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- Editorial: natural compounds in food safety and preservationPublication . Ferreira, Susana; Sanchez, Gloria; Alves, Maria J.; Fraqueza, M. J.
- Co-inoculation with Staphylococcus equorum and Lactobacillus sakei reduces vasoactive biogenic amines in traditional dry-cured sausagesPublication . Dias, Igor; Laranjo, Marta; Potes, Maria Eduarda; Santos, Ana Cristina Agulheiro; Ricardo Rodrigues, Sara; Fialho, Ana Rita; Véstia, Joana; Fraqueza, M. J.; Oliveira, Margarida; Elias, Miguel: Dry-cured sausages are traditional in Mediterranean countries, and Paio do Alentejo (PA) is one of the most popular in South Portugal. The aim of the present work was to evaluate the effect of combined starters on the safety and quality of PA preserving its sensory quality. Physicochemical parameters, namely pH and water activity (aW), microbiological parameters, biogenic amines, color, texture, and sensory attributes were assessed. Three starter cultures were used, namely Staphylococcus equorum S2M7 and Lactobacillus sakei CV3C2, both separate and combined with the 2RB4 yeast strain at a concentration of 106 cfu/g. Dextrose 0.25% was added to the meat batter. Starters had a significant effect on the reduction of aW values (0.845 to 0.823). The treatment with L. sakei as well as the co-inoculation of L. sakei with S. equorum effectively reduced the L. monocytogenes counts to undetectable levels. Sausages co-inoculated with S. equorum S2M7/L. sakei CV3C2 showed a significant reduction in the content of vasoactive amines, namely tryptamine (26.21 to 15.70) and β-phenylethylamine (4.80 to 3.69). Regarding texture, control PA showed higher hardness values, and the starters promoted the cohesiveness of the batter while reducing chewiness. The studied starters did not compromise the sensory characteristics of PA.
- Assessment of biofilm formation by Campylobacter spp. isolates mimicking poultry slaughterhouse conditionsPublication . Araújo, P. M.; Batista, E.; Fernandes, M. H.; Fernandes, M. J.; Gama, Luis; Fraqueza, M. J.This research aimed to assess the biofilm formation ability of Campylobacter strains under temperature and oxygen stress conditions, similar to those found in the industrial environment, to explain the persistence of this pathogen on the poultry slaughter line. A collection of C. jejuni and C. coli isolates (n = 143) obtained from poultry samples (cecal content and neck skin), collected at slaughterhouse level, from diverse flocks, on different working days, was genotyped by flaA-restriction fragment length polymorphism (RFLP) typing method. A clustering analysis resulted in the assignment of 10 main clusters, from which 15 strains with different flaA-RFLP genotypes were selected for the assessment of biofilm formation ability and antimicrobial susceptibility. Biofilm assays, performed by crystal violet staining method, were conducted with the goal of mimicking some conditions present at the slaughterhouse environment, based on temperature, atmosphere, and contamination levels. Results indicated that many C. jejuni strains with similar flaA-RFLP profiles were present at the slaughterhouse on different processing days. All the strains tested (n = 15) were multidrugresistant except for one. Biofilm formation ability was strain-dependent, and it appeared to have been affected by inoculum concentration, temperature, and tolerance to oxygen levels. At 10 degrees C, adherence levels were significantly lower than at 42 degrees C. Under microaerobic and aerobic atmospheres, at 42 degrees C, 3 strains (C. jejuni 46E, C. jejuni 61C, and C. coli 65B) stood out, exhibiting significant levels of biofilm formation. C. jejuni strains 46E and 61C were inserted in clusters with evidence of persistence at the slaughterhouse for a long period of time. This study demonstrated that Campylobacter strains from broilers are capable of forming biofilms under conditions resembling the slaughterhouse environment. These results should be seen as a cue to improve the programs of hygiene implemented, particularly in those zones that can promote biofilm formation.
- Staphylococcus spp. and Lactobacillus sakei Starters with High Level of Inoculation and an Extended Fermentation Step Improve Safety of Fermented SausagesPublication . Dias, Igor; Laranjo, Marta; Potes, Maria Eduarda; Agulheiro-Santos, Ana Cristina; Ricardo-Rodrigues, Sara; Fraqueza, M. J.; Oliveira, Margarida; Elias, MiguelABSTRACT - Paio do Alentejo (PA) is one of the most popular dry-fermented sausages in Portugal. The aim of the present work was to evaluate the effect of a high concentration of starter cultures with an extended fermentation step on the safety and quality of PA. Physicochemical parameters, microbiological parameters, biogenic amines, colour, texture profile, and sensory attributes were assessed. Five starters were selected based on our previous works. Staphylococcus equorum S2M7, Staphylococcus xylosus CECT7057, Lactobacillus sakei CV3C2, Lactobacillus sakei CECT7056, and a yeast strain (2RB4) were co-inoculated in meat batters at a concentration of 108 cfu/g for bacteria and 106 cfu/g for yeast strain, and 0.25% dextrose was added. Inoculated starters significantly reduced pH, Listeria monocytogenes counts, and total content in biogenic amines. The studied starter cultures did not compromise the sensory characteristics of PA, and thus, their use can be considered to protect these sausages and contribute to their safety