Yogurt bacteria have limited activity at < 10 ºC (Tamime & Robinson; 1999a); therefore the objective of cooling is to arrest the metabolic activity of yogurt bacteria once the desired pH of yogurt is achieved (Chandan & O‟Rell, 2006b; Tamime & Deeth, 1980). Stirred yogurt is then packaged in the retail cups, predominately plastic (high-impact polystyrene) containers with metal foil seals or plast ic „snap-on‟ lids (Varnam & Sutherland, 2001a).