IQUIR   05412
INSTITUTO DE QUIMICA ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of calcium salts on the quality of wheat flour dough and bread making properties
Autor/es:
ROSSI, M.; REVELANT, G.; SANCHEZ, H.; OSELLA, C.; VERDINI, R.A.
Lugar:
Concordia
Reunión:
Congreso; lnternational Conference on Food Innovation 2014; 2014
Institución organizadora:
Universidad Nacional de Entre Ríos
Resumen:
The incidence of foodborne pathogens such as Escherichia coli continues to increase in many countries. Shiga-toxin producing Escherichia coli (STEC) strains are human pathogens that can cause diarrhea as well as hemolytic uremic syndrome in humans. Also, enteropathogenic E. coli (EPEC) strains are responsible for human outbreaks worldwide, thus both foodborne pathogens represent a serious health threat. Bacteriophages have proved to be useful tools against pathogenic Escherichia coli strains. The first step in the phage life cycle is the adsorption on the host cell surface. Three Myoviridae phages (DT1, DT5 and DT6) were used to characterize the adsorption process on three pathogenic E. coli strains (two STEC and one EPEC) to evaluate the influence of physicochemical parameters in order to maximize adsorption efficiency on food environments. Adsorption was performed by mixing 100 μl of phage (105 PFU), with 500 μl of bacteria (DO630nm=1) at a multiplicity of infection of 0.001. The suspension was incubated at 37ºC for 10 min and centrifuged at 14,000 x g for 5 min, and the phage titer remaining in the supernatant was determined by the double-layer plaque technique. Nonadsorbing control was performed in each assay (Hershey broth) for setting the 100% free-phage titer. The influence of Na+ (0.3, 2 and 4%), Mg2+ (1, 5 and 10mM), temperature (4, 37 and 50°C), pH (7.5, 5.7 and 4.5), periodate (1 mM), proteinase K (0.2 mg/ml) and physiological cell state on phage adsorption was investigated. The three phages evaluated showed high adsorption rates at pH 7.5 and 5.7 (up to 96.5%) while were moderate and ranged from 45.0 to 74.0% at pH 4.5. Phage particles were adsorbed either in the presence or absence of Mg2+, while increasing Na+ concentration resulted in lower adsorption values for all systems evaluated. Regarding temperature, phage adsorption was slightly affected at 4°C and 50°C and ranged from 83.2 to 92.9%, while reached its maximum at 37°C, namely ~98%. Adsorption rates decreased up to 37.6% after the thermal inactivation of cells, though, when chloramphenicol was used as protein-synthesis inhibitor, adsorption values were similar on treated and untreated cells. In addition, periodate was able to decrease phage adsorption (average adsorption ~ 25%) thus suggesting that receptors possess carbohydrates on their structure. Results showed that the adsorption process was only partially affected and most tested conditions were suitable for phage adsorption. Therefore, phages evaluated can be used to prevent foodborne diseases on several foods matrices since covered a wide range of environmental conditions.