Log Unit Reduction Research Articles

Comparative analysis of thermal-assisted high pressure and thermally processed mango pulp: Influence of processing, packaging, and storage.

Storage stability and shelf-life of mango pulp packed in three different packaging films and processed using an optimized thermal-assisted high pressure processing treatment 'HPP' (600 MPa/52 ℃/10 min) was analyzed during refrigerated (5 ℃) and accelerated (37 ℃) storage and compared with the conventional thermal treatment 'TT' (0.1 MPa/95 ℃/15 min). After processing, HPP resulted in relatively lower total color difference (3.5), retained higher ascorbic acid (95%), total phenolics (106%), total flavonoids content (118%) in mango pulp compared to TT, with values of 5.0, 62, 83, 73%, respectively. However, HPP led to ∼50% enzymes inactivation (pectin methylesterase, polyphenol oxidase, peroxidase) in comparison to >90% obtained during TT. Both HPP and TT resulted in > 5 log10 units reduction of the studied microorganisms to give a safe product. In contrast to the refrigerated storage, quality changes under accelerated conditions were found to be considerably rapid and dependent on packaging material irrespective of the method of processing. Shelf-life under refrigeration was limited by microbial growth and sensory quality; whereas, browning restricted the shelf-life during accelerated storage. HPP in aluminum-based retort pouch was adjudged superior processing -packaging combination for maximizing the shelf-life of mango pulp to 120 and 58 days during refrigerated and accelerated storage, respectively. In comparison, TT led to higher quality changes upon processing than HPP and resulted in shelf-life of 110 and 58 days under the same packaging and storage conditions, respectively.

Microbial inactivations with hydrolysed lactoferrin and other natural antimicrobials in fresh-cut fennel

Natural antimicrobials (nisin, lactoferrin, thymol and citrus extract) were studied as sustainable alternatives to conventionally used NaOCl in fresh-cut (FC) fennel. Enterobacteriaceae was the most sensitive microbial group to studied sanitizers according to δ values, while psychrophiles were the most resistant. Based on inactivation modelling and sensory scores, nisin (N-250; 0.250 g L−1), lactoferrin (L-50; 50 g L−1), together with hydrolysed L-50 (LFH), were selected and studied comparing to water-washed (CTRL) and NaOCl (150 mg NaOCl L−1) on FC fennel. LFH achieved the highest psychrophilic reduction of 2.5 log units. Although NaOCl achieved the highest mesophilic, Enterobacteriaceae, lactobacilli and yeasts and moulds reductions of 1.7, 1.0, <1.7 and 1.6, respectively, N-250 still achieved 0.50–1.0 log unit reductions compared to CTRL. Conclusively, LFH and N-250 are natural antimicrobial treatments with good microbial inactivation rates which may be a good alternative to conventional NaOCl used by the FC industry.

Active packaging of chicken meats with modified atmosphere including oxygen scavengers

The effects of modified atmosphere packaging (MAP-70% CO2/30%N2) and iron-based oxygen scavengers (OS) with various absorption capacities (Ageless® ss100, ss300, and ss500) as an active packaging system on microbiological and oxidative changes in chicken thigh meats were evaluated during refrigerated storage (4°C) for 19 d at 3-day intervals. Total aerobic mesophilic bacteria counts exceeded the acceptability limit at d 7 in the control group without MAP (AIR), and at d 19 in MAP and OS containing samples. OS utilization resulted in around 1.5 and 1.0 log unit reductions in Pseudomonas spp. counts at d 7 and d 10 of storage, respectively, as compared with AIR and MAP groups (P < 0.05). MAP and OS groups had fewer (P < 0.05) coliform counts than did the AIR group, with an approximately 1.0 log reduction observed at d 10. Although in some cases OS utilization resulted in lower TBARS values and carbonyl and sulphydryl contents, particularly during later stages of refrigerated storage as compared to AIR and MAP groups, in general, these effects were not always apparent. The results of this study suggested that MAP suppressed microbiological growth and retarded lipid and protein oxidation in chicken thigh meats, with a 9-day shelf-life extention with insignificant effects of OS.

Ultraviolet (UV-C) inactivation of Enterococcus faecium, Salmonella choleraesuis and Salmonella typhimurium in porcine plasma.

The objective of this study was to assess the effectiveness of an ultraviolet (UV-C, 254 nm) irradiation system on reducing the load of Salmonella typhimurium (S. typhimurium), Salmonella choleraesuis (S. choleraesuis) resistant to streptomycin and Enterococcus faecium (E. faecium) inoculated in sterile porcine plasma and then subjected to different UV-C irradiation doses (750, 1500, 3000, 6000 and 9000 J/L) using a pilot plant UV-C device working under turbulent flow. Results indicated that UV-C treatment induced a viability reduction of 0.38, 1.18, 3.59, 4.72 and 5.06 log10 S. typhimurium when irradiated at 750, 1500, 3000, 6000 and 9000 J/L, respectively. The observed log10 reduction of S. choleraesuis was 1.44, 2.68, 5.55, 7.07 and 7.97 at 750, 1500, 3000, 6000 and 9000 J/L, respectively. The best-fit inactivation for S. choleraesuis was the Weibull distribution curve, while the best-fit curve for S. typhimurium was the Weibull plus tail model, indicating that around 102 cfu/mL resistant S. typhimurium was detected when the liquid plasma was UV-C irradiated at doses up to 9000 J/L. Viability reduction for E. faecium was 0.44, 1.01, 3.70, 5.61 and 6.22 log10 when irradiated at 750, 1500, 3000, 6000 and 9000 J/L, respectively, with no bacterial resistance observed with UV-C doses of 6000 J/L or higher. The biphasic model was the best fit model for the inactivation curve for E. faecium. For the three microorganisms tested, about a 4 log-unit reduction was achieved when the liquid plasma was irradiated at 3000J/L. Overall results demonstrate the usefulness of the UV-C system to inactivate bacteria in liquid plasma before spray-drying. We conclude that the UV-C system can provide an additional biosafety feature that can be incorporated into the manufacturing process for spray-dried animal plasma.

Study of Crystal Formation and Nitric Oxide (NO) Release Mechanism from S-Nitroso-N-acetylpenicillamine (SNAP)-Doped CarboSil Polymer Composites for Potential Antimicrobial Applications.

Stable and long-term nitric oxide (NO) releasing polymeric materials have many potential biomedical applications. Herein, we report the real-time observation of the crystallization process of the NO donor, S-nitroso-N-acetylpenicillamine (SNAP), within a thermoplastic silicone-polycarbonate-urethane biomedical polymer, CarboSil 20 80A. It is demonstrated that the NO release rate from this composite material is directly correlated with the surface area that the CarboSil polymer film is exposed to when in contact with aqueous solution. The decomposition of SNAP in solution (e.g. PBS, ethanol, THF, etc.) is a pseudo-first-order reaction proportional to the SNAP concentration. Further, catheters fabricated with this novel NO releasing composite material are shown to exhibit significant effects on preventing biofilm formation on catheter surface by Pseudomonas aeruginosa and Proteus mirabilis grown in CDC bioreactor over 14 days, with a 2 and 3 log-unit reduction in number of live bacteria on their surfaces, respectively. Therefore, the SNAP-CarboSil composite is a promising new material to develop antimicrobial catheters, as well as other biomedical devices.

Bactericidal effect of plasma jet with helium flowing through 3% hydrogen peroxide against Enterococcus faecalis.

The aim of the present study was to assess the antimicrobial activity of plasma jet with helium (He) flowing through 3% hydrogen peroxide in root canals infected with Enterococcus faecalis. A total of 42 single-rooted anterior teeth were prepared, sterilized, inoculated with an E. faecalis suspension and incubated for 7 days. Next, the teeth were randomly divided into six experimental groups (including groups treated by plasma jet with or without He for different time durations) and one control group treated without plasma. The number of surviving bacteria in each canal was determined by counting the colony forming units (CFU)/ml on nutrient agar plates. The results indicated that statistically significant reduction in CFU/ml (P<0.005) existed for all treatment groups relative to the control group. The greatest reductions in CFU/ml were observed for Group 3 (7.027 log unit reduction) and Group 2 (6.237 log unit reduction), which were treated by plasma jet sterilization with He flowing through 3% hydrogen peroxide for 4 min or for 2 min, respectively. In addition, the reduction in Group 3 was significantly greater compared with that in Group 2 or in the groups treated by plasma jet sterilization without He flowing through 3% hydrogen peroxide for 1, 2 or 4 min. In conclusion, plasma jet with or without He flowing through 3% hydrogen peroxide can effectively sterilized root canals infected with E. faecalis and should be considered as an alternative method for root canal disinfection in endodontic treatments.

Performance of constructed wetland applied for domestic wastewater treatment: Case study at Boimorto (Galicia, Spain)

The study aims at evaluating the performance of a horizontal subsurface flow constructed wetland used for secondary treatment of domestic wastewater since May 2011 at Galicia (Spain). A septic tank was used as primary treatment. The wetland consists of two cells in parallel: cell-A with 350m2 and cell-B with 280m2, constructed with a depth of 0.6m, filled with gravel of 30mm of average size and planted with common reeds. The performance of wastewater treatment was controlled from June 2011 to September 2015. The rural agglomeration is served by a gravity sewer system with high rates of infiltration/inflow during wet weather. Thus, concentration and flow rate of wastewater have high seasonal variability. Average primary effluent BOD5, COD, suspended solids (TSS), total nitrogen (TN) and total phosphorous (TP) concentrations (in mg/L) were: 105, 197, 43, 29 and 3.4, respectively. Meanwhile, average secondary effluent BOD5, COD, SS, TN and TP values (in mg/L) were: 19, 44, 12, 14.3 and 1.9, respectively. A 2.2 log unit reduction for faecal coliforms was observed in the global system. The wetland required to be harvested at the end of each October. The sludge produced by the septic tank has not yet required to be removed. The wetland system presented no problems for vectors or nuisance odours.

Photosensitizer-Embedded Polyacrylonitrile Nanofibers as Antimicrobial Non-Woven Textile.

Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por(+). Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens (Staphylococcus aureus; vancomycin-resistant Enterococcus faecium; Acinetobacter baumannii; and Klebsiella pneumonia), as well as Escherichia coli. Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm2; 400–700 nm) by a minimum of 99.9996+% (5.8 log units) regardless of taxonomic classification. PAN-Por(+) also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL) and vesicular stomatitis virus (>7 log units reduction in PFU/mL). When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por(+) are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.

Effective antimicrobial activity of Cbf-14, derived from a cathelin-like domain, against penicillin-resistant bacteria

Cbf-14, a cationic peptide derived from a cathelin-like domain, was designed by inserting the highly α-helical sequence RLLR into an antibacterial sequence and deleting the inactive amino acids in Cbf-K16. Clinical penicillin-resistant isolates as well as NDM-1-carrying Escherichia coli and a correspondingly infected mice model were employed to evaluate Cbf-14 antibacterial activity. The results showed that Cbf-14 possessed potent antimicrobial effects with an MIC of 8–64 μg/ml, and killed almost all bacteria within 240 min. Cbf-14-treated mice achieved an 80% survival rate and approximate 2.5 log unit reduction in CFU in tissues; additionally, this peptide significantly suppressed the production of pro-inflammatory cytokines by the disaggregation of lipopolysaccharide (LPS), suggesting its anti-inflammatory effects. Furthermore, Cbf-14, concentration higher than 2 × MIC value, increased membrane uptake to NPN and PI dye by 96.2% and 63.7%, respectively, neutralised the negative zeta potential of LPS and bacteria surface, and induced 100% leakage of liposome-entrapped calcein and cytoplasmic membrane disruption of E. coli, indicating obvious membrane permeation. Finally, it bound to DNA and respectively evoked 85.0% and 63.3% inhibition of gene replication and protein expression of NDM-1 at sub-MIC concentration in E. coli BL21 (DE3)-NDM-1. These data indicated that Cbf-14 possessed effective antimicrobial activity against penicillin-resistant bacteria in vitro/vivo through membrane disruption, DNA binding, down-regulating NDM-1 expression by plasmid replication inhibition, and anti-inflammatory activity by LPS disaggregation, suggesting a potential anti-infective clinical agent.

Changes in nutritional value and application of thyme (Thymus vulgaris) essential oil on microbial and organoleptic markers of Persian clover (Trifolium resupinatum) sprouts

In this study, effect of the 4-day germination on the chemical composition, antioxidant activity and fatty acids profile of Persian clover seeds (Trifolium resupinatum) was investigated. In addition, clover sprouts was immersed in 0.5, 1 and 2% thyme (Thymus vulgaris) essential oil (EO) solutions, packaged in polyethylene containers and stored at refrigerated temperature (4 °C) for 10 days. As seedling progressed, the moisture, protein, crude fibre and ash content increased, whilst fat and carbohydrate reduced. After 4-day germination, ascorbic acid, total phenolic content and antioxidant activity indicated 1.3, 2 and 1.5 fold increase, respectively. Sprouting caused significantly (p < 0.05) increase in measured organic acids and minerals (except K). Moreover, oleic acid showed an increase of 3.4% compared to raw seed. In respect to microbial quality, the treated clover sprout demonstrated a significant reduction in the population of total aerobic bacteria, coliforms, molds and yeast count followed by increasing EO concentration compared to the control. Total aerobic bacteria, total coliforms, molds and yeast count of clover sprouts with 2% thyme EO showed 3.2, 2.3 and 2.2 log10 unit reduction, just after treatment. During storage, the population of natural microflora increased significantly (p < 0.05) in all treatments.

Origin of Long-Term Storage Stability and Nitric Oxide Release Behavior of CarboSil Polymer Doped with S-Nitroso-N-acetyl-D-penicillamine.

The prolonged and localized delivery of nitric oxide (NO), a potent antithrombotic and antimicrobial agent, has many potential biomedical applications. In this work, the origin of the long-term storage stability and sustained NO release mechanism of S-nitroso-N-acetyl-d-penicillamine (SNAP)-doped CarboSil 20 80A polymer, a biomedical thermoplastic silicone-polycarbonate-urethane, is explored. Long-term (22 days) localized NO release is achieved by utilizing a cross-linked silicone rubber as topcoats, which can greatly reduce the amount of SNAP, NAP, and NAP disulfide leaching from the SNAP-doped CarboSil films, as measured by LC–MS. Raman spectroscopy and powder X-ray diffraction characterization of SNAP-doped CarboSil films demonstrate that a polymer–crystal composite is formed during the solvent evaporation process when SNAP exceeds its solubility in CarboSil (ca. 3.4–4.0 wt %). Further, when exceeding this solubility threshold, SNAP exists in an orthorhombic crystal form within the bulk of the polymer. The proposed mechanism of sustained NO release in SNAP-doped CarboSil is that the solubilized SNAP in the polymer matrix decomposes and releases NO, primarily in the water-rich regions near the polymer/solution interface, and the dissolved SNAP in the bulk polymeric phase becomes unsaturated, resulting in the dissolution of crystalline SNAP within the bulk of the polymer. This is a very slow process that ultimately leads to NO release at the physiological flux levels for >3 weeks. The increased stability of SNAP within CarboSil is attributed to the intermolecular hydrogen bonds between the SNAP molecules that crystallize. This crystallization also plays a key role in maintaining RSNO stability within the CarboSil polymer for >8 months at 37 °C (88.5% remains). Further, intravascular catheters fabricated with this new material are demonstrated to significantly decrease the formation of Staphylococcus aureus biofilm (a leading cause of nosocomial bloodstream infections) (in vitro) over a 7 day period, with 5 log units reduction of viable cell count on catheter surfaces. It is also shown that the NO release catheters can greatly reduce thrombus formation on the catheter surfaces during 7 h implantation in rabbit veins, when compared to the control catheters fabricated without SNAP. These results suggest that the SNAP-doped CarboSil system is a very attractive new composite material for creating long-term NO release medical devices with increased stability and biocompatibility.

Photodynamic antimicrobial chemotherapy activity of gallium tetra-(4-carboxyphenyl) porphyrin when conjugated to differently shaped platinum nanoparticles

This work reports on the conjugation of differently shaped Pt nanoparticles (PtNPs) with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (ClGaTCPP). The resulting conjugates were used for photodynamic antimicrobial chemotherapy against Staphylococcus aureus. The degree of photo-inactivation is dependent on concentration of the conjugates, light dose (fluence) and illumination time. The log reduction obtained for ClGaTCPP when conjugated to cubic PtNPs was 4.64 log (which indicate 99.99% of the bacteria have been killed), which is much higher than 3.94 log unit for ClGaTCPP-Hexagonal PtNPs and 3.31 log units for ClGaTCPP-Unshaped PtNPs. ClGaTCPP alone gave a log unit reduction of less than 3, showing the importance of conjugation to PtNPs.

Antiviral, Antifungal and Antibacterial Activities of a BODIPY-Based Photosensitizer.

Antimicrobial photodynamic inactivation (aPDI) employing the BODIPY-based photosensitizer 2,6-diiodo-1,3,5,7-tetramethyl-8-(N-methyl-4-pyridyl)-4,4′-difluoro-boradiazaindacene (DIMPy-BODIPY) was explored in an in vitro assay against six species of bacteria (eight total strains), three species of yeast, and three viruses as a complementary approach to their current drug-based or non-existent treatments. Our best results achieved a noteworthy 5–6 log unit reduction in CFU at 0.1 μM for Staphylococcus aureus (ATCC-2913), methicillin-resistant S. aureus (ATCC-44), and vancomycin-resistant Enterococcus faecium (ATCC-2320), a 4–5 log unit reduction for Acinetobacter baumannii ATCC-19606 (0.25 μM), multidrug resistant A. baumannii ATCC-1605 (0.1 μM), Pseudomonas aeruginosa ATCC-97 (0.5 μM), and Klebsiella pneumoniae ATCC-2146 (1 μM), and a 3 log unit reduction for Mycobacterium smegmatis mc2155 (ATCC-700084). A 5 log unit reduction in CFU was observed for Candida albicans ATCC-90028 (1 μM) and Cryptococcus neoformans ATCC-64538 (0.5 μM), and a 3 log unit reduction was noted for Candida glabrata ATCC-15545 (1 μM). Infectivity was reduced by 6 log units in dengue 1 (0.1 μM), by 5 log units (0.5 μM) in vesicular stomatitis virus, and by 2 log units (5 μM) in human adenovirus-5. Overall, the results demonstrate that DIMPy-BODIPY exhibits antiviral, antibacterial and antifungal photodynamic inactivation at nanomolar concentrations and short illumination times.

Microbial decontamination of dried laver using corona discharge plasma jet (CDPJ)

In the present study, atmospheric pressure corona discharge plasma jet (CDPJ) was used for surface microbial decontamination of thin sheets of dried laver, which is commonly used in ready-to-eat Korean rice roll, gimbap (kimbab). Microbial contaminants namely aerobic bacteria, molds, and marine bacteria were found on the surface of commercial dried laver sheets. CDPJ was generated at an output voltage of 20kV DC and frequency of 58kHz. Upon exposure to the CDPJ, greater than 2 log (99%) unit reductions in viable cell count of aerobic bacteria was observed over a 20min period. The inactivation pattern fitted well to Singh–Heldman model or pseudo-first order kinetics. Compared to plasma-unexposed laver, no changes in color characteristics, total phenolic content and DPPH radical scavenging activity were observed in plasma-exposed laver. Furthermore, CDPJ-exposed laver sheets had exerted minimal to no impact on sensory characteristics of gimbap (kimbab), while extending the shelf life of the product. In conclusion, CDPJ can be used for surface decontamination of dried laver without adversely affecting its physical as well as functional properties.

Continuous, low-dose oral exposure to sodium chlorate reduces fecal generic Escherichia coli in sheep feces without inducing clinical chlorate toxicosis.

Our objectives were to determine an effective, yet safe, daily dose of sodium chlorate for reducing fecal shedding of generic Escherichia coli in mature ewes. In a completely randomized experimental design, 25 Targhee ewes (age ∼ 18 mo; BW = 62.5 ± 7.3 kg, mean ± SD) were assigned randomly to 1 of 5 sodium chlorate treatments, which were administered in the drinking water for 5 consecutive days. Treatments were control group (no sodium chlorate) and 4 targeted levels of daily sodium chlorate intake: 30, 60, 90, and 120 mg · kg(-1) BW · d(-1) for 5 d. Individual ewe ad libitum intake of water (with treatments) was measured daily, and BW was measured at the beginning of and 15 and 51 d after the 5-d treatment period. Serum chlorate, whole blood methemoglobin and packed-cell volume (PCV), and fecal generic E. coli and general Enterobacteriaceae coliforms were measured from corresponding samples collected at the end of the 5-d treatment period. Average daily intakes of sodium chlorate from drinking water treatments were 95%, 91%, 90%, and 83% of the target treatment intakes of 30, 60, 90, and 120 mg · kg(-1) BW · d(-1), respectively. Daily sodium chlorate intake remained constant for all treatment groups except for ewes offered 120 mg NaClO3 · kg(-1) BW · d(-1), which decreased (quadratic; P = 0.04) over the course of the 5-d treatment period. This decrease in sodium chlorate intake indicated that the 120-mg NaClO3 level may have induced either toxicity and/or an aversion to the drinking water treatment. Serum chlorate concentrations increased (quadratic; P < 0.001) with increasing sodium chlorate intake. At the end of the 5-d treatment period, mean (least squares ± SEM) serum chlorate concentrations for ewes offered 30, 60, 90, and 120 mg NaClO3 · kg(-1) BW · d(-1) were 15.6 ± 14.1, 32.8 ± 15.8, 52.9 ± 14.1, and 90.3 ± 14.1 μg/mL, respectively. Whole blood methemoglobin and PCV were similar (P = 0.31 to 0.81) among the control group and ewes offered sodium chlorate. Likewise, BW was not affected by sodium chlorate (P > 0.27). Ewes consuming approximately 55 mg NaClO3 · kg(-1) BW · d(-1) or more (i.e., ewes offered 60, 90, and 120 mg) had a >1.4 log unit reduction in fecal E. coli and Enterobacteriaceae coliforms compared with control ewes. We suggest that for a short-term, 5-d dosing strategy, 55 to 81 mg NaClO3 · kg(-1) BW · d(-1) is an effective, yet safe, daily oral dose range for mature ewes to achieve a 97% to 99% reduction in fecal shedding of generic E. coli.

Virucidal effect of cold atmospheric gaseous plasma on feline calicivirus, a surrogate for human norovirus.

Minimal food-processing methods are not effective against foodborne viruses, such as human norovirus (NV). It is important, therefore, to explore novel nonthermal technologies for decontamination of foods eaten fresh, minimally processed and ready-to-eat foods, and food contact surfaces. We studied the in vitro virucidal activity of cold atmospheric gaseous plasma (CGP) against feline calicivirus (FCV), a surrogate of NV. Factors affecting the virucidal activity of CGP (a so-called radio frequency atmospheric pressure plasma jet) were the plasma generation power, the exposure time and distance, the plasma feed gas mixture, and the virus suspension medium. Exposure to 2.5-W argon (Ar) plasma caused a 5.55 log10 unit reduction in the FCV titer within 120 s. The reduction in the virus titer increased with increasing exposure time and decreasing exposure distance. Of the four plasma gas mixtures studied (Ar, Ar plus 1% O2, Ar plus 1% dry air, and Ar plus 0.27% water), Ar plus 1% O2 plasma treatment had the highest virucidal effect: more than 6.0 log10 units of the virus after 15 s of exposure. The lowest virus reduction was observed with Ar plus 0.27% water plasma treatment (5 log10 unit reduction after 120 s). The highest reduction in titer was observed when the virus was suspended in distilled water. Changes in temperature and pH and formation of H2O2 were not responsible for the virucidal effect of plasma. The oxidation of viral capsid proteins by plasma-produced reactive oxygen and nitrogen species in the solution was thought to be responsible for the virucidal effect. In conclusion, CGP exhibits virucidal activity in vitro and has the potential to combat viral contamination in foods and on food preparation surfaces.

Pediococcus acidilactici as a potential probiotic to be used in food industry

SummaryThe objective of this study was to compare the results obtained between a commercial probiotic bacterium and a strain of Pediococcus acidilactici isolated from a food matrix. Besides the characterisation of the isolates, the main focus of this work was to evaluate their ability to survive through simulated gastrointestinal tract passage as well as the effect of the spray drying process to be used as concentrated cultures in the food industry. Both lactic acid bacteria produced any of the virulence determinants investigated; they exhibited no significant antibiotic resistances and &lt;1 log unit reduction in viable counts was obtained after exposure to simulated gastrointestinal tract conditions. Concentrated cultures of P. acidilactici HA‐6111‐2 in 10% (w/v) of reconstituted skim milk were obtained by spray drying and, after 60 days of storage at 4 °C, &lt;1 log unit reduction in viable count was recorded. In conclusion, from these preliminary characterisation tests and its extended viability in the dried form, this P. acidilactici strain should be considered as a potentially useful probiotic.

Improved oral therapeutic potential of nanoencapsulated cryptdin formulation against Salmonella infection

An encapsulated system for cryptdin-2 (a Paneth cell antimicrobial peptide) was developed, with a view to help it sustain adverse gut conditions and to ensure its bioavailability on oral administration. The formulation was characterized on the basis of particle size, zeta potential and polydispersity index. Cryptdin-2 loaded nanoparticles of size 105±7nm, formulated by ionotropic gelation method using chitosan: tripolyphosphate (5:2), revealed 60% drug entrapment efficiency with 65% in vitro release in 4.5h. Developed system was evaluated for its therapeutic application against Salmonella Typhimurium infection in mice, on the basis of survivability of animals, bacterial load in tissues, histo-architecture and oxidative damage markers. Infected mice when treated with the encapsulated peptide showed 83% survivability and approximately 2 log unit reductions in the bacterial load in the tissues versus 100% mortality observed with the free peptide. The encapsulated cryptdin-2 also achieved a decrease in the level of oxidants, particularly nitrite by 3.25 folds and increased the level of antioxidant catalase by 2 folds when compared to the levels exhibited by the free peptide. The bacteriological and biochemical alterations illustrated by encapsulated peptide co-related well with the histo-architectural studies. The study is a first pre-clinical report on the oral effectiveness of cryptdin-2 by its suitable encapsulation and has potential for future clinical applications.

Water reconditioning by high power ultrasound combined with residual chemical sanitizers to inactivate foodborne pathogens associated with fresh-cut products

The suitability of high power ultrasound (HPU, 20 kHz, 0.28 kW/l) combined with residual chemical sanitizers for water reconditioning was studied. A synergetic disinfection effect was observed when HPU was combined with peroxyacetic acid (PAA) or a commercial mix of organic acids and phenolic compounds (OA/PC). In recycled water (RW) with a chemical oxygen demand (COD) of 500 mg O2/l, PAA inactivated 2 log units of Escherichia coli O157:H7 at concentrations of 3.2, 6.4, 16 mg/l after 7 min, 2 min, 29 s, respectively. The OA/PC or HPU treatments alone needed 26 min treatments to achieve the same reduction. The addition of TiO2 (5 g/l) to HPU (sonocatalysis) did not improve E. coli O157:H7 inactivation. However, when HPU was combined with a residual concentration of PAA (3.2 mg/l), the total inactivation of E. coli O157:H7 and Salmonella (6 log unit reductions) occurred after 11 min, but for Listeria monocytogenes only 1.7 log reductions were detected after 20 min. When HPU was combined with OA/PC, a synergistic effect for the inactivation of E. coli O157:H7 was also observed, but this sanitizer significantly modified the physical-chemical quality characteristics of the RW. These results show that the residual PAA concentration that can be found in the wash water combined with HPU could result in an environmentally friendlier and toxicologically safer strategy for water reconditioning of the fresh-cut industry. The use of the sanitizer alone requires higher concentrations and/or longer contacts times. Even though the residual PAA in combination with HPU was adequate for water reconditioning, it is not appropriate for the process wash water because this wash water must be instantaneously disinfected.

Antimicrobial Activity of Acidified Sodium Chlorite and Cell Free Culture Supernatent of Lactic Acid Bacteria against &amp;lt;i&amp;gt;Salmonella&amp;lt;/i&amp;gt; Typhimurium

Most methods used by food industries to decontaminate eggs involve washing of egg surface with various chemicals. In this study, the effectiveness of two organic decontaminants viz., acidified sodium chlorite (ASC) and cell free culture supernatant (CFCS) of two lactic acid bacteria (Lactobacillus plantarum and Pediococcus cerevisiae) was evaluated for the decontamination of spiked Salmonella Typhimurium on chicken egg shell surface. Acidified sodium chlorite at 100 μl/L concentration with the contact time of 20 min completely inhibited S. Typhimurium on egg shell surface while at 50 μl/L concentration 1 - 2 log10 units reduction was observed in counts of S. Typhimurium as compared to control group. Likewise, CFCS of P. cerevisiae completely inhibited the growth of S. Typhimurium on 30 min contact, whereas L. plantarum and combination of both were revealed significant reduction in the counts of S. Typhimurium counts.