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Min Treatment (min + treatment)
Selected AbstractsEFFECT OF HIGH PRESSURE ON LACTOCOCCAL BACTERIOPHAGESJOURNAL OF FOOD SAFETY, Issue 1 2009M. DILEK ABSTRACT Four different host-specific lactococcal bacteriophages were subjected to high hydrostatic pressure and heat treatments. Pressure treatments were done at room temperature at 300 and 350 MPa for 5,40 min. Complete inactivation of bacteriophages was observed starting at 350 MPa for 20-min treatment at room temperature. The effect of heat on the bacteriophages was analyzed by heat treatment at 71.7C for predetermined lengths of time (1,5 min). Decrease in bacteriophage number was observed after 3 min of heat treatment at 71.7C. Pressure treatment at 350 MPa/5 min and heat treatment at 71.7C/3 min were both found to be effective for the inactivation of lactococcal bacteriophages. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis indicated that protein profiles of pressure-treated (350 MPa, 25 min) bacteriophages were altered. PRACTICAL APPLICATIONS Bacteriophages are still a problem for the production of fermented dairy products, as there has not been a process to eliminate them completely from the fermentation environment. Processes such as pasteurization are not adequate to eliminate bacteriophages. However, new food preservation methods have been developed, one of which is high hydrostatic pressure (HHP) processing. HHP has potential application for the inactivation of viruses. Here, we demonstrate the application of HHP to inactivate the bacteriophages of dairy starter culture Lactococcus in comparison with heat treatment. [source] Inactivation of Shigella boydii 18 IDPH and Listeria monocytogenes Scott A with Power Ultrasound at Different Acoustic Energy Densities and TemperaturesJOURNAL OF FOOD SCIENCE, Issue 4 2007Edgar Ugarte-Romero ABSTRACT:, The effect of acoustic energy density (AED) on inactivation of Shigella boydii 18 IDPH and Listeria monocytogenes Scott A in a cell suspension was studied at sublethal temperatures and at AEDs of 0.49, 0.85, and 1.43 W/mL. The effect of temperature on ultrasonic inactivation of L. monocytogenes Scott A at 35, 50, and 65 °C was examined at an AED of 1.43 W/mL. Increasing AED increased the rate of inactivation for both S. boydii and L. monocytogenes. The destruction of S. boydii and L. monocytogenes followed 1st order kinetics in a 20-min treatment, except for S. boydii inactivation at 1.43 W/mL where a tailing effect was observed after 15 min. At sublethal temperatures, the D-values of S. boydii were 8.8, 4.3, and 2.5 min for AEDs of 0.49, 0.85, and 1.43 W/mL, whereas those for L. monocytogenes at the 3 AED levels were 31.5, 13.5, and 7.3 min, respectively. Ultrasonic treatment of L. monocytogenes at 35 and 50 °C enhanced inactivation. However, at 65 °C, application of ultrasound did not result in additional inactivation compared to thermal treatment alone at the same temperature. With the experimental conditions and the ultrasound system used in this study, an upper temperature limit for thermosonication was evident above which no added killing due to ultrasound was observed. [source] Possible nutritional and health-related value promotion in orange juice preserved by high-pressure treatment,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2002Begoña de Ancos Abstract Effects of high-pressure treatment on the orange juice carotenoids (,-carotene, ,-carotene, zeaxanthin, lutein and ,-cryptoxanthin) associated with nutritional (vitamin A) and health-related (radical-scavenging capacity) values were investigated. Various high-pressure treatments (50,350 MPa) combined with different temperatures (30 and 60,°C) and times (2.5, 5 and 15,min) of treatment were assayed. The carotenoid content of the orange juice was analysed by HPLC-UV, the vitamin A value was determined as retinol equivalents (RE) and the free radical-scavenging capacity was evaluated using the DPPH (2,2-diphenyl-1,1-picrylhydrazyl) radical model system. A storage study was carried out at refrigeration temperature (4,°C). High-pressure treatments at 350,MPa produced significant increases of 20,43% in the carotenoid content of fresh orange juice (from 3.99 to 4.78,5.70,mg,l,1). A non-uniform behaviour of high-pressure treatments was detected. An increase in time (beyond 5,min) or temperature (above 30,°C) of treatment did not improve the amount of carotenoids extracted. Owing to better extraction of carotenoids, an increase in vitamin A value from 164 to 238,RE,l,1 (45%) was achieved with the 350,MPa/30,°C/5,min treatment. No correlation was found between the increase in carotenoid amount extracted and the free radical-scavenging activity. © 2002 Society of Chemical Industry [source] Characterization for water vapour barrier and heat sealability properties of heat-treated paperboard/polylactide structurePACKAGING TECHNOLOGY AND SCIENCE, Issue 8 2009Kimmo Lahtinen Abstract The moisture barrier and heat sealability properties of polylactide (PLA) extrusion-coated paperboard were investigated. The first part of the study focused on the influences of coating weight and surroundings temperature and relative humidity on the water vapour transmission rate (WVTR) of the structure. The outcome arising from this part was a simple and practical equation that allows calculating the WVTR as a function of PLA coating weight under specific thermo-hygrometric conditions. The second part of the study investigated the effect of heat treatments between 100 and 150°C on the WVTR and heat sealability of a 20,g/m2 PLA-coated paperboard. According to the results, the lowest WVTR values achieved were about 2.5 times lower than the WVTR of the untreated structure. Presumably, the PLA coating experienced two types of reordering mechanisms: crystalline growth and packing of the amorphous structure. The greatest barrier improvement was achieved when both of these mechanisms were accumulated effectively. This was observed from the samples after a 40,min treatment at 130°C. Ultimately, the crystalline growth was experienced by PLA at 100,130°C temperatures. The packing of the amorphous section, which was also accumulated at higher temperatures, was suggested to be the decisive factor influencing WVTR. According to the heat sealing results, the heat treatments causing crystalline growth resulted in considerably increased sealing temperatures and reduced applicability of the material in high-speed packaging applications. The treatments at 140,150°C caused only a slight increase in the sealing temperature and maintained the sealing performance of PLA. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effect of Nonthermal Treatment on the Molecular Properties of Mushroom PolyphenoloxidaseJOURNAL OF FOOD SCIENCE, Issue 5 2003N.K. Sun ABSTRACT To elucidate the mechanism of inactivation of mushroom polyphenoloxidase (PPO) by nonthermal treatment, PPO solutions were irradiated up to 10 kGy or pressurized at 600 MPa and 800 MPa, respectively. PPO activities were significantly affected by , irradiation, and treatment at 5 kGy decreased the activity by 93%. Treatment of PPO at 600 MPa decreased the activity slightly, yet 10 and 20 min treatments at 800 MPa decreased the activities by 28% and 43%, respectively. Circular dichroism study showed that nonthermal treatment altered the ellipticity values in the range of 210 and 225 nm, resulting in decrease of the ordered structure. Fluorescence spectroscopy indicated that nonthermal treatment quenched the emission intensity. [source] | ||||||||||