Bulletin USAMV, nr. 66 (1-2)/2009
Print ISSN 1843-5254; Electronic ISSN 1843-5394
Compositional Corrections Applied in Obtaining Semi Dry and Semi Sweet
White Wines in Iasi Vineyard
Petronela Cristina MOGARZAN, Valeriu V. COTEA, Cintia COLIBABA,
Igor CONDORACHI
University of Agricultural Sciences and Veterinary Medicine Ion Ionescu de la Brad,
3 Aleea M. Sadoveanu St., 700490, Iasi, Romania; [email protected]
Abstract. Compositional corrections - sugar and acid adjustments, as well as biological
degradation of malic acid, wines blending- are used to enhance or diminish the content of certain
substances. Fetească albă, Fetească regală, Muscat Ottonel and Tămâioasă românească grape varieties,
harvested in 2008 from Iaşi vineyard, center of Copou–Adamachi farm were used. The grapes were
processed through the classic technology of obtaining white dry wines. The wines were corrected with
rectified concentrated must (RCM) and concentrated must (CM) in order to obtain semi-dry and semisweet wines. Tartaric acid was also added. The analyses were done according to international standards
and specific literature. The main physical-chemical characteristics of the obtained wines show an increase
in reductive sugars, non-reductive extract and density.
INTRODUCTION
The grapes characteristics differ from year to year and from vineyard to vineyard.
However by rightful choosing of the harvest time and wine making technologies, a wine that is
constant in quality and authentic, can be obtained.
When the compositional characterises of grapes differ too much to the normal ones, the
winemaker must apply certain corrections (treatments). Their role is to help in offering the
consumer a quality wine that is constant from year to year. The most frequent corrections are the
ones regarding sugar and acidity, while colour and tannins are rarely corrected. These actions are
regulated by the Vine and Wine Law 244/2002, completed by HG 645/2005.
MATERIAL AND METHOD
For this study, the grape varieties Fetească albă, Fetească regală, Muscat Ottonel and
Tămâioasă românească were used from Adamachi farm, Copou- Iasi vineyard.
Harvesting was done manually; the grapes were processed at the oenological laboratory of the
University of Agricultural Sciences and Veterinary Medicine Iasi, using the common technology
for obtaining white wines.
After the end of alcoholic fermentation, the obtained wines had very small quantities of
reductive sugar as follows: Fetească albă – 1,77 g/L, Fetească regală – 1,21 g/L, Muscat Ottonel
– 2,39 g/L, Tămâioasă românească – 2,25 g/L.
The following corrections were applied to the basic obtained dry white wines:
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- acidity adjustment with tartaric acid ( at the initial time the total acidity values were as follows:
6,40 g/L C4H6O6 - Fetească albă, 5,26 g/L C4H6O6 - Fetească regală, 5,52 g/L C4H6O6 - Muscat
Ottonel, 6,43 g/L C4H6O6 - Tămâioasă românească).
- sweetening for obtaining semi dry and semisweet wines, addition of rectified concentrated must
(RCM) and concentrated grape must. The main characterises of these musts can be seen in Tab. 1.
Specific quantities of RCM and CM were added to the four basis wines in order to obtain
wines with 10 g/L - 30 g/L (table 2).
Tab. 1
Physical- chemical properties of the used musts
Free
SO2
(mg/L)
46,3
Must type
RCM
CM
reductive sugar
dry wine
1,77g/L
Total
SO2
(mg/L)
210,4
Reductive
sugars
(g/L)
832,2
756,4
Total acidity
(g/L C4H6O6)
19,43
746,4 part of
dry wine
10
g/L
reductive sugar
must 756,4 g/L
8,23 part of
must
Fig. 1. Example of Cramer formula
10  0,75 L
= 9,8 mL RCM / 0,75 L wine
756,4  8,23
The formula used for determining the quantity of concentrated must that must be added to
obtain demy dry white wine with 10 g/L reductive sugars and demy sweet white wines with
30g/L reductive sugars was calculated by Cramer rule. As it can be seen from the above diagram,
for obtaining 0.75 L semi dry F.A with 10 g/L reductive sugars, 9.8 ml CM were added. In table
number 1, the Quantities of RCM and CM used to obtain semi dry (10 g/L) and semi sweet (30
g/L) wines, can be seen.
RCM I is the quantity of rectified concentrated must used for obtaining semidry wines (in
our case: 9 mL/0,75 L) and RCM II represents the quantity if the same rectified concentrated
must used for obtaining semisweet wines (in our case: 27 mL/0,75 L).
CMI is the quantity of concentrated must used for obtaining semidry wines (in our case:
9.8 mL/0,75 L) and CM II represents the quantity if the same concentrated must used for
obtaining semisweet wines (in our case: 29.8 mL/0,75 L).
The formula used: x =
322
Tab.. 2
Quantities of RCM and CM used to obtain semi dry (10 g/L) and semi sweet (30 g/L) wines
Grape varieties
Must type
F.A.
F.R.
M.O.
T.R.
RCM I (mL/0,75 L wine
9
9,2
8,9
9
RCM II (mL/0,75 L wine)
27
27,1
27,1
27
CM I (mL/0,75 L wine)
9,8
9,9
9,9
10
CM II (mL/0,75 L wine)
29,8
29,7
29,8
30
Analyses concerning compositional characteristics of the newly obtained wines were done
during April-May 2009, in the oenological laboratory of the University of Agricultural Sciences
and Veterinary Medicine Iasi
The physical chemical analyses were done according to international standards and
specific literature.
In table number 2,the following characteristics of FA, FR, TR, MO are registered: free
and total sulphur dioxide, volatile and total acidity, density, alcoholic concentration, reductive
sugars, total dry extract an non-reductive extract.
RESULTS AND DISCUSSIONS
Table number 2 presents the main compositional characterises of the analysed wines. The
free sulphur dioxide has the highest values in FA(62,28), while the lowest is in TR(13,61). The
values of volatile acidity are higher in FR (0,66 g/L C2H4O4) and lowest in TR (0,33 g/L
C2H4O4). Total acidity has values very similar in order with the volatile acidity.
The differences in density are relatively small, minimum of 0,9922 (Muscat Ottonel) and
maximum of 0,9952 ( Fetească regală).
The alcoholic concentration varies between 11,68 % vol. in Tămâioasă românească wine
and 12,93 % vol. in Muscat Ottonel wine.
The quantity of reductive sugars (table 3) prove the fact that the wines are dry, 1,21 g/LFetească regală and 2,39 g/L g/L-Muscat Ottonel.
Total dry extract and non-reductive extract has high values in Fetească regală wine and
lower values in Tămâioasă românească wine.
Table 5 registers the values of free and total sulphur dioxide after sweetening. A slow
decrease of these values is noticeable because of air contact. The volatile acidity slowly
increases, with small differences (0,11 g/L in sweetened Fetească albă).
A drop in total acidity values (g/L tartaric acid) is noticed in treated wines according to
the must with which the wines were treated. In general, one can notice that the smallest variation
in total acidity values are found in the wines treated with concentrated must, it having a total
acidity of 19,43 g/L tartaric acid.
The density is an important parameter which gives us a first indication on wine
authenticity and quality. The wines with density values of 0,9968-0,9975 are classified as semidry white wines, while the once with values of 1,0031-1,0039 are semi-sweet.
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Following the compositional corrections, the quantity of reductive sugar was much more
modified: from dry wines to semi-dry wines (8,02 g/L-11,34 g/L) and semisweet (27,68 g/L 31,47 g/L).
The non-reductive extract of the treated wines has higher values than the basis wines.
Tartaric acid is most used in acidity adjustment determining in table 4 a growth in total
acidity of 1,05 g/L in Fetească albă wine, of 1,1 g/L in Fetească regală wine, of 1,07 g/L in
Muscat Ottonel and of 1,04 g/L in Tămâioasă românească wine, when adding 1 g/L tartaric acid.
Tab. 3
Main compositional characteristics of basis wines obtain from Fetească albă (F.A.), Fetească regală (F.R.), Muscat
Ottonel (M.O.) and Tămâioasă românească (T.R) grape varieties
Free
Grape
SO2
variety (mg/L)
Total Volatile
SO2 acidity (g/L
mg/L) C2H4O4)
1
F.A.
62,28
179,8
2
F.R.
26,05
75,8
3
M.O.
53,84
4
T.R.
13,61
No.
Total
acidity
(g/L
C4H6O6)
Density
0,40
6,40
0,9931
12,36
1,77
24,20
22,43
0,53
5,26
0,9952
11,79
1,21
27,90
26,69
134,0
0,66
5,52
0,9922
12,93
2,39
23,50
21,11
75,5
0,33
6,42
0,9927
11,68
2,25
21,10
18,85
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Alcoholic
conc. (%
vol.)
Total
Reductive
dry
sugars
extract
(g/L)
(g/L)
Nonreductive
extract
(g/L)
Tab. 4
Main compositional characteristics of wines obtain from Fetească albă (F.A.), Fetească regală (F.R.), Muscat Ottonel (M.O.) and Tămâioasă românească (T.R)
grape varieties after sweetening
Grape
variet
y
F.A.
F.R.
M.O.
T.R.
Sugar
corrections
RCM I
RCM II
CM I
CM II
RCM I
RCM II
CM I
CM II
RCM I
RCM II
CM I
CM II
RCM I
RCM II
CM I
CM II
Free SO2
(mg/L)
45,22
38,96
48,22
49,07
26,18
29,06
31,61
37,36
40,22
39,96
44,82
48,61
13,96
16,06
18,61
24,01
Total
SO2
(mg/L)
153,67
155,89
163,83
175,96
89,10
91,65
94,21
102,83
109,01
110,21
114,52
123,32
89,07
92,06
95,61
102,52
Volatile
acidity
(g/L
C2H4O4)
0,54
0,51
0,51
0,51
0,56
0,55
0,54
0,54
0,67
0,68
0,66
0,66
0,35
0,33
0,35
0,36
Total
acidity
(g/L
C4H6O6)
6,32
6,30
6,38
6,34
5,19
5,22
5,24
5,18
5,40
5,42
5,48
5,49
6,32
6,37
6,39
6,43
Density
Alcoholic
conc.
(% vol.)
Reductive
sugars
(g/L)
Total dry
extract
(g/L)
0,9968
1,0039
0,9968
1,0038
0,997
1,0029
0,997
1,0029
0,9975
1,0039
0,9971
1,0039
0,9969
1,0031
0,9969
1,0031
12,04
11,94
12,28
12,32
11,79
11,65
11,55
11,58
12,55
12,83
12,74
12,9
11,66
11,43
11,52
11,33
9,07
29,35
8,96
28,82
9,25
28,43
9,35
29,82
8,02
31,47
9,96
28,09
11,34
29,87
8,67
27,68
31,8
49,6
32,3
50,4
32,6
47,5
32
47,3
31,5
53,5
35,7
53,8
32
47,3
31,5
47,5
Nonreductive
extract
(g/L)
22,73
20,25
23,34
21,58
23,35
19,07
22,65
17,48
23,48
22,03
25,74
24,9
20,66
17,43
22,83
19,82
Conductiv
ity
(µs/cm)
1888
1794
1961
1809
1696
1606
1648
1600
1521
1434
1631
1592
1972
1848
2030
1945
Tab. 5
Acidity adjustment with tartaric acid
Grape variety
Fetească.albă
Fetească regală
Muscat Ottonel
Tămâioasă românească
Adding of tartaric
acid
(g/L)
Volatile acidity
(g/L C2H4O4)
Total acidity
(g/L C4H6O6)
Acidity increase after adding of tartaric acid
(%)
1
1
1
1
0,39
0,56
0,62
0,41
7,45
6,36
6,59
7,47
14,09
17,30
16,24
13,92
325
CONCLUSIONS
The technology of compositional corrections was correctly applied, fact
demonstrated by the results by the above mentioned results.
Physical-chemical characteristics varied according to the type and quantity of must
The reductive sugar quantity grew according to quantity of concentrated must
added.
The values of density are correlated with the quantity of added must and with the
total dry extract. Non-reductive extract varies according to type and quantity of added
must, generally being higher in sweetened wines.
The conductivity of sweetened wines is interdependent with the non-reductive
extract, fact proven by the above analyses.
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