Effects of Acetic-Lactic Acid Treatments Applied to Beef Trim on Populations of Escherichia coli O157:H7 and Listeria monocytogenes in Ground Beef

Abstract

The efficacy of organic acid sprays for eliminating Escherichia coli O157:H7 and Listeria monocytogenes from beef trim used in a model ground beef production scheme was determined. Beef trim pieces with ca. 20% fat inoculated with E. coli O157:H7 or L. monocytogenes (ca. 3 log10 CFU/g) were utilized as controls or treated by spraying with 2 or 4% acetic and lactic acids. Propylene glycol (20%) was the carrier for each treatment. Following acid treatment, intact pieces were stored at 4°C for 12 or 24 h, ground, divided into 4 100-g retail packages and stored at 4°C for 0, 1, 2, or 4 days, at which time surviving populations of E. coli O157:H7 or L. monocytogenes were enumerated. High populations (>2.6 log10 CFU/g) of the pathogens persisted in all treatments. The 2% acid spray reduced (P < 0.01) the E. coli O157:H7 population by only 0.1 log10 CFU/g. The 2 and 4% acid sprays reduced (P < 0.001) the L. monocytogenes populations by 0.36 and 0.44 log10 CFU/g, respectively. Storing beef trim intact prior to grinding resulted in lower populations of E. coli O157:H7, and storage following grinding did not affect populations of either pathogen. The acid treatments tested were only slightly effective as sanitizers for beef trim destined for ground beef production.

A Review on Some Organic Acids Additives as Shelf Life Extenders of Fresh Beef Cuts

“…It is commonly known as vinegar which has antimicrobial capabilities due to its ability to lower the pH and cause instability of bacterial cell membranes [60] . Acetic acid has been shown to be effective against E. coli O157 H7, reducing this pathogens by 0.1 log 10 colony forming unit (cfu g −1 ) [61,62] . Also it reduced Salmonella typhimurium by 0.73 log cfu cm −2 on carcass tissue surfaces [63,64] but colour deterioration of whole muscle cut surfaces have been reported already [65] .…”

The Relative Efficacy of Thermal and Acidification Stresses on the Survival of E. coli O157:H7, Salmonella, and Listeria Monocytogenes in Ground Beef

“…The authors reported that the use of 2 and 4% acid spray in beef trim stored at 4 °C reduced Listeria monocytogenes (initial concentrations 3 log 10 CFU/g) by 0.36 log 10 CFU/g and 0.44 log 10 CFU/g, respectively. The reduction in E. coli O157:H7 was lower than Listeria monocytogenes under similar conditions (Conner et al, 1997).…”

“…The acid treatments for reducing E. coli O157:H7and Listeria monocytogenes levels in beef trim were found to be effective (Conner, Kotrola, Mikel, & Tamblyn, 1997). The authors reported that the use of 2 and 4% acid spray in beef trim stored at 4 °C reduced Listeria monocytogenes (initial concentrations 3 log 10 CFU/g) by 0.36 log 10 CFU/g and 0.44 log 10 CFU/g, respectively.…”

Survival or Growth of Escherichia coli O157:H7 in a Model System of Fresh Meat Decontamination Runoff Waste Fluids and Its Resistance to Subsequent Lactic Acid Stress

“…However, there is a need to evaluate the potential for development of acid resistance in E. coli O157:H7 during application of acid decontamination interventions in meat (31). Studies have shown that the pathogen may survive decontamination of meat with lactic or acetic acid (7,16,17), suggesting that survivors can exist and may potentially adapt to the residual organic acid in situ in commercial meat processing environments (31).Berry and Cutter (6) demonstrated that previous acid adaptation of E. coli O157:H7 by culturing in media with 1% glucose (9) reduced the effectiveness of a 2% acetic acid solution to inactivate it on decontaminated beef. Recent studies from our laboratory have used meat decontamination runoff waste fluids of different pHs (acidic, acid-diluted, or nonacid-water spray washings) as a model system to evaluate responses of E. coli O157:H7 under conditions simulating those in meat plant environments (33,34,35,37,42).…”

“…However, there is a need to evaluate the potential for development of acid resistance in E. coli O157:H7 during application of acid decontamination interventions in meat (31). Studies have shown that the pathogen may survive decontamination of meat with lactic or acetic acid (7,16,17), suggesting that survivors can exist and may potentially adapt to the residual organic acid in situ in commercial meat processing environments (31).…”