Effect of Meat Binding Formulations on Thermal Inactivation of Escherichia coli O157:H7 Internalized in Beef

Abstract

This study evaluated the effects of meat binding or restructuring formulations, including salt/phosphate, algin/calcium, ActivaRM, and Fibrimex, with or without 0.27% (wt/wt) lactic acid, on thermal inactivation of internalized Escherichia coli O157:H7 in ground beef, serving as a model system for restructured products. Ground beef batches (700 g; approximately 5% fat) were mechanically mixed with a 5-strain composite of E. coli O157:H7 (7 log CFU/g) and then with the restructuring formulations. Product portions (30 g) were extruded into plastic test tubes (2.5 x 10 cm) and stored at 4 degrees C (18 h), before heating to 60 or 65 degrees C in a circulating water bath to simulate rare or medium-rare doneness of beef, respectively. Cooking to 60 or 65 degrees C reduced (P < 0.05) bacterial counts of control samples by 1.8 and 3.2 log CFU/g, respectively. Thermal destruction at 60 degrees C was not different (P > 0.05) among all treatments and the control. At 65 degrees C, greater (P < 0.05) thermal inactivation of E. coli O157:H7, as compared to the control, was obtained in samples treated with lactic acid alone (reductions of 4.9 log CFU/g), whereas for all other treatments, microbial destruction (reductions of 2.2 to 4.5 log CFU/g) was comparable (P > 0.05) to that of the control. Cooking weight losses were lower (P < 0.05) in salt/phosphate samples (<1%) compared to other formulations and the control (7.4% to 15.9%). Findings indicated that, under the conditions examined, restructuring of beef with salt/phosphate, algin/calcium, ActivaRM, or Fibrimex did not affect inactivation of internalized E. coli O157:H7 in undercooked (60 or 65 degrees C) samples, whereas inclusion of lactic acid (0.27%) in nonintact beef products enhanced pathogen destruction at 65 degrees C.

Inactivation of Escherichia coli O157:H7 during cooking of non-intact beef treated with tenderization/marination and flavoring ingredients

“…0.05) changes in bacterial populations were observed following overnight storage of samples at 4 C, regardless of the treatment or plating medium (Tables 2e4). Consistent with previous studies (Calicioglu, Sofos, Samelis, Kendall, & Smith, 2002;Mukherjee et al, 2008;Yoon, Calicioglu, Kendall, Smith, & Sofos, 2005;Yoon et al, 2009), overnight acidified marination at 4 C did not lead to dramatic reductions of E. coli O157:H7 populations in raw beef.…”

“…This finding is most likely due to the lowering of the pH of samples containing AA (Table 5), which sensitized the microbial cells to heat during cooking (Yoon et al, 2009). Mukherjee et al (2008) and Yoon et al (2009) also found enhanced destruction during cooking to the same final temperature, of E. coli O157:H7 internalized in AA-treated beef samples. In the latter studies, AA was tested alone, or in combination with one or two tenderizing/flavoring ingredients; specifically, NaCl (0.5%), NaCl þ calcium ascorbate (0.86%), or NaCl þ calcium chloride (0.23%).…”

“…Overall findings of these studies (Mukherjee et al, 2008;Yoon et al, 2009) were that destruction of E. coli O157:H7 during cooking was enhanced in organic acid-containing (especially acetic acid) treatments, and was generally not affected by any of the tested tenderizing salts, as compared to the control; however, once calcium salts were combined with an organic acid, reductions of the pathogen generally increased after cooking. The present study is a continuation of this work and includes testing of combinations of up to five ingredients, including sodium chloride plus sodium tripolyphosphate (ingredients commonly used by the industry in meat products), or calcium chloride, in combination with selected previously tested (Mukherjee et al, 2008;Yoon et al, 2009) tenderizing/marinating compounds, and a mixture of flavoring agents. Thus, the overall objective of this study was to evaluate various combinations of tenderizing/marinating and flavoring ingredients on thermal inactivation of E. coli O157:H7 in a lean ground beef model system.…”

“…Thus, the overall objective of this study was to evaluate various combinations of tenderizing/marinating and flavoring ingredients on thermal inactivation of E. coli O157:H7 in a lean ground beef model system. As previously reported (Mukherjee et al, 2008;Yoon et al, 2009), the ground beef model system was used to allow uniform inoculation, ingredient mixing, and heating of samples.…”

“…Previous work by the authors (Mukherjee et al, 2008) screened individual ingredients used for tenderization or marination of beef (i.e., calcium ascorbate, calcium chloride, calcium lactate, potassium lactate, sodium chloride, acetic acid, and citric acid) for their effect on destruction during cooking (60 and 65 C) of E. coli O157:H7 internalized in a lean ground beef model system (simulating non-intact products). In a study that followed (Yoon et al, 2009), logical combinations of two or three of the above ingredients were tested under the same conditions.…”