Consumer preferences, internal color and reduction of shigatoxigenic Escherichia coli in cooked hamburgers.

The aim of this study was to relate consumer preferences and preparation of hamburgers to color change, internal temperature and reduction of shigatoxigenic Escherichia coli (STEC) serogroups O157 and the "Big Six" (O26, O45, O103, O111, O121, O145) under two ground beef packaging scenarios: 75% O2 MAP and vacuum. 75% O2 MAP hamburgers cooked to 60 °C core temperature appeared done and showed less internal red color (lower a*) than corresponding vacuum hamburgers. Similar STEC reduction (<4 log10) was found for both hamburgers at core temperatures ≤ 66 °C. In a representative survey (N=1046) most consumers reported to judge hamburger doneness by the color and many preferred undercooked hamburgers. Premature browning of 75% O2 MAP hamburgers represents a risk of foodborne illness, when considering consumers' food handling practices. The risk is even greater if such ground beef is prepared by consumers who prefer undercooked hamburgers and judge doneness by color.