EFFECT OF LACTIC ACID ON Escherichia coli O157:H7 AND ON COLOR STABILITY OF VACUUM-PACKAGED BEEF STEAKS UNDER HIGH STORAGE TEMPERATURE

The effect of lactic acid (LA) addition on Escherichia coli O157:H7 survivability as well as the color stability was determined in vacuum-packaged beef steaks storage at 10°C for 50 days. Longissimus dorsi muscle was portioned into beef steaks and inoculated with Escherichia coli O157:H7. Afterwards, the samples were submitted at three treatments: without lactic acid addition or non-treated (NT); with 0.56 M (5%, v/v) (L5), and with 1.13 M (10%, v/v) (L10) of lactic acid addition. Same division was performed with samples non inoculated. All samples were package at vacuum and stored at 10ºC during 50 days. L10 demonstrated an efficient bacteriostatic effect (P < 0.05) against E. coli O157:H7 and total aerobic mesophilic bacteria. Nonetheless, LA induced a decrease (P < 0.05) in a* values in samples after application and during storage, promoting discoloration of beef steaks. Therefore, L10 was efficient in controlling E. coli O157:H7 even at abusive storage temperatures. However, this decontamination treatment affects negatively the color stability of beef.