Effect of pulsed light treatments on quality and antioxidant properties of fresh-cut strawberries.

Fresh-cut strawberries were subjected to pulsed light treatments (4, 8, 12 and 16 J·cm-2) combined with a stabilizing dip. Quality changes and antioxidant properties were evaluated for 14 days at 5 °C. The treatments delayed fungal for the studied period. Surface color of treated fresh-cut strawberries was preserved in both internal and external surfaces. Doses of 4 and 8 J·cm-2 reduced softening incidence over storage. No significant differences between the total phenolic contents of untreated and treated fresh-cut strawberries were observed during storage. Vitamin C and total anthocyanin contents of the samples treated at low energy doses were maintained, whereas those of slices treated at the highest energy dose decreased between 20 and 30%, respectively. On the other hand, initial antioxidant capacity was better kept in all samples during storage regardless the applied dose. Hence, 4 and 8 J·cm-2 were the most effective treatments for maintaining quality and antioxidant properties of fresh-cut strawberries. INDUSTRIAL RELEVANCE: Fresh-cut strawberries may be sold as a highly convenient, healthy and fully edible product. However, processing and packaging conditions need to ensure the maintenance of their quality characteristics and content of bioactive compounds. This study provides scientific evidence regarding the beneficial effects of pulsed light treatments combined with a quality-stabilizing dip for extending the shelf-life of fresh-cut fruit. These combined treatments may be economically viable at industrial level because of their low energy requirements and reduced treatment time.

Minimal processing of iceberg lettuce has no substantial influence on the survival, attachment and internalization of E. coli O157 and Salmonella.

The influence of a selection of minimal processing techniques (sanitizing wash prior to packaging, modified atmosphere, storage conditions under light or in the dark) was investigated in relation to the survival of, attachment to and internalization of enteric pathogens in fresh produce. Cut Iceberg lettuce was chosen as a model for fresh produce, Escherichia coli O157:H7 (E. coli O157) and Salmonella enterica were chosen as pathogen models. Care was taken to simulate industrial post-harvest processing. A total of 50±0.1g of fresh-cut Iceberg lettuce was packed in bags under near ambient atmospheric air with approximately 21% O2 (NAA) conditions or equilibrium modified atmosphere with 3% O2 (EMAP). Two lettuce pieces inoculated with E. coli O157 BRMSID 188 or Salmonella Typhimurium labeled with green fluorescent protein (GFP) were added to each package. The bags with cut lettuce were stored under either dark or light conditions for 2days at 7°C. The pathogens' capacity to attach to the lettuce surface and cut edge was evaluated 2days after inoculation using conventional plating technique and the internalization of the bacteria was investigated and quantified using confocal microscopy. The effect of a sanitizing wash step (40mg/L NaClO or 40mg/L peracetic acid+1143mg/L lactic acid) of the cut lettuce prior to packaging was evaluated as well. Our results indicate that both pathogens behaved similarly under the investigated conditions. Pathogen growth was not observed, nor was there any substantial influence of the investigated atmospheric conditions or light/dark storage conditions on their attachment/internalization. The pathogens attached to and internalized via cut edges and wounds, from which they were able to penetrate into the parenchyma. Internalization through the stomata into the parenchyma was not observed, although some bacteria were found in the substomatal cavity. Washing the cut edges with sanitizing agents to reduce enteric pathogen numbers was not more effective than a rinse with precooled tap water prior to packaging. Our results confirm that cut surfaces are the main risk for postharvest attachment and internalization of E. coli O157 and Salmonella during minimal processing and that storage and packaging conditions have no important effect.

Comparación in vitro de la difusión iónica de pastas de hidróxido de calcio usadas como medicación intraconducto con diferentes vehículos / In vitro comparison of ionic diffusion of calcium hidroxide pastes used as intracanal medication with different vehicles

La medicación intraconducto consiste en la colocación de un medicamento en el interior del conducto radicular. En la actualidad, la pasta de hidróxido de calcio es la más utilizada. Su mecanismo de acción se basa en la disociación de iones oxhidrilos y calcio, responsables de efectos antibacterianos y de reparación tisular. El objetivo de este trabajo fue comparar la difusión de iones calcio y oxhidrilos de la pasta de hidróxido de calcio en el tiempo, utilizando como vehículo agua tridestilada, polietilenglicol y gel de aloe vera. Se utilizaron 45 caninos, se realizó radiografías preoperatorias, aperturas, determinación de la longitud de trabajo para la preparación biomecánica de los conductos. Se rellenaron los especímenes con cada una de las pastas tomando radiografías postoperatorias. Se colocaron las muestras en un medio de análisis almacenándolas en estufa a 37ºC durante 3, 24, 72,168 y 336 horas. Se realizó por triplicado la determinación del pH con pH-metro Metrohm 692 y de la concentración de calcio total utilizando el método espectrofotométrico (reacción del calcio con cresolftaleína complexona a pH 11). Los datos se analizaron estadísticamente por medio de ANOVA aplicando el test de LSD (alfa= 0,05). El comportamiento difusional de las pastas alcalinas con vehículo agua tridestilada y polietilenglicol fue similar en las primeras etapas de experimentación y difirió en las etapas finales. La pasta alcalina con gel de aloe vera mostró un comportamiento de iones oxhidrilos diferente en las primeras etapas de experimentación, el comportamiento de iones calcio fue similar hasta las 168 horas

The intracanal medication consists in placing a medication inside the root canal. At present, the calcium hydroxide paste is most often used. Its mechanism of action is based on the dissociation of calcium ions and hydroxyls responsible for antibacterial effects and tissue repair. The aim of this study was to compare the diffusion of calcium ions and hydroxyls of calcium hydroxide paste in time, using triple distilled water as a vehicle, polietilienglicol and aloe vera gel. 45 canine teeth were used, was performed preoperative radiographs, openings, determining the working length to the biomechanical canal preparation. Specimens with each of the pastes were filled and postoperative radiographs were taken. The samples were placed in a medium of analysis were stored in an oven at 37 ° C for 3, 24, 72,168 and 336 hours. Was performed triplicate pH determination with Metrohm 692 pH meter and the total calcium concentration using the spectrophotometric method (reaction of calcium with cresolphthalein complexone to pH 11). The data were statistically analyzed by ANOVA using the LSD test ( = 0.05). The diffusional behavior of alkaline pasta with water tridistilled -polyethylene vehicle was similar in the initial stages of experiment and in the final stages different. The alkaline paste with aloe vera gel showed a different behavior of hydroxyls ions in the early stages of testing, the behavior of calcium ions was similar up the 168 h