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Analytical Note The present work describes the development and validation of a high pressure microwave-assisted mineralization procedure for the determination of metals in grape must by spectrometric techniques. Metals of special oenological and food safety importance (Al, Co, Cu, Cd, Pb) were used as model elements to achieve the optimum working conditions. The study was conducted by monitoring their concentration in experimental samples by ETAAS. Different combinations of HNO3 and H2O2 were tested and an optimal volume of 1 mL of each reagent, added to 2 mL of sample, was selected for further studies. In comparison with experimental conditions described in literature for the mineralization of grape must and wine by HPMW, the proposed procedure requires very low reagent consumption. Time and temperature were regarded as factors in the optimization study of microwave oven program, resulting in 72 minutes of extension including ventilation. The procedure trueness and precision were evaluated using grape must and wine samples. For each element three different levels of addition were performed. The recovery range was from 94% (Co) to 113% (Pb) in grape must and from 96% (Cu) to 128% (Al) in wine. Relative standard deviations ranged from 1% (Cd) to 11% (Al) in grape must and from 2% (Cd, Pb) to 9% (Co) in wine (n = 10). The proposed procedure is suitable for grape must and wine mineralization with a view to trace element analysis.

A descrição de uma prática enológica deverá conter o seu objectivo, o seu campo de aplicação, os limites à sua utilização e, quando for o caso, os aditivos e os auxiliares tecnológicos envolvidos. É o que se passa na OIV, com as Fichas do Código Internacional de Práticas Enológicas e do Codex Enológico. Assim, considerando designadamente os limites da sua utilização, seria pois necessário haver a disponibilidade de metodologias para controlar uma correcta aplicação dessas práticas. Passando-se em revista as diferentes práticas enológicas reconhecidas internacionalmente, descritas no Código Internacional de Práticas Enológicas, verifica-se uma enorme carência destas metodologias de controlo, concluindo-se pois pela necessidade de distinguir as prescrições de informação ou de parecer sobre a utilização das práticas enológicas (como integrando um “Código de Boas Práticas”) das prescrições obrigatórias (necessárias para assegurar a segurança alimentar dos produtos e a lealdade da competitividade). Description of an enological practice will be including the objective, the application area and their limits and, if applicable, the additives and technological auxiliaries concerned. The International Code of Enological Practices and the Enological Codex of OIV respect these criteria. So, considering the applications limits of these enological practices, it is indispensable the availability of methodologies to control the proper application of these practices. But in the Code of Enological Practices of OIV, there is a great need of these control methodologies, concluding for the necessity of distinguishing the information prescriptions on the use of the enological practices (like integrating a “Code of Good Practices”) of the compulsory prescriptions (necessary to the food security guard of the products and the loyalty of the competitiveness).

Approximately ten years after a first critical review of the authors on the occurrence of contaminant elements in wine, the subject remains of the utmost importance within the technological, food safety and legal concern. Future developments on toxicological and analytical field, as well as on international trade, will promote changes in existing regulations. Increasing concern with wine food safety may lead to the enlargement of the list of elements to control, and the change of terms in which the acceptable maximum limits are established. This paper, based on the introduction chapter of a Doctoral Thesis, presents a brief approach to the mineral composition of wine, and reviews a large group of contaminant elements (information also systematized in a table), including research results obtained by the authors. Aspects such as origin, levels of occurrence, evolution throughout the technological processes, potential sources of contamination, distribution under different chemical species, toxicity, analytical determination and acceptable maximum limits, vary considerably among contaminant elements.

The release of mineral elements from six bentonites to wine and to the test solution established by the OIV was evaluated in order to compare the extraction performance of both solutions.Significant differences between wine and tartaric solution results for 34 mineral elements analyzed by AAS, ETAAS and ICP-MS were observed, suggesting that the extraction solution proposed by the OIV is not suitable for bentonite quality control purposes.

The release of mineral elements from six bentonites to wine and to the test solution established by the OIV was evaluated in order to compare the extraction performance of both solutions. Significant differences between wine and tartaric solution results for thirty-four mineral elements analysed by AAS, ETAAS and ICP-MS were observed, suggesting that the extraction solution proposed by the OIV is not suitable for bentonite quality control purposes. Taking into account bentonite maximum extractable amounts defined by the OIV, some samples showed higher concentrations for Na (B3 and B8), Al (B8), Fe (B5) and As (B9). An additional extraction essay involving two bentonites, wine and two complex test solutions containing the major mineral elements of wine (K, Ca, Na and Mg) and protein (wine protein and BSA) was carried out. Significant differences were observed for all elements with exception of Sc, Mn, Co, W and Bi. For several elements, such as Na, Mg (test solution with BSA) V, Ni, Ga, Zr, Cd, In, Sb, Tl and U, the similarity of wine and test solutions content variations was satisfactory. The protein nature of test solutions seemed to have a decisive role in some element changes, probably related to wine protein and BSA distinct volume. In general, the test solution containing wine protein was a slightly better simulator of wine performance. However, the above mentioned test solutions did not simulated wine performance in a total satisfactory way, and further work should be performed on extraction solution composition. Tendo por objectivo principal avaliar e comparar a capacidade de extracção mineral da solução teste indicada pelo OIV relativamente à capacidade de extracção de um vinho, realizou-se um ensaio experimental envolvendo seis bentonites. A composição mineral das soluções de extracção foi determinada por FAAS, ETAAS e ICP-MS, observando-se diferenças significativas entre as variações dos teores de 34 elementos no vinho e na solução de ácido tartárico estabelecida pelo OIV, verificadas em consequência da adição de bentonite. A solução teste indicada pelo OIV parece assim inadequada para fins de controlo da qualidade das bentonites, uma vez que não reflecte o enriquecimento mineral observado no vinho. Algumas bentonites apresentaram teores extraíveis de Na, Al, Fe e As superiores aos estabelecidos pelo OIV. Um segundo ensaio de extracção foi realizado com duas bentonites, vinho e duas soluções teste contendo elementos minerais maioritários no vinho (K, Ca, Na e Mg), proteína de vinho (BSA, em alternativa). Observaram-se diferenças significativas entre as variações de teores no vinho e nas soluções teste para todos os elementos, com excepção do Sc, Mn, Co, W and Bi. Para os elementos Na, Mg (solução teste com BSA), V, Ni, Ga, Zr, Cd, In, Sb, Tl e U, os resultados obtidos foram considerados aceitáveis. A natureza da proteína utilizada nas soluções teste parece importante nas alterações de concentração verificadas por alguns elementos. De um modo geral a solução com proteína de vinho conduziu a resultados mais favoráveis. Contudo, os resultados não são ainda completamente satisfatórios pelo que se considera ser necessário prosseguir os estudos com vista à obtenção de uma solução teste capaz de simular a capacidade de extracção do vinho. On a effectué un essai expérimental concernant six bentonites, en envisageant l’objectif d’évaluer et comparer la capacité d’extraction minérale de la solution teste proposée par l’OIV, relativement à la capacité d’extraction d’un vin. La composition minérale des solutions d’extraction a été déterminée par FAAS, ETAAS et ICP-MS. On a observé des différences significatives entre les variations des teneurs de 34 éléments dans le vin et dans la solution de l’acide tartrique établie par l’OIV, vérifiées en conséquence de l’addition de bentonite. La solution teste proposée par l’OIV se montre ainsi impropre pour les fins de contrôle de la qualité des bentonites, une fois qu’elle n’est pas concernée à l’enrichissement minéral observé dans le vin. Quelques bentonites ont présenté des teneurs extractibles de Na, Al, Fe et As plus grandes aux établies par l’OIV. Dans un deuxième essai d’extraction, on a employé deux bentonites, un vin et deux solutions teste en contenant les éléments minéraux majoritaires dans les vins (K, Ca, Na et Mg) et une protéine de vin (BSA, en alternative). On a observé des différences significatives entre les variations des teneurs dans le vin et dans les solutions teste pour tous les éléments, sauf pour Sc, Mn, Co, W et Bi. Pour les éléments Na, Mg (solution teste avec BSA), V, Ni, Ga, Zr, Cd, In, Sb, Tl et U ; les résultats obtenus sont acceptables. La nature de la protéine employée dans les solutions teste paraît importante pour les modifications de concentration vérifiées pour quelques éléments. D’une façon générale, la solution avec la protéine de vin a donné des résultats plus favorables. Cependant, les résultats ne sont pas encore complètement satisfaisants. Ainsi, il y a besoin de continuer ces études en envisageant l’obtention d’une solution teste capable de simuler la capacité d’extraction du vin.

A OIV (Organisation Internationale de la Vigne et du Vin) é a organização internacional intergovernamental com competência no sector vitivinícola mundial. No seu âmbito, são nomeadamente definidas as práticas enológicas aceites internacionalmente, por intermédio de Resoluções aprovadas na sua Assembleia Geral. Nos últimos anos, tem sido aprovado um considerável número destas Resoluções, regulando práticas já há muito aplicadas generalizadamente ou aprovando outras completamente inovadoras no seio da Enologia. A completa descrição destas práticas está compilada nas fichas do " Código Internacional de Práticas Enológicas", documento de referência internacional editado por esta organização. Nesta Nota Técnica, apresenta-se sumariamente essas prá ticas, com referência às respectivas Resoluções da OIV e a algumas das limitaç ões da sua aplicabilidade. Para algumas delas, tecem-se alguns comentários sobre a sua aplicabilidade com base, designadamente, na actividade de I&DE desenvolvida pela Estação Vitivinícola Nacional (Portugal), expressa em bibliografia recentemente publicada. L’OIV (Organisation Internationale de la Vigne et du Vin) est l’organisation intergouvernementale compétente pour le secteur vitivinicole mondial. Dans l’ensemble de son activité, elle approuve les pratiques œnologiques acceptées internationalement par des Résolutions votées en Assemblée Générale. Dans les dernières années, un considérable nombre de ces Résolutions a été approuvé, concernant soit des pratiques déjà appliquées universellement soit des pratiques complètement innovatrices au sein de l’œnologie. La complète description de ces pratiques est compilée dans les fiches du « Code International des Pratiques Œnologiques », document de référence international, édité par cette organisation. Dans cette Note Technique, on présente sommairement ces pratiques, en référence aux respectives Résolutions de l’OIV et à quelques limitations de leur applicabilité. Pour quelques-unes de ces pratiques, on fait des commentaires sur leur applicabilité, basé s nommément dans l’activité de R&D développée par l’ Estação Vitivinícola Nacional (Portugal), publiée en récente bibliographie. The OIV (International Organisation of Vine and Wine) is an intergovernmental organisation with competence on the world of Viticulture and Enology. In their activity, the enological practices accepted internationally are recognised by Resolutions approved in General Assembly. In last years, an important number of these Resolutions were approved, concerning enological practices with general application and others completely news in Enology. The complete description of these practices is collected on the files of the " International Code of Enological Practices", document of international reference, published by the organization. In this Technical Note, we presented briefly these practices with reference to respective Resolutions OIV and any limits to their application. To some practices we presented any comments about their applicability based namely on the activity of "Estação Vitivinícola Nacional" (Portugal), published in recent bibliography.

A bentonite é um produto enológico com vasta aplicação na clarificação e estabilização proteica de mostos e vinhos brancos, representando um risco não negligenciável de introdução de contaminação mineral, com possíveis implicações ao nível da sua qualidade higiénica, organoléptica e legal. O conhecimento dos fenómenos de extracção e cedência de elementos minerais para o meio, e dos factores com influência nesses fenómenos, é fundamental para prevenir a ocorrência dessas contaminações. No presente artigo, são apresentados resultados parcelares de um estudo envolvendo ensaios de extracção com 6 bentonites, em solução de ácido tartárico e em vinhos, sendo investigada a influência do pH do meio nos fenómenos de extracção e cedência de elementos minerais. A avaliação da fracção mineral, envolvendo o doseamento de mais de 50 elementos, maioritários, minoritários, vestigiais e subvestigiais, foi realizada com recurso às técnicas analíticas de FAAS, GFAAS e ICP-MS. Os resultados encontrados não podem ser directamente extrapolados no que respeita à quantidade de elemento cedida ou retirada ao vinho, dado terem sido obtidos em condições experimentais específicas. Verificaram-se enriquecimentos nos teores de Na, Ca, Al e diminuição do teor de K. De acordo com a bentonite aplicada, ocorreram aumentos e decréscimos no teor de Pb. O pH exerce efeito significativo na cedência de Ca (aumentando com o pH), Al e Pb (diminuindo com o pH), não afectando a cedência de K e Na (no intervalo de pH 2,9 a 3,6). As características físico-químicas das bentonites utilizadas são um factor determinante, tendo-se observado grande variabilidade de comportamento e nas quantidades cedidas, nas mesmas condições experimentais. Bentonites are enological products widely utilised on clarification and proteic stabilization of musts and white wines. The risk of mineral contamination, associated with hygienic, sensory and legal quality of wines, should not be neglected. The knowledge of extraction and mineral elements release phenomena and influence factors are very important to prevent this contamination. The aim of the present work was to investigate the extraction phenomena, the nature of extraction solution and pH level. 6 different bentonites, in wine and tartaric acid solution, at 3 pH levels (2,9 to 3,6), were studied. The analysis of extraction solutions were realised by FAAS, GFAAS and ICP-MS. More than 50 mineral elements (major, minor and trace elements) were analysed. The results were obtained at specific experimental conditions, so, they should not be directly applied to wine, concerning the mineral contents. Bentonite-treated wines showed higher Ca, Na and Al contents, while K contents decreased. The influence of bentonite on Pb contents was very important: some bentonites increased this metal content, while others decreased it. The pH effect showed to be significant on Ca, Al and Pb releases: higher Ca contents were found at pH 3,6. On the other hand, Al and Pb extraction and release decreased with pH increase. Bentonite factor was determinative on mineral elements amounts released, depending on pH value. Les bentonites sont des produits œnologiques largement utilisés dans la stabilisation protéique et dans la clarification des moûts et des vins. Les risques des contaminations minérales ne doivent pas être minimisés, à cause de leurs implications sur la qualité des vins, sous les points de vue sensorielle, légal et de sécurité alimentaire. La connaissance des phénomènes concernant l’extraction des éléments minéraux et des facteurs influents est très importante pour éviter les contaminations. Dans cet article, on présente l’évaluation de l’influence des bentonites employées, de la nature de la solution d’extraction et du niveau du pH. On a étudié 6 différentes bentonites, dans le vin et dans une solution d’acide tartrique, pour 3 niveaux de pH (2,9 à 3,6). Les analyses des solutions d’extraction ont été réalisées par FAAS, GFAAS et ICP-MS. On a analysé plus que 50 éléments minéraux. Les résultats trouvés ne pourront pas être directement extrapolés en ce qui concerne la quantité des éléments cédée ou retirée au vin, parce qu’ils ont été obtenus dans conditions différentes de la pratique œnologique. Pour les vins traités avec des bentonites, les teneurs de Ca, Na et Al sont plus élevées, tandis que la teneur de K est inférieure. L’influence sur la teneur en Pb est moins importante : quelques bentonites pourront conduire à une augmentation de cette teneur, tandis que des autres la pourront baisser. L’effet du pH est négligenciable pour le Ca, Al et Pb ; des valeurs plus élevées ont été trouvées pour le Ca à pH de 3,6. L’extraction de Al et Pb diminue avec l’augmentation du pH. Les caractéristiques physicochimiques des bentonites sont déterminantes, avec des différences significatives pour l’extraction des différents éléments et pour l’influence du pH.

O conhecimento dos teores de cobre (Cu) e de ferro (Fe) em vinhos e aguardentes assume especial importância pelas implicações na sua estabilidade físico-química. No presente trabalho, para cada um dos elementos referidos, foi validado intralaboratorialmente o método de análise descrito na Norma Portuguesa, com recurso à técnica de espectrofotometria de absorção atómica com chama. A aplicação destes métodos para doseamento de Cu em vinhos e de Fe em aguardentes apresenta algumas dificuldades, dados os baixos teores em que normalmente surgem. Nestes casos, é vulgar o recurso ao método das adições de padrão, cuja precisão foi avaliada, concluindo- se que este é menos preciso que o método que recorre à comparação com uma curva de referência. Apresentam-se ainda os resultados da participação num ensaio interlaboratorial. The knowlegde of copper and iron contents in wines and brandies is important because these metals may involve haze formation during their storage. This paper presents the determination of total contents of the two metals in these beverages, by flame atomic spectrometry. The methods described by portuguese normas, were validated and its analytical characteristics were verified. Their apliccation for determination of some wines and brandies with low contents, may present some dificulties. The method of standard additions, widely practised in these situations, was also studied, and the precision of the two methods was compared. Because it is an extrapolation method, is thus less precise than the interpolation methods. We also presents the results of the participation in an interlaboratory assay. La connaissance des teneurs en cuivre (Cu) et en fer (Fe) des vins et des eaux-de-vie présentent une très grande importance face à leur stabilité physico-chimique. Dans cet article, pour le Cu et le Fe, on présente les paramètres de validation intralaboratoire des méthodes d’analyse décrites dans les Normes portugaises, en employant la spectrométrie d’absorption atomique de flamme. L’application de ces méthodes pour le dosage de Cu dans les vins et de Fe dans les eaux-de-vie présente quelques dificultés, en liaison avec les faibles teneurs de sa présence. Dans ces conditions, il est commun l’application de la méthode des additions d’étalon: on a conclu que cette méthode est moins précise que la méthode basée sur la comparaison avec une courbe de référence. On présente aussi les résultats d’un essai interlaboratoire concernant ces déterminations.