terclim by ICS banner
IVES 9 IVES Conference Series 9 CHARACTERIZATION OF ENOLOGICAL OAK TANNIN EXTRACTS BY MULTI-ANALYTICAL METHODS APPROACH

CHARACTERIZATION OF ENOLOGICAL OAK TANNIN EXTRACTS BY MULTI-ANALYTICAL METHODS APPROACH

Abstract

Oak tannin extracts are commonly used to improve wine properties. The main polyphenols found in oak wood extracts are ellagitannins¹ that release ellagic acid upon hydrolysis and comprise numerous structures². Moreover, oak tannin extracts contain other compounds giving a complex mixture. Consequently, the official OIV method based on gravimetric analysis of the tannin fraction adsorbed on polyvinylpolypyrrolidone is not sufficient to describe their composition and highlight their chemical diversity.

Eight commercial oak tannins were characterized by a combination of analytical approaches, Polyphe-nols were analyzed using the official OIV method, UV spectrophotometry, UPLC-UV-MS analysis be-fore and after acidic methanolysis, and HPLC-SEC-UV. Neutral sugars and polyols were determined as alditol acetates by GC-FID analysis, before and after hydrolysis. Protein content was estimated by the Kjeldahl method. Finally, samples were compared by a non-targeted metabolomic approach based on UHPLC−HRMS/MS.

Gravimetric analysis, absorbance values at 280 nm, and the quantities of ellagic acid released by methanolysis revealed some differences between samples, indicating variations in their tannin composition. This was confirmed by HPLC-SEC-UV analysis evidencing differences in tannin size distribution, particularly in larger polymer content.

All samples contained significant quantities of sugars, and in particular xylose, mostly found in the linked form, and of quercitol, a polyol marker of oak origin. These compounds contributed to up to 25% of the whole extract composition, the proportions of free and combined sugars and polyols also showing large variations between tannins. The protein content was very low, generally representing less than 1% of the mass. Non targeted UPLC-HRMS analysis detected major ellagitannins such as vescalagin, castalagin, and ro-burins A-E, but also a large number of derivatives as well as other molecules such as lignans and quercotriterponosides, and highlighted large differences between samples. Tannin extracts also contained aldehydes (HMF, furfural, syringaldehyde, sinapaldehyde, vanillin) in variable quantities.

This work demonstrates the variability in the composition of commercial oak tannin extracts, likely to impact their properties, and emphasizes the need for detailed multi-method characterization in the frame of quality control and selection of tannins for specific applications.

 

1. Simón, B. F. de; Cadahía, E.; Conde, E.; García-Vallejo, M. C. Ellagitannins in Woods of Spanish, French and American Oaks. 1999, 53 (2), 147–150. https://doi.org/doi:10.1515/HF.1999.024.
2. Moutounet, M.; Souquet, J.-M.; MEUDEC, E.; Leaute, B.; DELBOS, C.; Doco, T. Analyse de La Composition de Tanins Oenolo-giques. Rev. Fr. Oenologie 2004, No. 208, 22–27.

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Poster

Authors

Hélène Hallea,² , Kevin Pascotto³ , Aude Watrelot1,2,4, Aurélie Roland1,2, Emmanuelle Meudec1,2, Pascale Williams 1, Stéphanie Car-rillo 1, Bertand Robillard 3, Nicolas Sommerer 1,2, Céline Poncet-Legrand 1, Véronique Cheynier 1,2

1. Univ. Montpellier, SPO, INRAE, Institut Agro Montpellier Supagro, 34070 Montpellier, France
2. INRAE, PROBE research infrastructure, PFP polyphenols analysis facility, 34070 Montpellier, France
3. Institut Œnologique de Champagne, Epernay, France
4. Iowa State University, Department of Food Science and Human Nutrition, Ames, USA

Contact the author*

Keywords

Oak extract, Ellagitanins, oses and polyols, HRMS

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

PHENOTYPIC DIVERSITY AND BIO-PROTECTION CAPABILITY OF METSCHNIKOWIA SP. IN OENOLOGY

Nowadays, the trend is to reduce the use of chemical inputs in the food sector, including in oenology. One of the inputs widely used in the wine making process are sulfites, for its several properties: antimicrobial and antioxidiant. This use isn’t without consequences on consumer’s health and environment, it can lead for example to allergic reactions and pollution. To limit the addition of chemical inputs, microbial alternatives are used. It consists to inoculate in grape must, a micro-organism able to inhibit the growth of the negative indigenous flora during the phase before the fermentation and to guarantee the sensory qualities of wines.

THE EFFECT OF PRE-FERMENTATIVE GLYPHOSATE ADDITION ON THE METABOLITE PROFILE OF WINE

The synthetic herbicide glyphosate has been used extensively in viticulture over many decades to combat weeds. Despite this, the possible influence of residual glyphosate on both the alcoholic fermentation of grape juice and the subsequent metabolite profile of wines has not been investigated. In this study, Pinot noir juice supplemented with different concentrations of glyphosate (0 µg L-1, 10 µg L-1 and 1000 µg L-1) was fermented with commercial Saccharomyces cerevisiae yeast strains. Using a combination of analytical methods, 80 metabolites were quantified in the resulting wines.

INVESTIGATION OF FILM COATINGS AS A PROTECTIVE LAYER IN REDUCING THE ABSORPTION OF SMOKE PHENOLS INTO PINOT NOIR GRAPES

Wine grapes exposed to wildfire smoke have resulted in wines with burnt and ashy sensory characteristics¹, that are undesirable qualities in wine. In extreme wildfire events, this can lead to total loss of grape crop. Currently there are no effective solutions in the market to prevent the uptake of smoke compounds into grapes. In this study, previously developed innovative film coatings were tested to analyze their effectiveness in reducing smoke phenol absorption². Four different cellulose nanofiber-based film types were investigated.

SUB-CRITICAL WATER: AN ORIGINAL PROCESS TO EXTRACT ANTIOXIDANTS COMPOUNDS OF WINE LEES

Wine lees are quantitatively the second most important wine by-product after grape stems and marc [1]. In order to recycle, distilleries recovered ethanol and tartaric acid contained in wine lees but yeast biomass is often unused. It has already been demonstrated that this yeast biomass could be upcycled to produce yeast extracts of interest for wine chemical stabilization [2]. In addition, it is well known that lees, during aging, release compounds that preserve wine from oxidation.

TARTARIC STABILIZATION MAY AFFECT THE COLOR AND POLYPHENOLIC COMPOSITION OF TANNAT RED WINES FROM URUGUAY

Tartrate precipitation affects the properties of wines, due to the formation of crystals that cause turbidity, even after being bottled. The forced tartaric stabilization is carried out frequently for young wines, through various physicochemical procedures. The traditional treatment for tartaric stabilization is refrigeration, but it can have a negative effect on wine’s sensory properties, and particularly on the color of red wines. The aim of this study was to evaluate the effect of different tartaric stabilization options on the color and phenolic composition of Tannat red wines from Uruguay.