Comparison of pathogenic and spoilage bacterial levels on refrigerated poultry parts following treatment with trisodium phosphate

Bacterial Contaminants of Poultry Meat: Sources, Species, and Dynamics

With the constant increase in poultry meat consumption worldwide and the large variety of poultry meat products and consumer demand, ensuring the microbial safety of poultry carcasses and cuts is essential. In the present review, we address the bacterial contamination of poultry meat from the slaughtering steps to the use-by-date of the products. The different contamination sources are identified. The contaminants occurring in poultry meat cuts and their behavior toward sanitizing treatments or various storage conditions are discussed. A list of the main pathogenic bacteria of concern for the consumer and those responsible for spoilage and waste of poultry meat is established.

Stress enhances the sensitivity of Salmonella enterica serovar Typhimurium to bacteriocins

AIMS

The aim of this study was to evaluate the potential application of bacteriocins against Gram-negative bacteria when associated with others food preservation methods.

METHODS AND RESULTS

Salmonella was subjected to heat, cold, acid and chemical (with ethylenediaminetetracetate and trisodium phosphate) stresses. Then, the cells were recovered and subjected to treatment with bacteriocins (500 AU ml(-1) ) for 6 h. Heat and cold stress were those that promoted more sensitization to bactericidal activity of nisin. Under the same conditions, bovicin HC5 acted more rapidly than nisin reducing the number of viable cells to undetectable levels after 20 min of treatment. Similar results with use of nisin only were observed after 6 h of treatment.

CONCLUSIONS

Stress conditions used in food industry, such as temperature and pH, and use of chelating agents or membrane disruptors, sensitized Salmonella Typhimurium cells to bacteriocins produced by lactic acid bacteria, such as nisin and bovicin HC5.

SIGNIFICANCE AND IMPACT OF THE STUDY

Food preservation methods sensitized Gram-negative bacteria to bacteriocins activity, which demonstrate the potential of nisin and bovicin HC5 to inhibit the growth of Salmonella.

The effect of sodium lactate and lactic acid combinations on the microbial, sensory, and chemical attributes of marinated chicken thigh

The present study was undertaken to evaluate the chemical, microbiological, and sensory effects of different sodium lactate (SL) and lactic acid (LA) combinations on marinated chicken thigh. The latter were treated with SL and LA combined at various concentrations, namely 0.3 and 0.03; 0.5 and 0.05; 0.6 and 0.06; 0.75 and 0.075; and 0.9 and 0.09%, respectively. The findings indicated that those combinations were efficient (P < 0.05) against the proliferation of various spoilage microorganisms, including aerobic plate count, psychrotrophic populations, Pseudomonas spp., Staphylococcus aureus, Enterobacteriaceae, and Salmonella spp. The results from chemical analyses revealed that the treated thigh underwent significant decreases (P < 0.05) in terms of pH values and total volatile base nitrogen contents. Significant differences (P < 0.05) were, however, detected with regard to their sensory attributes, with SL-LA concentrations of 0.9 and 0.09 yielding the highest scores for the color, texture, and flavor attributes. Overall, the findings demonstrated that the addition of 0.9% SL and 0.09% LA to marinated chicken can help delay the proliferation of spoilage microorganisms, prevent the generation of undesirable chemicals, improve the levels of sensory attributes, and extend the shelf life of products during refrigerated storage.

Inhibition of Listeria monocytogenes and Salmonella enteritidis on chicken wings using scallop-shell powder

The present study was designed to determine the inhibitory effect of scallop-shell powder (SSP) on Listeria monocytogenes and Salmonella enteritidis on chicken wings. Chicken wings artificially inoculated with L. monocytogenes (8.3 log(10) cfu/g) or S. enteritidis (8.8 log(10) cfu/g) were immersed in distilled water (0.10 or 0.50% wt/vol) of SSP slurries for 10 or 30 min, respectively. The amount of L. monocytogenes, S. enteritidis, mesophilic aerobic bacteria (MAB), and yeast or mold was determined for the chicken wings at d 0 or 7 of storage at 4°C. Results indicated that 0.5% SSP decreased the amount of L. monocytogenes and S. enteritidis on chicken wings by 3.7 and 5.0 log(10) cfu/g, respectively. The growth of L. monocytogenes, S. enteritidis, MAB, and yeast or mold was inhibited by SSP during the 7-d refrigerated storage. Color and odor of chicken wings were not significantly changed by SSP treatment (P > 0.05).

Decontamination of chicken skin surfaces inoculated with Listeria innocua, Salmonella enteritidis and Campylobacter jejuni by contact with a concentrated lactic acid solution

1. The aim was to establish how poultry skin could be efficiently decontaminated without changing its organoleptic properties. 2. Chicken skins were surface inoculated with Listeria innocua and treated with different acid solutions (2 and 10% lactic acid for 1 and 30 min). Surviving bacteria were enumerated immediately after treatment and after 7 d storage at 4 degrees C. 3. Reductions of up to 2.6 log were reached immediately after treatment. The treatment effect persisted for 7 d storage, when the reduction exceeded 4.59 log for the strongest treatment. 4. Residual levels of lactic acid were not significantly higher than in untreated controls, except for the strongest treatment. A tasting panel found no significant difference between controls and samples. 5. After the initial results, an apparently optimal treatment (5% lactic acid for 1 min) was applied on chicken skins' surface inoculated with a mix of Listeria innocua, Salmonella enteritidis and Campylobacter jejuni. Treatment efficacy was assessed immediately after treatment and after 1, 4 and 7 d storage. 6. This treatment seems to be very promising from a food processing standpoint, being fast and allowing decimal reductions of 2.00 log for Listeria innocua and 2.38 log for Salmonella enteritidis after 7 d storage, neither significantly increasing skin lactic acid nor causing any organoleptic modifications to the product. The effect of the treatment is significant after one day storage for Listeria innocua and after 4 d storage for Salmonella enteritidis.

The inhibitory effect of natural bioactives on the growth of pathogenic bacteria

The objective of this study was to evaluate the inhibitory activity of natural products, against growth of Escherichia coli (ATCC 25922) and Salmonella typhimurium (KCCM 11862). Chitosan, epigallocatechin gallate (EGCG), and garlic were used as natural bioactives for antibacterial activity. The testing method was carried out according to the disk diffusion method. All of chitosan, EGCG, and garlic showed inhibitory effect against the growth of E. coli and Salmonella typhi. To evaluate the antibacterial activity of natural products during storage, chicken skins were inoculated with 10(6) of E. coli or Salmonella typhi. The inoculated chicken skins, treated with 0.5, 1, or 2% natural bioactives, were stored during 8 day at 4. The numbers of microorganisms were measured at 8 day. Both chitosan and EGCG showed significant decrease in the number of E. coli and Salmonella typhi in dose dependent manner (P < 0.05). These results suggest that natural bioactives such as chitosan, EGCG may be possible to be used as antimicrobial agents for the improvement of food safety.

Variation in Salmonella resistance to poultry chemical decontaminants, based on serotype, phage type, and antibiotic resistance patterns

Chemical decontaminants are currently under review for final approval by the European Union authorities with the aim of reducing the number and/or prevalence of pathogenic microorganisms on poultry. The purpose of the research being reported here was to determine the association, if any, of decontaminant resistance with the serotype, phage type, and antibiotic resistance of Salmonella strains. Sixty poultry isolates of Salmonella enterica (serotypes Enteritidis: phage types 1, 4, 4b, 6a, 14b, and 35; Typhimurium; Newport; Infantis; Poona; Virchow; Agona; Derby; and Paratyphi B) showing resistance to none (sensitive), one (resistant), two, three, four, five, six, seven, or nine (multiresistant) antibiotics were screened for resistance to 1,000 ppm acidified sodium chlorite, 1.2% trisodium phosphate, or 25% citric acid. D-values (seconds required for 1-log reduction in the number of bacteria) in peptone water, using a linear regression, of Salmonella in the presence of acidified sodium chlorite varied widely with serotype (the highest resistance levels were shown by serotypes Typhimurium, Newport, and Derby) and antibiotic resistance pattern (average values of 8.37 +/- 1.69 s for multiresistant strains as compared with 5.96 +/- 0.54 s for sensitive, P < 0.05). A positive relationship (0.775, P < 0.001) was found between acidified sodium chlorite D-values and the number of antibiotics to which strains were resistant. Both serotype and antibiotic resistance had only a slight influence over Salmonella resistance to trisodium phosphate, with average D-values from 12.44 +/- 0.91 s (sensitive strains) to 13.28 +/- 0.77 s (multiresistant) (P < 0.05). Neither serotype nor antibiotic profile was associated with Salmonella resistance to citric acid (average D-value of 12.20 +/- 0.81 s). Minimal differences in resistance to decontaminants were found among Salmonella Enteritidis phage types. Results in the present study highlight the importance of selecting an adequate strain (serotype and antibiotic resistance pattern) when acidified sodium chlorite and trisodium phosphate are tested against Salmonella to ensure that concentrations capable of inactivating all strains are used.