1,721,057 research outputs found
Characterization of a traditional semi-hard italian cheese produced by soaking in wine
No full textA traditional type of semi-hard cheese which, after a ripening period in the warehouse, is soaked in wine or fermented must, was studied. In particular, the effect of the soaking phase on the characteristics of the cheese and on the profiles of the volatile compounds was investigated. The study proved that it is the alcohols and the short-chain ethyl esters which chiefly contribute to the distinctive aromatic fraction of the product. These compounds migrate from the wine into the cheese as a result of the different concentrations existing between the two systems. © 2007 Elsevier Ltd. All rights reserved
Relazione tra composizione e proprietà antiossidanti di derivati di lievito commerciali
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Characterization of Non-Saccharomyces Yeast Strains Isolated from Grape Juice and Pomace: Production of Polysaccharides and Antioxidant Molecules after Growth and Autolysis
Full text linkNon-Saccharomyces yeasts (NSY) represent a relevant part of must and wine microbiota, contributing remarkably to the composition of lees biomass. Despite a number of studies indicate their capacity to increase wine polysaccharide content, their contribution to wine quality during aging on lees (AOL) has not been well elucidated yet. In the present study, twenty yeast strains (13 non-Saccharomyces and 7 Saccharomyces) were isolated from grape must and pomace and identified by morphologic and genetic characterization. Biomass production, cell growth and the release of soluble molecules (polysaccharides, amino acids, thiol compounds and glutathione) were evaluated after growth and after autolysis induced by β-glucanases addition. Differences between strains were observed for all parameters. Strains that produced higher amounts of soluble compounds during growth also showed the highest release after autolysis. Hanseniaspora spp. showed the greatest production of polysaccharides and antioxidant molecules, and biomass production and cell viability comparable to the commercial S. cerevisiae and T. delbrueckii used as reference. The aptitude of certain NSY to release antioxidants and polysaccharides is an interesting feature for managing AOL through sequential or mixed fermentations or for the production of inactive autolyzed yeasts for winemaking
Effect of a yeast autolysate produced by high pressure homogenization on white wine evolution during ageing
Full text linkThe enological characteristics and the performances of a yeast autolysate produced by high pressure homogenization (HPH-YD) were investigated for the first time in white wine and model solution, in comparison with a thermolysate (T-YD) and a commercial yeast derivative (COMM). In wine-like medium, HPH-YD showed a significant release of glucidic colloids (on average, slightly higher than the other products), also leading to a greater glutathione solubilization with respect to T-YD. Concerning the volatile composition of the autolysates, HPH-YD was characterized by the highest concentration of alcohols and esters, while showing an average amount of fatty acids, carbonyls and heterocyclic compounds lower than COMM. These features are potentially linked to a more favorable impact of this product on the composition of wine aroma, should these compounds be released into the wine itself. HPH-YD determined minor modifications on wine volatile profile when added for short contact times, without releasing unwanted compounds and with a slightly lower binding capacity towards wine esters. The effects of the three yeast derivatives (YDs) on wine color during ageing was also investigated in comparison with sulfur dioxide (SO2). HPH-YD was the most efficient preparation, limiting wine color changes due to oxidation during four months and behaving more similarly to SO2. The use of HPH for the production of yeast autolysates for winemaking may represent an interesting alternative to thermal treatments, improving the enological characteristics of these additives, particularly their antioxidant capacity, leading anyhow a significant release of colloidal molecules and a limited impact on wine aroma composition
Potential Applications of High Pressure Homogenization in Winemaking: A Review
Full text linkHigh pressure homogenization (HPH) is an emerging technology with several possible applications in food sector, such as nanoemulsion preparation, microbial and enzymatic inactivation, cell disruption for the extraction of intracellular components, as well as modification of food biopolymer structure to steer their functionalities. All these effects are attributable to the intense mechanical stresses, such as cavitation and shear forces, suffered by the product during the passage through the homogenization valve. The exploitation of the disruptive forces delivered during HPH was recently proposed also for winemaking applications. In this review, after a general description of HPH and its main applications in food processing, the survey will be extended to the use of this technology for the production of wine and fermented beverages, particularly focusing on the effects of HPH on the inactivation of wine microorganisms and the induction of yeast autolysis. Further enological applications of HPH technology, such as its use for the production of inactive dry yeast preparations, will be also discusse
Biotechnological Strategies for Controlling Wine Oxidation
No full textApart from the controversial positive effects of moderate wine consumption on human health, wine antioxidant capacity plays a key role in winemaking technology. From juice extraction to bottle storage, oxygen management is one of the most critical points for making quality wines. In the past, the protection of juice and wine from oxidations was based on the sole use of sulfur dioxide; more recently, the toxicity and the allergenic potential of this additive, together with the increased knowledge on wine oxidation mechanisms, have given rise to new biotechnological approaches and producing trends, leading to a significant reduction of sulfites in winemaking. The aim of this paper is to review the oxidation mechanisms of grape juice and wine and to discuss the opportunities to reduce as much as possible sulfur dioxide addition by a proper management of alcoholic and malolactic fermentation and by the supplementation of some important yeast nutritional factors (e.g., thiamine). The use of natural antioxidants complementing the activity of sulfites (i.e., ascorbic acid, glutathione, yeast lees, and yeast derivatives) is also discusse
Pulsed electric fields processing of crushed grapes and effects on wine composition
No full textPulsed electric fields (PEF) is a non-thermal method for food processing and preservation, based on the application of short pulses of high-voltage current to food products positioned between two electrodes. PEF technology derives from food industry, where it has been proposed for inactivating pathogenic microorganisms, in alternative to the traditional thermal processing methods (e.g. pasteurization), with the major advantage of better preserving food sensory characters and nutritional value. PEF processing promotes the electrically-induced formation of pores in the cell membranes, which may be reversible or irreversible, depending on the intensity of the electric field applied; this leads to the occurrence of specific phenomena, known as cell electroporation, or dielecric breakdown. Basing on such considerations, PEF was also proposed for the extraction of bioactive compounds from vegetal matrices, including fruits, apples and grapes. In the present study, Pulsed Electric Fields processing of grapes after crushing – destemming was evaluated concerning the extraction of phenolic substances and aroma compounds. The overall effects of the treatment on wine composition and sensory characters were also considered. In the conditions tested, PEF did not affect neither the behavior of alcoholic fermentation, nor juice and wine basic quality control parameters (e.g. residual sugars, total acidity, alcoholic strength, yeast assimilable nitrogen). Contrary, it promoted a fast and intense extraction of color and phenolic compounds (e.g. proanthocyanidins and anthocyanins), even in higher amounts with respect to what obtained by pectolytic enzymes. PEF also determined a higher concentration of certain varietal aroma compounds in the grapes after processing, with a potential positive effect on wine aroma composition. From the sensory point of view, wines processed by PEF were averagely perceived as more colored and full-bodied, with respect those obtained from unprocessed grapes. On the basis of these results, the application of PEF in enology might be an interesting perspective, particularly in certain winemaking situations, such as the processing of low-ripe grapes or grapes affected by Botrytis; moreover, this technology might be also useful for the production of concentrated musts obtained from red grape varieties
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