Commercial Wineries Research Articles

Development and Commercialization of a Complete Vineyard Mechanization System

A major research thrust of the University of Arkansas Enology and Viticulture Program for the past 37 years has been the development of a total vineyard mechanization system. This new system allows the mechanization of almost all practices in vineyard operations, including dormant and summer pruning, leaf removal, shoot and fruit thinning, canopy management, and harvesting while fruit quality is maintained or enhanced. Research efforts aimed to accomplish these tasks on the 12 major trellising systems used throughout the industry and to derive plans for the sequencing and timing of operations on each of the trellis systems. In 2002, the University of Arkansas patented the Morris-Oldridge Vineyard Mechanization System (M-O System). OXBO International Corp., Clear Lake, WI, purchased the patent and market M-O System components under the name Korvan™ Vineyard System. The objective of this study was to evaluate the effectiveness of mechanized (machine-farmed) pruning, shoot thinning, and fruit thinning using the M-O System vs. traditional methods of canopy management using hand labor (hand-farmed) in a commercial Vitis vinifera vineyard in the central coast region of California. V. vinifera cultivars evaluated included Chardonnay, Sauvignon blanc, and Syrah trellised on a lyre system and Merlot, Zinfandel, and Sangiovese trellised on a vertical shoot-positioned (VSP) system. Yield, fruit growth, fruit composition, wine quality, wine sensory attributes, and economics of mechanization were evaluated on machine- and hand-farmed grapes. Mechanized studies were initiated at French Camp Vineyards, Santa Margarita, CA, in 2002. French Camp Vineyards used a balanced cropping concept which incorporated three operations: 1) machine dormant pruning, 2) machine shoot thinning, and 3) machine fruit thinning. Results of research from 2002 to 2005 showed that yield and quality characteristics of machine-farmed grapes were not statistically different from those of hand-farmed grapes for the V. vinifera cultivars in this study. Wines from each cultivar and treatment were produced at a commercial winery and after appropriate aging, were sensory-evaluated by a professional wine analysis service. Few sensory differences were found between wines from the two farming systems. Further objective analyses of the wine components showed no commercially practical differences. In 2006, cost estimates were derived for the three vineyard activities necessary to achieve balanced cropping. Use of machine farming for balanced cropping operations resulted in savings over hand farming of 45% on the lyre trellis, 49% on the VSP system, and 62% on the quadrilateral trellis for the operations studied. Studies of mechanization of vineyard activities using the M-O System to achieve balanced cropping have shown that grapes and their wines were equivalent to those obtained using hand labor for these operations with the added benefit of cost savings for the operations evaluated.

Development of a Rapid “Fingerprinting” System for Wine Authenticity by Mid-infrared Spectroscopy

This paper reports on the development of a rapid and simple method for red wine authenticity confirmation during transport and processing; namely, a wine "fingerprinting" system. When wine is transported between two sites, a sample is taken and a mid-infrared (MIR) spectrum is obtained. One hundred sixty-one (n = 161) samples of three main red wine varieties grown in Australia, Shiraz, Cabernet Sauvignon, and Merlot, were collected from six commercial wineries across Australia and scanned in transmission on two MIR spectrophotometers located at The Hardy Wine Company's main site at Reynella, South Australia (Foss WineScan FT 120) (926-5012 cm-1). A similarity index (SI) method was used as a tool to classify wine samples on the basis of their spectral data. The results showed that high rates of classification were obtained when wine samples scanned in different instruments were analyzed. The SI has been proven to provide an acceptable measurement for authentication of red wine integrity during transportation. In five of the six winery data sets, the SI correctly classified 98% of the wines. It was also observed that less than 1% of wines were misclassified between the different wineries investigated. Further studies are needed in order to test the applicability of the SI in a commercial situation and to evaluate its potential as a rapid quality control tool for routine use to authenticate wine samples during transport.

In-line dosing for bentonite fining of wine or juice: Contact time, clarification, product recovery and sensory effects

Field tests to evaluate in-line dosing with bentonite followed by centrifugation as an alternative to batch fining for protein haze control in white wine or juice were undertaken. The tests were performed at a commercial winery with a Sultana wine and Gordo (Muscat of Alexandria) juice and using two types of bentonite: Vitiben and SIHA-Active-Bentonite G. Fining performance was monitored by heat testing and quantification of heat unstable protein by HPLC. Heat test turbidity and heat unstable protein concentration decreased to stable values between 30 s and 2 min after bentonite injection. Sensory evaluation of Sultana wine fined with Vitiben by balanced reference duo-trio difference tests detected no difference between untreated, in-line dosed, and batch fined wine. Furthermore the volume of wine or juice occluded in lees can be substantially reduced by centrifugal compaction. However, incomplete separation of bentonite from wine or juice during centrifugation produced a carryover of 30% of the added bentonite into the clarified wine. This carryover problem may be mitigated, inter alia, by reducing operating flowrate through the centrifuge or using multiple centrifugation steps (in parallel or series). Therefore, inline dosing followed by centrifugation provides a rapid processing method for protein haze reduction in wine or juice with a decreased volume of lees. It can reduce significant value losses presently arising in the wine industry from batch fining and the resulting quality downgrades that occur in wine recovered from bentonite lees by rotary drum vacuum filtration.

A Comparison Between Underground Wine Cellars and Aboveground Storage for the Aging of Spanish Wines

This article examines the advantages of cellars compared with aboveground storage for aging of wine. The literature on winemaking points out the importance of a constant low temperature and high relative humidity inside buildings where wine is stored, in order to produce a high-quality end product as well as to reduce wine losses. An analytical model for calculation of the soil temperature was used as an approach for the assessment of the possible energy savings in underground cellars. In addition, various traditional underground wine cellars were monitored in comparison with commercial wineries in the Ribera del Duero appellation of origin (Spain), and the results showed the advantages of underground cellars.

Occurrence and significance of Bacillus thuringiensis on wine grapes

Wine grapes harvested at different stages during cultivation from several vineyards in New South Wales, Australia, harboured Bacillus thuringiensis at viable populations of 10 2–10 6 cfu/g. Commercial preparations of B. thuringiensis had been sprayed onto the grapes as a biological insecticide. B. thuringiensis (10 1–10 3 cfu/ml) was isolated from grape juice and fermenting grape juice in a commercial winery. Although B. thuringiensis remained viable when inoculated at 10 3–10 4 cfu/ml into grape juice and wine (pH 3.0–6.0), it did not grow. Using in vitro agar culture assays, B. thuringiensis inhibited several grape-associated yeasts and bacteria as well as various species of fungi associated with grape spoilage and ochratoxin A production. B. thuringiensis did not inhibit Saccharomyces cerevisiae in agar culture or during alcoholic fermentation of grape juice. B. thuringiensis inhibited the malolactic bacterium, Oenococcus oeni, in agar culture but not during mixed cultures in a liquid medium.

Survey of molecular methods for the typing of wine yeast strains

A survey of the genetic polymorphisms produced by distinct methods was performed in 23 commercial winery yeast strains. Microsatellite typing, using six different loci, an optimized interdelta sequence analysis and restriction fragment length polymorphism of mitochondrial DNA generated by the enzyme HinfI had the same discriminatory power: among the 23 commercial yeast strains, 21 distinct patterns were obtained. Karyotype analysis gave 22 patterns, thereby allowing the discrimination of one of the three strains that were not distinguished by the other methods. Due to the equivalence of the results obtained in this survey, any of the methods can be applied at the industrial scale.

Impact of Yeast Strain on the Production of Acetic Acid, Glycerol, and the Sensory Attributes of Icewine

High concentrations of volatile acids, consisting mainly of acetic acid, are often found in icewine. Wine yeasts produce acetic acid as a by-product of the hyperosmotic stress response caused by high sugar concentrations (&gt;35 Brix) in grape must. Volatile acid levels in icewine often exceed legal limits. We compared seven commercially available wine yeast strains (ST, N96, Vin13, Vin7, EC1118, 71B, V1116) for icewine production. Yeast strains were evaluated for acetic acid and glycerol formation, fermentation rates, and sensory characteristics. Fermentations were conducted using both synthetic grape must and Riesling icewine grape must obtained from a commercial winery. Fermentations were conducted until approximately 11% (v/v) ethanol was produced. The yeast strains fermented Riesling icewine must at different rates and fermentations were completed in 17 to 49 days. Acetic acid and glycerol formation were significantly different (<i>p</i> &lt; 0.05) and linked to the yeast strain. Sensory analysis of the icewines produced with the different yeast strains showed significant differences for overall quality, perceived sulfur-like aroma, and color (<i>p</i> &lt; 0.05). ST, N96, and EC1118 were identified as the most suitable yeast strains for the production of icewine.

2000/2001 Survey of Winery Laboratory Proficiency

In 2000, the ASEV Technical Projects Committee's (TPC) Laboratory Proficiency Testing Guidance Committee established a continuous and frequent interlaboratory proficiency-testing scheme for the American wine industry. Results are reported for the first six rounds of the ASEV Laboratory Proficiency Testing Program for nine standard wine analyses performed in commercial winery laboratories. Proficiency was tested for analysis of ethanol, total and free sulfur dioxide, titratable acidity, volatile acidity, specific gravity, pH, residual sugar, and L-malic acid. The wineries were free to choose their methods of analysis, and the participants remained anonymous. Depending upon the assay, from 31 to 56 wineries participated, representing more than 90% of United States wine production capacity. The proficiency test showed satisfactory results in all rounds for the analysis of ethanol in wine with coefficients of variation among the wineries of 1.2 to 1.9%. The coefficients for titratable acidity (2.1 to 4.2%) and specific gravity (1.3 and 4.4% adjusted for table wine) were relatively low, but for the sulfite measurements, free (12 to 29%) and total (5.2 to 16%), they were considerably high. pH measurements on a logarithmic scale varied 5.7 to 9.1%. The combined relative errors for free SO2 and pH were between 19 and 39%, impacting the presence of sufficient amounts of molecular SO2 in the wines. Proficiency in the analysis of volatile acidity (6.7 to 25%) and malic acid (3.9 to 34%) was inadequate, as were the results for residual sugar (8 to 39%). The statistical results of the proficiency-testing program suggest a continuing need for improved laboratory quality-management systems. As a next step, wineries need to establish performance criteria for the different wine analyses that reflect the significance of their accuracy and precision for the quality and stability of wine. Acknowledgments: The ASEV TPC Laboratory Proficiency Testing Guidance Committee (Glenn Andrade, Gordon Burns, Christian Butzke, Janice Byington, George Peterson, Ray Walker) acknowledges the wineries who participated in the ASEV Laboratory Proficiency Testing Program, especially those who provided the commercial wines for the first six test rounds (E. & J. Gallo Winery, Trinchero Family Estates, The Wine Group, Ironstone Vineyards, Bronco Wine Company, Delicato Vineyards). Furthermore, the committee recognizes Terry Lee, E. & J. Gallo Winery, for chairing the original TPC subcommittee Analytical Quality and for his industry leadership and vision. We thank Patricia Howe, formerly of Ascent Laboratory, and Sue Weeks, Bibber International, for their valuable advice and participation in the ASEV TPC Winery Interlab Group meetings and the Preharvest Wine and Grape Quality Air and Road Show 2001. We are grateful to Christopher Czyryca, Collaborative Testing Services, for his management of the program and the preparation of the survey reports, a summary and analysis of which is presented here.

Use of WL Medium to Profile Native Flora Fermentations

Vineyard, winery, barrel, and controlled temperature fermentation samples from a single commercial winery (Luna Vineyards) conducting fermentations with indigenous organisms were plated onto Wallerstein Laboratory Nutrient Agar (WL) to evaluate colony diversity. Seventeen unique colony morphologies were identified. Sequence analysis of the DNA encoding a portion of the large ribosomal 26S rRNA indicated that the colony types defined members of six genera: <i>Hanseniaspora uvarum</i> (<i>Kloeckera apiculata</i>), <i>Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia kluyveri, Candida olephelia</i>, and <i>Metschnikowia.</i> Distinct colony subtypes were identified within the pulcherrimin producers traditionally classified as a single species, <i>Metschnikowia pulcherrima</i>. Sequence analysis of the D1/D2 region of the 26S rDNA of these biotypes showed a high degree of divergence, suggesting that these organisms might define separate species. Analysis of fermentations revealed that colony type as indicated on this medium could be used to monitor the yeast population dynamics.

RAPD marker polymorphism among commercial winery yeast strains

Random amplified polymorphic DNA (RAPD) analysis was employed to characterize commercial winery yeast strains currently used in Brazilian industries and to examine the relationship between them. Sixteen strains were subjected to RAPD analysis using eight primers, selected from the 40 primers of the kits B and X of Operon Techn. From the total of 93 scorable bands, 39 (41.9%) were polymorphics. Using the accumulated information of several reactions, all strains under investigation were differentiated. Cluster analysis revealed three groups. Most of the strains (11) were clustered in one group. The highest distance (28%) was obtained with the strain Redstar (Universal Food Corp.).

Survey of Analytical Methods and Winery Laboratory Proficiency

Results of a survey of methods of analysis for five basic measurements of wine composition (pH, titratable acidity, volatile acidity, ethanol, and residual sugar) used in commercial winery laboratories are reported. A laboratory proficiency test was conducted with cooperating wineries for the same measurements. The proficiency test showed satisfactory results for the analysis of pH and ethanol in wine with coefficients of variation between wineries of 1.2% and 1.8%, respectively. Less than 20% of the wineries were proficient in measuring titratable acidity or volatile acidity. The range of reported volatile acidity concentrations varied more than two-fold. The analysis for residual sugar yielded unsatisfactory results, with a coefficient of variation of 140% and reported values ranging from 0.01 to 4.0 g/L. The results of this preliminary proficiency test suggested a need for improved laboratory quality management systems, especially with respect to analytical method standardization and validation, and for the establishment of proficiency testing program for American wineries. An "ASEV Winery Laboratory Quality Systems" CD-ROM was developed to guide wineries from the first steps of setting up a quality management system all the way to winery lab accreditation, and a continuous and frequent inter-laboratory proficiency testing scheme has been established.

White Wine Composition and Quality as Influenced by Method of Must clarification

Grapes were crushed at a commercial winery, divided, treated with and without pectic enzymes, and clarified in several ways. Five-gallon lots were fermented under controlled conditions. The composition of the wines was changed slightly by the treatments. The main differences were in the sensory characteristics. Two distinct styles of wine resulted. Those clarified rapidly were light and very fruity. Those with longer solids contact time were highly flavored and complex. It was concluded that it would be up to the winemaker to determine style since the wines were not significantly different in absolute qualities.

White Wine Composition and Quality as Influenced by Method of Must clarification

Grapes were crushed at a commercial winery, divided, treated with and without pectic enzymes, and clarified in several ways. Five-gallon lots were fermented under controlled conditions. The composition of the wines was changed slightly by the treatments. The main differences were in the sensory characteristics. Two distinct styles of wine resulted. Those clarified rapidly were light and very fruity. Those with longer solids contact time were highly flavored and complex. It was concluded that it would be up to the winemaker to determine style since the wines were not significantly different in absolute qualities.

Influence of different yeasts on the growth of lactic acid bacteria in wine.

AbstractThe influence of various yeasts on the growth of lactic acid bacteria in wine was tested by inoculating Lactobacillus hilgardii, L. brevis and two strains of Leuconostoc mesenteroides into experimental wines made with twelve different yeasts of the genus Saccharomyces. Wines made from juice which had been infected with several spoilage yeasts and then fermented with a wine yeast were also tested in this way. It was found that the yeasts differed considerably in their effects on bacterial growth. In some of the experimental wines bacterial growth was delayed or failed altogether. Generally, the unfavourable influence of any yeast on bacterial growth was much reduced if the wines were left in contact with the yeast cells for some weeks after the fermentation.The significance of these results in relation to the occurrence of malo‐lactic fermentation in commercial wineries is discussed.