Sterilization Purposes Research Articles

Research on the Development of Ultra High Pressure Fresh-Keeping Packaging Technology

<b> </b>Ultra high pressure technology is a new type of non thermal processing technology; it is mainly through the structure of the cell wall and cell membrane and cell space destruction of microorganisms, the protein composition of degeneration, the enzyme activity decreased to achieve the purpose of sterilization. This article from the ultra high pressure technology in aquatic products industry, meat industry and fruit and vegetable and its products industry and other aspects of the application status and development direction of ultra high pressure sterilization technology, hope to be able to provide certain support theory in the study of ultra high pressure technology.

Microbicidal effectiveness of X-rays used for sterilization purposes

The radiation response of spores of Bacillus pumilus was examined for irradiation with 5–7 MeV X-ray at commercial sterilization facilities. The response was found to be the same as that for irradiation with cobalt 60 photons, 10 MeV electrons and low energy electrons at 100 and 80 keV.

Delamination onset and design criteria of multilayer flexible packaging under high pressure treatments

Delamination phenomena frequently occur when multi-layer flexible polymeric films are employed for high pressure treatments of food packaging for pasteurization and sterilization purposes, thus potentially limiting the reliability of this treatment technology. The motivation of delamination is however not yet well understood. For this reason, to catch the key factors leading to interlaminar stress fields which can be prodromal to localized delamination events, the issue of mechanical failure of bi-layer structures under high pressure is thoroughly addressed in the present work, by constructing analytical models and Finite Element based numerical simulations. The theoretical results highlight the crucial role played by the mismatch of Young's moduli and Poisson ratios of the laminated film sheets in promoting delamination. These outcomes are in full agreement with experimental findings obtained by performing tests on high pressure-treated food multilayer packages realized coupling different polymeric materials, that is polypropylene-polyethyleneterephthalate, polypropylene-cast polyamide and polypropylene-bioriented polyamide. High pressure processing is a promising food preservation method endowed with minimal quality loss. To allow a safe use of this technique one cannot address the sole issues related to the effect of treatment on food itself, but also suitability of packaging materials to be used for this technology. In this contribution the attention is focused on multilayer flexible packaging with the aim of supplying guidelines for the proper choice of film structures able to withstand the loads associated with high pressure treatments.

Microwave Plasmas at Atmospheric Pressure

AbstractMicrowave plasmas at atmospheric pressure are used for surface treatments like for example cleaning, sterilization or decontamination purposes, for a pre‐treatment to increase the adhesion of lacquer, paint, or glue, and for the deposition of different kind of layers and coatings. Micro plasma jets can also be applied for biomedical applications and for treatment of small and complex geometries like for example the inside of capillaries. Larger plasma torches which exhibit higher gas temperatures can also be used for chemical syntheses like waste gas decomposition, methane pyrolysis, or carbon dioxide dissociation and for plasma spraying purposes.In the present publication an overview on the development and the investigation of the operating principle of two atmospheric pressure microwave plasma torches at frequencies of 2.45 GHz and 915 MHz will be presented. The plasma sources are based on a cylindrical resonator combined with coaxial structures. To explain how these plasma sources work, simulations of the electric field distribution will be discussed. Furthermore, some physical characteristics of an air and an Ar/H2 atmospheric plasma like gas temperatures, excitation temperatures and densities as well as the heating of the plasma by the microwave will be investigated. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of gamma ray on poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends as biodegradable food packaging films

Poly(lactic acid) (PLA)/poly(vinyl acetate-co-vinyl alcohol) [P(VAc-co-VA)] blends as new transparent film packaging materials were prepared at various blend compositions and different vinyl alcohol contents. The blends and pure PLA were irradiated by gamma rays to investigate the extent of changes in the packaging material during gamma ray sterilization process. The miscibility of the blends was dependent on the blend composition and vinyl alcohol content; gamma irradiation had little effect on the extent of miscibility. The glass transition temperature of pure PLA and PLA/P(VAc-co-VA) miscible blends reduced after irradiation. On the other hand in PLA/P(VAc-co-VA) immiscible blends, while the glass transition temperature of the PLA phase decreased; that of the copolymer phase slightly increased. The reduction in the glass transition was about 10 percent for samples irradiated with 50kGy indicating dominance of chain scission of PLA molecules at high irradiation dose. The latter was verified by drop in mechanical properties of pure PLA after exposing to gamma irradiation at 50kGy. Blending of PLA with the copolymer P(VAc-co-VA) compensated greatly the adverse effects of irradiation on PLA. The oxygen-barrier property of the blend was superior to the neat PLA and remained almost intact with irradiation. The un-irradiated and irradiated blends had excellent transparency.Gamma ray doses used for sterilization purposes are usually less than 20kGy. It was shown that gamma irradiation at 20kGy had no or little adverse effects on PLA/P(VAc-co-VA) blends mechanical and gas barrier properties.

Study of Effects of Low Doses UV Radiation on Microporous Polysulfone Membranes in Sterilization Process

Synthetic membranes have gained an important place in chemical technology and are used in a broad range of applications. UV irradiation is an age old process used for disinfection as well as for sterilization purposes. It is used for sterilizing equipment in which polysulfone (PSf) membranes are used. As a result, short time UV irradiation of polymer membranes has acquired importance in recent times. In the present study, microporous polysulfone membranes with0.108 mmthickness have been prepared using phase inversion method. Effect of UV irradiation on the membranes for short time intervals (0 - 60 minutes) has been investigated using UV-Vis and FTIR spectrophotometer, and SEM. The performance of the membranes has studied by filtration techniques. UV-Vis and IR spectra analysis and SEM images obtained suggest that chains scission and crosslink have occurred simultaneously in the irradiated membranes by UV radiation in a dose dependant manner. The pure water flux (PWF) values of irradiated membranes obtained from filtration studies were higher compared to that of the control membrane. These results show that a very short UV irradiation (2 minutes) affected the physicochemical characteristics of microporous polysulfone membrane which it increases with increase in time.

The Effect of Sodium Hypochlorite Solutions on the Viability and In Vitro Regeneration Capacity of the Tissue

Although there are many chemicals used for sterilization purposes such as ethanol, hydrogen peroxide, bromine water, mercuric chloride, silver nitrate and antibiotics, sodium hypochlorite solutions have been most widely used. Since NaOCl has a strong oxidizing property which makes it highly reactive with amino acids, nucleic acids, amines, and amides, it is highly effective against all kinds of bacteria, fungi, and viruses. The general reaction between amino acids and NaOCl produces the respective aldehyde, NH4Cl and CO2. Thus, during the sterilization process, direct contact of the tissue with NaOCl depending on it’s concentration, application period and temperature may have a hazardous effect on the health of the tissue. In plant tissue culture studies, high-frequency shoot regeneration which is highly affected by tissue health, is a prerequisite for an efficient gene transformation system and a clonal propagation of plants. The most important treatment prior to culture initiation is the sterilization of the tissue. In plant tissue culture, elimination of microorganisms from the tissue has great importance. From one hand, sterilization process aims to eliminate all microorganisms that can easily grow on the tissue; on the other hand, it should guarantee the tissue’s viability and regeneration capacity. This review has focused on the effects of concentration, application period and temperature of NaOCl using for eliminating microorganisms on the viability and in vitro regeneration capacity of the tissue.

Ethanol‐Dispersed Polymer Nanofibers as a Highly Selective Cell Isolation and Release Platform for CD4+ T Lymphocytes

AbstractA novel cell isolation and release platform using electrospun polystyrene‐poly(styrene‐co‐maleic anhydride) (PS‐PSMA) nanofibers is presented. Ethanol treatment of PS‐PSMA nanofibers, employed for the purpose of sterilization, significantly increases their inter‐fiber space for both antibody conjugation and subsequent cell separation. For the selective isolation of CD4+ T cells from heterogeneous mixtures of mouse lymph nodes, capture efficiencies of up to 100% are achieved while maintaining cellular integrity and viability. Once captured, CD4+ T lymphocytes can also be released from the NF scaffolds, further demonstrating its potential functionality as an immune cell‐supporting and releasing matrix. This is the first demonstration of lymphocyte‐culture scaffolds enabling selective isolation, accommodation, and sustained release of CD4+ T cells for the purpose of cell therapies.

DRY HEATING OF PALM FRUITS: EFFECT ON SELECTED PARAMETERS

This study reports on the effects of dry heating of oil palm fruits for the purpose of sterilization and solvent extraction with various oil parameters. Steam sterilization of oil palm fresh fruit bunches was required as a pre-treatment to deactivate enzymes that give rise to Free Fatty Acids (FFA) before the oil could be extracted. While the use of high-pressure steam was effective, large amount of water used ends up as palm oil mill effluent, which requires appropriate treatment. Dry heating of oil palm fruits was carried out in an oven for 1-4 and 5 min time duration. The heated fruits were extracted for its oil by solvent means. Oil yield, Deterioration Of Bleachability Index (DOBI), oxidative stability and FFA content were investigated. The FFA content in the oil extracted from dry heated oil palm fruits ranged from 1.02-2.19%, DOBI from 4.19-6.72 and oxidative stability from 14.3-19.1 h. Dry heated oil palm fruits yield crude oil with comparable quality to that of commercial crude palm oil, which is steam sterilized.

Characterization of sodium hyaluronate blends using frit inlet asymmetrical flow field-flow fractionation and multiangle light scattering

We characterized ultrahigh molecular weight sodium hyaluronate (NaHA) and blended pharmaceutical products containing NaHA using flow field-flow fractionation and multiangle light scattering-differential refractive index (FlFFF-MALS-DRI). NaHA is a water-soluble polysaccharide with a range of molecular weights (MW; 10(5)~10(8) Da) that is found in body fluids and tissues. NaHA is also used commercially in pharmaceutical and cosmetic applications. We used a frit inlet asymmetrical FlFFF channel to separate aqueous polymers according to their hydrodynamic size, and we used on-line measurements of light scattering to obtain the MW distribution (MWD) as well as structural information about NaHA in aqueous solution. In this study, we investigated NaHA and anti-adhesive blend mixtures of NaHA (a commercial NaHA blend mixture containing sodium carboxymethyl cellulose and a new blend with hydroxyethyl starch (HES)) to determine the molecular weight distribution MWD of NaHA and the blend mixtures and to obtain structural information about these compounds in aqueous solution. We also examined the characteristics of NaHA-HES-polylactic-co-glycolic acid film products exposed to gamma radiation for sterilization purposes.

Enhanced inactivation of bacteria by metal‐oxide nanoparticles combined with visible light irradiation

In recent years nano-metaloxides which easily penetrate into the cells with special interest due to their higher chemical reactivity as compared to that of similar materials in the bulk form. Of particular interest are nano-TiO(2) and ZnO, which have been widely used for their bactericidal and anticancerous properties. The aim of the present study was to examine the bactericidal properties of nano-TiO(2) and ZnO combined with visible light on S. aureus and S. epidermitis, known for their high prevalence in infected wounds. Using the technique of electron-spin resonance (ESR) coupled with spin trapping, we examined the ability of TiO(2) and ZnO nanoparticle suspensions in water to produce reactive oxygen species (ROS) with and without visible light irradiation. The possibility of exciting these nanoparticles with visible light in order to enhance their antimicrobial activity was also tested. Electron-spin resonance measurements revealed that ZnO and TiO(2) nanoparticles are able to produce ROS in water suspension. A remarkable enhancement of ROS production was found following illumination with blue light. In addition, illumination significantly enhanced the antibacterial activity of the nanoparticles. The results suggest that nanoparticles combined with visible light can be used for sterilization purposes and may be effective for treating infected wounds.

Confirmation of Biologic Ingrowth into a Polyester Matrix in the Endometrial Cavity in an Animal Model

Study Objective: To determine the ability to achieve biologic ingrowth into a polyester matrix in the endometrial cavity in an animal model. The purpose of this is to allow further investigation into the use of polyester to promote biologic ingrowth into the endomyometrium near the uterotubal junction for sterilization purposes. Design: Devices were inserted into four Nubian goats on the same day. Because of anatomic differences from the human model, the devices could not be placed transcervically. A device was placed in each horn via a small hysterotomy incision and secured with non-reactive suture material. The animals were recovered. The uterus was removed from a goat on each of the successive four weeks. The uteri were sent to a pathology lab with expertise in staining for biologic ingrowth. Serial sections were obtained and stained to determine the degree of biologic ingrowth into the polyester matrix. Setting: The devices were inserted into the animal models in a qualified veterinary surgical facility. Measurements and Main Results: Pathologic determination of progressive biologic ingrowth into the polyester matrix was confirmed. By Week 1, early ingrowth was readily identified. By Week 4, ingrowth of tissue into the polyester matrix was confirmed, with the endometrium essentially replaced by ingrowth. The ingrowth provided contact of the polyester to an depth close to the myometrium. Conclusion: Biologic ingrowth into a polyester matrix can be acheived in the endometrial cavity. With the local destruction of the endometrial layer and ingrowth to a depth approaching the myometrium by Week 4, there should be no concern about the device being expelled during menses. Further investigation into the usefulness of this finding is necessary to determine if the concept can be applied to a transcervical sterilization device.

Synergy effect of heat and UV photons on bacterial-spore inactivation in an N2–O2 plasma-afterglow sterilizer

As a rule, medical devices (MDs) made entirely from metals and ceramics can withstand, for sterilization purposes, elevated temperatures such as those encountered in autoclaves (moist heat ⩾120 °C) or Poupinel (Pasteur) ovens (dry heat ⩾160 °C). This not the case with MDs containing polymers: 70 °C seems to be a limit beyond which their structural and functional integrity will be compromised. Nonetheless, all the so-called low-temperature sterilization techniques, relying essentially on some biocidal chemistry (e.g. ethylene oxide, H2O2, O3), are operated at temperatures close to 65 °C, essentially to enhance the chemical reactivity of the biocidal agent. Based on this fact, we have examined the influence of increasing the temperature of the polystyrene Petri dish containing B. atrophaeus bacterial spores when exposing them to UV radiation coming from an N2–O2 flowing plasma afterglow. We have observed that, for a given UV radiation intensity, the inactivation rate increases with the temperature of the Petri dish, provided heat and UV photons are applied simultaneously, a clear case of synergistic effect. More specifically, it means that (i) simply heating the spores at temperatures below 65 °C without irradiating them with UV photons does not induce mortality; (ii) there is no additional increase in the inactivation rate when the Petri has been pre-heated and then brought back to ambient temperature before the spores are UV irradiated; (iii) no additional inactivation results from post-heating spores previously inactivated with UV radiation. Undoubtedly, the synergistic effect shows up only when the physico-chemical agents (UV photons and temperature) are simultaneously in action.

Comparison of the effectiveness of sterilizing endodontic files by 4 different methods: An in vitro study

Sterilization is the best method to counter the threats of microorganisms. The purpose of sterilization in the field of health care is to prevent the spread of infectious diseases. In dentistry, it primarily relates to processing reusable instruments to prevent cross-infection. The aim of this study was to investigate the efficacy of 4 methods of sterilizing endodontic instruments: Autoclaving, carbon dioxide laser sterilization, chemical sterilization (with glutaraldehyde) and glass-bead sterilization. The endodontic file was sterilized by 4 different methods after contaminating it with bacillus stearothermophillus and then checked for sterility by incubating after putting it in test tubes containing thioglycollate medium. The study showed that the files sterilized by autoclave and lasers were completely sterile. Those sterilized by glass bead were 90% sterile and those with glutaraldehyde were 80% sterile. The study concluded that autoclave or laser could be used as a method of sterilization in clinical practice and in advanced clinics; laser can be used also as a chair side method of sterilization.

Pilot Project Aims to Ease Standards Comparisons

A AMI is launching a pilot project to provide red line versions of standards so users can readily identify changes from the prior edition of a document. The red line version uses strikethrough to identify text deleted during the revision process. New text is clearly displayed in red and underline. This formatting makes it easy for users to quickly identify additions, deletions, and other changes between new and old editions.While it may be extremely useful, the red line document is not the official AAMI standard. Since it may be difficult to adequately depict all changes between editions of a standard, users are encouraged to consult the current edition, and prior editions as necessary.The red line version is available in PDF and is offered along with the PDF of the official standard. For convenience, and to ensure that users also receive the official document, the red line and official standard are packaged together as one PDF.With a red line document, you no longer need to compare a revised and prior standard—saving you time and eliminating the need for line-by-line comparisons.The first document offered as a red line is ANSI/AAMI/ISO 14161:2009, Sterilization of health care products—Biological indicators—Guidance for the selection, use and interpretation of results. The red line compares the 2000 and 2009 editions of 14161.The 14161 standard contains updated guidance on the application of biological indicators to validate a sterilization process.Biological indicators are used to detect any problems within a sterilization process and for various sterilization methods such as ethylene oxide and steam. “Since the purpose of sterilization is to destroy microbes, the only way to test microbial inactivation sterilization is to test it against microbes. Biological indicators are used because of their consistent resistance and population as a reproducible measure of microbial lethality,” says Gregg Mosley, president of Biotest Laboratories Inc., and co-chair of AAMI's Biological Indicators Working Group.The standard is ideally suited for users of biological indicators. “Anyone who manufactures devices or pharmaceuticals and uses biological indicators as part of routine monitoring or sterilization validation would find use in the document,” Mosley says. The standard has been updated to comply with the ANSI/AAMI/ISO 11348 series, which are a series of biological indicator standards revised in 2006.The standard also has additional information on determining the resistance of a biological indicator, including survival/kill response characteristics. “There is a time defined at which all of the indicators tested would be positive, which is a survival time, and then the kill time is the point at which all indicators are rendered inactive,” says Phil Schneider, senior consultant for LexaMed Inc. and co-chair of the AAMI Biological Indicators Working Group.

Antifungal Activity of Silver Ions and Nanoparticles on Phytopathogenic Fungi.

Silver in ionic or nanoparticle forms has a high antimicrobial activity and is therefore widely used for various sterilization purposes including materials of medical devices and water sanitization. There have been relatively few studies on the applicability of silver to control plant diseases. Various forms of silver ions and nanoparticles were tested in the current study to examine the antifungal activity on two plant-pathogenic fungi, Bipolaris sorokiniana and Magnaporthe grisea. In vitro petri dish assays indicated that silver ions and nanoparticles had a significant effect on the colony formation of these two pathogens. Effective concentrations of the silver compounds inhibiting colony formation by 50% (EC50) were higher for B. sorokiniana than for M. grisea. The inhibitory effect on colony formation significantly diminished after silver cations were neutralized with chloride ions. Growth chamber inoculation assays further confirmed that both ionic and nanoparticle silver significantly reduced these two fungal diseases on perennial ryegrass (Lolium perenne). Particularly, silver ions and nanoparticles effectively reduced disease severity with an application at 3 h before spore inoculation, but their efficacy significantly diminished when applied at 24 h after inoculation. The in vitro and in planta evaluations of silver indicated that both silver ions and nanoparticles influence colony formation of spores and disease progress of plant-pathogenic fungi. In planta efficacy of silver ions and nanoparticles is much greater with preventative application, which may promote the direct contact of silver with spores and germ tubes, and inhibit their viability.

An overview of modelling of low-pressure post-discharge systems used for plasma sterilization

We present the modeling of a low pressure post-discharge system used for plasma sterilization, which consists of a flowing microwave discharge, an early-afterglow region developed downstream of the discharge in the same tube, and a large post-discharge reactor. The kinetic model valid for the discharge and early-afterglow region is based on the Boltzmann and rate balance equations, while in the post-discharge reactor a 3-D hydrodynamic model is used. The calculations are conducted in an N2-O2 mixture, which has seen to constitute an efficient system for sterilization purpose. The possibilities offered by modeling is presented through a discussion of the effects on relevant species densities and distributions caused by varying: (i) the initial gas mixture composition; (ii) the length of early-afterglow zone; (iii) the gas flow rate and gas pressure.

Abuse of caesarean delivery in Brazil: geographic dimensions of a medical aberration

"Brazil is the world champion of caesareans." This prowess points out a serious public health problem. While the increase in the percentage of caesareans among all deliveries is an international phenomenon, it is highest by far in Brazil, where caesareans account for nearly 40% of births, that is, three times the maximum recommended by WHO. This abusive practice appears pandemic and has spread in recent years throughout the entire country, although at divergent rates. It weighs heavily on Brazil's national health insurance fund. After a critical examination of the information sources related to births, we analyze successively the principal factors likely to explain this abuse: level of development, emergence of family planning and the association of caesarean delivery with tubal ligation for sterilization purposes, and tension within the healthcare system, especially the role of private physicians in urban areas. By studying these aspects of the problem in their geographic dimensions, we find important regional differences that must be considered in defining policies to limit this excess.

Effects of supercritical carbon dioxide treatment for sterilization purpose on meat quality of porcine longissimus dorsi muscle

The objective of this study was to investigate the effect of supercritical carbon dioxide (SC-CO 2) treatment for the sterilization purpose on meat quality and protein denaturation of the porcine longissimus dorsi muscle. The conditions of SC-CO 2 treatment were 7.4 and 15.2 MPa at 31.1 °C for 10 min. SC-CO 2 treatment had no effect on muscle pH, tenderness, and water-holding capacity (WHC). However, the samples treated at 7.4 MPa had a higher lightness value (52.97 vs. 46.94, P<0.001) and a more pronounced extent of sarcoplasmic protein denaturation (73.80 vs. 80.73, P<0.01) than the control samples. These results suggest that the paler color of samples treated with SC-CO 2 was associated with the sarcoplasmic protein denaturation, and the major denaturated proteins were determined to be phosphorylase b (PH), creatine kinase (CK), triosephophate isomerase (TPI), and one unknown protein. On the other hand, other quality traits were generally unaffected by the SC-CO 2 treatments at 7.4 or 15.2 MPa.

High pressure versus heat treatments for pasteurisation and sterilisation of model emulsions

Heat treatments can have considerable influence on the droplet size distribution of oil-in-water emulsions. In the present study, high-pressure (HP) pasteurisation and sterilisation were evaluated as alternatives for heat preservation of emulsions. HP conditions used were 600 MPa, 5 min, room temperature and 800 MPa, 5 min, 80 °C initial temperature, 115 °C maximum temperature for HP pasteurisation and HP sterilisation respectively. The effects on droplet size of these conditions were compared to heat treatments for whey protein isolate (WPI) and soy protein isolate (SPI) emulsions at two pH values and two ionic strengths. For WPI, also the effect of protein in the bulk phase was evaluated. Both HP and heat pasteurisation treatments resulted in similar or slightly decreased average droplet sizes compared to the untreated samples. For neutral SPI emulsions, heat sterilisation increased the average droplet size from 1.6 μm to 43.7 μm, while HP sterilisation resulted only in a small increase towards an average droplet size of 2.1 μm. The neutral WPI emulsions, except those with a high ionic strength, gave similar results with respect to the droplet size, showing that for neutral pH WPI or SPI emulsions HP sterilisation is preferable above heat sterilisation. Concerning the low pH WPI emulsions, the droplet sizes were unaffected after both heat and HP sterilisation. Heat pasteurisation and sterilisation are effective treatments to preserve food products that are based on emulsions with respect to microbial safety. However, heat treatments can negatively affect emulsion stability. Currently, in addition to high pressure at room temperature, high-pressure treatments at elevated temperature received a great deal of interest to achieve sterilised products. This study evaluated the effects of both heat and high-pressure pasteurisation and sterilisation on droplet size of whey protein isolate and soy protein isolate emulsions. It was shown that for pasteurisation treatments, both heat and high pressure have minor effects on the droplet size of the emulsion. However, for sterilisation purposes high-pressure treatment is preferable for emulsion at neutral pH. High-pressure sterilisation can therefore be interesting alternatives to heat treatments to preserve emulsion stability.