Helene Hopfer

The combined impact of vineyard origin and processing winery on the elemental profile of red wines

The combined effects of vineyard origin and winery processing have been studied in 65 red wines samples. Grapes originating from five different vineyards within 40 miles of each other were processed in at least two different wineries. Sixty-three different elements were determined with inductively coupled-plasma mass spectrometry (ICP-MS), and wines were classified according to vineyard origin, processing winery, and the combination of both factors. Vineyard origin as well as winery processing have an impact on the elemental composition of wine, but each winery and each vineyard change the composition to a different degree. For some vineyards, wines showed a characteristic elemental pattern, independent of the processing winery, but the same was found for some wineries, with similar elemental pattern for all grapes processed in these wineries, independent of the vineyard origin. Studying the combined effects of grapegrowing and winemaking provides insight into the determination of geographical origin of red wines.

The Combined Effects of Storage Temperature and Packaging Type on the Sensory and Chemical Properties of Chardonnay

Californian Chardonnay was stored in five different wine-packaging configurations at three different temperatures for a period of 3 months to study the combined packaging and temperature effects on the sensory and chemical properties of the wines. A trained descriptive panel evaluated aroma, taste, mouthfeel, and color attributes, and the sensory results were correlated to physical and chemical measurements including volatile compounds, SO(2), titratable and volatile acidity, oxygen consumption, and wine color, using partial least squares regression. In general, increased storage temperatures induced the largest changes in the wines; however, significant packaging--temperature effects were found for some attributes as well. Particularly wines stored in bag-in-boxes at 40 °C showed significant increases in oxidized and vinegar aromas and yellow color. Volatile esters also decreased in these wines, while increased levels of compounds generally associated with age- or heat-affected wine were found including 1,1,6-trimethyl-1,2-dihydronaphthalene and furfuryl ether, consistent with previously reported chemical aging reactions. In summary, storing unoaked Chardonnay in different packages significantly changes the sensory and chemical properties depending on the storage temperature. After a storage period of 3 months, bottle storage with various closures (natural cork, synthetic cork, and screw cap) changed the wine in a different way than bag-in-box storage.

The combined effects of storage temperature and packaging on the sensory, chemical, and physical properties of a Cabernet Sauvignon wine.

A Californian Cabernet Sauvignon was stored for 6 months at three different constant temperatures to study the combined effects of storage temperature and packaging configuration. Glass bottles with natural cork, synthetic cork, and screw cap closure, as well as two Bag-in-Box treatments, were used in the experiment. A trained sensory panel was able to detect significant changes in aroma, flavor, taste, mouthfeel, and color attributes among the samples, differences that were found also with various chemical and physical measurements (volatile profile, polyphenol pattern, enological parameters, color space). Additionally, two commonly used polyphenol assays were compared to each other in terms of their ability to detect the changes in the polyphenol profile. Generally, sample changes were more pronounced due to the different storage temperatures, with 30 sensory attributes differing significantly among the three different storage temperatures, while only 17 sensory attributes showed a significant packaging effect. With increasing storage temperature the packaging effect became more pronounced, resulting in the largest changes in the Bag-in-Box samples stored at the highest temperature of 40 °C. At the highest storage temperature, all wines showed oxidized characters, independent of the wine packaging configurations, but to a varying degree. Generally, wines that received highest oxygen amounts and storage temperatures were much lighter, less red, and more brown-yellow at the end of the 6-month storage period, compared to their counterparts stored at 10 °C. These changes in color and polyphenols, respectively, were also detected with the two spectrophotometric assays. With increasing storage temperature both assays measured reduced concentrations in total phenols and total anthocyanins, while total tannins, degree of ionized anthocyanins, and color density increased. Various volatile compounds differed significantly among the samples, with largest relative concentration changes in acetates, organic acids, and alcohols, in good agreement with previous literature reports, with some being well correlated to specific sensory attributes too; for example, various acetates correlated to cherry and fruit aromas and flavors. The study shows that storage at elevated temperatures could be a valuable tool for wine packaging screening and testing new and improved wine packaging types under the worst conditions, which are unfortunately not unrealistic.

How Blending Affects the Sensory and Chemical Properties of Red Wine

Three monovarietal wines (Cabernet Sauvignon, Merlot, and Cabernet franc) were used to produce 11 two-wine blends and four three-wine blends to study the changes in the sensory perception of the blends using descriptive analysis. In addition, chemical analyses (solid-phase microextraction and gas chromatography–mass spectrometry, polyphenol composition, titratable and volatile acidity, and pH) were performed to evaluate whether the sensory perception of the wine blends was matched by chemical parameters. A comparison of all data sets was performed with multifactor analysis and revealed that the overall results of both sensory and chemical analyses were very similar to those obtained from the sensory analysis alone, but none of the chemical analyses provided the same results as descriptive analysis.

Profiling the trace metal composition of wine as a function of storage temperature and packaging type

The effect of wine packaging and storage temperature on the elemental profile of a commercial Cabernet Sauvignon wine was studied using inductively coupled plasma-mass spectrometry (ICP-MS). In the method, 14 trace elements were monitored in a concentration range between 0.1 and 500 μg L−1, with five of these elements showing significant concentration differences among the samples as a result of the different wine packaging and storage temperatures. Among others, increased tin levels were found in screw capped samples, probably originating from the tin liner used inside the screw caps.

Evaluation of GC-ICP-MS/MS as a New Strategy for Specific Heteroatom Detection of Phosphorus, Sulfur, and Chlorine Determination in Foods.

For the first time in the literature, application of a GC-ICP-MS/MS method for the selective and sensitive detection of specific heteroatoms of phosphorus, sulfur, and chlorine has been accomplished. As a proof of concept, organophosphorus, organosulfur, and organochlorine pesticides in various food matrices have been studied. For the detection of organophosphorus and organosulfur pesticides, oxygen was used in the collision reaction cell (CRC) to convert P (m/z 31) to PO(+) (m/z 47) and S (m/z 32) to SO(+) (m/z 48). Similarly, ClH2(+) (m/z 37) was monitored after the reaction of Cl (m/z 35) with hydrogen in the CRC for the determination of organochlorine pesticides. Real food samples (baby food purees, fresh vegetables, loose tea) were screened for their pesticide content, following preparation of triplicate extracts using QuEChERS (quick, easy, cheap, effective, rugged, and safe). Excellent linearity with correlation coefficients R ≥ 0.997 was achieved, and the lowest detection limits obtained for the organophosphorus, organosulfur, and organochlorine pesticides were 0.0005, 0.675, and 0.144 μg/kg, respectively.

Total arsenic analysis in Californian wines with hydride generation – microwave plasma – atomic emission spectroscopy (HG-MP-AES)

The total arsenic concentrations of forty Californian wine samples were analyzed using a novel hydride generation-microwave plasma atomic emission spectroscopy (HG-MP-AES). Prior to analysis, various arsenic species were reduced with potassium iodide, and detected as gaseous arsenic trihydride. The method detection limit was determined to be 0.38 μg L−1. Total arsenic levels of the different tested wine styles (white, rose, red, Port, sparkling) ranged from below the detection limit to 43.8 μg L−1. The developed method provides quick and reliable quantitation of total arsenic content for a variety of wine styles down to levels below the EPA drinking water limit (10 μg L−1). This is the first report of HG-MP-AES, utilizing the Multimode Sample Introduction System (MSIS), for the determination of total arsenic.

Correlating Wine Quality Indicators to Chemical and Sensory Measurements

Twenty-seven commercial Californian Cabernet Sauvignon wines of different quality categories were analyzed with sensory and chemical methods. Correlations between five quality proxies—points awarded during a wine competition, wine expert scores, retail price, vintage, and wine region—were correlated to sensory attributes, volatile compounds, and elemental composition. Wine quality is a multi-faceted construct, incorporating many different layers. Depending on the quality proxy studied, significant correlations between quality and attributes, volatiles and elements were found, some of them previously reported in the literature.

Red blotch disease alters grape berry development and metabolism by interfering with the transcriptional and hormonal regulation of ripening

&NA; Grapevine red blotch‐associated virus (GRBaV) is a major threat to the wine industry in the USA. GRBaV infections (aka red blotch disease) compromise crop yield and berry chemical composition, affecting the flavor and aroma properties of must and wine. In this study, we combined genome‐wide transcriptional profiling with targeted metabolite analyses and biochemical assays to characterize the impact of the disease on red‐skinned berry ripening and metabolism. Using naturally infected berries collected from two vineyards, we were able to identify consistent berry responses to GRBaV across different environmental and cultural conditions. Specific alterations of both primary and secondary metabolism occurred in GRBaV‐infected berries during ripening. Notably, GRBaV infections of post‐véraison berries resulted in the induction of primary metabolic pathways normally associated with early berry development (e.g. thylakoid electron transfer and the Calvin cycle), while inhibiting ripening‐associated pathways, such as a reduced metabolic flux in the central and peripheral phenylpropanoid pathways. We show that this metabolic reprogramming correlates with perturbations at multiple regulatory levels of berry development. Red blotch caused the abnormal expression of transcription factors (e.g. NACs, MYBs, and AP2‐ERFs) and elements of the post‐transcriptional machinery that function during red‐skinned berry ripening. Abscisic acid, ethylene, and auxin pathways, which control both the initiation of ripening and stress responses, were also compromised. We conclude that GRBaV infections disrupt normal berry development and stress responses by altering transcription factors and hormone networks, which result in the inhibition of ripening pathways involved in the generation of color, flavor, and aroma compounds.

Predicting the Composition of Red Wine Blends Using an Array of Multicomponent Peptide-Based Sensors

Differential sensing using synthetic receptors as mimics of the mammalian senses of taste and smell is a powerful approach for the analysis of complex mixtures. Herein, we report on the effectiveness of a cross-reactive, supramolecular, peptide-based sensing array in differentiating and predicting the composition of red wine blends. Fifteen blends of Cabernet Sauvignon, Merlot and Cabernet Franc, in addition to the mono varietals, were used in this investigation. Linear Discriminant Analysis (LDA) showed a clear differentiation of blends based on tannin concentration and composition where certain mono varietals like Cabernet Sauvignon seemed to contribute less to the overall characteristics of the blend. Partial Least Squares (PLS) Regression and cross validation were used to build a predictive model for the responses of the receptors to eleven binary blends and the three mono varietals. The optimized model was later used to predict the percentage of each mono varietal in an independent test set composted of four tri-blends with a 15% average error. A partial least square regression model using the mouth-feel and taste descriptive sensory attributes of the wine blends revealed a strong correlation of the receptors to perceived astringency, which is indicative of selective binding to polyphenols in wine.