Effect of microwave treatment for wine microbial stabilisation: Potential use of a Weibullian mathematical model

An in-vitro pharmacokinetic model was used to study the antibacterial activity of meropenem. Strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were exposed to meropenem concentrations likely to be produced in an adult by rapid iv infusion of 3 g once a day (q24h regimen), 1.5 g twice a day (ql2h regimen) or 1 g three times a day (q8h regimen). Each of these three dosing regimens produced a rapid reduction in viable bacterial count over the first 16 h after dosing. There were no differences in the pattern of reduction in viable count with the q24h, q12h or q8h regimens with any of the three bacterial strains tested over the first 16 h. However, reduction in viable counts was poorer at 24 h with the q24h than q12h or q8h regimens. A simulation lasting 48 h of the q24h dosing regimen indicated a reduction in bacterial count below the limit of detection from the model with E. coli but not with P. aeruginosa or S. aureus. The time for which the meropenem concentration was higher than the MIC for the bacteria correlated best with the reduction in viable bacterial count at 24 h. The AUC for the bacterial time-kill curve, which may be a better measure of antibacterial efficacy, was not related to the length of time for which the concentration was above the MIC or the peak concentration/MIC ratio. The antibacterial effect of the conventional q8h dosing simulation was indistinguishable from that given by the q12h simulation, and both the q8h and q12h regimens offered minor advantages over a q24h regimen. Dosing of meropenem 12 hourly or 24 hourly in humans should be investigated.

The aim of this study was to determine the effect of pulsing chlorhexidine gluconate, at concentrations commonly used in mouthwashes, on Streptococcus sanguis biofilms and microcosm dental plaques in vitro. Biofilms were grown on bovine enamel and nutrients were supplied in the form of artificial saliva. Pulsing experiments were carried out on steady-state biofilms using 0.05 or 0.2% chlorhexidine solutions delivered twice daily for 1 min. In a separate study, the enamel discs on which the biofilms were formed were pre-treated with chlorhexidine and pulsed directly after inoculation and then at regular intervals. With both concentrations of chlorhexidine used, a c.2 log10 reduction in the viable counts of S. sanguis was achieved with the initial pulse, but as pulsing continued, the bacterial population recovered, albeit not to the previous level. A c.1 log10 reduction in the total viable counts of the microcosm plaques was seen after the first pulse with 0.2% chlorhexidine. The total count then recovered rapidly and, after the fifth pulse, the total viable counts were not significantly different from those before pulsing. The total counts then remained at a similar level throughout the course of the experimental runs. Pre-treatment of the enamel discs with 0.2% chlorhexidine before inoculation produced viable counts of c.10(5) cfu/mm2, a 1 log10 reduction compared with untreated discs. After pulsing with 0.2% chlorhexidine at 8 h, a 3 log10 reduction was seen in the total aerobic and anaerobic counts, but again the viable counts subsequently increased despite twice-daily chlorhexidine pulsing. Regardless of the nature of the biofilm, pulsing initially achieved substantial kills, but the viability of the biofilms subsequently increased despite continued pulsing. Chlorhexidine was effective at reducing the viability of microcosm plaques when it was applied to the substratum before exposure to bacteria and subsequently pulsed on to the biofilms.

Poor sanitation of food contact surfaces has been a contributing factor in food borne disease outbreaks, especially those involving Listeria monocytogenes, Salmonella spp., Escherichia coli, Staphylococcus aureus etc. The objectives of this study were therefore to: 1. Determine the efficiency of a disinfectant based on chlorine dioxide in suspension in a closed system in a dairy plant. 2. Evaluate the possibility of disinfection of working surfaces with a disinfectant based on chlorine dioxide. In order to determine the germicidal effect of the disinfectant based on chlorine dioxide by suspension test (BSEN 1276:1997); the following test organisms were used: Listeria monocytogenes, Proteus mirabilis, Escherichia coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa clinical isolate. The corrosive properties of the disinfectant based on chlorine dioxide were tested by IDF 077:1977 standard. The efficacy of this disinfectant was investigated in a closed system in a dairy plant. Results indicated a 100% reduction of >108 cfu/ml L. monocytogenes, E. coli, Proteus mirabilis, Pseudomonas aeruginosa, S. aureus, viable count after 1 minute of exposure to 100 ppm of the disinfectant based on chlorine dioxide and 400 ppm for Bacillus cereus. In the presence of 2% skim milk and 4 % skim milk concentrations of 200 and 250 ppm resulted in 100% reduction in numbers of the five of six test microorganisms, respectively. The spore former, Bacillus cereus is less susceptible to the disinfectant. Therefore, the efficient concentration for 100% reduction in viable count after 1 minute exposure was 500 ppm. The corrosive properties of the disinfectant were not determined. In the case of closed system disinfection in a dairy plant, reduction in viable count after 15 minute exposure to 100 ppm of disinfectant based on chlorine dioxide ranged from 80 to 100%.

Synergistic effect of UV, laser and microwave radiation or conventional heating on E. coli and on some spoilage and pathogenic bacteria

Inactivation of bacterial and viral fish pathogens by ozonation or UV irradiation in water of different salinity

Use of Nisin and Microwave Treatment Reduces Clostridium sporogenes Outgrowth in Precooked Vacuum-Packaged Beef

Personalized nutrition aims to optimize health by addressing interindividual differences in metabolism, microbiota composition, and dietary responses. Modulating the gut microbiota through probiotics, prebiotics, and synbiotics is promising, yet conventional systems such as capsules or fermented foods offer limited control over dosage, release kinetics, and microbial viability. These formats often cause 2–4 log reductions in viable counts during processing and gastrointestinal transit, underscoring the need for advanced delivery technologies. Three-dimensional (3D) food printing enables digital design of edible matrices with programmable geometry and composition to enhance microbial protection and controlled release. Coaxial and gel-in-gel architectures have retained over 90–96% of probiotic cells after printing and 80–85% after simulated digestion. Synbiotic formulations combining probiotics with fructooligosaccharides or whey protein achieve 98–99% survival and stability for 35 days. This review summarizes advances in formulation, encapsulation, and printing strategies, highlighting how 3D food printing uniquely overcomes challenges of viability, release control, and personalized dosage in microbiota-based nutrition.

PurposeThe purpose of this paper is to evaluate effects of simultaneous supplementation of milk protein concentrate (MPC) as texture modifier and microencapsulated Lactobacillus paracasei (L. paracasei) (entrapped in gellan–caseinate) on physico-chemical, sensorial and microbial characteristics of yogurt during storage time.Design/methodology/approachL. paracasei cells were encapsulated through unique pH triggered gelation technique using combination of sodium caseinate-gellan gum as protective shell material. MPC was also used to improve physico-chemical indices of probiotic yogurt at different levels (0–3 percent).FindingsThe results showed that yogurt samples containing encapsulated L. paracasei showed lower post-acidification and higher viability. Samples containing encapsulated L. paracasei showed less syneresis amount, due to possible hydration of shell material, also application of MPC could reduce this attribute during storage time. The numbers of probiotic bacteria were remained above the recommended therapeutic minimum throughout the samples.Practical implicationsThe findings suggest a practical ingredient in probiotic dairy product. Simultaneous usage of this kind of encapsulation via MPC enhanced sensorial and physical properties of probiotic yogurt while of no reduction in viable counts survival.Originality/valueThis study revealed usage of microcapsules of L. paracasei prepared by the gelation of sodium caseinate-gellan gum could be a suitable manner for delivery of probiotics in fermented dairy products like yogurt.

Environmental factors influencing the inactivation of Cronobacter sakazakii by high hydrostatic pressure

To evaluate the behavior of the relevant microbial populations during stretched cheese production, quantitative microbiological analysis was performed during the critical steps of the preparation. The obtained data distributions proved statistically significant increases in all indicators, on average by 4.55 ± 0.64 log CFU/g of presumptive lactococci counts, 4.06 ± 0.61 of lactobacilli, 1.53 ± 0.57 log CFU/g of coliforms, 2.42 ± 0.67 log CFU/g of Escherichia coli, 1.53 ± 0.75 log CFU/g of yeasts and molds, and 0.99 ± 0.27 log CFU/g of presumptive Staphylococcus aureus, from the early stage of milk coagulation until curd ripening (0–24 h). The following steaming/stretching process caused reductions in viable counts with the most significant inactivation effect on coliform bacteria, including E. coli (−4.0 ± 1.0 log CFU/g). Total viable counts and yeasts and molds showed 2 and almost 3 log reduction (−2.2 ± 1.1 log CFU/g and −2.6 ± 0.9 log CFU/g), respectively. The lowest decreases in presumptive S. aureus counts were estimated at the level of −1.50 ± 0.64 log CFU/g. The counts of yeasts and molds showed the best indicatory function during the entire storage period of vacuum-packaged cheeses at 6 °C.

Nisin Reduces the Thermal Resistance of Listeria monocytogenes Scott A in Liquid Whole Egg

Phototoxic effect of hypericin alone and in combination with acetylcysteine on Staphylococcus aureus biofilms

An in vitro dilutional pharmacokinetic model of infection was used to study the pharmacodynamics of doripenem in terms of the ability to kill Pseudomonas aeruginosa or Acinetobacter baumannii and also changes in their population profiles. In dose-ranging studies, the cumulative percentages of a 24-h period that the drug concentration exceeds the MIC under steady-state pharmacokinetic conditions (T(MIC)s) required for doripenem to produce a 24-h bacteriostatic effect and a -2-log-unit reduction in viable count were 25% ± 11% and 35% ± 13%, respectively, for P. aeruginosa (MIC range, 0.24 to 3 mg/liter) and 20% ± 11% and 33% ± 12%, respectively, for Acinetobacter spp. (MIC range, 0.45 to 3.0 mg/liter). A T(MIC) of >40 to 50% produced a maximum response with both species at 24 h or 48 h of exposure. After 24 h of exposure to doripenem at a T(MIC) in the range of 12.5 to 37.5%, P. aeruginosa and A. baumannii population profiles revealed mutants able to grow on 4× MIC-containing medium; such changes were further amplified by 48 h of exposure. Dose-fractionation experiments targeting T(MIC)s of 12.5%, 25%, or 37.5% as six exposures, two exposures, or a single exposure over 48 h with a single strain of P. aeruginosa indicated that changes in population profiles were greatest with multiple exposures at T(MIC) targets of 12.5 or 25%. In contrast, multiple exposures at 37.5% T(MIC) most effectively suppressed total bacterial counts and changes in population profiles. Simulations of human doses of doripenem of 500 mg, 1,000 mg, 2,000 mg, and 3,000 mg every 8 h over 96 h showed marked initial killing up to 6 h but growback thereafter. Changes in population profiles occurred only in the regimen of 500 mg every 8 h against P. aeruginosa but occurred with all dose regimens for A. baumannii strains. A doripenem T(MIC) of ≥40 to 50% is maximally effective in killing P. aeruginosa or A. baumannii and suppressing changes in population profiles in short-term experiments for up to 48 h; however, a T(MIC) of 12.5 to 25% amplifies population changes, especially with exposures every 8 h. In longer-term experiments, up to 96 h, even doripenem doses of 4 to 6 times those used in human studies proved incapable of pathogen eradication and prevention of changes in population profiles. The association of a T(MIC) of 25 to 37.5% with changes in population profiles has implications in terms of future clinical breakpoint setting.

The aim of this study was to determine the effect of household bleach, a sodium dichloroisocyanurate (NaDCC)-based disinfectant and an eco-friendly cleaning agent (EFCA) on four Staphylococcus aureus strains, including two isolated from community infections. The products were assessed using the suspension (EN 1276) and surface (EN 13697) tests, while biofilm activity was determined using the 96-well plate method. Bleach and NaDCC caused > 5 log reduction in viable counts within 5 min in suspension, whilst on surfaces the reduction was < 3 log. Bleach at 5000 ppm free available chlorine completely eradicated MSSA NCTC 13297 and PVL CA MSSA biofilms within 10 min, but not at 500 and 50 ppm, NaDCC was less effective against biofilms. The EFCA demonstrated no antimicrobial activity. It is of concern that at the recommended “use” dilution, bleach did not eradicate biofilms. Although increasing contact time and/or concentration should improve the activity, this may not be acceptable to the user.

Fungistatic data were obtained from measurements of mycelial growth of several fungal species in the presence of acid or alkaline glutaraldehyde. Alkaline glutaraldehyde in concentrations &gt; 0·1% (w/v) prevented growth of all species examined while 0·5% (w/v) acid glutaraldehyde was necessary to achieve this effect. Further fungistatic data were obtained using a Coulter Counter method to measure spore swelling. Fungicidal determinations resulted in a 99·99% reduction in viable count after 90 min contact with 0·5% (w/v) alkaline glutaraldehyde. A considerable drop in spore production was also observed after treatment with alkaline glutaraldehyde.