No abstract

Consumer demand for foods manufactured without the direct addition of chemical preservatives, such as sodium nitrite and organic acid salts, has resulted in a unique class of “naturally” cured meat products. Formulation with a natural nitrate source and nitrate-reducing bacteria results in naturally cured processed meats that possess traits similar to conventionally cured meats. However, previous research has shown that the naturally cured products are more susceptible to pathogen growth. This study evaluated Listeria monocytogenes growth on ham manufactured with natural curing methods and with commercially available clean-label antimicrobials (cultured sugar and vinegar blend; lemon, cherry, and vinegar powder blend) and assessed impacts on physicochemical characteristics of the product. Hams made with either of the antimicrobials supported L. monocytogenes growth similar to that in the traditionally cured control (P > 0.05). Hams made with prefermented celery juice powder had the lowest residual nitrite concentrations (P < 0.05), and when no antimicrobial was added, L. monocytogenes growth was similar to that of the uncured control (P > 0.05). Aside from residual nitrite and nitrate concentrations, few physicochemical differences were identified. These findings show that ham can be produced with natural curing methods and antimicrobials to provide similar L. monocytogenes inhibition and physicochemical traits as in traditionally cured ham.

This study evaluated the effectiveness of synthetic and natural antioxidants, green tea, commercial grape seed extracts/combinations, and TBHQ, with varying concentrations of lipid oxidation of nonirradiated and irradiated chicken breast meats stored at 5 degrees C for 12 days. Fresh boneless and skinless chicken breast meats were vacuum-infused with varying concentrations of antioxidants: green tea, grape seed extracts alone/in combination, and TBHQ. The irradiation dosage was 3.0 kGy. Carbonyl values of raw chicken meat and thiobarbituric acid reactive substances (TBARS) values of raw and cooked chicken meat were determined for 0-12 days at 5 degrees C storage. TBARS values for 0-12 days of storage at 5 degrees C ranged from 1.21 to 7.3 and 1.22 to 8.51 mg malondialdehyde/100 g chicken for nonirradiated and irradiated raw chicken, respectively. TBARS values of cooked chicken ranged from 2.19 to 35.83 and 2.45 to 45.72 mg malondialdehyde/100 g chicken for nonirradiated and irradiated chicken, respectively. Irradiation increased TBARS values of both controls and plant extracts. The carbonyl content in meat lipid ranged from 1.7 to 2.9 and 1.7 to 4.41 micromol acetophenone/10 g of nonirradiated and irradiated chicken meat, respectively, and meat protein ranged from 1.4 to 2.07 and 1.41 to 2.72 micromol/10 g meat. Infusion of chicken meat with selected plant extracts is an effective method to minimize lipid oxidation and volatiles developments caused by irradiation.

Fresh meat products can become contaminated with the pathogen Escherichia coli O157:H7 during the slaughter process; therefore, an E. coli O157:H7 indicator to verify the effectiveness of process controls in slaughter establishments would be extremely useful. The hides of 20 beef cattle were sampled, and 113 bacterial isolates were obtained. Thirteen of these isolates representing four genera, Escherichia, Enterobacter, Providencia, and Serratia, were selected based on growth and biochemical characteristics similar to those of five clinical strains of E. coli O157:H7. The temperature sensitivity was determined for the individual isolates and the five E. coli O157:H7 strains at 55 and 65 degrees C. D65-values for all 13 isolates were not significantly different from D65-values of the E. coli O157:H7 strains. E. coli isolates were the only isolates whose D55-values were not significantly different from those of the E. coli O157:H7 strains. E. coli isolates P3 and P68 were more resistant to the effects of 55 degrees C than were the other E. coli isolates but were not significantly different from E. coli O157:H7 WS 3331 (P > 0.05). The remaining E. coli isolates (P1, P8, and P14) were not significantly different from E. coli O157:H7 strains ATCC 35150, ATCC 43894, ATCC 43895, and WS 3062 (P > 0.05). Prerigor lean and adipose beef carcass tissue was artificially contaminated with stationary-phase cultures of the five E. coli beef cattle isolates or a cocktail of five E. coli O157:H7 strains in a fecal inoculum. Each tissue sample was processed with the following microbial interventions: 90 degrees C water; 90 degrees C water followed by 55 degrees C 2% lactic acid; 90 degrees C water followed by 20 degrees C 2% lactic acid; 20 degrees C water followed by 20 degrees C 2% lactic acid; 20 degrees C water followed by 20 degrees C 20 ppm chlorine; and 20 degrees C water followed by 20 degrees C 10% trisodium phosphate. The appropriateness of the E. coli isolates as potential E. coli O157:H7 indicators was dependent upon the microbial intervention utilized. For all microbial intervention methods applied irrespective of tissue type, the mean log reductions of at least two E. coli isolates were not significantly different from the mean log reduction of the E. coli O157:H7 cocktail (P > 0.05). Because of the frequent employment of multiple microbial interventions in the cattle industry, no single isolate can realistically represent the effectiveness of all microbial interventions for reduction of E. coil O157:H7. Thus, the use of a combination of E. coli isolates may be required to accurately predict the effectiveness of microbial intervention methods on the reduction of E. coli O157:H7 in beef carcass tissue.