Spoilage bacteria are bacteria typically involved in the spoilage of foods rather than in causing illness: organisms such as Pseudomonas on chilled meats and fish, lactic acid bacteria in vacuum packs, and Erwinia on vegetables. They cause off-odours, slime, discoloration, gas, and texture breakdown that make food unacceptable long before it becomes dangerous. Refrigeration, modified-atmosphere packaging, and good hygiene slow them, but because some, like Pseudomonas, grow well in the cold, chilled shelf life is always finite. Distinguishing spoilage flora from pathogens is a core skill in food microbiology and shelf-life work.