Extended shelf-life milks in NorthAmerica: a perspective The background to the development ofextended-shelf-life (ESL) dairy products, the differences between ESL and asepticproducts, and requirements for the US and Canadian markets are set out. Themicrobiological quality of the raw milk and various aspects of processing are discussed;descriptions of the Pure-Lac system and a microfiltration process are included. Methodsfor improving plant hygiene and reducing contamination are considered. Properties ofpackaging materials and necessary temperature conditions for storage and distribution arealso covered.