Prediction of astringency in red wine using tribology approach to study in-mouth perception
Andrea VERSARI, Università degli Studi di Bologna (ITALY)
Arianna Ricci, Università degli Studi di Bologna (ITALY)
Giuseppina Paola Parpinello, Università degli Studi di Bologna (ITALY)
Luigi Ragni, Università degli Studi di Bologna (ITALY)
Elena Babini, Università degli Studi di Bologna (ITALY)
Email contact: andrea.versari[@]unibo.it
AIM: Astringency is described as a ‘dry puckering-like sensation’ following consumption of tannins1 that affect consumer preference of foods and beverages, including red wine2. To improve the understanding of astringency, which is a complex interaction due to multiple mechanisms occurring simultaneously, further studies are needed. In this view, oral tribology is considered a useful technique for beverage study to evaluate the thin-film lubrication properties of saliva resulting in oral friction-related sensations3. The aim of this study was to examine the film behavior of selected protein-based fluids under controlled friction conditions, to understand polyphenol-protein interactions involved in the sensation of astringency.
METHODS: A mini-traction device was self-assembled to evaluate friction during a dynamic process under different test conditions. Moreover, several oenological tannins and red wines were analyzed to relate instrumental and sensory results, and the effect of selected parameters involved in astringency perception (acidity, ethanol, polysaccharides) was investigated.
RESULTS: After a preliminary screening of several proteic fluids based on friction behavior, the addition of oenological tannins at increasing levels showed empirical evidence of linear range of interaction with protein (R2 up to 0.97) with increasing friction values. Results were greatly affected by the botanical origin of tannins, their degree of purity and the tannin-to-protein ratio. The tribological findings were confirmed by the chemical and sensory analysis of red wines, which highlighted the great contribution of phenolic compounds, in particular tannins.
CONCLUSIONS: The inherent properties of the selected protein-based fluid allow a satisfactory prediction of astringency in wine and future work will focus on friction and film formation across a broader set of conditions to improve the characterization of wine astringency based on tribology-sensory relationship.
1. Haslam, E. 1998. Practical Polyphenolics: From Structure to Molecular Recognition and Physiological Action. Cambridge University Press, Cambridge, UK.
2. Gawel, R. 1998. Red wine astringency: a review. Australian Journal of Grape and Wine Research, 4, 74–96;
3. Brossard, N., Cai, H., Osorio, F., Bordeu, E., Chen, J. 2016. “Oral” tribological study on the astringency sensation of red wines. Journal of Texture Studies, 47, 392–402.
Sensory profile: a tool to characterize originality of wines produced without sulfites
E. Pelonnier-Magimel*, S. Windholtz*, I. Masneuf-Pomarède, J.-C. Barbe
Unite´ de Recherche Œnologie, EA 4577, USC 1366 INRAE, Univ. Bordeaux, Bordeaux INP, F33882 Villenave d’Ornon France
Email contact : firstname.lastname@example.org
AIM: A trend to reduce chemical inputs in wines exists, especially sulfur dioxide (SO2). This additive is widely used due to its antioxidant, antiseptic and antioxidasic properties. During without sulfites vinification, bioprotection by adding yeast on harvest could be a sulfites alternative. With extension of this wine market, sensory impact linked to sulfites absence and/or sulfites alternative should be evaluated. That’s what this approach proposes to do, focusing on sensory characteristics of wines produced with or without SO2 addition during the winemaking process.
METHODS: Wines were elaborated from Merlot grapes of two maturity levels according to three modalities: SO2, without SO2 and bioprotection on harvest (mix of Torulaspora delbrueckii and Metschnikowia pulcherrima). SO2 modality was sulfited throughout the winemaking and aging processes whether other modalities received any addition. After two years of aging, sensory studies were carried out with a specific panel for one month. First, descriptors were generated to differentiate the wines, then panelists were trained on these specific descriptors for five sessions and finally wines sensory profiles were elaborated.
RESULTS: The panel generated thirteen descriptors to differentiate the wines on which they have been trained: nine olfactive, three gustative and one trigeminal. After training, the nine presenting a consensus between judges were finally used. Wines without SO2 were characterized by freshness (mint and coolness) and cooked black cherries; bioprotection by fresh blackcurrant and with SO2 by smoke. Hierarchical clustering applied to this sensory approach lead to significantly differentiate wines produced with or without SO2.
CONCLUSIONS: This approach allow to highlight sensory specificities of without sulfites wines. Therefore, with a dozen of descriptors, tasters could differentiate wines which have been sulfited or not but cannot differentiate among not sulfited ones those who have received bioprotection from those which have got any addition, regardless grapes maturity level.
*The contribution of E. Pelonnier-Magimel and S. Windholtz to this work was identical.
References:Campo, E., Ballester, J., Langlois, J., Dacremont, C., & Valentin, D. (2010). Comparison of conventional descriptive analysis and a citation frequency-based descriptive method for odor profiling: An application to Burgundy Pinot noir wines. Food Quality and Preference, 21(1), 44 55.
Lawless, H. T. (1999). Descriptive analysis of complex odors: Reality, model or illusion? Food Quality and Preference, 10(4 5), 325 332.
Morgan, S. C., Tantikachornkiat, M., Scholl, C. M., Benson, N. L., Cliff, M. A., & Durall, D. M. (2019). The effect of sulfur dioxide addition at crush on the fungal and bacterial communities and the sensory attributes of Pinot gris wines. International Journal of Food Microbiology, 290, 1 14.
Murray, J. M., Delahunty, C. M., & Baxter, I. A. (2001). Descriptive sensory analysis: Past, present and future. Food Research International, 34(6), 461 471.
Simonin, S., Alexandre, H., Nikolantonaki, M., Coelho, C., & Tourdot-Maréchal, R. (2018). Inoculation of Torulaspora delbrueckii as a bio-protection agent in winemaking. Food Research International, 107, 451 461.
Long-term sensorial and compositional effects of copper fining on the wine containing ‘reductive’ and ‘tropical’ volatile sulfur compounds
Matija LESKOVIC 1, Marlize BEKKER 2, Jeanne BRAND 1, Allie KULCSAR 2, Wessel DU TOIT 1
1South African Grape and Wine Research Institute/Department Viticulture and Oenology, University of Stellenbosch, Private Bag X1, Matieland (Stellenbosch) 7602, South Africa
2 The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia, 5064.
Email contact: matija[@]sun.ac.za
The aim of this study was to investigate long-term sensorial and compositional effects of copper addition to the white wine naturally high in varietal thiol levels, with added volatile sulfur compounds [hydrogen sulfide (H2S) and methanethiol (MeSH)]. The novelty of this study lies in the inclusion of sensory analysis at each time point by using Check-All-That-Apply and Descriptive Analysis methods to evaluate the sensory interaction between ‘reductive’ thiols and tropical thiols after copper fining. The Chenin Blanc wine was used as control (base) wine to which combinations of 40 µg/L H2S and 20 µg/L of MeSH were added, followed by an addition of 0,3 mg/L of copper to selected samples. The wine samples were stored for 24 hours, 6 weeks and 1 year. At each time point chemical analysis of varietal thiols, volatile sulfur compounds and copper levels were performed. The chemical results after 1 year of wine storage, showed a significant increase in the levels of varietal thiol 3-sulfanylhexanol (3-SH) and a decrease of 3-sulfanylhexyl acetate (3-SHA) concentration levels. However, a significant loss of 3-SH occurred in all the copper treated wines after 1 year of storage. On the other hand, the decrease of 3-SHA levels over time was less influenced by copper treatment, but rather due to acid hydrolyses and a subsequent increase in 3-SH (Makhotkina & Kilmartin, 2012). The presence of copper seem to further increase levels of bound- H2S in wine samples, which after 1 year of storage amounted to more than 25 µg/L. Chemical analysis of MeSH showed the significant increase in free and bound MeSH after 1 year of storage in wine samples spiked with MeSH. However, the addition of copper to the MeSH-spiked samples resulted in significant decrease of free and bound MeSH.
The most significant sensory impact of the addition of H2S and MeSH to control wine was the suppression effect on “fruitiness” of wine after 24 hours which after 6-weeks and 1-year wine storage period decreased, potentially due to wine matrix absorption of H2S and MeSH (Nikolantonaki & Waterhouse, 2012). Sensory results after 1 year of wine storage showed that “guava”, a “tropical” attribute, was not suppressed with the addition of H2S and MeSH and low doses of “reductive” aromas deriving from H2S and MeSH in wine might even contributed to its sensory perception. Copper additions mainly decreased the perception of “guava” after 1 year. In contrast, the “passionfruit”, also a “tropical” attribute, was slightly suppressed when H2S and MeSH were present. The perception of the ester-derived attributes namely “peach” and “banana” increased in the samples containing copper after 1 year of storage, suggesting that a decrease of the 3-SH varietal thiol due to copper addition may enhance the perception of ester-derived aromas in wine.
Makhotkina, O., & Kilmartin, P. A. (2012). Hydrolysis and formation of volatile esters in New Zealand Sauvignon blanc wine. Food Chemistry, 135(2), 486–493. https://doi.org/10.1016/j.foodchem.2012.05.034
Nikolantonaki, M., & Waterhouse, A. L. (2012). A method to quantify quinone reaction rates with wine relevant nucleophiles: A key to the understanding of oxidative loss of varietal thiols. Journal of Agricultural and Food Chemistry, 60(34), 8484–8491. https://doi.org/10.1021/jf302017
Whole bunch fermentation: adding complexity, or just making ‘green’ wine?
Keren Bindon (1) - Martin Day (1) - Dimitra Capone (2) - Stella Kassara (1) - Eleanor Bilogrevic (1) - Damian Espinase-nandorfy (1) - Flynn Watson (1) - Leigh Francis (1)
THE AUSTRALIAN WINE RESEARCH INSTITUTE, RESEARCH, ADELAIDE, Australia (1) - ARC Training Centre for Innovative Wine Production, THE UNIVERSITY OF ADELAIDE, ADELAIDE, Australia (2)
Email contact: keren.bindon[@]awri.com.au
AIM: Certain grape varieties contain negligible levels of isobutyl methoxypyrazine (IBMP) in grapes. However, it has long been known that grape stems may have a high concentration of IBMP. The study aimed to discover the extent to which whole bunch addition during fermentation contributes to ‘capsicum’ (green) flavour and aroma in wine by imparting IBMP. It was also of interest to determine whether additional tannin could be extracted from stem contact, which was expected to impact wine astringency.
METHODS: Pinot noir and Shiraz grapes were either fermented either completely crushed, or as 100% whole bunches. Other treatments had proportional whole bunch addition at 25%, 50% or 75%. Wines were put through descriptive sensory analysis after 10 months and multiple volatile and non-volatile compounds were analysed at the same time.
RESULTS: For both varieties, the sensory scores for ‘green capsicum’ and the concentration of IBMP were highly correlated with the proportion of whole bunches in the ferment. Volatile compounds other than IBMP were increased by whole bunch fermentations, and were α-terpineol, β-citronellol and E-2-hexenol. For Shiraz, the wood-derived volatiles guaiacol and vanillin increased with whole-bunch inclusion, while for Pinot noir ethyl cinnamate increased, possibly reflecting that some carbonic maceration occurred. In Shiraz wines, the concentration of tannin and the perception of astringency increased with the inclusion of whole
bunches, but this was not observed for Pinot noir. Whole-bunch ferments from both grape varieties had lower levels of polysaccharide in the finished wine, primarily due to a lower contribution of pectic material.
CONCLUSIONS: This study showed that winemakers can substantially alter wine volatile and non-volatile composition through whole bunch fermentation. The results will be discussed in terms of potential wine style outcomes for the respective grape varieties, whether whole bunch inclusion might improve the complexity of a wine, or simply introduce unwanted ‘green capsicum’ attributes.