Stabilization, wine

The removal of macromolecules by ultrafiltration has often been used in the production of clear fruit juices and wine (Girard and Fukumoto, 2000). This treatment removes both proteins and polysaccharides. Ultrafiltration through a 10,000 Da cut-off membrane has been shown to stabilize wines against haze formation (Flores, 1990). 

Commercial wines are commonly tested for protein stability. Wine proteins, upon denaturation by heat or cold, may cause cloudiness and unsightly deposits after bottling. In addition, proteins may combine with iron and copper salts to form flocculate material in bottled wines. The reaction and absorption of proteins on bentonite is an effective means of removing protein from wines (109, 110, 111). Therefore, fining wines... 

A number of sensory tests have so far revealed no difference in the organoleptic properties of ED- and cold-stabilized wines (Bach et al., 1999 Cameira dos Santos et al., 2000 Goncalves et al., 2003 Paronetto et al., 1977 Riponi et al., 1992 Wucherpfennig and Krueger, 1975). 

Even in this case, the use of a hybrid process combining NF, IE, and ED appears to improve the economics and performance of the tartaric stabilization of wines. For instance, Ferrarini (2001) proposed to split raw wine into a retentate and permeate by NF. The permeate, being richer in minerals, was processed by using in sequence cationic and anionic exchange resins and ED to reduce its potassium, calcium, and tartrate ion contents. By recombining the de-ashed permeate with the NF retentate, Ferrarini (2001) asserted to obtain a stabilized wine retaining almost all the flavor and aroma compounds originally present in raw wine. 

However, the economics of the wine industry were so precarious that in 1894 (partially because of the national economic depression), seven of the leading wine firms organized the California Wine Association to stabilize wine prices. As Peninou and Greenleaf (3) state, From that time on until the coming of Prohibition, the history of winemaking in California is largely the history of the California Wine Association. ... 

Gerbaux, V., VUla, A., Monamy, C. Bertrand, A. (1997). Use of lysozyme to inhibit malo-lactic fermentation and to stabilize wine after malolactic fermentation. Am. J. Enol. Vitic.,48, 49-54. 

Use of Adjuvants for Stabilizing Wine with Respect to Tartrate Salt Crystallization. 147... 

Use of Mannoproteins to Stabilize Wines as Regard to Protein Haze. 151... 

The inhibition of malo-lactic fermentation can be obtained by SO2 (/w30 mg/liter), maintainance of storage temperature at less than 18°C and adjustment of pH to at least below 3.3. Killing or removing the bacteria from wine is a more definite step to stabilize wine against malo-lactic fermentation. Pasteurization and particularly HTST treatment (high temperature, short time -98 C for one second - with rapid cooling) is often used. Sterile filtration has also been used with 0.45 (un membrane filters. 

Whatever the technology used, and regardless of any treatment used preparatory to bitartrate stabilization, wine treated with artificial cold must be clean, i.e. not excessively contaminated with yeast or bacteria, as is often the case with wines stored in large vats. These wines should, therefore, be filtered on a simple continuous earth filter. Another advantage of filtration is the elimination of part of the protective colloids. Fine filtration is not useful at this stage, and is certainly not recommended, as there is a risk of eliminating microcrystals likely to act as crystallization nuclei. 

Table 1.17. Changes in the physicochemical parameters of cold-stabilized wine when the contact tartrate was recycled (Manjean et al., 1986)...

Stabilizing wines to prevent precipitation of calcium tartrate is not easy, as the crystallization of potassium bitartrate does not indnce that of calcium tartrate, despite the fact that these two salts should logically syncrystallize as they have the same crystal systems. On the contrary, crystallization of TCa may induce that of KTH. The prevention of calcium tartrate precipitation is further complicated by the fact that the solubility of TCa (Postel, 1983) is not very temperature-sensitive. Thns, TCa is hardly three times more soluble at 20°C than at —4°C. 

A distinction should be made in terms of cellar work between two separate issues. The aim, on the one hand, is to obtain total clarity by appropriate methods and, on the other hand, to achieve stability by means of efficient treatments. Wine treatments are differentiated by their purposes. For instance, filtration clarifies but does not stabilize, fining does both and treatment with gum arabic stabilizes wine but does not clarify it. 

The objective of stabilization is to ensure longterm clarity and prevent deposits, whatever the temperature, oxidation or lighting conditions where the wine is stored. The chemical and biological mechanisms likely to cause turbidity or deposits are now well known and may be predicted by laboratory tests. Efficient treatments are available for stabilizing wines, when necessary, before bottling. 

Table 10.1. The main treatments available for clarifying and stabilizing wines. They are not all recognized by legislation in every country and several are not permitted in the European Union...

Clarification dnring fermentation by repeating this operation several times, it is possible to stabilize wine permanently through the gradual elimination of yeast and nitrogenated nntrients. 

Stabilizing Wine by Physical and Physico-chemical Processes... 

Cold stabilization is mainly used to cause two types of precipitation that help to stabilize wine ... 

Fig. 12.1. Schematic diagram of a cold-stabilization installation A, untreated wine (- -14°C) B, treated wine (- -5°C) C, wine during stabilization (—5°C) 1, untreated wine pump 2, treating wine at —5°C (refrigeration system and plate heat exchanger) 3, filter at the end of cold treatment 4, pump for cold-stabilized wine, ready to be filtered 5, heat exchanger for precooling wine to be treated by using it to warm treated wine...

Refrigerating the environment is another way of utilizing cold to stabilize wine. Winter cold may be used for this purpose, as well as specialized vat room installations where a chilled atmosphere makes it possible to keep wine at a temperature in the vicinity of 0°C for one or two months. The wine must previously have been filtered. Vats may be equipped with individual exchangers to accelerate cooling. This type of installation is highly effective. Furthermore, it minimizes the risk of oxidation, as the wine does not need to be handled. This system may also be used for fermenting white wines, maintaining a fermentation temperature of around 18-20°C, or even lower. 

Montonnet et al. (1994) did a great deal of work on defining the conditions for using electrodialysis to stabilize wine, identifying suitable membranes and process control so that each wine is treated according to its specific level of instability. This has made electrodialysis technology reliable and effective, while avoiding excessive alterations in the wine s chemical composition. 

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