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Vino je po končani alkoholni fermentaciji moten in nestabilen medij, ki ga je potrebno stabilizirati, da ohranimo njegovo kakovost do porabe. Namen magistrske naloge je bil spremljanje spontane beljakovinske in tartratne stabilizacije dveh mladih belih vin v treh različnih zorilnih posodah. Beljakovinsko in tartratno stabilnost vina smo spremljali z analizami vrednosti pH, skupnih (titrabilnih) kislin, posameznih organskih kislin, koncentracije mineralov kalija in kalcija, s toplotnim testom beljakovinske stabilnosti, s konduktometrično določitvijo tartratne stabilnosti in z merjenjem specifične električne prevodnosti. Na koncu praktičnega dela smo izvedli senzorično analizo vzorcev vina s petčlansko strokovno komisijo po 100-točkovni OIV metodi. Beljakovinska in tartratna stabilnost sta se vsem vzorcem vina med poskusom zorenja konstantno izboljševali. Na koncu poskusa sta se obema vinoma najbolj izboljšali z zorenjem v barrique sodih. Kisik pozitivno vpliva na doseganje tartratne stabilnosti in na doseganje beljakovinske stabilnosti, vendar v kombinaciji s spojinami iz lesa. Noben vzorec na koncu ni dosegel tartratne stabilnosti, saj je spontana stabilizacija dolgotrajen proces. Pri senzorični analizi vzorcev so najslabšo skupno oceno dosegli vzorci vina, ki so zoreli v barrique sodih. Wine is a turbid and unstable medium after completion of alcoholic fermentation, which needs to be stabilized in order to maintain its quality until consumption. The purpose of the master's thesis was to monitor spontaneous protein and tartrate stabilization of two young white wines in three different maturation vessels. Protein and tartaric stability of wine were monitored by analysis of pH value, total (titratable) acidity, individual organic acids, the concentration of two minerals, potassium and calcium, by heat test of protein stability, conductometric determination of tartrate stability and measurement of specific electrical conductivity. At the end of the practical part, we performed a sensory analysis of wine samples with a commission consisting of five experts using 100-point OIV method. Protein and tartaric stability was constantly improving during maturation of all wine samples. At the end of the experiment, both wines improved the most by maturing in barrique barrels. Oxygen has a positive effect on achieving tartrate stability and has a positive effect on achieving protein stability, but in combination with woods compounds. No sample ultimately achieved tartrate stability, as spontaneous stabilization is a lengthy process. The sensory analysis revealed the worst overall score was given to wine samples matured in barrique barrels.

Submitted by Ana Rebelo (amsr@isep.ipp.pt) on 2019-11-07T16:04:16Z No. of bitstreams: 1 DM_AnaSilva_2019_MEQ.pdf: 4878171 bytes, checksum: cfda817413a1e292ba5439c8066f6f36 (MD5) Approved for entry into archive by Ana Rebelo (amsr@isep.ipp.pt) on 2019-11-07T16:04:31Z (GMT) No. of bitstreams: 1 DM_AnaSilva_2019_MEQ.pdf: 4878171 bytes, checksum: cfda817413a1e292ba5439c8066f6f36 (MD5) Made available in DSpace on 2019-11-07T16:04:31Z (GMT). No. of bitstreams: 1 DM_AnaSilva_2019_MEQ.pdf: 4878171 bytes, checksum: cfda817413a1e292ba5439c8066f6f36 (MD5) Previous issue date: 2019

Tartaric precipitation in bottled wine is an important problem for the wine industry by the sensory undesirable aspect and, therefore, wineries employed several treatments to prevent this precipitation to satisfy the quality criteria of wine consumers. For example, according to Resolution 43/2000 [1], the addition of certain stabilizers, such as metatartaric acid and carboxymethylcellulose (CMC) or the treatment of the wine with ion exchange resins, are accepted and have been successfully used to prevent tartaric precipitation in white and red wine [2,3]. However, there are few studies regarding rosé wine. The main difference concerning these two stabilization processes is that the ion exchange resins removes the compounds that contribute to tartrate instability. Anion exchangers are not allowed by the OIV [1] due to the negative effects on the wine physiochemical and sensory quality [4,5]. Therefore, the aim of this study was to evaluate the effect of cation exchange resins on rosé wine tartaric stabilization efficiency and wine sensory quality compared to the effect of the addition of different enological stabilizers. In this study a rosé wine from the Douro Valley demarcated region, 2015 vintage, was used, and ion exchange resin versus tested concerning their tartaric stabilization efficiency and sensory quality. In this work almost 30% from the total rosé wine volume was treated by ion exchange resins. As expected, all treatments assayed stabilized the rosé wine. The cation exchange resins process could be a useful tool to maintain wine quality, as the sensory analysis data showed. Main differences were obtained for the wine visual descriptor, namely limpidity attributes, which was higher scored in the wine treated with ion exchange resins. These results show that ion exchange resins could be an interesting process for rosé wine tartaric stabilization. This work was funded by the Chemical Research Centre (CQ-UTAD). Additional thanks to AEB Bioquímica Portuguesa info:eu-repo/semantics/publishedVersion

Submitted by Ana Rebelo (amsr@isep.ipp.pt) on 2018-04-17T10:37:44Z No. of bitstreams: 1 DM_AnaBessa_2017_MEQ.pdf: 4147695 bytes, checksum: 15a44a1652174112af6278de0bc09fe2 (MD5) Approved for entry into archive by Ana Rebelo (amsr@isep.ipp.pt) on 2018-04-17T10:38:07Z (GMT) No. of bitstreams: 1 DM_AnaBessa_2017_MEQ.pdf: 4147695 bytes, checksum: 15a44a1652174112af6278de0bc09fe2 (MD5) Made available in DSpace on 2018-04-17T10:38:07Z (GMT). No. of bitstreams: 1 DM_AnaBessa_2017_MEQ.pdf: 4147695 bytes, checksum: 15a44a1652174112af6278de0bc09fe2 (MD5) Previous issue date: 2017

El vino debe estabilizarse respecto de las precipitaciones del bitartrato de potasio. Uno de los métodos de estabilización más empleado es la formación del precipitado por efecto del frío con siembra de cristales. Este método tiene un alto costo. La estabilización por electrodiálisis es un método alternativo, que consiste en eliminar el catión potasio, por medio de una membrana selectiva y un campo eléctrico, y así se impide la precipitación del bitartrato de potasio. El objetivo de este trabajo fue determinar si los vinos estabilizados mediante el tratamiento de frío por método de contacto difieren de los vinos estabilizados por electrodiálisis en cuanto a sus características físico-químicas y organolépticas. Se realizaron dos ensayos a nivel industrial: uno con 4 vinos blancos y otro con 3 vinos tintos. Todos los vinos se estabilizaron mediante tratamiento de frío por método de contacto (FMC) y por electrodiálisis (ED). El diseño estadístico fue bloques completos al azar. Los vinos blancos estabilizados por ED presentaron menores concentraciones de Ca+2 y Mg+2 que los FMC. Los vinos estabilizados por FMC contuvieron menos K+ que los vinos estabilizados por ED. Los vinos tintos estabilizados por FMC presentaron menor contenido de SO2 libre que los tratados con ED. Un panel de degustadores no encontró diferencias entre ambos tratamientos en vinos blancos, ni en tintos. Es posible reemplazar el tratamiento de estabilización tartárica FMC por ED. Se producen mínimas modificaciones de las características físico-químicas de los vinos, pero estos cambios no son detectados por medio del análisis organoléptico. Wine has to be stabilized in respect of potassium bitartrate precipitations. One of the most used methods of stabilization is the precipitate formation as a result of cold with crystal seeding. This method implies an elevated cost. The stabilization by electrodialysis may be an alternative, which consists in removing the potassium cation, through a selective membrane and an electric field, so as to prevent the precipitation of potassium bitartrate. The purpose of this project was to determine if wines stabilized with respect to tartaric precipitations through cold stabilization by contact process are different from wines stabilized by electrodialysis, concerning their physics-chemical and organoleptic characteristics. Two industrial tests were carried out: one of them included 4 white wines and the other with 3 red wines. All wines were stabilized by cold stabilization by contact process (FMC in Spanish) and electrodialysis (ED). The tests were conducted using a randomized block statistical design. The white wines stabilized by ED have lower concentrations of Ca+2 and Mg+2 than those stabilized by FMC. The wines stabilized by FMC contain less K+ than the wines stabilized by ED. The red wines stabilized by FMC have lower concentrations of free SO2. A panel of tasters found no difference between both treatments, neither in white wines nor in red wines. Therefore, it is possible to replace the tartaric stabilization by contact process (FMC) with ED. Although minimum changes are produced in the physics-chemical characteristics of wines, these changes are not detected by means of the organoleptic analysis. Fil: Corti, Silvia Violeta. Fil: Paladino, Silvia Cristina. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Cátedra de Enología I.

Industrial minerals, particularly bentonites, have long been used in treatments to improve the stability and shelf life of white wines. We evaluated a new combination of rocks and minerals, including steam-treated bentonites and natural zeolites (chabazite and phillipsite), to greatly reduce the risk of protein and tartaric instability of wines. Detailed mineralogical, chemical and electrokinetic studies of these materials were conducted using powder X-ray diffraction (PXRD), X-ray fluorescence (XRF), microporosimetry, BET surface-area analysis and zeta-potential measurements. Several model wine solutions containing Bovine Serum Albumin (BSA) were prepared to evaluate the oenological performance of the rock/mineral combinations. UV-VIS spectrophotometry and ion chromatography were used to evaluate the degree of wine stabilization from the protein and tartaric point of view.The experimental results showed that steam treatment modifies both the microporosity and external surface area of the bentonite. These changes in surface area, along with creation of hydrophobic surfaces, significantly modified the behaviour of the steam-treated bentonites, requiring an increase in the amount of material necessary to bring the protein content to required levels. An important benefit derived from the use of steam-treated bentonites is that the pre-mixing with water before addition to wine is not necessary, as the material is readily dispersed. Finally, the addition of natural zeolites effectively decreased the potassium content, thereby improving the tartaric stability of white wines. In addition, this procedure results in minimal waste, as the bentonite-zeolite mixture can be reused as soil amendments in agriculture.

A instabilidade do vinho em relação ao ácido tartárico e seus sais é ainda um problema para os produtores de vinhos, sendo a estabilização tartárica dos mesmos, uma prática corrente em enologia. A eliminação de uma fração do ácido tartárico é geralmente conseguida pela sua precipitação pelo frio, com intervenção de catiões presentes no vinho, nomeadamente potássio (K) e cálcio (Ca). Existem no entanto outras alternativas, como por exemplo resinas de troca iónica que removem os catiões K e Ca, evitando a precipitação do ácido tartárico. Este estudo pretende contribuir para a compreensão do fenómeno de precipitação deste ácido nas formas de tartarato de cálcio e de hidrogenotartarato de potássio, avaliando a estabilidade tartárica em diferentes vinhos brancos e tintos, de seis ensaios feitos à escala industrial com recurso a um equipamento de troca iónica de permutadores catiónicos, comparativamente a outras técnicas tradicionais de estabilização tartárica, como sejam o tratamento pelo frio e o tratamento com a adição de ácido metatartárico. O estudo efetuado permitiu concluir que a utilização do equipamento de troca iónica conduz a vinhos estáveis do ponto de vista tartárico, sendo que as principais alterações nas características dos vinhos se verificam nos valores de pH e da acidez total, com consequências na cor dos vinhos, especialmente no caso dos vinhos tintos; Tartrate Stabilization of Wine Abstract: Wine instability concerning tartaric acid and its salts is still a difficult problem for wine producers, as tartaric stabilization is a normal practice in winemaking. The elimination of some tartaric acid occurs normally through its precipitation at low temperatures, with intervention of cations present in wine, mainly potassium (K) and calcium (Ca). Nowadays ion exchange resins can be used to remove K and Ca cations, avoiding tartaric acid precipitation. This study aims to gain insight of tartaric acid precipitation phenomena, either in the form of calcium tartrate or potassium hydrogen tartrate, evaluating the tartaric stability of white and red wines using an equipment of ion exchange and comparing it with the traditional tartaric stabilization methods, cold stabilization and metatartaric acid. Tartaric acid content by HPLC and cations by flame atomic absorption spectrometry were determined. Tartaric stability was evaluated by mini contact and saturation temperature methods. With the use of the ion exchange resins, stable wines were obtained. Differences in pH and total acidity were also observed with consequences in color, especially regarding red wines.

Tartaric instability of wines still represents a serious problem in terms of the commercial value of bottled wines, particularly whites, leading consumers to be suspicious as regards the effective healthiness or wholesomeness of products. The study, carried out on 536 Italian wines, investigated the potential of using Fourier Transform Infrared Spectroscopy, distinguishing between white and red/rose wines, to create models predicting the instability of wines, assessed in comparison to two of the most widespread methods of reference: the “mini-contact test” (10 min, 0 °C, KHT) and the “cooling test” (5 days, −4 °C). The models proposed, constructed using 80% of the samples and based on Partial Least Squares-Regression and Artificial Neural Networks, were shown to work well in terms of correct classification (from 89% to 97%) of the external validation subset (20%). As regards the more problematical question of technical management of wines before bottling, in the worst cases only 4–6% of unstable samples were erroneously classified as stable.

Mestrado Vinifera EuroMaster - Instituto Superior de Agronomia The sensitivity of metatartaric acid (MA) to high temperatures is the main limit for its actual use in enology. For this reason MA is generally used only for ready-to-drink wines that are stored for few months in bottle. The objective of this work was to obtain more information about the use of MA in order to prevent tartaric salts precipitation in wine by monitoring its effectiveness along the time. Tartaric stability was followed in a white wine during a ten-week experiment. 10 g/Hl of MA was added to wines with different five pH values, namely 3.0, 3.2, 3.5, 3.7 and 3.9 at room temperature (20°C), and to wines at original pH of 3.2 under three different temperatures commonly found in real storage conditions, precisely 12°C, 20°C and 35°C. To monitor tartaric stability we used a test based on the electrical conductivity developed by Boulton (1983). At the end of the experiment we found both a pH and a temperature effect. It was found a polynomial relation (R2 = 0,85) between tartaric stability and pH. The highest the pH, the highest the instability and the shortest the protection against tartrates precipitation. Furthermore, over 20°C we observed a rapid general decrease of MA effectiveness and that there was a linear relation (R2 = 0,99) between temperature and tartaric stability, so that we can affirm that the highest the temperature, the higher the wine instability; this is probably due to a faster MA hydrolysis. Metatartaric acid is surely able to prevent tartrates precipitation, but since in our experimental conditions it could not protect the wine for longer than one month, we would suggest extreme prudence about its use especially during long storage periods

The purpose of this research is to provide a new mixture of Campanian zeolitized tuffs for solving two specific problems in the production of white wines: the protein and tartaric stability. In fact, a very frequent cause of turbidity and formation of organic deposits in white wines is the occurrence of thermolabile and thermostable proteins colloidal suspensions which precipitate in time, especially in summertime and during the storage and transport. Normally, to mitigate this risk wine producers use organic and inorganic stabilizers and clarifiers. The best known treatment, recognized also by the International Organisation of Vine and Wine (OIV) foresees the use of bentonite with a montmorillonite content not lower than 80%. The present paper aims at evaluating the use of two high zeolite grade Italian volcanoclastites such as the Neapolitan Yellow Tuff (NYT) and the Yellow Facies of the Campanian Ignimbrite (YFCI), in the treatment of three peculiar white wines of the Campanian region (Southern Italy): Falanghina, Fiano di Avellino and Greco di Tufo. Granulates were produced starting from tuff blocks as provided by quarries. Some grain size fractions have been prepared to investigate the zeolite content (phillipsite + chabazite + analcime) by X-ray diffraction (XRD). A 2-5 mm grain size fraction was chosen for NYT and a 5-10 mm for YFCI. Three Campanian monocultivar white wines were used for the test: the Falanghina 2006 vintage, the Fiano di Avellino DOCG 2007 vintage, and the Greco di Tufo DOCG 2008 vintage. 48 samples with mixture of the zeolitized tuffs, 1 sample with mixture of a synthetic zeolite A and 1 sample with mixture of a commercial sodium activated bentonite were prepared. ICP-OES analysis for the determination of ECEC, Ion Chromatography (IC) analyses for the determination of some major cations and Turbidimetric tests for the definition of the protein stabilization process before and after treatments were also carried out. It was evidenced that high zeolitized tuff/wine ratios enable the protein stabilization whereas a significant decrease of potassium ion after the treatment with a zeolite-rich powder improves the tartaric stability, a serious problem in all the wine productions. The results of these tests refer to a laboratory scale research. A transfer of the experiment to a pilot plant scale is in progress.

Some mannoproteins which are extracted by enzymatic hydrolysis of yeast's cell wall with the aid of commercial preparation composed with beta-glucanases (Glucanex™) inhihits the tartaric acid's salt breakdown in model solution as well as in wines for an addition between 10 and 25 g/hl. On the other hand, heat extracted mannoproteins arc inactive on the tartaric precipitation stabilization. Furthermore, the crystallization inhibitor activity of the enzymatic extracted mannoproteins is due to the presence of sharply glycosylated mannoproteins of mediummolecular weight (30 to 50 kda) which are not heat extracted. That is why the heat extracted mannoproteins are inactive. The enzymatic extracted mannoproteins are produced at a pilot plan. This preparation (Mannostab™), soluble in wines, colourless and without any flavour, stabilize with the same efficiency than a freeze treatment and this effective live is superior to the metatartric acid. Moreover, the necessary steps were been taked to permit experimentally this new product : Mannostab™