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UNIVERSITATEA DIN CRAIOVA

UNIVERSITY OF CRAIOVA

Ser ia : Biologie Hort icultur Tehnologia prelucr ri i produse lor agrico le

Ingineria med iuluiVol . XII I ( XLIX ) - 2008

THE COMPARATIVE STUDY OF SOME EVALUATIVE METHODS OF THEASTRINGENT FEATURE OF THE RED WINES

Delia Statescu 1, Maria Avramescu 1, Valentina Danisor 2

KEY WORDS: astringency, red wine, tannin

ABSTRACT

One of the most important sensory attributes of a red wine is the astringent feature, that inmost of the cases is estimated by tasting the product. The esteem has to be done by a group of expert tasters and it is not always objective. There is the possibility to make some esteems,by determining theIndex of the gelatin, (Glories, 1978) or by using an other new method, elaborated by a group of

scientists from Spain (Llaudy and the collaborators 2003). In this work we present by comparison, theresults obtained by using three methods of evaluation of the astringent characteristics of some red wines from the 2002 harvest, obtained by the treatment with enzymes at I.C.D.V.V., ValeaCalugareasca.

1. INTRODUCTION

The present oenolog has well defined technologies and modern practices, whichallow him to elaborate wines with organolepctical features wanted by him or by theconsumer. The astringency of the young red wines is not always a well-appreciated feature,specially by the wine consumer who doesnt know very well the changes that take placeduring wine maturing and getting older process.

To evaluate the astringency of the red wines obtained by the experiments withenzymes preparations from the autumn 2002 at I.C.D.V.V. Valea Calugureasca, we havemade a comparative study of the results obtained through sensory analysis and through twochemical methods.

In order to evaluate the level of their astringency after the methods described byGlories (the index of gelatin, 1978) and Llaudy and the collaborators (2003), there havebeen chosen and analyzed twelve red wines from the twenty-eight experimental varietiesobtained with different enzymes preparations at different work conditions. At the same timewith the lab analysis, a group of five expert authorized tasters have done the organolepticalevaluation of the wines. The total polyphenol concentration of the studied wines wasdetermined as the Index of the total polyphenol (Ipf) by measuring the absorbing waves of the diluted wines 1/100 at 280 nm.

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1 I.C.D.V.V. Valea Calugareasca2 SC. Doljchim SA Isalnita


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2. MATERIAL AND METHODS

The twelve red analyzed wines were that from Cabernet Sauvignon variety andwere obtained through the classical process of fermentation of the grapes in metal rotativevessels by the help of the enzyme preparations, with different contact time depending onthe temperature. The analyzed wine samples were the following:

1. Basic wine without SO 2 and without pectolitical enzymes2. Wine 60mg/l SO 2 without pectolitical enzymes3. Wine 60 mg/l SO 2 with pectolitical enzymes (Vinozym)4. Wine 60 mg/l SO 2 with pectolitical enzymes (Ultrazym)5. Wine 90 mg/l SO 2 with pectolitical enzymes (Vinozym)6. Wine 90 mg/l SO 2 with pectolitical enzymes (Ultrazym)7. Wine 90 mg/l SO 2 without pectolitical enzymes

8. Wine - 120 mg/l SO 2 with pectolitical enzymes (Vinozym)9. Wine 120 mg/l SO 2 with pectolitical enzymes (Ultrazym)10.Wine lower ph (Ca carbonate added) with pectolitical enzymes (Vinozym)11.Wine 60 mg/l with pectolitical enzymes (Vinozym) with short timefermentation12.Wine 60 mg/l with pectolitical enzymes (Vinozym) long term fermentationThe obtained wine have been analyzed and submitted to some conditioning and

stabilizing operations and surveyed during the maturation process for 1 year.

2.1. THE DETERMINATION OF THE INDEX OF GELATINAs it is known the tannins have the property to react with the proteins forming

stable combinations; Glories (1978) applied this property for determining the index of gelatin .

Work method: in 50 ml of wine there have been added 5 ml from a solution of solved gelatin of 70 g/l; this corresponds to a concentration of 7 g gelatin in a litre of wine. It has been kept for three days at 10 0 C for completing the tannin reaction with thegelatin and then used with the centrifuge for 10 min at 3500 rpm and it was determined thecontent of tannins. The tannins were determined in the diluted wine 1/50 through the aciddipolymeric reaction and by measuring the red color at wave length of 550 mm obtaineddue to the formation of the composed (Vivas and the collaborators, 2003). There have beendetermined the tannins from the basic wine (to 50 ml of wine there have been added 5 ml of distilled water and was diluted 1/50).

The aggressive tannins have been calculated by the difference from the totalconcentration in the tannins and the tannins remained after deposing the gelatin.

So the index of the deposed tannins with gelatin or the index of gelatin is givenby:

I = [(C 0 C)/ C 0 ]*100 where C 0 represents the concentration (g/l) of the tannins from thebasic wine and C represents the concentration (g/l) of the tannins after the reaction withgelatin.

The index of gelatin can be seen as a reflection of the astringent feature of thewine and when it is higher than 50, the wine can be considered rough, astringent.

2.2. THE METHOD WITH THE OVALBUMIN (Llaudy and the collaborators 2003)In the method elaborated by Llaudy and the collaborators there have been used

ovalbumin solutions (with concentration between 0,0 and 8,0 g/l) and tannic acid (with


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concentration between 0,0 and 1,0 g/l) which had been prepared in a synthetic winesolution (4 g/l of tartric acid. 95 g/l ethanol, adjusted at ph 3,5 with NaOH). The solutionsof tannic acid (0; 0,2; 0,4; 0,6; 0,8 and 1 g/l) have been used as standard. As protein fordeposing the astringent tannins, it has been used the ovalbumin solution of differentconcentrations 0; 0,4; 0,8; 1,6; 2,4; 3,2; 4,0; 4,8; 5,6; 6,4; 7,2 and 8,0. There have beentaken twelve test tubes where have been put the ovalbumin solution (0,0 and 8,0 g/l). Ineach test tube has been added the tannic acid solution or the analyzed wine. After shakingand letting it for 10 min, it has been used the centrifuge and the solution was diluted 1/50with distilled water. Then it was measured the absorbing wave length at 280 nm in a quartzbath with the optical stratum width of 1 cm.

2.3. THE SENSORY ANALYSISAs a result of the sensory analysis made by the five experts in testing the wines

from I.C.D.V.V. Valea Calugareasca, the astringency of each wine was marked with valuesfrom 1 to 100 points. All the data were statistically expressed by an average of threerepeated tests.

3. THE RESULTS AND DISCUSSIONS

The obtained results by the two chemical methods were compared to thoseresulted after the organoleptical determination.

3.1 THE METHOD OF DETERMINING THE INDEX OF GELATIN GLORIESFrom fig.1 it can be seen that the sample with the most astringent feature of the

wine, regarding the value of the index of gelatin and the organoleptic determination, wassample No.12 and the sample with the less important astringency of the wine was sample

No.1. There have been noticed significant differences in evaluating the astringency of thewines using the two methods with the samples No. 7, 10 and 11. So the sample No.7 seemsless astringent than it is indicated by the index of gelatin and sample No. 11seems to bethe most astringent sample.

Fig. 1. The estimation of the astringency using the method of the index of gelatin(Glories, 1978) and the mark after tasting

3.2. THE METHOD WITH OVALBUMINFollowing the results presented in fig. 2, it has been noticed as above, that the

sample No. 12 took the first place, as being the most astringent sample, and the sample No

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1 took the last position, as being the less astringent sample. This time the differencesbetween the organoleptical determination and the determination of the tannins afterovalbumin deposing were less significant than presented above. A close difference has beennoticed with the sample No. 11 between the organoleptical determination and the tannindetermination after gelatin or ovalbumin deposing.

Fig. 2. The determination of the astringent feature using the method with ovalbumin and themark after tasting

3.3. THE SENSORY ANALYSIS

The marks obtained after the organoleptical determination of the twelve samplesvaried from 25,2 (the wine No. 1 the less astringent wine) and 75,1 (the wine No.12 themost astringent wine) (table 1)

The marks obtained at tasting the wines for samples No. 1 and 12 depended on thetotal polyphenol content expressed through Ipf as well as the content in tannins remainedafter deposing the gelatin and ovalbumin.

Table 1The results in evaluating the astringency of the analyzed wines

SampleNo.

Ipf Igelat The ovalbumin method(g/l acid tanic)

Tasting mark

1 21,87 29,4 0,129 25,22 36,89 42,5 0,144 44,53 31,26 34,8 0,156 38,34 35,46 45,7 0,192 39,75 37,56 53,5 0,294 42,16 41,02 57,9 0,289 51,47 29,08 39,2 0,172 35,38 37,04 49,6 0,329 58,69 38,29 51,2 0,318 56,8

10 63,26 61,5 0,381 68,211 69,07 64,3 0,338 66,512 66,64 65,4 0,571 75,1

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To firmly pronounce upon the precision and results of this new method, of deposing the astringent tannins with ovalbumin, there have to be always mademore determinations comparing to the Index of gelatin and sensory analysisin more labs for studying the chemistry of the wine in our country.

BIBLIOGRAPHY

1. Glories, Yves, THESE Docteur dEtat es Sciences, Recherche sur la matierecolorante des vins rouge, p.72-73, 1978

2. Llaudy, M.C., Canals, R, Canals, J.M, Rozes, N.Zamora, F.2003, A new method forevaluating the astringency in red wine In vino analytica scientie, p.123, 2003

3. N.Vivas, N.Vivas de Gaulejac, M.F. Nonier Sur lestimation et la quantification descomposes phenoliques des vins.Bull.de LOIV, 865-866, p.294, 2003

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