Patent ID: 8637271

Claim:
A method for detecting whether food is spoiled or contaminated with microbes such that said spoiled or contaminated food is not edible, said method comprising: a) placing a portion of said food proximal to a polymeric indicator comprising: i) polyvinyl alcohol and ii) a plurality of hydroxy phenyl pH indicating moieties covalently bound to the polyvinyl alcohol backbone through a linking group that is attached at one end to a phenyl ring of the hydroxy phenyl pH indicating moiety and at another end to the polyvinyl alcohol backbone; wherein the pH indicating moieties undergo a detectable, colorimetric change in response to a pH change brought on by the presence of metabolic byproducts from microorganisms; and wherein the polymeric indicator is free from DMSO; b) detecting the presence or absence of a colorimetric change in the polymeric indicator; and c) correlating the presence or absence of a colorimetric change in the polymeric indicator to whether the food is non-edible or edible; wherein the linking is selected from the group consisting of a C1-C20 akylene group, a C1-C19 alkylene ether group, or the reaction product of formaldehyde, paraformaldehyde or glutaraldehyde with the hydroxy phenyl pH indicating moieties and the polyvinyl alcohol.