Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2004
Publication Date: 5/1/2004
Citation: Juneja, V.K., Thipparedii, H. 2004. Control of Clostridium perfringens in a model roast beef by salts of organic acids during chilling. Journal of Food Safety. 24:95-108.
Interpretive Summary: One of the most common types of food poisoning in the United States is caused by the bacterium, Clostridium perfringens. Illnesses have been traditionally associated with inadequate cooling practices in retail food service operations. Thus, there was a need to determine the cooling time and temperature for cooked meat products to remain pathogen-free and provide vital data for performing risk assessment on cooked meat. We determined that cooling times for roast beef products after heat processing can be extended to 21 hours by incorporation of the antimicrobial ingredients, sodium lactate, sodium lactate supplemented with sodium diacetate, buffered sodium citrate, and buffered sodium citrate supplemented with sodium diacetate, at more than or equal to 1.5% in the formulation to reduce the potential risk of C. perfringens germination and outgrowth. These findings will be of immediate use to the retail food service operations and regulatory agencies to ensure the safety of the cooked foods.
Technical Abstract: Control of Clostridium perfringens germination and outgrowth by the following salts of organic acids, sodium lactate (Purasal S/SP; 1.50, 3.00 and 4.80%), sodium lactate supplemented with sodium diacetate (Purasal Opti.form, 1.50, 3.00 and 4.80%), buffered sodium citrate (Ional, 0.75, 1.00 and 1.30%) and buffered sodium citrate supplemented with sodium diacetate (Ional Plus, 0.75, 1.00 and 1.30%) was evaluated during continuous chilling of a model roast beef product. Beef rounds were ground through an 1/8" plate and NaCl, potato starch and potassium tetra pyrophosphate were added to final concentrations of 0.85, 0.25 and 0.20%, respectively and mixed. Portions (250 g) of the meat were mixed with either Purasal (1.5, 3.0 or 4.8%), Optiform (1.5, 3.0 or 4.8%), Ional (0.75, 1.0 or 1.3%) or Ional Plus (0.75, 1.0 or 1.3%) along with a control that did not have any added antimicrobials. Each product was mixed with a three-strain spore cocktail of C. perfringens to obtain a final spore concentration of ca. 2.2 log10 spores/g. Inoculated products (10 g) were packaged into vacuum bags (2 in. x 3 in.), vacuum sealed, cooked at 60C for 1 h, and subsequently chilled from 54.4C to 7.2C in 18 or 21 h following exponential chilling rates. Products were sampled immediately after cooking to enumerate the C. perfringens populations (spores surviving heat treatment) and subsequent to chilling (total C. perfringens populations, including spores and vegetative cells resulting from germination and outgrowth of the spores). Chilling of cooked, model ground roast beef following 18 and 21 h chill rates resulted in germination and outgrowth of C. perfringens spores to 6.33 and 7.60 log10 CFU/g populations, from initial spore populations of ca. 2.2 log10 CFU/g. Incorporation of Purasal (1.5-4.8%), Optiform (1.5'4.8%), Ional and Ional Plus (0.75-1.3%) substantially inhibited germination and outgrowth of C. perfringens spores. Incorporation of antimicrobial ingredients resulted in less than 1.0 log10 CFU/g increase of the pathogen, except for model roast beef with Ional Plus at 0.75% concentration, following 18 h chilling rate. Similar results were obtained when 21 h chilling rate was followed, with roast beef containing ingredients (at all the concentrations) resulting in either reductions or less than 1.0 log10 CFU/g growth in total C. perfringens populations, except for Purasal and Ional Plus at 1.5 and 0.75% concentrations, respectively. Use of sodium salts of organic acids in formulation of model roast beef can reduce the risk of C. perfringens spore germination and outgrowth during extended chilling rates.