Effects of Pyruvic Acid, Succinic Acid, and Oregano Essential Oil on Salmonella, Natural Microflora, and Quality of Raw Ground Chicken

ObjectivesThe growing stringency of regulations related to pathogens in raw poultry and increasing consumer demand for more natural food ingredients makes it imperative to explore alternative antimicrobial agents. The aim of this study was to assess the anti-Salmonella effect of combinations of succinate or pyruvic acid with oregano essential oil in raw ground chicken. Additionally, their effect on natural microflora and quality of ground chicken over simulated retail display was evaluated.Materials and MethodsNalidixic acid (NA) adapted Salmonella Typhimurium was inoculated on skin-on broiler breast meat pieces. The antimicrobial treatments given to meat were 2 and 3% pyruvic acid (PA) or monosodium succinate (SA) in combination with 0.5% essential oil (EO). Agar at the concentration of 0.05% was added to water used to prepare antimicrobial solutions to disperse the essential oil. Mode of antimicrobial treatment was 30 s dip. The meat was then ground and evaluated for pathogen reduction. Data were analyzed using 1-way ANOVA. Surviving Salmonella were recovered on XLT-4 with 50 ppm NA. Non-inoculated meat was similarly treated with antimicrobial dip and ground. Ground chicken was packaged in foam trays with PVC overwrap, and evaluated for mesophilic aerobic plate count (APC), psychrotrophic count (PC), pH, instrumental color (CIE L*, a*, and b*), and expressible moisture over 8 d of simulated retail display.A factorial design was assigned to the experiment with antimicrobial treatments and display days as the fixed effect factors. Data were analyzed using a mixed general linear model that considered replicates as a random effect in addition to the mentioned fixed effects. All trials were conducted in three replicates.ResultsMaximum reduction obtained in Salmonella counts from ground chicken was 1.52 log CFU/g and 0.98 log CFU/g, resulting from 3% SA + 0.5% EO, and 3% PA + 0.5% EO, respectively. Three percent SA + 0.5% EO treatment resulted in ground chicken with approximately 1.2 log CFU/g lower APC on Day 8 that was significantly lower (P < 0.05) than all other treatments. This treatment also resulted in less pH variation over the entire shelf life duration and lighter color of ground meat on Day 8.ConclusionThese results indicate that combination of monosodium succinate and oregano essential oil provides effective reduction of Salmonella and improved raw quality of ground chicken. This antimicrobial combination can be employed as a clean label ingredient for raw chicken applications.

Anti-Salmonella Effects of Pyruvic and Succinic Acid in Combination with Oregano Essential Oil

ObjectivesEffective decontamination approaches will aid in improving safety of poultry products and help processors comply with pathogen performance standards. Increasing consumer demand for clean label and more natural ingredients presents a scope to explore alternative decontamination approaches for meat and food contact surfaces. This study aimed to evaluate the antimicrobial efficacy of combinations of pyruvic acid (PA), succinic acid (SA), and oregano essential oil (EO) against Salmonella Typhimurium in suspensions, cells inoculated on raw chicken, and cells attached to steel.Materials and MethodsMinimum bactericidal concentration (MBC) assays were conducted in Mueller-Hinton broth (5 mL). Bacterial cells were added to broth suspensions of antimicrobial agents or their combinations. A contact time not exceeding 10 s was provided. Surviving bacteria were recovered on tryptic soy agar (TSA). Bacterial inactivation was confirmed by enrichment in D/E broth. Experiment involved completely randomized design with each concentration of organic acid and essential oil being considered as one level. Data were analyzed using 1-way ANOVA. Aqueous solutions of PA, SA, EO, and the mixtures of PA+EO and SA+EO were prepared using 0.05% agar to suspend the essential oil. Skin-on raw chicken breast meat pieces (2.5 cu cm) were used as a substrate to inoculate nalidixic acid (NA) adapted Salmonella cells. Pieces were treated with antimicrobial agents for 30 s by dipping, and surviving Salmonella were recovered using D/E broth on XLT-4 agar with 50 ppm NA. Four different experiments with variable acid and essential oil concentrations were performed and data were analyzed using 1-way ANOVA. Each experiment included an inoculated untreated control. Stainless steel coupons (2 × 5 cm) were used as a substrate for Salmonella attachment. Cells were allowed to grow and attach on coupons submerged in tryptic soy broth for 24 h. Coupons were rinsed to remove planktonic cells. Attached cells remaining on the coupon were dip treated with antimicrobial agents for 5 min. Surviving cells were recovered on TSA. For antimicrobial treatments leading to no cell recovery, additional experiments were performed. The recovery broth was enriched in tryptic soy broth and streaked on TSA to confirm inactivation. Three different experiments were conducted while including their respective inoculated and untreated controls and analyzed using 1-way ANOVA. All experiments were conducted in three replicates.ResultsMBC for was found to be PA (0.5%), SA(3%), EO (0.04%), PA+EO (0.25 + 0.02%), SA+EO (0.25 + 0.02%), respectively. 1% PA + 0.08% EO combination produced the maximum reduction (1.42 ± 0.11 log CFU/cm2) followed by 6% SA + 0.08% EO (1.02 ± 0.08 log CFU/cm2) in Salmonella populations on raw chicken. More than 6 log CFU/coupon of attached Salmonella were inactivated by mixtures of 0.25% PA + 0.02% EO and 1.5% SA + 0.02% EO.ConclusionThe combinations of PA+EO and SA+EO both exhibited strong anti-Salmonella activity in cell suspensions, on cells attached to stainless steel, and were effective in reducing Salmonella populations on raw chicken. Therefore, these antimicrobial combinations merit further research for raw poultry, meat, and other sanitation applications.

Control of Listeria monocytogenes in turkey deli loaves using organic acids as formulation ingredients

The growth of Listeria monocytogenes in further-processed meat products has become a major concern and an important food safety issue. The meat and poultry industries have incorporated interventions such as organic acids in marinades to inhibit the growth of L. monocytogenes. In this study, organic acids were utilized in the raw product and as a postcook dip to determine their inhibitory effect on the growth of L. monocytogenes in turkey deli loaves. The turkey deli loaves were processed, cooked, cooled, inoculated with streptomycin-resistant L. monocytogenes, and then dipped. Treatments were potassium lactate (PL) in the raw product with sodium lactate (SL), sodium diacetate (SD) dip, PL with SL/PL/SD dip, SL with SL/SD dip, and SL with SL/PL/SD dip. There was also a positive (inoculated) and negative (noninoculated) control, which was dipped in distilled water. Days 0, 7, 14, 21, 28, 42, and 56 were sampled for L. monocytogenes. There were no differences (P>0.05) among the organic acid treatments in the turkey deli loaves at any time points; therefore, all of the treatments increased the lag phase of L. monocytogenes, extending the shelf-life of the product. However, there was a difference between the treatments and the positive control at d 7, 14, 21, 28, 42, and 56. The growth of L. monocytogenes increased immediately in the positive control, whereas the negative control appeared to have no growth. These organic acids can provide meat processors with a useful method for extending the lag phase of L. monocytogenes in ready-to-eat meat and poultry products.

Cecal carriage of Clostridium perfringens in broiler chickens given Mucosal Starter Culture

Day-of-hatch broiler chicks housed in isolation units were each given, by oral gavage, 0.1 ml of Mucosal Starter Culture (MSC) or saline control. Each of the treated and control chicks was subsequently given a composite culture of three strains of bacitracin-resistant Clostridium perfringens (Cp) previously isolated from chickens with symptoms of necrotic enteritis. Some chicks were maintained on a corn-based diet provided ad libitum. Others were given the feed supplemented with 50% rye (a predisposing factor for necrotic enteritis). At 7, 14, and 21 days after receiving Cp, chicks were euthanatized, and cecal contents were diluted and plated on selective agar containing bacitracin. For chicks on corn feed, Cp numbers were similar in control birds and birds given MSC in three of four trials. In two of the trials that demonstrated no effect of MSC on Cp numbers, enterotoxin presence was determined. The number of birds with detectable Cp enterotoxin in their small intestine and the mean toxin levels were lower in the MSC-treated birds. In a fourth trial with birds on corn-based feed, mean Cp numbers and the number of Cp-positive birds were lower in the MSC-treated birds. For the two trials involving chickens on rye-supplemented feed, Cp numbers and the percentage of Cp-positive birds were significantly reduced in MSC-treated birds compared with control birds. Enterotoxin in birds receiving the 50% rye diet was at low levels or not detected in control and MSC-treated birds. Results suggest that MSC may reduce intestinal proliferation of Cp, a causative agent of necrotic enteritis in poultry and of foodborne disease in humans.