Haze in beverages

Beverages such as beer, wine, clear fruit juices, teas, and formulated products with similar ingredients are generally expected by consumers to be clear (free of turbidity) and to remain so during the normal shelf life of the product. Hazy products are often regarded as defective and perhaps even potentially harmful. Since consumers are usually more certain of what they perceive visually than of what they taste or smell, the development of haze in a clear product can reduce the likelihood of repeat purchasing of a product and can have serious economic consequences to a producer. Hazes are caused by suspended insoluble particles of colloidal or larger size that can be perceived visually or by instruments. Hazes in clear beverages can arise from a number of causes, but are most often due to protein-polyphenol interaction. The nature of protein-polyphenol interaction and its effect on haze particles, analysis of haze constituents, and stabilization of beverages against haze formation are reviewed.