Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 47-48). Also available via the Internet.

Low nitrogen Chardonnay juice from an Oregon winery was fermented with a series of nutrient supplements, including diammonium phosphate (DAP), Fermaid K, Superfood, yeast extract, yeast hulls and thiamine. These treatments were evaluated for their contribution to the yeast assimilable nitrogen content (YANC) of the juice, which consists of the ammonium ion and α-amino acid content by NOPA (nitrogen by ophthaldialdehyde). The fermentation characteristics and the nutritional and chemical status of the finished wines were compared. Diammonium phosphate added 25 mg N/L from ammonia for every pound/1000 gallons (12.5 g/hL) used. Commercial yeast nutrient preparations were found to contribute around 10 mg N/L from ammonium ion per pound/1000 gallons (12.5 g/hL). NOPA and HPLC analysis of Superfood and Fermaid K indicated that they contributed only a small amount of amino acids. NOPA analysis of PL-50 yeast extract indicated that it may have added some nitrogen from amino acids. Nitrogenous compounds were taken up within the first few days of fermentation. Ammonium ion was depleted very quickly and did not reappear later in fermentation. Alpha-amino acids reached a low within approximately ten days of fermentation, then leveled out or increased towards the end of fermentation. Treatments containing high amounts of ammonia were observed to produce the most vigorous fermentations. These treatments were found to have the highest apparent levels of amino acids at the end of fermentation. The Control treatment, which had the lowest YANC content, appeared to utilize proline during fermentation. Sensory analysis was not conducted on the finished wines due to replication differences in reduced sulfur aroma found in preliminary screening. GC-MS analysis showed that the higher nitrogen treatments had levels of reduced sulfide compounds that were above sensory threshold, whereas moderate nitrogen treatments did not. Ethyl carbamate was not found in any of the finished wines. These data suggest that moderate levels of supplementation had a positive effect on both fermentation and finished wine quality. Higher levels of nutrient addition were effective at increasing fermentation rates but negatively affected the sulfide profile of finished wines. / Graduation date: 2001

The wine yeast Saccharomyces cerevisiae experiences a range of stress conditions during wine fermentation. These stresses include osmotic stress, hypoxia, nutrient starvation, cold stress and increasing ethanol stress as fermentable sugars are converted to ethanol. These various stresses affect the functionality of the plasma membrane, cell wall and subsequently the yeast’s efficiency during fermentation. Etp1, a poorly characterized protein has been shown to have several different fermentation related phenotypes; it is needed for the turnover of the hexose transporter Hxt3 upon a shift from glucose to ethanol, and the transcriptional activation of the stress response genes HSP12 and HSP26 under ethanol stress. The molecular function of Etp1 during fermentation is not understood. This research aims to understand the molecular mechanism of Etp1 function and its involvement in Chardonnay fermentation using the S. cerevisiae M2 wine yeast strain. / OMAFRA, Genome Canada

Hard red duplex soils (HRDS) cannot sustain economically productive vineyards without careful management. An experiment was conducted at Rosbercon Vineyard, Picola from 1995 to 1998 in a vineyard block of Chardonnay on Ramsey rootstock planted in 1972. The hypotheses tested were: a) transient waterlogging decreases root growth and grapevine performance, and b) hardening of soil decreases root growth and grapevine performance. (For complete summary open document)

This thesis discusses the use and effectiveness of fertilizers VIVE series of viticulture. For the experiment were selected white grape variety Chardonnay. This work includes four variants. Option 1 is the control and treatment without fertilizer. In Option 2 was used VIVE Super NPK fertilizer, in Option 3 it was fertilizer VIVE Super Ligno. In Option 4 was again used fertilizer VIVE Super NPK + wetting agent VIVE Wet and last option 5, it was fertilizer VIVE Ligno Super + wetting agent VIVE Wet. These variants were applied in the same terms and 28 days and 14 days before flowering. Then again 14 and 28 days after flowering. Comparison of all variants were performed on the base uvology and analytical values. Of uvology values measured weight of grapes from one bush, the weight of one grape, berry weight and 50 berries, and then even the weight of stem. The main indicators were selected analytical sugar content, acidity pH and assimilable nitrogen. Further analyzes were also performed sheets after the application of fertilizers. Results showed differences in nutrient content in the dry leaves between experimental and control variants fertilized variant. The best results in terms of nutrition were achieved in variants which used fertilizer VIVE Ligno Super Series. Compared with the control variant significantly increased the contents of macronutrients (+43,1%), secondary nutrients (78.4%) and micronutrients (+38.8%). It was demonstrated that the use of fertilizers to increase the yield of grapevine and reduced acidity. Achieving higher sugar after application of fertilizer series VIVE in this work confirmed, however, the yield increased. Preparations had a significant influence on the content of assimilable nitrogen, which is very important during fermentation must. Health status of grapes was good, which appeared in the analytical evaluation of pH, which is for all variants ranged from 3.16 to 3.21, but due to bad weather development was necessary to harvest crops early.

Natural, plant-based tannin antioxidants are capable of inhibiting lipid oxidation in ground beef and may be possible alternatives to industry synthetic and natural standards of BHA/BHT and rosemary extract, respectively. Ground beef was purchased on three different days, each defining a batch during study 1. Treatments, added based on meat weight, included a control, 0.2 percent rosemary (RM), 0.02 percent BHA/BHT, 0.5 percent Chardonnay grape seed flour (CG), 0.1 percent and 0.25 percent chestnut wood flour (CN), and 0.25 percent and 0.5 percent of four sorghum bran varieties: black (BS), black with tannin (BTS), white (WS), and high tannin (TS). Patties, formed in duplicate, were randomly designated as cooked or raw and by 0 to 5 day storage, and were aerobically stored at 4 degrees C. Cooked patties were analyzed using the TBARS method. Raw patties were analyzed for subjective and objective color, number of ingredient specks, and pH. In study 2, six treatments were chosen for sensory evaluation including a control, 0.2 percent RM, 0.02 percent BHA/BHT, 0.5 percent CG, 0.1 percent CN, and 0.5 percent BTS. Preparation, and raw and cooked analysis occurred similar to study 1. Additional patties were made for day 1 consumption by consumer panelists. In study 1, all treatments except 0.25 percent WS reduced TBARS values over time compared to 0.2 percent RM. Four treatments (0.5 percent BTS, 0.5 percent CG, 0.25 percent CN, and 0.1 percent CN) showed no significant increase in TBARS values over storage. BS and BTS yielded the lowest color space values (CIE L*, a*, and b*; P<0.0001). Ingredient specks were possible color measurement influences. In both studies antioxidant addition reduced TBARS values over time compared to the control (P<0.0001), and percent discoloration was highest in patties containing a sorghum treatment (P<0.0001). Patties containing 0.1 percent CN were significantly favored in terms of overall like (P<0.0002) and flavor like (P<0.0001). Patties containing 0.2 percent RM were ranked lowest in overall and flavor like, and ground beef-like bite. Patties containing 0.5 perent CG were least liked according to tenderness level (P<0.005). These results indicate that CG, CN, and certain varieties of sorghum bran can be added to pre-cooked ground beef products and provide better antioxidant protection than currently used ingredients of BHA/BHT and rosemary extract.

This paper assesses the influence of yeast agent on the final quality of wine. It consists of two main sections -- theoretical and practical. The Theoretical section explains where yeast is located, describes strains mportant for wine production, fermentation methods and factors that influence the process of fermentation. Next section is dedicated to the biochemistry of fermentation, constitution of wine and to aromatic substances. The last part describes enzymatic agents used for hydrolisis of pectins and glycosidic binding. The experimental part of the thesis describes production of Chardonnay. There is a description of analytical methods used and evalution of results in the form of a discussion in the concluding section.

Tesis para optar al Título Profesional de Ingeniera Agrónoma y al Grado de Magíster en Enología y Vitivinicultura / Actualmente la demanda agroalimentaria está en constante cambio, debido fundamentalmente, a que un segmento importante de los consumidores tiene acceso a más información y es consciente de su rol en la economía de mercado, lo que hace que sus preferencias varien todo del tiempo. Las propiedades organolépticas del vino ya no son una garantía del vino que será elegido en el momento de la compra. Ante estos hechos, la industria vitivinícola invierte a favor de lo que permita satisfacer de mejor manera la demanda por el producto. Esto se manifiesta tanto en el desarrollo de nuevos sistemas para producirlo, como en el diseño de los envases y los etiquetados, y en las vías de promoción del producto, como son las degustaciones y las atractivas ofertas de precios. El mercado ofrece vinos elaborados bajo dos sistemas: uno de tipo convencional y otro de tipo orgánico. Llama la atención que pese al éxito alcanzado por el método de tipo orgánico en Europa y en Estados Unidos, los consumidores chilenos no sigan esta tendencia. Esta investigación de tipo exploratoria, buscó conocer la posible existencia de diferencias de opiniones respecto a ambos métodos de producción del vino, entre 3 grupos de personas, y a la vez, proponer hipótesis que podrían ayudar a aumentar, entre los consumidores, la preferencia por los vinos de tipo orgánico. Para este propósito fueron encuestados 3 grupos de personas cuyos conocimientos sobre la producción, comercialización y aspectos gustativos (sensorial) del vino variaban. Un grupo estuvo formado por alumnos de la Escuela de Someliers de Chile. El segundo grupo estaba integrado por Enólogos calificados que trabajan en la producción de vinos. El tercer grupo estaba formado por personas que consumen vino, sin conocimientos técnicos de la producción. A la información obtenida de las encuestas se le aplicó un análisis descriptivo, el cual fue complementado con pruebas que permiten establecer diferencias estadísticas significativas, y se concluyó con un análisis sensorial descriptivo y con otro relativo a las preferencias por los vinos elaborados mediante alguno de los sistemas mencionados. Se observó diferencias entre los 3 grupos encuestados tanto en aspectos de la percepción de los sistemas de elaboración del vino, en la comercialización y también en aspecto sensoriales, aunque las diferencias estadísticas en este último no fueron significativas a nivel de encuesta. Sólo el grupo formado por los enólogos mostró coincidencias estadísticamente significativas en relación a las diferencias organolépticas establecidas en la encuesta entre ambos vinos y la degustación posterior, y fue el único grupo capaz de diferenciar los dos tipos de vino en la cata. Al analizar la preferencia al momento de comprar uno u otro tipo de vino, el principal factor considerado por los tres grupos fue el precio. Sin embargo, al conocer el tipo de vino y relacionarlo con el sistema de elaboración, los tres grupos mostraron preferencia por adquirir un tipo de vino orgánico cuyo valor en el mercado es de $5000 la botella. Esto podría demostrar que al tener la información sobre el sistema de producción, el consumidor preocupado por el medio ambiente, estaría dispuesto a pagar más por un vino orgánico que por uno convencional de la misma calidad.

Dans l’optique de comprendre et maitriser le vieillissement des vins, en particulier des vins blancs, il est nécessaire d’approfondir nos connaissances sur les mécanismes physico-chimiques d’oxydation liés aux processus d’oxygénation. Pour cela, il est important d’avoir des outils permettant la quantification de la capacité antioxydante des vins blancs, et l’identification des composés impliqués dans celle-ci, afin de pouvoir anticiper l’aptitude au vieillissement d’un vin.Lors de cette étude, des analyses de la capacité antioxydante par DPPH et Résonnance Paramagnétique Electronique (RPE) ont été réalisées sur un grand nombre de vins en cours d’élevage et issus de plusieurs millésimes. En parallèle des analyses métabolomiques, principalement par Chromatographie Liquide couplée à la Spectrométrie de Masse (UPLC-Q-TOF-MS) mais également par Spectrométrie de Masse à Résonance Cyclotronique des Ions et à Transformée de Fourier (FT-ICR-MS) ont été réalisées.L’optimisation de la méthode DPPH, pour l’analyse des vins blancs a révélé une réactivité importante des composés soufrés, avec des capacités antioxydantes similaires à celles des composés phénoliques. La comparaison de cette méthode optimisée à la méthode de référence du laboratoire (RPE) sur plus de 106 vins, a montré la complémentarité de l’information apportée par ces deux différentes méthodes de mesure de capacité antioxydante. Le traitement statistique des corrélations avec les analyses métabolomiques réalisées sur 287 vins a permis de révéler une liste de 380 marqueurs moléculaires associés à la capacité antioxydante des vins. Une méthode alternative de mesure du potentiel antioxydant des vins blancs a également été développée, qui repose sur l’identification de composés nucléophiles naturellement présents et susceptibles de piéger les quinones formées au cours de mécanismes d’oxydation. Outre des composés soufrés, nous avons montré que différents peptides ayant des propriétés antioxydantes présentent de telles propriétés nucléophiles. Dans un second temps, l’étude de différentes pratiques œnologiques (élevage, hyperoxygénation ou sulfitage) a permis de déterminer leurs impacts sur la capacité antioxydante des vins mais également sur les marqueurs moléculaires associés. Il apparait ainsi une augmentation significative de la capacité antioxydante des vins au cours de l’élevage. De plus, cette augmentation de la capacité antioxydante est associée à une consommation de peptides en début d’élevage, ainsi qu’à l’apparition de nouveaux composés dans les vins et ce indépendamment du millésime. Les composés qui apparaissent semblent être majoritairement des composés phénoliques provenant potentiellement du bois ou de l’autolyse des levures. Les vins issus de moûts protégés par l’ajout précoce de sulfites ont une capacité antioxydante plus élevée par rapport aux vins issus de moûts hyperoxygénés. De plus, la protection du moût à un impact important sur la composante moléculaire soufrée retrouvée dans les vins. Ainsi, il a été observé une quantité beaucoup plus faible de composés soufrés (peptides ou non) dans les vins issus de moûts hyperoxygénés montrant donc une consommation de ces composés dans les mécanismes d’oxydation du vin. En résumé, ces résultats révèlent pour la première fois l’importance des composés soufrés dans les mécanismes de protection des vins blancs de Bourgogne vis-à-vis de l’oxydation, par leur capacité de piégeur de radicaux mais également de piégeur de quinones. / In order to understand and control the aging of wines, particularly white wines, it is necessary to deepen our knowledge about the physico-chemical mechanisms of oxidation related to oxygenation processes. For this, it is important to have tools to quantify the antioxidant capacity of white wines, and to identify the compoiunds involved, in order to anticipate the aging ability of a wine.In this study, analyzes of the antioxidant capacity by DPPH and Electron Paramagnetic Resonance (EPR) were carried out on a large number of wines during aging and from several vintages, in parallel with metabolomic analyzes, mainly carried out by Liquid Chromatography Coupled to Mass Spectrometry (UPLC-Q-TOF-MS) but also by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS).Optimization of the DPPH method for the analysis of white wines, showed a high reactivity of sulfur compounds with similar antioxidant capacities to those of phenolic compounds. The comparison of this optimized method with the laboratory reference method (EPR) on more than 106 wines, showed the complementarity of the information provided by these two different methods of measuring an antioxidant capacity.Combining antioxidant capacity measurements and metabolomic analyzes, it was possible to determine a list of molecular markers related to the antioxidant capacity of white wines. During this study, a focus on nucleophilic compounds present in wines has also been realized, these compounds being able to react with the quinones formed during oxidation and thus to play a role in the oxidation mechanisms of white wines. Besides sulfur compounds, we showed that several peptides with antioxidant properties could exhibit such nucleophilic behavior. In a second step, the study of different oenological practices (aging, hyperoxygenation or adding SO2 to must) allowed to determine their impacts on the antioxidant capacity of wines but also on the associated molecular markers. It thus appears a significant increase in the antioxidant capacity of the wines during aging. In addition, this increase in antioxidant capacity is associated with a consumption of peptides at the beginning of aging, but also with the appearance of compounds in wines, regardless of the vintage. The compounds that appear are potentially phenolic compounds which can come from wood or lees autolysis. Wines from protected musts with sulfites addition, have a higher antioxidant capacity compared to wines from hyperoxygenated musts. In addition, the protection of musts has a significant impact on the sulfur component found in wines. Thus, a much smaller amount of sulfur compounds (peptides or not) has been observed in wines derived from hyperoxygenated musts, showing a consumption of these compounds in the oxidation mechanisms. Overall, these results reveal for the first time the importance of sulfur compounds in the mechanisms of protection of white wines from Burgundy against oxidation, by radical scavenging capacity and quinone trapping.

Hen egg white lysozyme is a hydrolytic enzyme effective at preventing the growth of Gram positive bacteria by degrading the bacterial cell wall to a point of cell lysis. Investigating lysozyme as a processing tool in wine to control the growth of lactic acid bacteria and malolactic fermentation has significant commercial interest. In this project, the interactions of lysozyme with wine components and wine was evaluated along with the efficacy of lysozyme in preventing malolactic fermentation (MLF) in Oregon Pinot Noir and Chardonnay. The information from this work, together with results from similar projects, will allow the development of guidelines for lysozyme use in commercial wine. Interactions of lysozyme with wine components were evaluated by measurement of enzymatic activity in the presence of wine acids, ethanol, and phenolics. Enzyme inhibition was observed, to various degrees, with all wine components. Crude grape tannin altered the availability of free enzyme by complexing to lysozyme and forming a precipitate. In a model wine system, lysozyme activity was reduced by 50% when tannin was present. Lysozyme addition to red wine resulted in a reduction in pigmented compounds and detectable sensory differences. Wine trials evaluated the efficacy of lysozyme in completely preventing malolactic fermentation (MLF) and terminating MLF midway through fermentation in Oregon Pinot Noir and Chardonnay. Vintages from 1993 and 1994 were treated without SO₂, with SO₂, with SO₂ plus a starter culture of Leuconostoc oenos. Each lot was divided into 0 ppm lysozyme (control), 250 ppm lysozyme, 500 ppm lysozyme, and 1000 ppm lysozyme. Lactic acid bacteria were enumerated monthly, for ten months. Lysozyme prevented malolactic fermentation in all wines at the treatment levels of 500 and 1000 ppm. In the 1993 Pinot Noir, 250 ppm lysozyme prevented MLF but only delayed MLF in the 1994 vintage. Lysozyme effectively terminated MLF at a concentration between 200 and 300 ppm in both Pinot Noir and Chardonnay. / Graduation date: 1996