Abstract: The present invention relates to a method for determining the presence or absence of contaminating bacteria in a packaged food sample comprising storing food in a package having as a lining a hydrophilic polymeric composition, said composition preferably being permeable to water and at least one gas dissolved in water or water vapor and being selected from the group consisting of carbon dioxide, carbon monoxide, hydrogen sulfide, sulfur dioxide, hydrogen and ammonia gas and containing an indicator for detecting the presence or abscence of said gas; said indicator being polymerized or dispersed throughout said polymeric composition or coated onto a hydrophobic polymeric composition.