Article pp.411-424 du Vol.23 n°3 (2003)

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SCIENCES DES ALIMENTS, 23(2003) 411-424

ARTICLE ORIGINAL ORIGINAL PAPER

Effect of fining treatments on the aromatic potential of white wines from Muscat Ottonel

and Gewurztraminer cultivars

T. Cabaroglu¹, A. Razungles*², R. Baumes², Z. Günata³**

RÉSUMÉ

Influence des adjuvants de collage sur le potentiel aromatique de vins blancs de Muscat Ottonel et de Gewurztraminer.

Des vins de Muscat Ottonel et de Gewurztraminer sont soumis à des traitements de collage par addition de différents adjuvants: bentonite, ichthyocolle, caséine et polyvinylpolypirrolidone (PVPP). Après collage, les composés d’arômes libres et glycosylés sont extraits des vins par passage sur colonne de résine d’amberlite XAD2, et analysés par chromatographie en phase gazeuse couplée à un spectromètre de masse (GC-MS). Les traitements de collage entraînent une diminution des teneurs de différents composés. Les composés glycosylés, constituant un potentiel important de l’arôme des vins, sont les plus affectés par les traitements, les pourcentages de leurs pertes varient entre 14 et 33 % de la valeur des vins témoins non traités. Pour certains composés, les pertes sont différentes selon le vin traité et le produit de collage utilisé. Par analyse sensorielle, seul le vin de Gewurztraminer traité à l’ichthyocolle présente une différence significative par rapport au vin témoin.

Mots clés

adjuvant, collage, vin, arôme, glycosides.

1. University of Cukurova, Faculty of Agriculture, Department of food engineering 01330, Adana / Turkey.

2. INRA-ENSAM, UMR Sciences pour l’œnologie, Unité de recherches biopolymères et arômes, 2 place Pierre-Viala, 34060 Montpellier Cedex 1 / France.

* Alain Razungles, Professeur d'œnologie,École Nationale Supérieure Agronomique de Montpellier, 2, place Pierre-Viala - 34060 Montpellier Cedex 1 - France. Tél. 33 (0)4 99 61 24 86, Fax 33 (0)4 99 61 28 57, e-mail : razungle@ensam.inra.fr.

3. Université de Montpellier II, Laboratoire de génie biologique et sciences des aliments, place Eugène- Bataillon, 34095 Montpellier Cedex 5 / France.

** Corresponding author, Phone : (33)499612558. Fax : (33)499612857. e-mail : gunata@arpb.univ- montp2.fr

6-EFFECT (411-424) Page 411 Jeudi, 30. octobre 2003 7:08 19

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412 Sci. Aliments 23(3), 2003 T. Cabaroglu et al.

SUMMARY

Muscat Ottonel and Gewurztraminer wines were subjected to fining treatments with fining agents bentonite, isinglass, casein and polyvinylpolypirrolidone (PVPP). After treatments, free and glycosidically bound volatile were isolated by extraction on Amberlite XAD-2 resin and analyzed by gas chromatography – mass spectrometry (GC-MS). Fining caused a decrease in the amount of several compounds. The bound volatiles, potentially important contributors to wine flavor, were more affected by the fining treatment, with a total loss ranging from 14 to 33% compared to the control wines. For some compounds the loss was dependent on the wine and the fining agent.

The only wine found significantly different from the control wine by sensory analysis was the isinglass treated Gewurztraminer wine.

Key words

fining, wine, aroma, volatiles, glycosides.

1 – INTRODUCTION

In winemaking, fining is commonly used for clarification, protein and color stabilization. Different food-grade agents of protein, mineral and synthetic poly- mers are used as fining agent to remove wine macromolecules through precipi- tation and/or adsorption (BLADE and BOULTON, 1988; RAZUNGLES et al., 1992 ; PUIG-DEUet al., 1996).

Despite clarification and stabilisation advantages, fining results in loss of wine volatiles (MILLER et al., 1985; CARNACINI et al., 1985; VOILLEYet al., 1990;

LUBBERSet al., 1996). Significant loss of alcohols and esters has been reported with bentonite treatment of wine (SIMPSON and MILLER, 1984). Additionally, the type of fining agents influenced the extent of loss in aroma components (MILLER

et al., 1985; SIMPSON, 1986). However, these studies were focused on a few aroma components and no data was available on glycosidically bound volatiles.

The latter are considered as important contributors to wine flavor since a key part of some flavor compounds are present as odorless glycoconjugates in grapes and wines (WILSONet al., 1984 ; VOIRINet al., 1992 ; GUNATAetal., 1993).

The objective of this research was to determine the effect of some commonly used fining agents on wine aroma compounds, i.e. free and bound volatiles.

Wines from Muscat Ottonel and Gewurztraminer from Alsace (France) were often subjected to fining treatment, particularly to avoid a protein haze. These varieties were known for their strong aromatic properties, and chosen in this work because of their richness in free and bound volatiles (GUNATAet al.,1985 ; VOIRINet al., 1992).

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Effect of fining treatments on wine aroma 413

2 – MATERIALS AND METHODS

2.1 Wine samples

Two aromatic white grape cultivars from Alsace region (France), Muscat Ottonel and Gewurztraminer were vinified by traditionnal white winemaking in the INRA-Colmar experimental winery station. The wines were cold-settled and not filtered for the subsequent fining treatment which was performed 3 months after fermentation.

2.2 Fining agents

Four types of fining agents were used to clarify wines; two from protein origin (casein, isinglass), one from mineral origin (bentonite) and a synthetic polymer, polyvinylpolypyrrolidone (PVPP). They were added into the wines at usual rates: 800 mg/L for bentonite, 500 mg/L for casein, 20 mg/L for isinglass and 400 mg/L for PVPP. PVPP was added directly to the wine, and the casein, isinglass and bentonite were hydrated in water prior to addition. 270 ml of wine was used for each fining treatment. The wines were shaken during 30 sec. after the addition of the fining agents for homogenization, and stored at 15 °C for one week. They were racked and clarified wine was used for analysis. Fining treatment were triplicated, and the triplicates were combined for analysis.

Turbidity test was performed on the control and treated samples using a Hach turbidimeter (Hach, Germany) calibrated with formazine standard solutions of 1.8, 18 and 180 NTU.

2.3 Free and glycosidically bound volatiles analysis

Wine sample (75 ml) was diluted five times with water and 30 µmg of 4-nonanol was added as an internal standard. Each sample was analysed in triplicate.

The concentration of aroma compounds were expressed as 4-nonanol equiva- lent. The sample was percolated on Amberlite XAD-2 resin (120 mm ^✕ 7 mm i.d.; 20-50 mesh, Fluka) to isolate free and glycosidically bound volatiles (GUNATAet al., 1985). The free compounds were eluted with 50 ml of pentane- dichloromethane (1:1, v:v) and the bound compounds with 50 mL of ethyl acetate/methanol (9:1, v:v) (VERSINI et al., 1994). Pentane-dichloromethane eluate was dried over anhydrous sodium sulfate and concentrated to about 500 µL using a Dufton column prior to GC-MS analysis. The ethyl acetate/methanol eluate was concentrated to dryness in vacuo, then taken in 0.2 mL of 0.2 M cit- rate-phosphate buffer (pH 5.0). Pektolase 3PA (1.2 mg) (Grinsted, France) containing the relevant glycosidase activities: β-glucosidase (2.8 nkat), α-arabi- nosidase (4.5 nkat), α-rhamnosidase (0.05 nkat) and β-apiosidase (0.36 nkat) (GUNATA et al., 1993) were added and the mixture was incubated at 40 °C for 12h. Released aglycones were extracted with pentane-dichloromethane (1:1, v:v) (5x 500 µL). The organic layer was added with 30 mmg of 4-nonanol and concentrated to about 500 µL using a Dufton column, then analyzed by GC-MS.

GC analyses of free volatiles and released aglycones were performed using a Varian 3400 Chromatograph equipped with a fused capillary column coated

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with DB-Wax (30m ^✕ 0.32 mm i.d., 0.5 mmm film thickness, JW, Folsom, CA, USA). One microliter was injected on column. The injector temperature was programmed from 20°C to 250°C at 180°C.min^-1. The oven temperature was held at 60°C for 3 min., then programmed from 60 to 220°C at 2°C.min^-1, from 220 to 245°C at 3°C.min^-1, then held at 245°C for 20 min. The FID temperature was 250°C. The carrier gas was hydrogen with flow rate of 1.6 mL.min^-1. Electron impact mass spectra were recorded for the free volatiles and the aglycones enzymatically released from the glycosides by coupling the same GC column than above to a Finnigan Mat ITD 700 mass spectrometer as described previously by VOIRINet al. (1992). Identification was obtained comparing the linear retention index based on a series of n-hydrocarbons (VAN DEN DOOL and KRATZ, 1963), and EI mass spectra with published data or with authentic compounds (VOIRIN et al., 1992; WIRTHet al., 2001 ). The statistical significance of the effect of fining on free and bound aroma compound values analysed in triplicate, was determined by one-way of analysis of variance (ANOVA) using Statlab software.

The statistical test (ANOVA) was performed for each compound between control wine and each treated wine.

2.4 Sensory analysis

The wines were subjected to a triangle test to assess the differences between the control and the treated wines (ROESSLERet al., 1978). A panel of thirteen persons, experienced with the triangle test, from the Institut des Pro- duits de la Vigne, Montpellier (France), experienced in evaluating a wide variety of wines, served as judges. Wines were presented, in coded, covered, tulip- shapped black glasses to mask color differences, at 18°C. The olfactive evalua- tion was performed only by direct olfaction because of the better homogeneity of the results than that obtained by-mouth olfaction (KOTSERIDIS et al., 2000).

The significance of the test (p < 0.05) was determined from statistical tables (LARMOND, 1969).

3 – RESULTS AND DISCUSSION

As expected a serious decrease in the turbidity of the treated wines has been observed compared to the control wines after one week of fining, from 25 and 27 Nephelometric Turbidity Units (NTU) for Muscat Ottonel and Gewurz- traminer, respectively, to values between 0.9 to 2.3 NTU.

3.1 Effect of the fining on the aromatic potential of wines.

Several free and bound volatiles were identified in wines. Only those potenti- aly odorous (ETIEVANT, 1991) were reported in the tables.

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3.2 Effect of the fining on the free volatiles

The level of volatiles was higher in the Muscat wine than in the Gewurz- traminer wine. Terpenes were the most abundant varietal aroma components in accordance with the volatile composition of both cultivars (GUNATAet al., 1985 ; VOIRINet al., 1992).

As the consequence of fining treatment, the level of volatiles decreased depending on the wine and the fining agent (figure 1). Fining reduced the concentration of several groups of volatiles, notably terpenic compounds, in both wines (table 1 and 2).

Figure 1

Effect of fining agents on total volatile compounds in Muscat Ottonel and Gewurztraminer wines

The decreases of terpenic compounds of Muscat Ottonel was highly significant for some coupounds. The highest decrease in terpenes was observed for geraniol (22 to 37%). In contrast the loss in linalool was at lesser extent (5 to 14%). That could be attributed to their alcohol functions, primary in geraniol, but tertiary in linalool. The differences among the fining agents studied for the elimination of terpenols were low.

In the case of esters, the effect of the fining treatments was significantly different for only a few compounds, especially in Gewurztraminer wine. The ester levels decreased, particularly with the bentonite. The losses in homologous fatty acid ethyl esters, ethyl hexanoate, ethyl octaonate and ethyl decanoate which were reported as aroma compounds of young wines (ETIEVANT, 1991) increased with increasing hydrophobicity. The same elimination of fatty acid ethyl esters was previously reported in bentonite treated Riesling wines (SIMPSON, 1986).

These results were consistent with the positive correlation observed in a model wine solution between the retention of volatiles by proteins and their hydrophobicity (LUBBERS et al., 1993, 1996).

Muscat Ottonel Gewurztraminer 250

200

150

100

50

0

Volatile compounds (mg/L)

control bentonite casein isinglass pvpp

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Table 1

Effect of fining agents on the levels of volatile compounds in Muscat Ottonel wine Compounds

(µg/l) Control Bentonite (800mg/L) Sig¹

Casein

(500mg/L) Sig. Isinglass

(20mg/L) Sig. PVPP (400mg/L) Sig.

Terpenes

Linalool 774 733 ns 732 ns 733 * 728 *

α-Terpineol 152 144 * 143 ns 145 * 147 *

Geraniol 111 71 ** 74 ** 79 ** 86 **

Hotrienol 109 95 ns 83 ** 82 ** 77 ***

Esters

Ethyl hexanoate 1032 829 ns 917 ns 1010 ns 977 ns

Ethyl octanoate 714 503 ** 648 * 593 *** 682 *

Ethyl decanoate 242 117 ns 125 ** 144 ** 239 ns

Isoamyl acetate 1307 1139 ns 1222 ns 1299 ns 1243 ns

Higher alcohols

2-Phenyl ethanol 66753 61877 * 61377 * 63807 ns 61017 *

Benzyl alcohol 38 33 ns 27 * 29 * 24 *

Six-carbon alcohols

1-Hexanol 684 632 * 641 * 642 * 635 *

(E)-3-Hexen-1-ol 9 7 ns 7 * 6 * 7 *

Phenols

Methyl vanillate 66 50 ns 42 * 28 * 46 ns

Vanillin 34 11 * 22 ns 20 ns 17 *

Tyrosol 993 871 ns 756 ns 681 ns 469 *

1. Significance at which means differ as shown by analysis of variance; *, **, *** denote significances at p<0.05, p<0.01, and p<0.001, respectively; ns: not significant.

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Table 2

Effect of fining agents on the levels of volatile compounds in Gewürztraminer wine

The decreases of the levels of more polar organic acid esters (ethyl lactate, mono and diethyl succinates) and ethyl 3-hydroxy and 4-hydroxybutanoate depended on the wines and the fining agents. Thus, the decreases of ethyl 3- hydroxybutanoate level were 22 and 32% respectively with bentonite and casein in Muscat wine, but only 7 and 3% with the same fining agents in Gewürztraminer wine. The highest decrease (62%) in esters occurred for monoethylsuccinate in the Muscat Ottonel wine treated with PVPP, while this treatment removed only 2% diethylsuccinate in the same wine.

The level of the most abundant fusel alcohol, 2-phenylethanol was slightly reduced in the treated wines. Similar results were observed by bentonite fining of a Riesling wine (SIMPSON, 1986).

Compounds

Casein

Terpenes

Linalool 21 19 ns 18 * 19 ns 18 ns

α-Terpineol 6 4 ns 5 ns 5 ns 5 ns

Geraniol 35 22 * 23 ** 26 * 26 ns

Esters

Ethyl hexanoate 687 631 * 633 ns 646 ns 629 *

Ethyl octanoate 438 379 ns 431 ns 334 ns 435 ns

Ethyl decanoate 100 74 ns 74 ns 89 ns 97 ns

Isoamyl acetate 1090 933 ns 903 * 909 ns 895 **

Higher alcohols

2-Phenyl ethanol 39013 35198 ns 35400 ns 37407 ns 36262 ns

Benzyl alcohol 42 40 ns 39 ns 36 * 37 ns

1-Butanol 71 56 ns 58 * 43 ns 55 ns

1-Hexanol 1087 959 ** 942 ** 993 ns 1021 ns

E-3-Hexen-1-ol 30 26 ns 26 ns 27 ns 27 ns

Phenols

Methyl vanillate 44 36 ns 33 ns 28 ns 29 ns

Vanilline 6 4 ns 5 ns 5 ns 3 ns

Tyrosol 172 157 ns 119 ns 113 ns 57 ns

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Fining agents lowered the total levels of volatile phenols. PVPP was the most effective, causing about 50% loss. That could be attributed to the affinity of this polymer with phenolic groups as previously observed for total and polymeric phenols (SIMS et al., 1995). A potent flavor compound, vanillin was strongly eliminated by PVPP as well as by bentonite. The concentration of this compound in both control wines was below its threshold detection (CHATONNET et al., 1992).

The losses observed for the six carbon compounds were low as reported previously in bentonite treated Riesling wine (SIMPSON, 1986). 1-hexanol, was more efficiently eliminated by casein in model wine solution (VOILLEY et al., 1990).

3.3 Effect of the fining on the glycosidically bound volatiles

The levels of bound compounds were higher in Muscat wine than in Gewurz- traminer wine. The bound fraction is dominated by monoterpenols in Gewurz- traminer (approximately 50%) as well as in Muscat wine (more than 50%), followed by other alcohols and phenols (tables 3 and 4). Geraniol was the most abundant monoterpenol in the Gewurztraminer wines as reported previously (GUNATA et al., 1985; VOIRIN et al., 1992).

Table 3

Effect of fining agents on the levels of glycosidically bound compounds in Muscat Ottonel wine

Compounds

(µg/l) Control Bentonite (800mg/L) Sig

1 Casein

Terpenes

Linalool 37.7 34.6 * 30.4 ns 32.0 ns 21.3 ***

α-Terpineol 11.7 10.8 ns 9.0 ns 10.1 ns 6.5 **

Citronellol 3.5 3.1 ns 2.8 ns 2.4 * 2.1 **

Nerol 48.2 43.0 ns 39.9 ns 28.6 * 35.1 *

Geraniol 86.7 78.5 ns 69.4 ns 60.5 ns 54.1 **

Hotrienol 19.6 12.9 ns 9.4 * 15.3 ns 8.5 *

Higher alcohols

2-Phenyl ethanol 135.4 109.7 ns 82.7 ns 80.1 ns 77.8 *

Benzyl alcohol 81.3 76.6 ns 68.4 * 41.6 * 68.8 ns

1-Hexanol 12.6 11.8 ** 10.7 * 8.2 * 8.6 ***

(Z)-3-hexen-1-ol 6.1 5.8 ns 5.1 * 4.4 * 4.3 **

Phenols

Eugenol 1.8 1.5 ns 1.5 * 1.7 ns 1.4 ns

Methyl vanillate 5.6 4.2 ns 5.4 ns 4.6 ns 5.0 ns

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Table 4

Effect of fining agents on the levels of glycosidically bound compounds in Gewürztraminer wine

Zingerone 6.3 5.1 ns 4.9 ns 5.7 ns 4.7 ns

Tyrosol 172.7 130.3 ns 124.7 ns 132.2 ns 99.8 ns

C-13 norisoprenoids 3-Hydroxy-β- damascone

29.3 26.9 * 27.0 ns 19.3 * 20.8 **

3-Oxo-α-ionol 9.8 9.3 ns 9.4 ns 7.4 ns 6.1 ***

Compounds

Casein

Terpenes

Linalool 4.3 1.7 ns 3.2 ns 3.2 ns 3.4 ns

α-Terpineol 2.1 1.8 ns 1.6 ns 1.9 ns 2.0 ns

Citronellol 8.0 5.6 ns 5.4 ns 6.8 ns 7.3 ns

Nerol 42.8 28.4 ns 29.3 * 34.6 ns 39.8 ns

Geraniol 227.5 161.3 ns 169.7 *** 189.4 *** 209.8 ns

Higher alcohols

2-Phenyl ethanol 68.4 62.2 ns 49.8 * 53.0 * 62.0 ns

Benzyl alcohol 146.3 102.3 ns 113.0 ns 83 * 128.1 ns

1-Hexanol 18.0 14.6 ns 13.8 ns 14.5 ns 15.5 ns

(Z)- 3-hexen-1-ol 2.3 1.8 ns 1.5 * 1.6 ** 1.8 **

Phenols

Eugenol 2.3 1.8 ns 1.7 ns 2.2 ns 1.8 ns

Methl vanillate 1.8 1.5 ns 1.0 ns 0.6 ns 0.3 ns

Zingerone 5.9 4.6 ns 4.3 ns 4.2 ns 4.0 ns

Tyrosol 144.9 140.7 ns 118.9 ns 118.9 ns 102.9 *

C-13 Norisoprenoids

3-Hydroxy-β- damascone

23.7 19.3 ns 18.7 * 18.3 ns 19.6 *

3-Oxo-α-ionol 7.7 6.2 ns 5.8 ns 4.4 * 5.6 ns

Compounds

Casein

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The fining treatments caused a higher decrease in the total amounts of gly- cosidically bound volatiles (figure 2) than in the total amounts of free volatiles (figure 1). This is in clear contradiction with those observed in model wine solution fined by proteins, where the level of retention of the volatiles increased with their hydrophobicity (VOILLEY et al., 1990; LUBBERS et al., 1993, 1996). Indeed glycosylation results in decrease of hydrophobicity of the compounds.

Figure 2

Effect of fining agents on total glycosidically bound compounds in Muscat Ottonel and Gewurztraminer wines

The extent of loss (14 to 33%) in bound volatiles varied with wine and fining agent as observed for free volatiles. The levels of the aglycones known to be potentially aroma contributors (WILSON et al., 1984 ; ETIEVANT, 1991 ; GUNATA et al., 1993) are given in tables 3 and 4. PVPP and isinglass induced the highest decrease in bound volatiles. The levels of some flavoring terpenols, geraniol, nerol, hotrienol were 30 to 50% lower in the treated wines. As expected bound volatile phenols were removed more efficiently by PVPP. Moreover the levels of bound C₁₃-norisoprenoids were also lower in treated wines, but these differences were not always statistically significant.

3.4 Sensory analysis

Sensory analyses of control and treated wines were performed by means of a triangle test. Results of a triangle test indicate if a detectable difference exists between two samples (LARMOND, 1969). Isinglass treated Gewurztraminer wine was the only wine to be found significantly (p<0.001) different from the control wine. This fining agent was found to be the most effective in the elimination of free aroma compounds in Gewurztraminer wine (12.8% of total amount) .

Muscat Ottonel Gewurztraminer 0

Total glycosidically bound compounds (mg/L)

control bentonite casein isinglass pvpp 1600

1400 1200 1000 800 600 400 200

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The low losses in free volatiles by fining agents could explain why the other wines were not significantly differentiated from the controls. Nevertheless, it was important to emphasize that the wines studied in this work were coming from floral cultivars which are highly aromatic due to the abundance of free monoterpenols. Accordingly, the low losses in volatiles could not have been detected by the panel.

4 – CONCLUSION

This study suggested that the losses observed in the free and bound compounds after fining treatments, resulted not only from their adsorption on fining agents, but also from their possible removal through wine macromolecules (polysaccharides, mannoproteines, polyphenols) precipitated by fining agents (SIEBERT et al., 1996; SARNI-MANCHADO P. et al, 1999). The loss in aroma by fining treatments ranged from 23% to 46% depending on the wine and the fining agent used. The removal of glycosidically bound volatiles by fining agents reduced the important aroma potential of wine, since these precursors give rise during wine conservation to potent flavor components, monoterpenic, C₁₃-nori- soprenoidic and phenolic derivatives through acido-catalyzed reactions (FRAN- CIS et al., 1992 ; SEFTON et al., 1993). This phenomenon may be more detrimental to the aroma of wines made from non-floral cultivars in which some flavor components are mainly present in glycoconjugated forms (WILSON et al., 1984 ; GUNATA et al., 1993). Since fining agents are frequently used in winemaking to stabilize and clarify wines, they must be employed moderately and adapted to wine type.

ACKNOWLEDGMENTS

We thank A. SCHAEFFER (INRA-Colmar) for kindly providing the wine samples used in this study.

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Prix et récompenses

Prix de l’innovation 2003 de Cofresco Institute

Le 3 juillet dernier, les membres du comité scientifique des Prix de l’innovation 2003 du Cofresco Institute ont choisi de récompenser Issam Sebti pour son projet « Production d’emballa- ges antimicrobiens par adsorption de chitosane et/ou de nisine sur des sachets plastiques ou des films cellophane ».

Docteur ingénieur en agroalimentaire, Issam Sebti, 27 ans, enseigne la chimie et la biochimie alimentaire dans le département de génie biologique de l’IUT de Bourg-en-Bresse (université Claude-Bernard Lyon 1). Il mène ses activités de recherches au sein du laboratoire de recherche en génie industriel alimentaire, et s’est vu remettre la somme de 10 000 €. En dotant les sachets plastiques et de films cellophane usuels de propriétés antimicrobiennes, le but de son projet est de proposer aux consommateurs un emballage actif qui maintiendra les qualités microbiennes premières du produit, et limitera les risques microbiologiques (à Listeria notamment) des restes alimentaires conservés au réfrigérateur.

Joint-venture associant depuis 1996 Melitta Group (Allemagne) et SC Johnson (USA), Cofresco détient un tiers du marché européen de l’emballage ménager, avec un chiffre d’affaires annuel d’environ 200 millions d’euros, grâce à des marques telles qu’Albal, Handy Bag, Toppits ou Glad.

Le Cofresco Institute a été lancé en novembre 2001 pour faire progresser la recherche ayant des applications possibles dans l’emballage alimentaire domestique.

Pour respecter le champ de recherche fixé, candidats à l’édition 2003 des Prix de l’innovation devaient présenter des « solutions actives permettant de préserver les qualités des produits alimentaires et d’assurer une alimentation saine, lors des différentes manipulations de ces produits à la maison ». Le comité scientifique les a départagés sur trois critères : l’innovation et la valeur scientifique du projet, ainsi que ses avantages pour le consommateur.

Un prix d’honneur de 2 000 € a également été attribué à un groupe d’étudiants de l’ÉSIEC (Reims), pour leur concept d’assiette diététique de légumes frais allant au micro-ondes. L’assiette contient différents légumes emballés sous atmosphère modifiée (80 % de CO₂ et 20 % de N₂), qui sont cuits à la vapeur grâce à un sachet d’eau gélifiée.

Le thème de recherche pour 2004 a d’ores et déjà été défini : il s’agira de proposer avant le 30 mars 2004 des « idées ou solutions innovantes qui permettent de garder les aliments frais plus longtemps à la maison ».

Cofresco Institute 2004 Innovation Prizes Melittastraße 17 D-32427 Minden

www.cofrescoinstitute.com