Cross-flow microfiltration applied to oenology: A review

The cross-flow microfiltration applied to wine filtration has become a legitimate alternative to conventional filtration processes. However, membrane fouling which affects the operating costs and the plant maintenance, limits the widespread application of this technique. The aim of this review is to provide a better understanding of the development of the cross-flow microfiltration in wine industry, as well as the complexity of wine composition and its consequences on membrane fouling. This review covers also the impact of the operating conditions and the membrane characteristics on fouling mechanisms. Strategies to limit fouling as well as the latest innovations and commercial proposal are discussed in this paper

The Role of Research in Wine: the Emergence of a Regional Research Area in an Italian Wine Production System

The process of technological modernisation of the wine industry has increasingly become a global phenomenon involving both traditional wine producing countries – such as France, Italy and Portugal – as well as new emerging producers –as the US, Australia, South Africa, Chile and Argentina. At this respect, the literature (Aylward, 2003; Unwin, 1991) remarks that in the industry the process of technological renovation has been spurred by the consistent investment of new producer countries, as California, Australia, New Zealand and South Africa, in creating or strengthening research institutions. These efforts have led to the creation of a specialised wine research system. Conversely, it seems that producers in traditional wine producing areas have often been locked in old technologies and methods of production, due to path dependency. The aim of this paper is to shed some light on how old producing countries have reacted to the increased technological competition by emerging producers. In particular we focus on role played by research organisations (e.g. universities, public research centres) and intermediate institutions (e.g. sectoral associations, extension agencies, technological transfer centres) in generating and diffusing knowledge within the industry. The paper is based on first and second hand information collected in Piemonte, where it is located one of the most important Italian wine cluster. There, we have conducted an extensive fieldwork and interviewed several key informants working at research organisations; extension agencies, associations of producers and other associations acting as opinion/lobbying groups. The information collected are elaborated to reconstruct a detailed picture of actors, linkages and processes underpinning the regional innovation and production wine system.

Highlight on the problems generated by p-coumaric acid analysis in fermentations

p-Coumaric acid is a natural hydroxycinnamic acid existing in grapes and wine. It is the precursor of the 4-ethylphenol molecule through the bioconversion reaction by Brettanomyces yeast. Chromatographic methods are the most common techniques to detect p-coumaric acid. It is known that this acid is highly unstable in analysis and fermentation experiments. This paper highlights the problems occurring in p-coumaric acid analysis in wine fermentation conditions when studying its bioconversion. First, it was shown that p-coumaric acid was unstable at elevated temperature. On the other hand, it was found that in our experimental conditions p-coumaric acid reacted with ethanol. This work revealed also that the p-coumaric acid is partially adsorbed on Brettanomyces yeast, certainly on cell walls. Because of these phenomena the quantity of p-coumaric acid which can participate to the bioconversion into ethylphenol decreases

Impact of the co-culture of Saccharomyces cerevisiae–Oenococcus oenion malolactic fermentation and partial characterization of a yeast-derived inhibitory peptidic fraction

The present study was aimed to evaluate the impact of the co-culture on the output of malolactic fermentation and to further investigate the reasons of the antagonism exerted by yeasts towards bacteria during sequential cultures. The Saccharomyces cerevisiae D strain/Oenococcus oeni X strain combination was tested by applying both sequential culture and co-culture strategies. This pair was chosen amongst others because the malolactic fermentation was particularly difficult to realize during the sequential culture. During this traditional procedure, malolactic fermentation started when alcoholic fermentation was achieved. For the co-culture, both fermentations were conducted together by inoculating yeasts and bacteria into a membrane bioreactor at the same time. Results obtained during the sequential culture and compared to a bacterial control medium, showed that the inhibition exerted by S. cerevisiae D strain in term of decrease of the malic acid consumption rate was mainly due to ethanol (75%) and to a peptidic fraction (25%) having an MW between 5 and 10 kDa. 0.4 g l-1 of L-malic acid was consumed in this case while 3.7 g l-1 was consumed when the co-culturewas applied. In addition, therewas no risk of increased volatile acidity during the co-culture. Therefore, the co-culture strategy was considered effective for malolactic fermentation with the yeast/bacteria pair studied

Estimation of the rate of return to wine grape research and technology development expenditures in South Africa

This article evaluates the impact of research and technology development in the wine grape industry in order to determine the rate of return (ROR) to these investments, and to make specific recommendations on funding. The analysis illustrates the applied and adaptive nature of the research conducted in the industry, with RORs of roughly 40 percent for R&D and extension. This is high, providing excellent motivation for increased investment in R&D.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Materials and Methods of the Study of Influence of Agrotechnical Methods on Sensory Characteristics of Technical Sorts of Grape

The topicality of using the sensory analysis of berries in enological practice at planning of agrotechnical complex at vineyard to receive the certain style and quality of production was grounded. For study of the influence of agrotechnical methods on sensory characteristics of technical sorts of grape Zagrey and Fragrant, selected by NSC “IVaW named after V.E. Tairov” (Ukraine), there was elaborated the algorithm of research, including field experiment and laboratory sensory analysis. The method of organoleptic analysis of berries, consisted of 20 parameters for assessment of visual, tactile and gustatory properties of pulp, peel and seeds, was approbated. Mathematical processing of experimental data was carried out by the methods of one- and two-factor analysis of variance and analysis of main components in the environment of package of applied programs MS Excell 2010, Statistica Statsoft ver. 7. 0 (Tulsa, USA).The sensory descriptors, characterizing the quality of studied sorts of grape, were determined. It was established, that agrotechnical methods of planting grape bushes influenced the sensory characteristics of berries of studied sorts

Critical evaluation of potentiometric redox titration in enology

Measurements of the zero current potential of a platinum electrode immersed in solutions of tanins or in wines of various origins, were performed during the additions of a solution of Ti(III), or of a solution of dichlorophenolindophenol (DCPIP), in order to obtain a global indication for the resistance to oxidation of some wines. The steady state intensity–potential curves on a platinum electrode highlight the occurrence of mixed potentials between the oxidation of ethanol or catechin and the reduction of oxygen present at very low concentrations, as well as the irreversibility of the redox system Ti(IV)/Ti(III). The adsorption of various species on the platinum and the slowness of the oxidation reactions by DCPIP exclude use of potentiometric titration theory. The shape of the potential–reagent volume curves depends on the nature of the solution and on the rate of reagent introduction. Generally, due to the slowness of the oxidation reactions with DCPIP it is impossible to find a linear relationship between the volume of titrant solution necessary to reach the inflexion point of the curves and the solution composition

Quantitative study of interactions between Saccharomyces cerevisiae and Oenococcus oeni strains

This study examines the interactions that occur between Saccharomyces cerevisiae and Oenococcus oeni strains during the process of winemaking. Various yeast/bacteria pairs were studied by applying a sequential fermentation strategy which simulated the natural winemaking process. First, four yeast strains were tested in the presence of one bacterial strain leading to the inhibition of the bacterial component. The extent of inhibition varied widely from one pair to another and closely depended on the specific yeast strain chosen. Inhibition was correlated to weak bacterial growth rather than a reduction in the bacterial malolactic activity. Three of the four yeast strains were then grown with another bacteria strain. Contrary to the first results, this led to the bacterial stimulation, thus highlighting the importance of the bacteria strain. The biochemical profile of the four yeast fermented media exhibited slight variations in ethanol, SO2 and fatty acids produced as well as assimilable consumed nitrogen. These parameters were not the only factors responsible for the malolactic fermentation inhibition observed with the first bacteria strain. The stimulation of the second has not been reported before in such conditions and remains unexplained

Wine Fining with Plant Proteins

: Fining treatments involve the addition of a substance or a mixture to wine, and are generally carried out in order to clarify, stabilize or modify the wine\u2019s organoleptic characteristics. Usually these fining agents will bind the target compound(s) to form insoluble aggregates that are subsequently removed from the wine. The main reasons to perform wine fining treatments are to carry out wine clarification, stabilization and to remove phenolic compounds imparting unwanted sensory characteristics on the wine, which is an operation that often relies on the use of animal proteins, such as casein, gelatin, egg and fish proteins. However, due to the allergenic potential of these animal proteins, there is an increasing interest in developing alternative solutions including the use of fining proteins extracted from plants (e.g., proteins from cereals, grape seeds, potatoes, legumes, etc.), and non-proteinaceous plant-based substances (e.g., cell wall polysaccharides and pomace materials). In this article, the state of the art alternative fining agents of plant origins are reviewed for the first time, including considerations of their organoleptic and technological effects on wine, and of the allergenic risks that they can pose for consumer