Quaternary Ammonium Compounds
Quaternary ammonium compounds or “Quats” are heat stable, non-corrosive chemicals that function over a broad pH to disrupt cell membranes. This bactericidal action is facilitated by the association of the positively charged quaternary ammonium groups with phospholipids forming micelle aggregates and lysing the cell. They tend to be most effective on Gram-positive bacteria, less so on Gram-negative bacteria. Quats are highly adhesive amphiphilic surfactants and degrade slowly. Because these compounds have both a hydrophilic and hydrophobic region, they are able to interact with the cellular membrane in aqueous solutions such as wine or water. Thus, applications for sanitation prove quite effective requiring weekly (rather than daily) treatments of surfaces. They can also be applied in low concentrations as a bleach boosting component in conjunction with organic mono-peroxyacids.
Quats can be a health hazard and should be handled with care. These compounds are especially irritable to the eyes and skin, so MSDS information should be made available to employees.
Application in Wine Microbiology:
Quats are used to inhibit mold formation on winery walls, floors, and tanks. It can also be applied as a sanitizer. Recommended concentrations for winery applications span from 200-400 mg/L with contact times of approximately 1-2 minutes. It should be applied at room temperature (24°C) for maximum effectiveness. However, though non-toxic, caution must be exercised in removing all remnants of Quats from machinery because contact with wine can confer off-aromas and characters. The taste threshold for Quats is 15 mg/L.
- Fugelsang, K.C. 1997. Wine Microbiology. Springer:New York.
- Glaasker, E., Heuberger, E.H.M.L., Konings, W.N., and B. Poolman. 1998. Mechanism of osmotic activation of the quaternary ammonium compound transporter (QacT) of Lactobacillus plantarum. J. Bacteriol. 180:5540-5546
- Joseph, C.M.L., Kumar, G., Su, E., and L.F. Bisson. 2007. Adhesion and biofilm production by wine isolates ofBrettanomyces bruxellensis. Am. J. Enol. Vitic. 58:373-378.
- MSDS Information accessed on 2/21/2010: http://www.chemcas.com/msds/cas/msds121/68424-85-1.asp