Genetic virulence of biofilm-forming Salmonella recovered from chicken sausages and nuggets

Aims@#Salmonella is one of the most common foodborne illnesses worldwide. Poultry meat and products are the main sources of human infection. Therefore, the main objective of the current study was to assess the genetic virulence of biofilm-forming Salmonella isolated from chicken sausage and nuggets.@*Methodology and results@#Isolation of Salmonella was carried out using XLD agar; suspected colonies were identified biochemically and then serotyped using the Kauffman-White scheme for detection of somatic (O) and flagellar (H) antigens. Congo red (CR) medium was used for the assessment of biofilm formation of the isolated strains. The invasion gene (invA), the heat-labile Salmonella enterotoxin gene (stn), plasmid-encoded fimbriae (pefA) genes, the protein effectors sopB, sopD and biofilm genes in six Salmonella isolates were investigated using mPCR, following QIAamp® DNA Mini Kit instructions and 1.5% agarose gel electrophoreses. Salmonella was detected in 12%, 8% and 4% of the examined frozen packaged raw chicken sausage, frozen packaged raw chicken nuggets and ready-to-eat sausage. The isolated strains were S. Typhimurium, S. Enteritidis, S. Essen and S. Montevideo. Moreover, mPCR indicated the presence of biofilm gene (csgD gene), stn, sopB and sopD virulence genes in all isolated strains (100%); however, pefA gene failed to be detected.@*Conclusion, significance and impact of study@#The current findings showed that every Salmonella isolate examined was capable of creating biofilm at room temperature. As a result, these isolates are more likely to persist on abiotic surfaces, which raises the danger of cross-contamination and foodborne outbreaks.

Extraction of bioactive compounds of lemongrass, antioxidant activity and evaluation of antimicrobial activity in fresh chicken sausage / Extração de compostos bioativos de capim-limão, atividade antioxidante e avaliação da atividade antimicrobiana em linguiça frescal de frango

ABSTRACT: The aim of this work was to determine the best extraction condition of bioactive compounds from lemongrass (Cymbopogon citratus), using the conventional method and ultrasonic assisted extraction, varying the temperature, in order to evaluate the antioxidant activity and the antimicrobial activity of the extract with higher antioxidant power in fresh chicken sausages during the storage period. The extracts were obtained by the conventional method (solvent extraction) and by ultrasound assisted extraction, varying the temperature (20°C, 40°C and 60°C). Phenolic compounds, total flavonoids and antioxidant activity were measured by the DPPH, FRAP, ORAC methods. Conventional extraction and ultrasound methods influenced the phenolic and total flavonoid content at all tested temperatures. Conventional and ultrasonic methods did not influence the IC50 at temperatures of 40°C and 60°C. The antioxidant activity by the DPPH method and by the FRAP method was superior in the conventional method at the temperature of 60°C, however by the ORAC method the best results were in the extraction by ultrasound. The results demonstrate that the conventional extraction at 60ºC was better to obtain extracts of lemongrass with greater amount of bioactive compounds. The antimicrobial capacity evaluated in sausage of fresh chicken showed that in the concentration of 1.0% of the extract protected the product as the growth of mesophilic aerobes and against the growth of psychrotrophic bacteria. Lemongrass can be considered as a natural alternative to obtain extracts rich in bioactive compounds, with antioxidant activity and high antimicrobial capacity.

RESUMO: O objetivo deste trabalho foi determinar a melhor condição de extração de compostos bioativos do capim-limão (Cymbopogon citratus), usando o método convencional e extração assistida por ultrassom, em diferentes temperaturas, a fim de avaliar a atividade antioxidante e a atividade antimicrobiana do extrato com maior poder antioxidante em linguiças de frango frescal durante o período de armazenamento. Os extratos foram obtidos pelo método convencional (extração com solvente) e por extração assistida por ultrassom, variando a temperatura (20°C, 40°C e 60°C). Foram medidos os compostos fenólicos, flavonoides totais e atividade antioxidante pelos métodos DPPH, FRAP, ORAC. Os métodos de extração convencional e ultrassom influenciaram no teor de fenólicos e flavonoides totais em todas as temperaturas testadas. Os métodos convencional e ultrassom não influenciaram no IC50 nas temperaturas de 40oC e 60oC. A atividade antioxidante pelo método DPPH e pelo método FRAP foi superior no método convencional na temperatura de 60°C, entretanto pelo método ORAC os melhores resultados foram na extração por ultrassom. Os resultados demonstram que a extração convencional a 60ºC foi melhor para obter extratos de capim-limão com maior quantidade de compostos bioativos. A capacidade antimicrobiana avaliada em linguiça frescal mostrou que na concentração de 1,0% do extrato protegeu o produto quanto o crescimento de aeróbios mesófilos e contra o crescimento de bactérias psicrotróficas. O capim-limão pode ser considerado uma alternativa natural para obtenção de extratos ricos em compostos bioativos, com atividade antioxidante e elevada capacidade antimicrobiana.

Antibacterial activity of bacteriocin-like substance P34 on Listeria monocytogenes in chicken sausage

The antimicrobial activity of the bacteriocin-like substance (BLS) P34 against Listeria monocytogenes was investigated in chicken sausage. The BLS was applied to chicken sausages (256 AU g-1) previously inoculated with a suspension of 10² cfu g-1 of L. monocytogenes. BLS P34 inhibited the indicator microorganism in situ in all incubation times for up to 10 days at 5 °C. The effectiveness of BLS P34 was increased when it was added in combination with nisin. The bacteriocin was also tested in natural eatable natural bovine wrapping (salty semi-dried tripe) against the same indicator microorganism, also showing inhibitory capability in vitro. BLS P34 showed potential to control L. monocytogenes in refrigerated meat products.

Quality Characteristics of Chicken Sausage Prepared with Turmeric (Curcuma longa L.) during Cold Storage

The purpose of this study was to evaluate the quality characteristics of chicken sausage prepared with turmeric (Curcuma longa L.) powder (T) during storage at 4degrees C for 20 days. The pH and color values (a and b values) of sausage containing turmeric powder were significantly higher (P<0.05) than the control for both uncooked and cooked sausage. The hardness, chewiness, and gumminess of control sausage significantly changed after 15 days of storage, while the hardness and gumminess of turmeric-supplemented sausages (T) significantly increased after 5 days (until 15 days) for cooked sausages. The total phenolic content and DPPH radical scavenging activity of turmeric-supplemented sausages was significantly higher (P<0.01) than the control for both uncooked and cooked sausage during storage. On the other hand, the acid value of the control was higher than the turmeric-supplemented sausages and the peroxide value of the control was significantly higher (P<0.05) than the turmeric-supplemented sausages after 15 days of storage. Microorganism analysis revealed that total plate counts of uncooked and cooked control sausages were significantly higher (P<0.05) than turmeric-supplemented sausages at 20 days of storage. As a result, sausages prepared with turmeric powder demonstrate antioxidative activity and lipid oxidative stability during storage.