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Preservation Methods (preservation + methods)
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] Onion Cells After High Pressure and Thermal Processing: Comparison of Membrane Integrity Changes Using Different Analytical Methods and Impact on Tissue TextureJOURNAL OF FOOD SCIENCE, Issue 7 2010Maria E. Gonzalez Abstract:, Two different analytical methods were evaluated for their capacity to provide quantitative information on onion cell membrane permeability and integrity after high pressure and thermal processing and to study the impact of these processing treatments on cell compartmentalization and texture quality. To determine changes in cell membrane permeability and/or integrity the methodologies utilized were: (1) measurement of a biochemical product, pyruvate, formed as a result of membrane permeabilization followed by enzymatic activity and (2) leakage of electrolytes into solution. These results were compared to previously determined methods that quantified cell viability and 1H-NMR T2 of onions. These methods allowed for the monitoring of changes in the plasma and tonoplast membranes after high pressure or thermal processing. High pressure treatments consisted of 5 min holding times at 50, 100, 200, 300, or 600 MPa. Thermal treatments consisted of 30 min water bath exposure to 40, 50, 60, 70, or 90 °C. There was strong agreement between the methods in the determination of the ranges of high pressure and temperature that induce changes in the integrity of the plasma and tonoplast membranes. Membrane rupture could clearly be identified at 300 MPa and above in high pressure treatments and at 60 °C and above in the thermal treatments. Membrane destabilization effects could already be visualized following the 200 MPa and 50 °C treatments. The texture of onions was influenced by the state of the membranes and was abruptly modified once membrane integrity was lost. Practical Application:, In this study, we used chemical, biochemical, and histological techniques to obtain information on cell membrane permeability and onion tissue integrity after high pressure and thermal processing. Because there was strong agreement between the various methods used, it is possible to implement something relatively simple, such as ion leakage, into routine quality assurance measurements to determine the severity of preservation methods and the shelf life of processed vegetables. [source] Effect of lucerne preservation method on the feed value of forageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2009Donato Andueza Abstract BACKGROUND: Natural climatic wilt (NCW) and induced industrial wilt (IIW) are widely used as preservation methods for lucerne. Both of these methods reduce the quality of green forage due to respiration under NCW and heat damage under IIW. We compared the influence of these two preservation methods on nutritive value across a wide range of harvest conditions. RESULTS: Cell wall content and cell wall-linked nitrogen values were higher (P < 0.05) in IIW than NCW. The preservation methods differed significantly (P < 0.05) in terms of soluble fraction, insoluble potentially degradable fraction of dry matter and effective degradability of dry matter. Nitrogen disappearance kinetics showed that the interactions of preservation by cut and preservation by phenological state were significant for the effective degradability of nitrogen. Organic matter digestibility was higher in lucerne preserved by NCW than IIW whereas cell wall digestibility was higher in lucerne preserved by IIW than NCW. Digestible organic matter intake did not differ between preservation methods (P > 0.05). CONCLUSION: Natural climatic wilt forage hay presents similar feed value to the induced industrial wilt alfalfa. Copyright © 2009 Society of Chemical Industry [source] The effect of culture preservation techniques on patulin and citrinin production by Penicillium expansum LinkLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2002I.M. Santos Aims: To study the influence of culture preservation methods and culture conditions on the production of the mycotoxins patulin and citrinin by Penicillium expansum. Methods and results: Ten strains of Penicillium expansum were preserved using subculture and maintenance at 4 °C, mineral oil, drying on silica gel and freeze-drying. Patulin and citrinin production was assessed on yeast extract sucrose agar (YES) and grape juice agar (GJ), using TLC before and after 0·5, 2,3, 6 and 12 months preservation. Citrinin was detected in all cultures for all preservation techniques on YES. The patulin profiles obtained differed with strain and culture media used. Conclusions: Citrinin production seems to be a stable character for the tested strains. There is a tendency for patulin detection with time apparently more consistent for silica gel storage and freeze-drying, especially when the strains are grown on GJ. Significance and Impact of the Study: Variability in the profiles of the mycotoxins tested seems to be more strain-specific than dependent on the preservation technique used. [source] An effective DNA extraction protocol for brown algaePHYCOLOGICAL RESEARCH, Issue 2 2001Naomi Phillips SUMMARY Successful extraction of total DNA from brown algae, which are generally polysaccharide and polyphenol rich, is often problematic using current methods. Persistent polysaccharide and polyphenolic compounds can hinder further application of modern molecular techniques requisite to molecular-based evolutionary studies. Our broad and long-term research goals with fucalean taxa, especially Sargassum, and problems with existing DNA extraction methods were an impetus to develop a reliable DNA extraction method. Initial research established hexadecyltrimethylammonium bromide (CTAB) based total-DNA methods as the most viable for further empirical development. Several constituents effective at either complexing secondary compounds or creating a reductive extraction environment were increased in concentration or added to the extraction buffer. These seemingly minor changes resulted in the creation of a highly reductive extraction buffer and effective total- DNA harvesting technique. We detail these modifications and demonstrate the reliability of the modified protocol with a variety of brown algae and tissue preservation methods. Such DNA is shown to be suitable for a variety of molecular techniques. [source] High Pressure Processing , a Database of Kinetic InformationCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 8 2008R. Buckow Abstract Hydrostatic high pressure technology is relatively new to food industry and is more and more considered as an alternative to traditional preservation methods like heat processing. The inactivation of bacteria, spores, viruses and enzymes has been demonstrated in numerous papers, and various schemes for modelling the experimental inactivation data have been suggested. Although there are similarities to heat inactivation kinetics it is generally agreed that the heat process safety assessment with its typical indicator organisms cannot simply be transferred to high pressure treatment. In this paper a database is introduced which aims at the comparison of published kinetic high pressure inactivation data by using suitable mathematical modelling tools. For the sake of clarity, the functional associations of pressure, temperature and exposure time is presented by means of pressure-temperature diagrams (pT -diagrams), which show pressure-temperature combinations yielding to a desired reaction (e.g. inactivation) rate constant. Thus, the database software was particularly designed to enable the user to call up pressure-temperature dependent function equations for a number of micro-organisms, enzymes and food constituents and to visualize them in pT -diagrams for predetermined treatment times or as kinetics under predetermined p - T conditions. In addition, the database also features a simple calculator tool which allows the user to make an entry in three of the four process conditions (pressure level, temperature level, inactivation level, dwell time) and calculate the remaining forth process condition. The database is accessible through the internet and is continuously updated on the basis of the most recent publications and own experimental data. [source] | |||||||||||||