) is formed by the reaction of carbamyl phosphate with ethanol (Ough, 1976a, 1984) and is, therefore, present in most fermented beverages. Ough (1976b, 1984) found urethane in commercial ales (0.5–four 25g/l), in saké (0.1–0.6 mg/l) and in some experimental (0.half-dozen–four.3 μg/50) and commercial wines (0.3–v.iv μk/l).

Numerous samples of distilled alcoholic beverages have been analysed for their urethane content, probably because of the high amounts found in stone fruit brandies. Christoph et al. (1986) reported urethane in Yugoslavian plum brandy (one.2–7 mg/fifty), in Hungarian apricot brandy (0.iii–1.5 mg/fifty), in various plum brandies (0.four–ten mg/fifty), in kirsch (2–7 mg/fifty), in fruit brandy (0.1–5 mg/l), in Scotch, American bourbon, Canadian and Irish whiskies (0.03-O.3 mg/50) and in cognac and armagnac (0.ii–0.6 mg/l). Urethane contents of alcoholic beverages reported by Mildau et al. (1987) are given in Table 40. Adam and Postel (1987) reported the following average urethane contents in some fruit brandies: kirsch (one.8 mg/fifty), plum brandy (1.vii mg/l), mirabelle plum brandy (4.3 mg/fifty), Williams pear brandy (0.18 mg/l), apple brandy (0.five mg/fifty), Jerusalem artichoke brandy (0.7 mg/l) and tequila (0.1 mg/50).

Table xl

Content (mg/l) of urethane in some alcoholic beverages.

(four) Asbestos

Asbestos (see IARC, 1977a, 1987a) fibres have been identified in some alcoholic beverages, maybe arising from the filters used for clarifying beverages, from water used during the production processes and from asbestos-cement water pipes. Biles and Emerson (1968) detected fibres of chrysotile asbestos in British beers by electron microscopy followed past electron diffraction examination. Cunningham and Pontefract (1971) found asbestos fibres in Canadian and US beers (1.1–vi.6 million fibres/l), in South African, Spanish and Canadian sherries (2.0–4.one million fibres/l), in Canadian port (2.ane one thousand thousand fibres/l), in French and Italian vermouth (i.8 and 11.7 million fibres/l), and in European and Canadian wine [concentrations not reported]. The asbestos fibres in Canadian beer and sherry were identified as chrysotile, while some of the European samples contained amphibole asbestos. Fibres of chrysotile asbestos were also plant by electron microscopy in 3 of nine samples of US gin (estimated maximal concentrations, 13–24 1000000 fibres/1; Wehman & Plantholt, 1974).

In some European countries, the utilise of asbestos to filter alimentary fluids has been prohibited (e.g., Ministère de fifty'Agronomics, 1980).

(5) Arsenic compounds, pesticides and adulterants

The use of arsenic-containing fungicides in vineyards may lead to elevated levels of arsenic in grapes and wines (see IARC, 1980, 1987a). Crecelius (1977) analysed nineteen samples of reddish and white wines and found arsenite (As+^three) at <0.001–0.42 mg/l and arsenate (As+⁵) at 0.001–0.11 mg/fifty. 4 samples were further analysed for full arsenic content by 10-ray fluorescence (diffractometry), which confirmed these results. A review of older studies by Noble et al (1976) reported concentrations ranging from 0.02 to 0.11 mg/l in nine US wines.

Aguilar et al (1987) accept investigated the occurrence of arsenic in Spanish wines. They found that crushing, pressing, cloud removal and yeast removal after fermentation and finally clarification and ageing markedly reduced the arsenic content of wine. Arsenic contamination of High german wines has been reported to have decreased since 1940, levelling out at 0.009 mg/fifty in wines after 1970. The natural arsenic content has been causeless to exist 0.003 mg/l, with earlier arsenic contents reaching the level of 1.0 mg/50 due to utilise of arsenic-containing pesticides and insecticides (Eschnauer, 1982).

The fungicides used in vineyards include zineb (see IARC, 1976a, 1987a), maneb (encounter IARC, 1976a, 1987a), mancozeb, nabam, metalaxyl, furalaxyl, benalaxyl, cymoxanil, triadimefon, dichlofluanid, captan (come across IARC, 1983b, 1987a), captafol, folpet, benomyl, carbendazim, thiophanate, methyl thiophanate, iprodione, procymidone, vinclozolin, chlozolinate (Cabras et al., 1987) and simazine (Anon., 1980). Residues of metalaxyl carbendazim, vinclozolin, iprodione and procymidone may be found in wine. In addition, ethylenethiourea (see IARC, 1974, 1987a), an impurity and a deposition production of ethylene bisdithiocarbamates (zineb, maneb, mancozeb, nabam), has been reported to be nowadays at trace levels in wine (Cabras et al., 1987). Hiramatsu and Furutani (1978) reported that the concentrations of trichlorfon and its metabolite, dichlorvos (encounter IARC, 1979b, 1987a), are college in wine than in berries, indicating that they may be accumulated in wine.

Fungicides that are prohibited in most European countries, Australia and the Usa but may be used in other countries include diethyl dicarbonate, dimethyl dicarbonate, pimaricin, 5-nitrofurylacrylic acid and due north-alkyl esters of 4-hydroxybenzoate (Ough, 1987).

Occasionally, illegal additives, which may be very toxic and which are not permitted for utilise in commercial product in near countries, have been identified in alcoholic beverages. These include methanol, diethylene glycol (used equally a sweetener), chloroacetic acid or its bromine analogue, sodium azide and salicylic acid, used as fungicides or bactericides (Ough 1987).

Source: https://www.ncbi.nlm.nih.gov/books/NBK531662/

Posted by: keoraws1985.blogspot.com

Share this post