Effect of Various Proteins on Different Molecular Weight Proanthocyanidin Fractions of Red Wine during Wine Fining

The effect of several proteins on three main wine proanthocyanidin containing fractions with the mean degree of polymerization (mDP) of 1.5 (FI), 3.4 (FII), and 4.9 (FIII) was studied. Although casein and potassium caseinate showed similar molecular weight (MW) distribution, casein decreased the FI fraction more than the twice as effectively as potassium caseinate. A gelatin with a medium MW polydispersion induced a similar decrease (~20%) in all tannin fractions. A gelatin with low MW primarily removed the tannin fractions of lower mDP (FI and FII), while a gelatin with a higher MW had a minor effect (5%) on the fraction of higher mDP (FIII). Neither of the two studied isinglasses reduced the FII fraction. The tannins of FI and FIII were removed by swim bladder isinglass twice as effectively as by fish skin isinglass. For the mDP of fined wines, egg albumin induced a decrease on mDP of 24% for the more polymerized tannin fraction (FIII); although within all assays there was a decrease ranging from 6 to 14%info:eu-repo/semantics/publishedVersio

Grape and Wine Metabolites: Biotechnological Approaches to Improve Wine Quality

Grape metabolites can be affected by many extrinsic and intrinsic factors, such as grape variety, ripening stage, growing regions, vineyard management practices, and edaphoclimatic conditions. However, there is still much about the in vivo formation of grape metabolites that need to be investigated. The winemaking process also can create distinct wines. Nowadays, wine fermentations are driven mostly by single-strain inoculations, allowing greater control of fermentation. Pure cultures of selected yeast strains, mostly Saccharomyces cerevisiae, are added to grape must, leading to more predictable outcomes and decreasing the risk of spoilage. Besides yeasts, lactic acid bacteria also play an important role, in the final wine quality. Thus, this chapter attempts to present an overview of grape berry physiology and metabolome to provide a deep understanding of the primary and secondary metabolites accumulated in the grape berries and their potential impact in wine quality. In addition, biotechnological approaches for wine quality practiced during wine alcoholic and malolactic fermentation will also be discussed

White wine protein instability: Mechanism, quality control and technological alternatives for wine stabilisation—an overview.

Wine protein instability depends on several factors, but wine grape proteins are the main haze factors, being mainly caused by pathogenesis-related proteins (thaumatin-like proteins and chitinases) with a molecular weight between 10~40 kDa and an isoelectric point below six. Wine protein stability tests are needed for the routine control of this wine instability, and to select the best technological approach to remove the unstable proteins. The heat test is the most used, with good correlation with the natural proteins’ precipitations and because high temperatures are the main protein instability factor after wine bottling. Many products and technological solutions have been studied in recent years; however, sodium bentonite is still the most efficient and used treatment to remove unstable proteins from white wines. This overview resumes and discusses the different aspects involved in wine protein instability, from the wine protein instability mechanisms, the protein stability tests used, and technological alternatives available to stabilise wines with protein instability problems.This research was funded by the Fundação para a Ciência e Tecnologia (FCT-Portugal) and Operational Competitiveness Programme (COMPETE, Portugal) through the projects Chemistry Research Centre-Vila Real (UIDB/00616/2020) and CIMO (UIDB/00690/2020).info:eu-repo/semantics/publishedVersio

Avaliação do efeito da aplicação de manoproteínas comerciais no incremento da qualidade de vinhos brancos

Face à exigência dos consumidores atuais, as características sensoriais de um vinho, assim como a sua estabilidade, são fatores determinantes para a sua aceitabilidade no mercado. A instabilidade proteica do vinho e consequente desnaturação/precipitação das proteínas depende de fatores (intrínsecos e extrínsecos) e é responsável pelo aparecimento de turvação nos vinhos brancos. Para prevenir a instabilidade proteica são usados vários produtos enológicos, com objetivo de remover as proteínas instáveis, no entanto com várias limitações, tais como eficiência e modificação das características físico-químicas e sensoriais no vinho. Nos últimos anos têm surgido diversos aditivos comerciais à base de manoproteínas, já que as mesmas podem ser uma via alternativa para a estabilização proteica do vinho. Neste trabalho foram selecionadas onze manoproteínas comerciais para avaliar o seu efeito na estabilização proteica, bem como o seu efeito na composição fenólica e nas características cromáticas e sensoriais num vinho branco. Os resultados obtidos mostraram que 9 das 11 manoproteínas testadas apresentaram efeito positivo na estabilização proteica do vinho. Além disso, todas as manoproteínas diminuíram o potencial de acastanhamento dos vinhos, e de um modo geral conduziram a um aumento da luminosidade. Na análise sensorial, apesar de não haver diferenças significativas relativamente ao vinho controlo, tendencialmente os vinhos mais pontuados foram os tratados com manoproteínas, nomeadamente ao nível da diminuição da cor, equilíbrio gustativo e na componente aromática, frutado e floral. Pelos resultados obtidos neste trabalho, podemos concluir que as manoproteínas parecem ser uma alternativa eficiente na estabilização proteica de vinhos brancos e que podem simultaneamente melhorar as características sensoriais do vinho, porém, convém salientar que estes resultados devem ser encarados como preliminares, sendo necessário realizar mais estudos com outros tipos de vinhos.info:eu-repo/semantics/publishedVersio

Analytical evaluation of fining treatments for white wines contaminated by Ochratoxin A

Mycotoxins are toxic secondary metabolites produced by certain molds. Ochratoxin A (OTA) is one of the most relevant. Its chemical structure is a dihydro-isocoumarin connected at the 7-carboxy group to a molecule of L--phenylalanine via an amide bond. OTA in wine is a risk to consumer health [1]. According to the Regulation No. 123/2005 of the European Commission, the maximum limit for OTA in wine is 2 µg/kg [2]. Then, it is important to control its occurrence. So, the aim of this work was to know the effect of different fining agents on OTA removal from white wine.This work was funded by FEDER funds through the COMPETE and by national funds through FCT, Ref. FCOMP-01-0124-FEDER-028029 and PTDC/AGR-TEC/3900/2012, respectively. Luís Abrunhosa received support through grant SFRH/BPD/43922/2008 from FC

Influence of several oenological fining agents on ochratoxin A removal

In Europe, wine is estimated to be the second source, after cereals, of ochratoxin A (OTA), one of the most important mycotoxin found in food and feed products [1]. Its chemical structure consists of a chlorine-containing dihydro-isocoumarin linked through the 7-carboxyl group to L--phenylalanine. In wine, this fungal metabolite represents a severe risk for consumer health. According to the European Commission Regulation (EC) No. 123/2005 the maximum limit for OTA in wine is 2 g/Kg [2]. Therefore, it is important to prevent and control their occurrence in wines. With the purpose to remove this toxin, several chemical, microbiological and physical methods were described in the literature [1, 3, 4]. Consequently, the aim of this work is to understand the interaction of different types of fining agents on OTA removal from wine. To evaluate their effectiveness, eleven commercial fining agents, including mineral, synthetic, animal and vegetable proteins were used to get new approaches on OTA removal from wine. Trials were performed in wines added of OTA. Most effective fining agent in removing OTA was a commercial formulation that contains activated carbon, a well-known adsorbent of mycotoxins. Reductions between 10 and 30% were also obtained with potassium caseinate, yeast cell walls and pea protein. However, with bentonites, carboxymethylcellulose (CMC), polyvinylpolypyrrolidone (PVPP) and chitosan no considerable reduction of OTA was verify. Also, the influence of these fining agents on the physicochemical wine characteristics, namely wine color, total phenolic compounds, flavonoids and non-flavonoids were studied. Final results could provide important information to the wine industry to select treatments based on fining agents to remove OTA, in order to reduce toxicity and consequently to improve wine safety and preserving wine quality.FEDER funds through the COMPETE and by national funds through FCT , Ref. FCOMP - 01 - 0124 - FEDER - 028029 and PTDC/AGR - TEC/3900/2012, respectively. This work was also funded by IBB/CGB - UTAD and Chemical Research Centre of Vila Real (CQ- VR). Additional thanks to SAI Lda., AEB Bioquímica Portuguesa, S. A. and Enartis companies for providing fining agents

Estabilização proteica de vinhos brancos por adição de manoproteínas e impacto na qualidade

A instabilidade proteica é um defeito que pode conduzir à rejeição do vinho. A desnaturação e precipitação das proteínas instáveis, podem afetar a limpidez e/ou originar depósitos amorfos. A concentração e composição das proteínas, dependem da casta, condições climáticas, estado de maturação das uvas e da vinificação. A colagem com bentonite é o processo mais comum na prevenção desta instabilidade, mas apresenta limitações, particularmente quando aplicada em doses elevadas. Assim, têm sido estudadas alternativas, como por exemplo as manoproteínas

Genotype, Environment and Management Practices on Red/ Dark-Colored Fruits Phenolic Composition and Its Impact on Sensory Attributes and Potential Health Benefits

Phenolic compounds are secondary metabolites abundant in our diet. These compounds may affect positively or negatively the sensory characteristics of food with important impacts on color, flavor, and astringency. An adequate consumption of phenolic compounds may also offer health benefits. After the consumption of fruits, the colon is the main site of microbial fermentation, where high molecular weight phenolic compounds are transformed into low molecular weight phenolic compounds such as phenolic acids or lactone structures by intestinal microbiota, which produce metabolites with biological and antioxidant activity, with evidence on health benefits for humans. A large amount of different phenolic compounds are responsible for physicochemical and sensory characteristics of table grapes and wines. Also, sweet cherry (Prunus avium L.) is one of the most popular temperate table fruits; they contain flavonoids, flavan‐3‐ols, and flavonols in addition to non‐flavonoid compounds. Anthocyanins are the major polyphenols in blueberries, and this group of phytochemicals is thought to be responsible for many of the health benefits of berry consumption. Therefore, considering the importance of red/dark‐colored fruits phenolic composition, the purpose of this chapter is to make a review of the most recent publications about these fruits’ phenolic composition and their impact on sensorial properties as well as the effect of microorganisms on fruit phenolic composition

Influence of structural features of mannoproteins in white wine protein stabilization

Proteins are presented in wine at low concentration, however these compounds could be responsible for colloidal instability and haze of wines.info:eu-repo/semantics/publishedVersio

Effect of different fining agents and additives in white wine protein stability

Proteins in white wine could become insoluble and precipitate causing the appearance of a haze in bottled wine. Protein instability may be due to intrinsically or extrinsically factor such as protein molecular weight, isoelectric point, ionic strength, alcohol degree and wine pH or storage temperature. These modifications may occur during aging, storage or when diverse wines are blended. The type and concentration of proteins in the wine depends on grape variety, maturation degree and winemaking operations (pre-fem1entative grape maceration, application of tannins, enzymes or bentonite fining). Usually, the treatment for wine protein instability is sodium bentonite fining. The adsorption of wine proteins onto bentonite is due to the cationic exchange capacity of bentonite, which carries a net negative charge and the wine proteins are mostly positive charged at wine pH, and thus can be exchanged onto bentonite. Sometimes even with high level of sodium bentonite wines do not stabilize. Thus, the main purpose of this work is to understand the interaction of different types of bentonites, tannins, carboxylmethylcellulose (CMC) and mannoproteins on white wine protein stability, to get new approaches to stabilize them. Some trials were performed in four white wines with high protein instability. Preliminary results showed that sodium bentonite and mannoproteins increase protein stability, in opposition, CMC and tannins seems to increase turbidity after stability tests, which means more instability. Final results could provide important information to the wine industry to select alternative treatments to remove unstable proteins to maintain or improve wine quality