Control of Clostridium perfringens in a model roast beef by salts of organic acids during chilling

Control of Clostridium perfringens germination and outgrowth by the following salts of organic acids, sodium lactate [Purasal(TM) S/SP (Purasal); 1.50, 3.00 and 4.80 %], sodium lactate supplemented with sodium diacetare [Purasal(TM) Opti.form(TM) (Optiform), 1.50, 3.00 and 4.80%], buffered sodium citrate [Ional(TM) (Ional), 0.75, 1.00 and 1.30]) and buffered sodium citrate supplemented with sodium diacetate [Ional Plus' (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 (10 g) inoculated with C. perfringens spores (ca. 2.2 log(10) spores/g) was packaged into vacuum bags (2 in. x 3 in.), vacuum sealed, heated to 60C within I h, and subsequently chilled from 54.4C to 72C 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 resulted in germination and outgrowth of C. perfringens spores; the population densities increased by 4.13 and 4.40 log(10) CFU/g, following 18 and 21 h chill rates, respectively. Incorporation of Purasal (1.5-4.8%), Optiform (1.5-4.8%), Ional and Ional Plus (0.75-1.3%) substantially (P less than or equal to 0.05) inhibited germination and outgrowth of C. perfringens spores. Incorporation of antimicrobial ingredients resulted in less than or equal to 1.0 log(10) 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 : 1.0 log(10) 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.