María de Lourdes Pérez-Chabela

Evaluation of the Effect of Tiger Nut Fibre as a Carrier of Unsaturated Fatty Acids Rich Oil on the Quality of Dry-Cured Sausages

The aim of this study was to evaluate the effect of the addition of tiger nut fibre (TNF) as a carrier of unsaturated fatty acids (UFA) rich oil on some quality parameters in a dry-cured sausage. Nine formulations of “Longaniza de Pascua”, a traditional Spanish dry-cured fermented sausage, were manufactured under normal industrial conditions but incorporating different combinations of TNF (1–2%) as a source of fibre and walnut oil (WO; 2.5–5%) as a source of UFA. The addition of TNF improved WO incorporation into the meat batter: the higher the amount of TNF added, the more WO incorporated. Sausages with TNF + WO had a higher moisture content than the control (hence lower weight loss), lower pH values, higher water activity, similar L* values and higher a* and b* values than the control. The only microorganisms that were affected by the formula were mould and yeasts, but in all cases the counts at the end of ripening were comparable to the results of the most studies on fermented sausages. The increase in lipid oxidation in sausages due to the addition of WO was controlled by the TNF, probably due to the antioxidant compounds (phenolics) it contains. The samples with 1% TNF + 2.5% WO and 2% TNF + 5% WO scored the same in terms of overall liking as the control.

Evaluation of thermotolerant capacity of lactic acid bacteria isolated from commercial sausages and the effects of their addition on the quality of cooked sausages

The thermotolerant capacity of several lactic acid bacteria strains isolated from cooked commercial sausages was determined. Four strains were positively identified as Lactobacillus plantarum, Lactobacillus curvatus, Pediococcus pentosaceus and Pediococcus acidilacti, after surviving thermal treatment (70 °C during 60 minutes). Thermotolerant strains were inoculated in sausage batters before cooking in order to determine their effect on color, texture, acceptance and inhibition of Enterobacteria during 12 days at 8 °C. No significant effect of the inoculated strains was detected on color parameters. Textural profile parameters, cohesiveness and resilience, were not affected by the inoculation of thermotolerant lactic acid bacteria, but L. curvatus sausages resulted softer than the rest of the treatments. Samples inoculated with L. curvatus also obtained the lowest scores for the sensory attributes evaluated, with the remaining treatments causing no unfavorable effects on sausage acceptance. There was a reduction in enterobacterial counts after 12 days of cold storage in inoculated samples. The performance of inoculated lactic acid bacteria strains can be explained in a similar way as that of starter cultures in dry-fermented sausages, where the growth in nests impairs other pathogenic microorganisms present in the rest of the sausage, since environmental conditions and the early inoculation of these thermotolerant strains favor them to become the dominant flora.

Physicochemical and Sensory Characteristics of Calcium Chloride‐Treated Horse Meat

Abstract Post rigor horse meat was marinated in 150 mM CaCl2 solution at 4°C and compared against untreated samples in order to evaluate characteristics associated with meat quality. Water holding capacity (WHC) and pH were recorded over 15 days period. Protein degradation was studied by sodium dodecyl sulfate SDS–PAGE electrophoresis, and rheological properties related to texture were evaluated by instrumental compression. Sensory evaluation was carried out with a trained panel. There were no significant differences in pH between treated and untreated samples. Water holding capacity in CaCl2‐treated samples was significantly higher, as a possible consequence of interfilament widening due to Ca2+ ion steric hindrance. Some degradation of high and low molecular weight (HMW and LMW) proteins in Ca2+‐treated samples was observed, although this fact could be due to factors not related to calpain activity. Sensory analysis demonstrated that treated meat had higher scores for overall intensity. There were no significant differences with respect to hardness, chewiness, cohesiveness, and juiciness.

Quantitative analyses of the bacterial microbiota of rearing environment, tilapia and common carp cultured in earthen ponds and inhibitory activity of its lactic acid bacteria on fish spoilage and pathogenic bacteria

The present study aimed to evaluate the bacterial load of water, Nile Tilapia and common Carp intestines from earthen ponds, isolate lactic acid bacteria (LAB) and assess their antimicrobial activity against fish spoilage and pathogenic bacteria. Following enumeration and isolation of microorganisms the antimicrobial activity of the LAB isolates was evaluated. Taxonomic identification of selected antagonistic LAB strains was assessed, followed by partial characterisation of their antimicrobial metabolites. Results showed that high counts (>4 log c.f.u ml−1 or 8 log c.f.u g−1) of total aerobic bacteria were recorded in pond waters and fish intestines. The microbiota were also found to be dominated by Salmonella spp., Vibrio spp., Staphylococcus spp. and Escherichia coli. LAB isolates (5.60%) exhibited potent direct and extracellular antimicrobial activity against the host-derived and non host-derived spoilage and pathogenic bacteria. These antagonistic isolates were identified and Lactococcus lactis subsp. lactis was found as the predominant (42.85%) specie. The strains displayed the ability to produce lactic, acetic, butyric, propionic and valeric acids. Bacteriocin-like inhibitory substances with activity against Gram-positive and Gram-negative (Vibrio spp. and Pseudomonas aeruginosa) bacteria were produced by three L. lactis subsp. lactis strains. In this study, the LAB from the microbiota of fish and pond water showed potent antimicrobial activity against fish spoilage or pathogenic bacteria from the same host or ecological niche. The studied Cameroonian aquatic niche is an ideal source of antagonistic LAB that could be appropriate as new fish biopreservatives or disease control agents in aquaculture under tropical conditions in particular or worldwide in general.Graphical abstract

Efecto del pH y de la adición de fosfatos de sodio sobre las propiedades de gelificación y emulsión de surimi de trucha arco-iris (Oncorhynchus mykiss)

Para la elaboracion de surimi se han empleado distintas tecnicas, sin embargo, es indispensable mantener la funcionalidad de las proteinas musculares durante su extraccion, ya que son afectadas principalmente por el pH. La incorporacion de fosfatos en productos carnicos afecta el pH, teniendo como consecuencia una mejora en la capacidad de retencion de agua de las proteinas musculares, alterando la funcionalidad de estos productos. Se utilizo la metodologia de superficie de respuesta para determinar el efecto de cinco niveles de pH y cinco concentraciones de una mezcla de fosfatos de sodio comercial sobre la funcionalidad de surimi de trucha arco-iris, evaluada por su capacidad de emulsion y trabajo de emulsion, fuerza de gel y trabajo de penetracion de geles de surimi. Los resultados obtenidos indican que el incremento en la concentracion de fosfatos de sodio mejoro la funcionalidad del surimi y a pH alcalino las propiedades de emulsion mejoraron, pero se afectaron negativamente las propiedades de gelificacion.

EFECTO DE BACTERIAS ÁCIDO LÁCTICAS TERMORESISTENTES EN SALCHICHAS COCIDAS THERMORESISTAN LACTIC ACID BACTERIA EFFECT ON COOKED SAUSAGES

Abstract Lactic acid bacteria (LAB) had been employed in fermented sausages as protective cultures, reducing the population of other non-desirable microorganisms. The isolation of LAB that can survive thermal treatment could be an alternative to improve the shelf-life of cooked products. Eight strains of LAB isolated from commercial sausages were heated in water baths at 50, 60 and 70°C during 30–60 min. four surviving strain were previously identified as L. alimentarius, L. lactis, L. piscicola and Enterococcus sp. These strains were inoculated in a sausage to determine their effect in product acceptation and enterobacteria population. L. alimentarius and L. lactis had higher acceptation scores close or higher than control. LAB population increased with storage time; enterobacteria population increased but in less amount than LAB. L. alimentarius y L. lactis presented a marked effect of enterobacteria during storage. Resumen Las bacterias ácido lácticas (BAL) han sido utilizadas en embutidos fermentados como cultivos protectores inhibiendo a otros microorganismos no deseables. El aislamiento de BAL que puedan sobrevivir al tratamiento térmico de productos cocidos podría ser una alternativa para mejorar la vida de anaquel de estos productos. Ocho cepas aisladas de salchichas comerciales fueron sometidas a pruebas de termoresistencia en baños de agua a 50, 60 y 70°C durante 30–60 min. Cuatro cepas sobrevivieron a los tratamientos y fueron previamente identificadas como L. alimentarius, L. lactis, L. piscicola y Enterococcus sp, las cuales fueron inoculadas en una salchicha para estudiar su efecto sobre la aceptación y el conteo de enterobacterias. L. alimentarius y L. lactis presentaron valores de aceptación similares o mejores al control. La población de BAL se incrementó respecto al tiempo de almacenamiento, mientras que las enterobacterias también aumentaron pero por abajo de BAL. L. alimentarius y L. lactis tuvieron un efecto más marcado sobre la población de enterobacterias durante el periodo de almacenamiento. Palabras clave: Bacterias ácido lácticas, termoresistencia, enterobacterias, vida de anaquel, salchichas

Effect of Calcium Chloride Marination on Electrophoretical and Structural Characteristics of Beef, Horse, Rabbit and Chicken Meat

Marinating with calcium chloride had been employed to activate the endogenous proteolitic enzymatic system in muscle tissue. The activation of calpains leads to the disruption of major proteins responsible for myofilament structure. Nonetheless, intrinsic differences regarding enzymatic activity between different species need to be established, which concerns protein degradation and ultrastructural changes. In this study, four species—horse, chicken, rabbit and beef—were marinated in 150 mM CaCl2 solution. Calpain activity was determined by low and high molecular weight protein degradations (SDS-PAGE) and light microscopy, which was compared to a non-treated control. All the studied species presented an increase in the number of low molecular weight bands, corresponding to the 30 kDa polypeptide that resulted from tropomiosin degradation. High molecular weight protein degradation corresponds to the formation of breakdowns and amorphous regions in tissue micrographs. These results support the evidence of meat quality improvement by calcium marination.