Protein casse

CMCs are also reputed to promote solubilization of proteins and stabilize solutions containing them (Federson and Thorp, 1993). This property is useful in winemaking for the purpose of preventing protein casse. These CMC-protein interactions may be compared to the carbohydrate-protein association in glycoproteins and yeast manno-proteins. 

AGPs also have a protective effect against protein casse in white wines (Pellerin et al., 1994 Waters et al., 1994). They are, however, less effective than yeast mannoproteins (Sections 3.7.1 and... 

Grapes and wine contain many proteins with a wide range of molecular weights (30000-150000). Some unstable proteins are responsible for protein casse in white wines. Other proteins are associated with a carbohydrate fraction, e.g. yeast mannoproteins. Other proteins are associated with a carbohydrate fraction, e.g. yeast mannoproteins and isolectin, recently identified in Chardonnay must (Berthier et al.,... 

Proteins in must are a well-known cause of instability, affecting the clarity of white wines. When they precipitate, they cause protein casse , reported by Laborde as early as 1904. For many years, this was confused with white casse or copper casse . The turbidity or deposits characteristic of protein casse appear in the bottle, usually when wines are stored at high temperatures. They may also occur when tannin is leached into wine from the cork. Tartrate crystallization and flocculated proteins are responsible for the main problems with clarity in bottled white wines. 

Bentonite treatment has been recommended for eliminating unstable proteins from white wine for over 50 years (Saywell, 1934 Ribereau-Gayon, 1935). However, the proteins responsible for protein casse were only studied much later, and further research is still required. 

The mechanism of protein casse in wine is usually (Ribereau-Gayon et al., 1976) included in the general diagram of flocculation of a hydrophihc colloid (Section 9.3.2). Flocculation requires the disappearance of two stabilizing factors charge and hydration. 

Principle of Stabilization Treatments to Prevent Protein Casse... 

Other methods for obtaining the mannoprotein (420 kDa), other than MP32, with a protective effect on protein casse (Waters et al., 1993) were tested by Dupin et al. (2000). The most effective extracts were obtained by treating whole yeast cells with EDTA. This mannoprotein was located in the entire cell wall by immunodetection and was linked to the other constituents by non-covalent bonds. 

Preventing Certain Types of Colloidal Precipitation Protein Casse and Copper Casse... 

Virginie Moine-Ledoux for her work on the use of yeast mannoproteins in preventing tartrate precipitation (Chapter 1), as well as the stabilization processes for protein casse (Chapter 5)... 

As lysozyme is deactivated by bentonite, this treatment should be delayed. For the same reason, wines treated with lysozyme react to the heat test, indicating protein instability. However, protein casse develops at high temperatures (50°C), which do not normally occur during wine shipment and storage. 

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