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Dealcoholization of Wine. Behaviour of the Aroma Components during the Process
Lebensm.-Wiss. u.-Technol., 32, 384}386 (1999)
Research Note
Dealcoholization of Wine. Behaviour of the Aroma Components during the Process E. Go2 mez-Plaza*, J. M. Lo2 pez-Nicola2 s, J. M. Lo2 pez-Roca and A. Mart12 nez-Cutillas
E. GoH mez-Plaza, A. MartmH nez-Cutillas: Centro de InvestigacioH n y Desarrollo Agroalimentario, ConsejermH a de Medio Ambiente, Agricultura y Agua de la RegioH n de Murcia (Spain) J.M. LoH pez-NicolaH s: Departamento de BioqumH mica y BiologmH a Molecular A, Facultad de Veterinaria, Universidad de Murcia (Spain) J. M. LoH pez-Roca: Unidad de TecnologmH a de los Alimentos, Facultad de Veterinaria, Universidad de Murcia (Spain) (Received March 8, 1999; accepted May 19, 1999)
The changes in the aromatic composition of a white wine during the dealcoholization process have been studied together with how the aromatic compounds accumulated in diwerent condensers during the process. The dealcoholization was carried out in an industrial system working under vacuum continuously at 1000 L/h. Samples were taken every 10 min in two diwerent sections of the system, where the volatile compounds were being condensed. Results show that esters and fatty acids do not need very low temperatures to condense and be recovered, whereas aliphatic alcohols need lower temperatures to condense due to their high volatility. The xnal product was lacking in almost all of the volatile compounds.
1999 Academic Press Keywords: wine; volatile compounds; dealcoholization
Introduction The partial or total dealcoholization of wines to obtain low alcoholic drinks seems a good choice for market expansion, and to improve the problem of excess wine that the enological industries su!er in Spain. The most common industrial process to obtain dealcoholized wines involves high temperature processes, semipermeable "lms (inverse osmosis and dialysis), cryoconcentration, #uid extraction and absorption on porous surfaces (1, 2). When thermal processes are used, wine distillation at atmospheric pressure is not recommended because of the changes that occur in the wine composition, but the process can be achieved at low pressure and low temperature (1, 3). Distillation promotes a dealcoholized wine with low levels of volatile compounds. This "nal product could be used as a base, after mixing it with new wine, for a low ethanol content product. Another option could be the recovery and concentration of the aromatic condensed fractions by means of distillation, to eliminate the ethanol, and this fraction could then be incorporated into the "nal product to
*To whom correspondence should be addressed. Current address: Encarna GoH mez-Plaza, Universidad de Murcia, Facultad de Veterinaria, Unidad Docente de Tecnologia de los Alimentos, Campus de Espinardo, 30071 Murcia, Spain
0023-6438/99/060384#03 $30.00/0 1999 Academic Press
obtain a low alcoholic beverage without any modi"cation to the organoleptic characteristics of the "nal product. This paper studies the changes that occur in the aromatic composition of a wine during the dealcoholization process and how the aromatic compounds accumulated in the di!erent condensed fractions during this process.
Materials and Methods The dealcoholization was carried out in an industrial system working under vacuum (50 to 60 mm Hg). A 1000 L volume of white wine (10.6 mL ethanol/100 mL wine) was introduced into the system at 25 3C. The system worked continuously at 1000 L/h giving 800 L of dealcoholized wine (0.3 mL ethanol/100 mL wine) and two condensed fractions (section A and section B) as shows in Fig. 1. Each cycle lasted 1 h. Every 10 min a sample was taken from each of the two sections of the system: section A ("rst condensed fraction at 8 3C) and section B (the combination of two condensed fractions at 4 3C and !10 3C).
Analysis of volatile compounds Duplicated analyses were performed on each sample. A 40 mL volume of wine or condensed fraction (or a
Article No. fstl.1999.0565 All articles available online at http://www.idealibrary.com on
384
Table 1 Volatile compounds identi"ed in the initial wine, "nal product and di!erent condensed fractions (mg/L) Compound Ethanol (% v/v)
Initial wine
A1
A2
A3
A4
A5
A6
B1
B2
B3
B4
B5
B6
Final wine
10.6
25.15
25.00
24.98
20.17
21.18
20.76
60.00
52.30
57.00
67.40
63.10
58.00
0.3
0.89 nd 1.11 0.27 4.78 0.09 nd nd
0.37 nd 0.99 0.12 5.20 0.08 nd nd
0.42 0.04 1.18 0.20 5.76 0.08 nd nd
0.36 0.04 1.14 0.22 5.86 0.09 nd nd
0.50 0.29 0.42 0.91 2.77 0.17 nd nd
0.29 0.93 0.62 1.25 4.18 0.15 nd nd
0.66 1.55 0.64 1.39 3.60 0.13 nd nd
1.19 1.09 0.45 1.46 2.44 0.13 nd nd
0.88 0.66 0.60 1.29 3.35 0.18 nd nd
0.56 0.37 0.61 1.01 3.64 0.16 nd nd
nd* nd 2.30 0.86 6.03 0.06 0.44 0.07
104.00 nd 0.07 0.27 3.21 0.167 0.99 nd 0.11 nd
53.70 nd 0.06 0.19 2.36 0.14 0.74 nd 0.13 nd
87.00 nd 0.07 0.23 2.66 0.16 0.47 nd 0.13 nd
70.90 nd 0.07 0.22 2.61 0.14 0.35 nd 0.13 nd
116.00 nd 0.20 0.49 5.48 0.15 nd nd nd nd
105.00 nd 0.20 0.40 4.98 0.23 nd nd nd nd
153.00 nd 0.19 0.46 5.40 0.18 nd nd nd nd
213.00 nd 0.25 0.56 6.82 0.20 nd nd nd nd
221.00 nd 0.27 0.66 7.81 0.25 nd nd nd nd
173.00 nd 0.20 0.55 6.60 0.21 nd nd 0.13 nd
0.17 nd nd nd nd nd nd 0.35 0.13 0.34
385
1.02 0.92 4.02 5.40 7.13 0.04 0.41 0.46
1.47 0.03 1.47 0.48 4.88 0.09 nd nd
1.03 nd 1.17 0.29 4.54 0.08 nd nd
Aliphatic alcohols Isoamilic alcohol 1-Pentanol 4-Methyl-1-pentanol 3-Methyl-1-pentanol 1-Hexanol 3-Hexen-1-ol 2-Ethyl-1-hexanol 2,3-Butanediol 1-Octen-4-ol 3-(Methylthio)-1-propanol
86.90 0.10 0.05 0.15 1.58 0.08 nd 1.30 0.25 0.42
146.00 nd 0.09 0.30 3.55 0.19 0.03 nd 0.11 nd
114.00 nd 0.08 0.27 3.20 0.16 0.43 nd 0.11 nd
Aromatic alcohols a. Terpineol Linalool 3,7-Dimethyl-6-octen-l-ol Geraniol 2-Phenyl-1-ethanol 4-Ethyl-guaiacol 4-Ethylphenol 3-Oxo-a-ionol Benzylic alcohol
0.03 0.15 0.98 0.94 58.20 0.07 0.06 0.11 0.07
0.11 0.33 0.09 0.12 6.93 nd nd nd 0.17
0.11 0.34 0.10 0.09 5.69 0.11 0.10 nd 0.18
0.13 0.37 0.10 0.07 5.80 0.12 0.10 nd 0.18
0.14 0.31 0.11 0.08 4.51 0.13 0.11 nd 0.19
0.12 0.31 0.09 0.11 7.07 0.13 0.11 nd 0.18
0.12 0.33 0.11 0.11 7.22 0.12 0.13 nd 0.20
0.14 nd 0.14 nd 1.80 nd nd nd 0.17
0.17 0.28 0.15 nd 3.06 nd nd nd 0.17
0.13 0.29 nd nd 2.98 nd nd nd 0.15
0.13 0.31 nd nd 1.93 nd nd nd 0.16
nd 0.42 nd nd 2.56 nd nd nd 0.10
0.16 0.33 nd 0.13 2.88 nd nd nd 0.16
nd nd 0.66 0.90 57.60 0.05 0.05 nd nd
Ketones 2-Octanone 3-Hydroxy-2-butanone Dihydro-b-ionone
0.04 0.51 0.07
0.04 0.34 nd
0.05 0.31 nd
0.04 0.33 nd
nd 0.33 nd
0.05 0.39 nd
0.05 0.37 nd
0.22 nd nd
0.26 0.35 nd
0.25 0.14 nd
0.25 0.21 nd
0.25 0.32 nd
0.23 0.33 nd
0.04 0.14 nd
Acids 2-Methyl-propanoic Butanoic 3-Methyl-butanoic Hexanoic Octanoic Nonanoic Decanoic Dodecanoic Tetradecanoic
0.54 0.48 1.35 1.11 0.82 0.13 0.11 0.26 0.07
0.24 0.09 0.51 0.60 1.50 0.10 0.26 0.04 0.08
0.20 0.07 0.42 0.58 1.63 0.10 0.28 0.06 0.09
0.21 0.07 0.42 0.64 1.78 0.10 0.28 0.05 nd
0.15 0.06 0.31 0.60 1.79 0.11 0.26 0.05 nd
0.23 0.07 0.51 0.72 1.77 0.11 0.29 0.05 nd
0.23 0.08 0.47 0.76 1.97 0.13 0.29 0.05 0.10
nd nd nd 0.21 0.72 nd 0.16 nd nd
nd nd 0.25 0.35 0.11 nd 0.22 nd nd
nd nd 0.24 0.35 0.95 nd 0.20 nd nd
nd nd 0.19 0.25 0.69 nd 0.18 nd nd
nd nd 0.23 0.31 0.87 nd 0.18 nd 0.26
0.15 nd 0.23 0.32 1.03 nd 0.20 nd nd
0.56 0.53 1.30 0.84 0.19 0.12 nd 0.18 0.12
Miscellaneous Ethylbenzene Butirolactone
0.15 0.11
0.26 nd
0.17 nd
0.15 nd
0.06 nd
0.10 nd
0.09 nd
1.36 nd
nd nd
0.15 nd
0.28 nd
0.23 nd
0.13 nd
nd 0.06
*not detected Aliphatic alcohols overall coe$cient of variation: 9%; Aromatic alcohols overall coe$cient of variation: 6%; Carbonyl compounds overall coe$cient of variation: 12% Esters overall coe$cient of variation: 3%; Fatty acids overall coe$cient of variation: 9% A1, A2, A3, A4, A5 and A6 represent the samples taken 10, 20, 30, 40, 50 and 60 min after the dealcoholization process started in section A B1, B2, B3, B4, B5 and B6 represent the samples taken 10, 20, 30, 40, 50 and 60 min after the dealcoholization process started in section B
lwt/vol. 32 (1999) No. 6
Esters Butyl acetate Ethyl hexanoate Ethyl lactate Ethyl octanoate Diethyl succinate 2-Phenylethyl acetate 2-Propenyl benzeneacetate 2-Phenylethyl isoamylate
lwt/vol. 32 (1999) No. 6
butanoic acids) have very stable concentrations in section A. From C6 to C14 the concentrations increased with time, being higher in A6. In section B, 2-methylpropanoic acid could only be found in B6, and butanoic acid could not be detected. The other fatty acids increased in concentration with time but the concentrations were lower than in section A. The temperature in section A was shown to be high enough to condense the main part of these compounds.
Fig. 1 Scheme of the dealcoholization system used in this study
mixture of condensed fraction : water (1 : 5 v/v) when analysing section B) were extracted with 4 mL of ether : hexane (1 : 1). This step was repeated twice with 2 mL of ether : hexane (1 : 1). The organic fractions were mixed and concentrated before analysis in the gas chromatograph. The concentrated extract was injected into a Hewlett-Packard 5890 gas chromatograph (Hewlett-Packard, Avondale, PA). Chromatographic analysis and identi"cations were performed as previously described (4).
Results and Discussion Table 1 shows the identi"ed compounds in the initial wine and the "nal product, as well as in the di!erent condensed fraction. After the dealcoholization process the "nal product was lacking in almost all of the volatile compounds. The "nal product would be an organoleptically unacceptable dealcoholized wine. Only the addition of the volatile fraction lost during the process or the addition of new wine would produced a desirable product from the organoleptic point of view.
Aromatic and terpenic alcohol. Linalool, a-terpineol and benzyl alcohol totally disappeared in the dealcoholized wine. The concentration of aromatic and terpenic alcohols in section A samples was very constant with time. In section B, 4-ethyguaiacol and 4-ethylphenol were not detected at any point. 4-Ethylphenol and 4-ethylguaiacol are potential contributors to wine aroma because of their low odour thresholds and very distinctive #avours (5) and were only recovered in section A. 2-Phenylethanol and geraniol were found at lower concentrations than in section A, but these two compounds undergo almost no reduction in their concentration in the dealcoholized wine. Linalool was the only compound that increased its concentration in section B. Aliphatic alcohols. This functional group had the highest losses during the process. Due to their high volatility, aliphatic alcohols are found mainly in section B, with the exception of 2-ethyl hexanol and 2,3-butanediol. In conclusion, the product obtained after the dealcoholization of wine is lacking in many of the volatile compounds and some of those that could be detected were found in lower concentrations than in the original wine. This dealcoholized wine is an unacceptable produce from an organoleptic point of view, but the results showed that most of these volatile compounds were retained in the condensed fractions. The temperature of the condenser is a very important factor in volatile compound recovery. It must be at least !10 3C for the aliphatic alcohols and esters to be recovered to a signi"cant extent. More studies are needed to check the overall percentage of recovery for each compound and the best system to recover the compounds and reconstitute the wine aroma.
Evolution of the volatile compounds in the diwerent condensed fractions References Esters. Diethyl succinate, 2-phenylethyl acetate and 2propenyl benzencacetate almost maintained their initial concentration in the dealcoholized wine. For the other esters, the largest concentrations were found in A1, mainly for the more volatile esters, indicating that they escape very quickly. The evolution of esters in section B, where the temperature is lower than in section A, showed that the concentration of compounds increased with time, being higher in B3 and B4, mainly for butyl acetate and ethyl hexanoate. Comparing with section A, it can be seen that ethyl lactate presented larger concentrations in section A than in section B. Fatty acids. Those fatty acids with lower molecular weight (2-methylpropanoic, butanoic and 3-methyl-
1 SCHOBINGER, U., DURR, P. AND WALDVOGEL, R.
386
Research Note
Dealcoholization of Wine. Behaviour of the Aroma Components during the Process E. Go2 mez-Plaza*, J. M. Lo2 pez-Nicola2 s, J. M. Lo2 pez-Roca and A. Mart12 nez-Cutillas
E. GoH mez-Plaza, A. MartmH nez-Cutillas: Centro de InvestigacioH n y Desarrollo Agroalimentario, ConsejermH a de Medio Ambiente, Agricultura y Agua de la RegioH n de Murcia (Spain) J.M. LoH pez-NicolaH s: Departamento de BioqumH mica y BiologmH a Molecular A, Facultad de Veterinaria, Universidad de Murcia (Spain) J. M. LoH pez-Roca: Unidad de TecnologmH a de los Alimentos, Facultad de Veterinaria, Universidad de Murcia (Spain) (Received March 8, 1999; accepted May 19, 1999)
The changes in the aromatic composition of a white wine during the dealcoholization process have been studied together with how the aromatic compounds accumulated in diwerent condensers during the process. The dealcoholization was carried out in an industrial system working under vacuum continuously at 1000 L/h. Samples were taken every 10 min in two diwerent sections of the system, where the volatile compounds were being condensed. Results show that esters and fatty acids do not need very low temperatures to condense and be recovered, whereas aliphatic alcohols need lower temperatures to condense due to their high volatility. The xnal product was lacking in almost all of the volatile compounds.
1999 Academic Press Keywords: wine; volatile compounds; dealcoholization
Introduction The partial or total dealcoholization of wines to obtain low alcoholic drinks seems a good choice for market expansion, and to improve the problem of excess wine that the enological industries su!er in Spain. The most common industrial process to obtain dealcoholized wines involves high temperature processes, semipermeable "lms (inverse osmosis and dialysis), cryoconcentration, #uid extraction and absorption on porous surfaces (1, 2). When thermal processes are used, wine distillation at atmospheric pressure is not recommended because of the changes that occur in the wine composition, but the process can be achieved at low pressure and low temperature (1, 3). Distillation promotes a dealcoholized wine with low levels of volatile compounds. This "nal product could be used as a base, after mixing it with new wine, for a low ethanol content product. Another option could be the recovery and concentration of the aromatic condensed fractions by means of distillation, to eliminate the ethanol, and this fraction could then be incorporated into the "nal product to
*To whom correspondence should be addressed. Current address: Encarna GoH mez-Plaza, Universidad de Murcia, Facultad de Veterinaria, Unidad Docente de Tecnologia de los Alimentos, Campus de Espinardo, 30071 Murcia, Spain
0023-6438/99/060384#03 $30.00/0 1999 Academic Press
obtain a low alcoholic beverage without any modi"cation to the organoleptic characteristics of the "nal product. This paper studies the changes that occur in the aromatic composition of a wine during the dealcoholization process and how the aromatic compounds accumulated in the di!erent condensed fractions during this process.
Materials and Methods The dealcoholization was carried out in an industrial system working under vacuum (50 to 60 mm Hg). A 1000 L volume of white wine (10.6 mL ethanol/100 mL wine) was introduced into the system at 25 3C. The system worked continuously at 1000 L/h giving 800 L of dealcoholized wine (0.3 mL ethanol/100 mL wine) and two condensed fractions (section A and section B) as shows in Fig. 1. Each cycle lasted 1 h. Every 10 min a sample was taken from each of the two sections of the system: section A ("rst condensed fraction at 8 3C) and section B (the combination of two condensed fractions at 4 3C and !10 3C).
Analysis of volatile compounds Duplicated analyses were performed on each sample. A 40 mL volume of wine or condensed fraction (or a
Article No. fstl.1999.0565 All articles available online at http://www.idealibrary.com on
384
Table 1 Volatile compounds identi"ed in the initial wine, "nal product and di!erent condensed fractions (mg/L) Compound Ethanol (% v/v)
Initial wine
A1
A2
A3
A4
A5
A6
B1
B2
B3
B4
B5
B6
Final wine
10.6
25.15
25.00
24.98
20.17
21.18
20.76
60.00
52.30
57.00
67.40
63.10
58.00
0.3
0.89 nd 1.11 0.27 4.78 0.09 nd nd
0.37 nd 0.99 0.12 5.20 0.08 nd nd
0.42 0.04 1.18 0.20 5.76 0.08 nd nd
0.36 0.04 1.14 0.22 5.86 0.09 nd nd
0.50 0.29 0.42 0.91 2.77 0.17 nd nd
0.29 0.93 0.62 1.25 4.18 0.15 nd nd
0.66 1.55 0.64 1.39 3.60 0.13 nd nd
1.19 1.09 0.45 1.46 2.44 0.13 nd nd
0.88 0.66 0.60 1.29 3.35 0.18 nd nd
0.56 0.37 0.61 1.01 3.64 0.16 nd nd
nd* nd 2.30 0.86 6.03 0.06 0.44 0.07
104.00 nd 0.07 0.27 3.21 0.167 0.99 nd 0.11 nd
53.70 nd 0.06 0.19 2.36 0.14 0.74 nd 0.13 nd
87.00 nd 0.07 0.23 2.66 0.16 0.47 nd 0.13 nd
70.90 nd 0.07 0.22 2.61 0.14 0.35 nd 0.13 nd
116.00 nd 0.20 0.49 5.48 0.15 nd nd nd nd
105.00 nd 0.20 0.40 4.98 0.23 nd nd nd nd
153.00 nd 0.19 0.46 5.40 0.18 nd nd nd nd
213.00 nd 0.25 0.56 6.82 0.20 nd nd nd nd
221.00 nd 0.27 0.66 7.81 0.25 nd nd nd nd
173.00 nd 0.20 0.55 6.60 0.21 nd nd 0.13 nd
0.17 nd nd nd nd nd nd 0.35 0.13 0.34
385
1.02 0.92 4.02 5.40 7.13 0.04 0.41 0.46
1.47 0.03 1.47 0.48 4.88 0.09 nd nd
1.03 nd 1.17 0.29 4.54 0.08 nd nd
Aliphatic alcohols Isoamilic alcohol 1-Pentanol 4-Methyl-1-pentanol 3-Methyl-1-pentanol 1-Hexanol 3-Hexen-1-ol 2-Ethyl-1-hexanol 2,3-Butanediol 1-Octen-4-ol 3-(Methylthio)-1-propanol
86.90 0.10 0.05 0.15 1.58 0.08 nd 1.30 0.25 0.42
146.00 nd 0.09 0.30 3.55 0.19 0.03 nd 0.11 nd
114.00 nd 0.08 0.27 3.20 0.16 0.43 nd 0.11 nd
Aromatic alcohols a. Terpineol Linalool 3,7-Dimethyl-6-octen-l-ol Geraniol 2-Phenyl-1-ethanol 4-Ethyl-guaiacol 4-Ethylphenol 3-Oxo-a-ionol Benzylic alcohol
0.03 0.15 0.98 0.94 58.20 0.07 0.06 0.11 0.07
0.11 0.33 0.09 0.12 6.93 nd nd nd 0.17
0.11 0.34 0.10 0.09 5.69 0.11 0.10 nd 0.18
0.13 0.37 0.10 0.07 5.80 0.12 0.10 nd 0.18
0.14 0.31 0.11 0.08 4.51 0.13 0.11 nd 0.19
0.12 0.31 0.09 0.11 7.07 0.13 0.11 nd 0.18
0.12 0.33 0.11 0.11 7.22 0.12 0.13 nd 0.20
0.14 nd 0.14 nd 1.80 nd nd nd 0.17
0.17 0.28 0.15 nd 3.06 nd nd nd 0.17
0.13 0.29 nd nd 2.98 nd nd nd 0.15
0.13 0.31 nd nd 1.93 nd nd nd 0.16
nd 0.42 nd nd 2.56 nd nd nd 0.10
0.16 0.33 nd 0.13 2.88 nd nd nd 0.16
nd nd 0.66 0.90 57.60 0.05 0.05 nd nd
Ketones 2-Octanone 3-Hydroxy-2-butanone Dihydro-b-ionone
0.04 0.51 0.07
0.04 0.34 nd
0.05 0.31 nd
0.04 0.33 nd
nd 0.33 nd
0.05 0.39 nd
0.05 0.37 nd
0.22 nd nd
0.26 0.35 nd
0.25 0.14 nd
0.25 0.21 nd
0.25 0.32 nd
0.23 0.33 nd
0.04 0.14 nd
Acids 2-Methyl-propanoic Butanoic 3-Methyl-butanoic Hexanoic Octanoic Nonanoic Decanoic Dodecanoic Tetradecanoic
0.54 0.48 1.35 1.11 0.82 0.13 0.11 0.26 0.07
0.24 0.09 0.51 0.60 1.50 0.10 0.26 0.04 0.08
0.20 0.07 0.42 0.58 1.63 0.10 0.28 0.06 0.09
0.21 0.07 0.42 0.64 1.78 0.10 0.28 0.05 nd
0.15 0.06 0.31 0.60 1.79 0.11 0.26 0.05 nd
0.23 0.07 0.51 0.72 1.77 0.11 0.29 0.05 nd
0.23 0.08 0.47 0.76 1.97 0.13 0.29 0.05 0.10
nd nd nd 0.21 0.72 nd 0.16 nd nd
nd nd 0.25 0.35 0.11 nd 0.22 nd nd
nd nd 0.24 0.35 0.95 nd 0.20 nd nd
nd nd 0.19 0.25 0.69 nd 0.18 nd nd
nd nd 0.23 0.31 0.87 nd 0.18 nd 0.26
0.15 nd 0.23 0.32 1.03 nd 0.20 nd nd
0.56 0.53 1.30 0.84 0.19 0.12 nd 0.18 0.12
Miscellaneous Ethylbenzene Butirolactone
0.15 0.11
0.26 nd
0.17 nd
0.15 nd
0.06 nd
0.10 nd
0.09 nd
1.36 nd
nd nd
0.15 nd
0.28 nd
0.23 nd
0.13 nd
nd 0.06
*not detected Aliphatic alcohols overall coe$cient of variation: 9%; Aromatic alcohols overall coe$cient of variation: 6%; Carbonyl compounds overall coe$cient of variation: 12% Esters overall coe$cient of variation: 3%; Fatty acids overall coe$cient of variation: 9% A1, A2, A3, A4, A5 and A6 represent the samples taken 10, 20, 30, 40, 50 and 60 min after the dealcoholization process started in section A B1, B2, B3, B4, B5 and B6 represent the samples taken 10, 20, 30, 40, 50 and 60 min after the dealcoholization process started in section B
lwt/vol. 32 (1999) No. 6
Esters Butyl acetate Ethyl hexanoate Ethyl lactate Ethyl octanoate Diethyl succinate 2-Phenylethyl acetate 2-Propenyl benzeneacetate 2-Phenylethyl isoamylate
lwt/vol. 32 (1999) No. 6
butanoic acids) have very stable concentrations in section A. From C6 to C14 the concentrations increased with time, being higher in A6. In section B, 2-methylpropanoic acid could only be found in B6, and butanoic acid could not be detected. The other fatty acids increased in concentration with time but the concentrations were lower than in section A. The temperature in section A was shown to be high enough to condense the main part of these compounds.
Fig. 1 Scheme of the dealcoholization system used in this study
mixture of condensed fraction : water (1 : 5 v/v) when analysing section B) were extracted with 4 mL of ether : hexane (1 : 1). This step was repeated twice with 2 mL of ether : hexane (1 : 1). The organic fractions were mixed and concentrated before analysis in the gas chromatograph. The concentrated extract was injected into a Hewlett-Packard 5890 gas chromatograph (Hewlett-Packard, Avondale, PA). Chromatographic analysis and identi"cations were performed as previously described (4).
Results and Discussion Table 1 shows the identi"ed compounds in the initial wine and the "nal product, as well as in the di!erent condensed fraction. After the dealcoholization process the "nal product was lacking in almost all of the volatile compounds. The "nal product would be an organoleptically unacceptable dealcoholized wine. Only the addition of the volatile fraction lost during the process or the addition of new wine would produced a desirable product from the organoleptic point of view.
Aromatic and terpenic alcohol. Linalool, a-terpineol and benzyl alcohol totally disappeared in the dealcoholized wine. The concentration of aromatic and terpenic alcohols in section A samples was very constant with time. In section B, 4-ethyguaiacol and 4-ethylphenol were not detected at any point. 4-Ethylphenol and 4-ethylguaiacol are potential contributors to wine aroma because of their low odour thresholds and very distinctive #avours (5) and were only recovered in section A. 2-Phenylethanol and geraniol were found at lower concentrations than in section A, but these two compounds undergo almost no reduction in their concentration in the dealcoholized wine. Linalool was the only compound that increased its concentration in section B. Aliphatic alcohols. This functional group had the highest losses during the process. Due to their high volatility, aliphatic alcohols are found mainly in section B, with the exception of 2-ethyl hexanol and 2,3-butanediol. In conclusion, the product obtained after the dealcoholization of wine is lacking in many of the volatile compounds and some of those that could be detected were found in lower concentrations than in the original wine. This dealcoholized wine is an unacceptable produce from an organoleptic point of view, but the results showed that most of these volatile compounds were retained in the condensed fractions. The temperature of the condenser is a very important factor in volatile compound recovery. It must be at least !10 3C for the aliphatic alcohols and esters to be recovered to a signi"cant extent. More studies are needed to check the overall percentage of recovery for each compound and the best system to recover the compounds and reconstitute the wine aroma.
Evolution of the volatile compounds in the diwerent condensed fractions References Esters. Diethyl succinate, 2-phenylethyl acetate and 2propenyl benzencacetate almost maintained their initial concentration in the dealcoholized wine. For the other esters, the largest concentrations were found in A1, mainly for the more volatile esters, indicating that they escape very quickly. The evolution of esters in section B, where the temperature is lower than in section A, showed that the concentration of compounds increased with time, being higher in B3 and B4, mainly for butyl acetate and ethyl hexanoate. Comparing with section A, it can be seen that ethyl lactate presented larger concentrations in section A than in section B. Fatty acids. Those fatty acids with lower molecular weight (2-methylpropanoic, butanoic and 3-methyl-
1 SCHOBINGER, U., DURR, P. AND WALDVOGEL, R.
386