Enology - Wine Chemistry and Phenolic Analysis Session

Effects of Contrasting Cap Management on ORP, Phenolic, and Volatile Outcomes in Pinot noir and Petite Sirah Wines

Dallas Parnigoni , Federico Casassa,* Sean Kuster, Bob Coleman, James Nelson and Jesus Villalobos

*Wine and Viticulture Department – Cal Poly San Luis Obispo, 1 Grand avenue , San Luis Obispo, CA, 93407, lcasassa@calpoly.edu

Pinot noir and Petite Sirah wines were produced using five and six cap management protocols: punch-downs (PD, twice daily); pump-overs (PO, two full volumes, twice daily); and gas mixing executed by gas injections into must: air mixing (AirMix, 1 hr, twice daily), nitrogen mixing (N₂Mix; 1 hr, twice daily); ORP-control through air additions (ORPConAir; 10-sec air when ORP < -40 mV); and in Pinot noir only, simultaneous N₂ additions coinciding with ORPConAir (ORPConN₂; 10-sec N₂). Oxidation-reduction potential (ORP), reduced glutathione (GSH), and oxidized glutathione (GSSG) were monitored throughout a 10-day alcoholic fermentation. In both varietals, average ORP values were similar between PD and PO wines; however, PO wines exhibited peaks ≥100 mV during pump-overs, while PD wines maintained a negative ORP at peak fermentation, even during punch-downs. At pressing, N₂Mix wines showed GSH:GSSG ratios of 6.6:1 and 5.0:1, while PD wines showed ratios of 0.7:1 and 1.3:1 in Pinot noir and Petite Sirah, respectively. At pressing, there were no differences in anthocyanin or tannin in any treatment other than AirMix wines in either varietal. Alternatively, AirMix wines showed reductions in total phenolics at pressing of 21% and 30% compared to PD wines in Pinot noir and Petite Sirah, respectively. Compared to PO wines, PD wines had increased flavan-3-ols by 48% and 8% in Pinot noir and Petite Sirah, respectively. Ethyl n-octanoate had the greatest odor activity values (OAV) in all treatments of Pinot noir, ranging from 147 (PO) to 116 (AirMix), while isoamyl acetate was most odorous in Petite Sirah, ranging in OAV from 248 (ORPConAir) to 120 (AirMix). These cap management protocols produced unique ORP evolutions, influenced GSH:GSSG ratios, and differentially affected phenolic and volatile composition, with consistent trends despite varietal differences.

Funding Support: Gallo

Giona Lo Parrino | Alessandro Tonelli | Giuseppe Floridia | Valentina Canuti*

In-line Monitoring of the Winemaking Process: Redox Variables and Antioxidant Power

Giona Lo Parrino, Alessandro Tonelli, Giuseppe Floridia and Valentina Canuti*

*DAGRI – Department of Agricultural, Food, Environmental, and Forestry Sciences and Technologies – University of Florence, via Donizetti, 6, Firenze – 50144, Italy, valentina.canuti@unifi.it

In-line monitoring of the winemaking process with a limited number of variables remains a current challenge in wine research, aiming to provide rapid assessment of wine stability, oxidizability, and precise dosing of additives or adjuvants. Two key variables related to wine redox status are redox potential (ORP) and antioxidant power (AP), poorly monitored during wine production due to the complexity of oxidation phenomena, the difficulty of performing current AP assessment tests directly in the winery, and the challenges in measuring and interpreting ORP. This study applied a rapid AP test, the wine antioxidant test (WAT, based on Fe³⁺/Fe²⁺), and an in-line multiparameter system for monitoring temperature, ORP, and dissolved oxygen (DO) during fermentation/maceration of Sangiovese red grapes (at 25°C, with replications), to understand the correlation between these variables and propose a new approach for in-line assessment of wine production. ORP and DO were measured continuously with probes, while WAT and DPPH were measured daily. Wine color and polyphenol content were analyzed using spectrophotometric indices, CIELab, and high-performance liquid chromatography-diode array detection. ORP was able to describe the evolution of alcoholic fermentation and polyphenol extraction, for the experimental condition applied. All parameters monitored during fermentation/maceration were used to create a predictive model for the AP measured by WAT (R² 0.97 for the calibration model and R² 0.76 for the validation model). In particular, WAT results correlated directly with wine polyphenol content, DPPH, and polymeric pigments, and indirectly with ORP. ORP, in turn, correlated with monomeric anthocyanins (R² 0.9013), polymeric pigments (R² 0.9013), DPPH (R² -0.8210), and DO (R² 0.9759). This study opens new avenues for research in the field of precision enology, supporting the development of in-line winemaking control.

Funding Support: none

Improved Red Wine Color Stability by the Prefermetation Addition of an Innovative Pomegranate Peel-Derived Tannin

Silvia D’Agostino,* Lorenzo Cecchi, Valentina Civa, Lapo Pierguidi, Bruno Zanoni and Valentina Canuti

*University of Florence, Via Gaetano Donizetti, 6, 50144, Firenze, Italy, Florence/50144, Italy, silvia.dagostino@unifi.it

Enological tannins are a class of coadjuvants employed in winemaking for their beneficial effects on must clarification, color, and mouthfeel sensations, while preventing oxidation. These polyphenol-rich extracts are regulated by the International Organization of Vine and Wine, which allows using tannins only from nutgalls, wood, and grape seeds and skins. However, growing attention to sustainability in the wine sector has prompted exploration of by-products from the food industry. Pomegranate peels, an important food industry by-product with ~ 0% discarded biomass of the fruit weight, can be valorized by extracting the tannin fraction for application in winemaking. Under the hypothesis that the unique chemical structure of pomegranate peel hydrolysable tannins, characterized by the gallagyl group, could be effective in preventing oxidation and stabilizing wine color, an innovative extraction method has been developed. Vinification of Sangiovese grapes was carried out, in which the addition of pomegranate peel tannin (PPT) was compared to the addition of nutgall tannin (NGT) and oak-derived tannin (ODT) and to a control (CON), with dosages adjusted according to the purity of the extracts. Polyphenol content, antioxidant activity, color indices, CIELab values, and sensory analysis were conducted at racking, after malolactic fermentation, and 6 mo after bottling. The results highlighted a significantly higher polyphenols content in PPT wines compared to the other treatments, resulting in an increased antioxidant activity comparable to NGT wines. The most notable effects were observed in color parameters: PPT wines had the statistically highest color intensity and presence of polymerized anthocyanins. Surprisingly, the addition of PPT led to significant reduction of wine bitterness. The study provided new practical insights on the advantages in using PPT in winemaking, strongly suggesting the possibility of extending the sources for recovery of effective enological tannins, while applying the principles of circular economy.

Funding Support: University of Florence

Danielle Fox | P. Layton Ashmore | Andrew L. Waterhouse | James F. Harbertson*

Wine Nucleophiles Expedite Structural Changes in Wine Tannins, Reducing Astringency and Altering Phenolic Composition

Danielle Fox, P. Layton Ashmore, Andrew L. Waterhouse and James F. Harbertson*

*Washington State University, 359 University Dr., Richland, WA, 99354, jfharbertson@wsu.edu

To understand how tannin structural changes that occur during aging affect wine sensory and chemical composition, a full-factorial design experiment was carried out by adding either an oxidative adjuvant (acetaldehyde) or two reductive adjuvants (sulfur dioxide and glutathione) to Cabernet Sauvignon and Petite Verdot wines adjusted to four pHs (pH 3.25, 3.50, 3.75, and 4.0). The wines were fermented in the fall of 2022, and the adjuvants were added midway through 2023, post-ion exchange, and tracked chemically for 1.5 yr. Descriptive analysis and time intensity analysis were performed a year after the additions on a subset of the wines (pH 3.25, 3.75 Petite Verdot). Chemically, the oxidative treatment strongly depended on pH and primarily affected the color components (anthocyanins and polymeric pigments, both small and large), while the addition of reductive adjuvants was not pH dependent. Due to the Cabernet Sauvignon wine having very low concentrations of both tannins (<300 mg/L) and anthocyanins (0 to 350 mg/L), the trends for polymeric pigment formation and changes in tannin were obscured compared to the Petite Verdot wine, which was rich in tannins (~800 to 1200 mg/L) and anthocyanins (200 to 800 mg/L). Acetaldehyde-treated wine reduced anthocyanins over time, while sulfur dioxide preserved anthocyanins to the extent that they exceeded the control at the end of the study. Glutathione significantly reduced the tannin concentration of the wine. Generally polymeric pigments declined over time and were highest in the acetaldehyde-treated wines, but their change was strongly dependent on pH and treatment. Multifactor analysis combining sensorial and chemical analysis showed that the wines were primarily separated by treatment. The glutathione-treated wines were inversely related to astringency and tannin concentration. Aroma characteristics were only affected by the sulfur dioxide treatment, which were related to the baking spice and earthy ortho-nasal attributes.

Funding Support: Washington Wine Commission, Washington Wine Grape Funds

Yanxin Lin | Robert (Sui) Qiang | Misha Kwasniewski* | Bruce Pan

Application of Tannin Fragmentation Fingerprint: A Rapid LC-MS/MS Approach for Structural Profiling and Quantification

Yanxin Lin, Robert (Sui) Qiang, Misha Kwasniewski* and Bruce Pan

*Food Science Department, Penn State University, Penn State University, Rodney A. Erickson Food Science Building, State College, PA, 16803, mtk5407@psu.edu

Wine tannins are categorized into condensed tannins (CTs) from grape skins and seeds and hydrolysable tannins (HTs), including ellagitannins (ETs) and gallotannins (GTs), predominantly introduced through oak aging and tannin additives. Both tannin types influence mouthfeel, astringency, and aging potential. However, traditional analytical methods often fail to correlate with perceived astringency and biological activity, particularly in wines with subtle tannin composition differences. This limitation arises because assays such as Folin-Ciocalteu and tannin affinity precipitation provide simplified total phenolic or tannin values, without accounting for structural diversity and polymerization variability. To address these challenges, we developed tannin fragmentation fingerprinting (TFF), an LC-MS/MS method using electrospray ionization in-source fragmentation. This technique enables detailed structural characterization of both CTs and HTs by depolymerizing tannins in the ion source and analyzing their subunit-specific fragmentation spectra. TFF has demonstrated superior analytical capabilities over conventional methods. For CTs, TFF distinguished Noiret wines from the 2022 vintage, with and without exogenous tannin additions (control versus exogenous tannin addition). While traditional methods suggested negligible effect on CT composition, TFF revealed clear separation via principal component analysis and a measurable increase in CT concentration, likely due to the enrichment of specific A-type procyanidins. For HTs, TFF has been optimized for high-throughput quantification, significantly reducing analysis time compared to the previous acid hydrolysis method, while providing precise differentiation between ETs and galloylated tannins (i.e., GTs and galloylated CTs). Analysis of 15 commercial oak products from three regions and five toasting levels showed that French oak had higher ET and GT concentrations than Hungarian and American oak, with higher toasting levels reducing both contents. This advancement enables oak product profiling, aging regime monitoring, and product authenticity verification, and has already been adopted by industry stakeholders for reliable data delivery.

Funding Support: None

8:15 am – 8:35 am	Effects of Contrasting Cap Management on ORP, Phenolic, and Volatile Outcomes in Pinot noir and Petite Sirah Wines Dallas Parnigoni, California Polytechnic State University, San Luis Obispo
8:35 am – 8:55 am	In-line Monitoring of the Winemaking Process: Redox Variables and Antioxidant Power Valentina Canuti, University of Florence, Italy
8:55 am – 9:15 am	Improved Red Wine Color Stability by the Prefermetation Addition of an Innovative Pomegranate Peel Derived Tannin Silvia D’Agostino, University of Florence, Italy
9:15 am – 9:35 am	Wine Nucleophiles Expedite Structural Changes in Wine Tannins, Reducing Astringency and Altering Phenolic Composition Danielle Fox, Washington State University, Tri-Cities
9:35 am – 9:55 am	Application of Tannin Fragmentation Fingerprint: A Rapid LC-MS/MS Approach for Structural Profiling and Quantification Yanxin Lin, The Pennsylvania State University, State College

Enology – Wine Chemistry and Phenolic Analysis Session

Research Reports

Moderator:

Speakers:

Share This Page