Comparison of Sodium Nitrite and ‘Natural’ Nitrite on the Inhibition of Spore Germination and Outgrowth of Clostridium sporogenes in Low- and High-Fat Frankfurters

Abstract

In the US, sodium and potassium nitrite are regulated food preservatives that prevent the germination of Clostridium spores in cured and processed meats. In recent years, the use of vegetable-derived nitrite (i.e., vegetable nitrate fermented to nitrite) has been designated as ‘natural nitrite’ to accommodate natural meats that cannot use artificial ingredients, and such meat products can be labelled as having ‘no added preservatives’. This new status and labelling allowance for microbially-modified nitrite provides for a ‘clean label’ application of nitrite against the stigma of chemical ingredients and has found increased use within the processed meat industry. The objectives of this study were to examine Clostridium sporogenes as a pathogen-surrogate challenge organism and the use of vegetable (celery) nitrite to prevent spore germination in cooked meat products. A three-strain spore crop of C. sporogenes ATCC 3584, ATCC 19404 and ATCC BAA-2695 was applied during ingredient formulation of low and high-fat hotdogs that were divided into three sub-batches (control without nitrite, hotdogs with sodium nitrite, hotdogs with celery nitrite). In both low and high-fat processes, sodium nitrite was compared to hotdogs made with comparable levels of celery nitrite (156 ppm). All treatments were performed with duplicate trial replication and triplicate sample testing within each trial. Comparisons were analyzed by repeated measures analysis of variance to determine significant difference (p < 0.05) of time course treatments. In shelf-life assays, growth was inhibited at both 5 °C and 15 °C, even if nitrite was absent; however, spore germination and growth readily occurred at 35 °C. Comparison of nitrite effects was best evaluated at 35 °C as a permissive condition to examine the effects of nitrite treatments. Celery nitrite showed no significant difference from sodium nitrite when used in both low and high-fat hotdogs, and spore outgrowth was only observed after 2–3 days at 35 °C compared to hotdogs without nitrite. Application of bacteriocin preparations in the formulation that were effective against Listeria monocytogenes, and moderately inhibitory towards the 3-strain spore mixture of C. sporogenes, were not effective in spore control in manufactured hotdogs. The nitrite validation hotdog trials described herein demonstrates that (celery or sodium) nitrite may prevent Clostridium spore germination for 24–48 h even under permissive conditions to help keep processed meat safe.

Evaluation of Various Lactic Acid Bacteria and Generic E. coli as Potential Nonpathogenic Surrogates for In-Plant Validation of Biltong Dried Beef Processing

“…Antibiotic resistance was determined using antibiotic susceptibility discs (BD BBL Sensi-Discs, BD Labs, Franklin Lakes, NJ, USA) to determine innate antibiotic resistance (Table 1). After identification of antibiotic resistances, cultures were then enumerated on media with and without antibiotics to ensure the absence of inhibition from the use of antibiotics in the media as described previously [4,28,30]. For some strains used as inoculum cocktails that did not have consensus of the same antibiotic resistances, antibiotic resistance was acquired by plating on low level antibiotics known to generate spontaneous antibiotic resistance (i.e., gentamycin and rifamycin).…”

Reduction of carcinogens in fermented fish (pla-ra and pla-som) by heating

“…In northeast Thailand, pla-ra (PR) and pla-som (PS) are the popular traditional dishes that contain fermented fish. Nitrates and nitrites are specifically used in food preparation to inhibit Clostridium botulinum growth [5][6][7] and lipid peroxidation [8]. However, the use of nitrites as curing agents for meat is a public concern because they can be a precursor of nitrosamines, many of which are known carcinogens [9].…”