General model, based on two mixed weibull distributions of bacterial resistance, for describing various shapes of inactivation curves

Modeling nonlinear inactivation of hygiene indicator bacteria in pig carcasses during scalding at different pHs

This study aimed to investigate the influence of adding an alkalizing agent to the scalding water of a slaughterhouse in Brazil to inactivate hygiene indicator bacteria in pig carcasses. Scalding is critical during carcass processing because slaughterhouses' scalding water is constantly renewed; therefore, it is usually contaminated with organic matter, such as faeces and dirt from the previous carcasses. The treatments evaluated consisted of counting Enterobacteriaceae and mesophilic bacteria in pork jowls at 62 °C, 65 °C, 68 C, and 72 °C after 0.0, 1.5, 3.0, 4.5, 6.0, and 7.5 min of simulated scalding at the pHs of 7.0 (control) and 11.0 (after addition of alkalizing agent). Decimal reduction times of hygiene indicator bacteria for all treatments were estimated with different nonlinear bacterial inactivation models. As a result, adding the alkalizing agent did not significantly inactivate most of the bacteria in the studied samples. However, it contributed to the inactivation of some bacteria, mostly belonging to the mesophilic group, at some specific temperatures. The results obtained in the current study can provide useful insights into dealing with pig carcass contamination in a real-world scenario and applying the obtained information in the industrial environment.

Combined antibacterial effect of 460 nm light-emitting diode illumination and chitosan against Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes on fresh-cut melon, and the impact of combined treatment on fruit quality

This study evaluated the combined antibacterial effect of 460 nm LED illumination and chitosan on Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes on fresh-cut melon surface and its impact on the quality of melon at a total dose of 2.4 kJ/cm2 at 4 and 10 °C. Results showed that the antibacterial effect of LED illumination in combination with chitosan (0.5 and 1.0%) was much better than that of LED illumination alone, showing their synergistic effect. Among the pathogens, L. monocytogenes was the most susceptible pathogen to LED illumination. Although the color of melons became paler after LED illumination, there was little to no change in ascorbic acid content, total flavonoid content, or antioxidant capacity of the illuminated fruits compared with non-illuminated fruits. Thus, these results suggest that chitosan-mediated 460 nm LED illumination could be applied to inactivate foodborne pathogens on fresh-cut melons during storage at food establishments.

Quantitative tools in microbial and chemical risk assessment

The EU-FORA programme 'Quantitative tools in microbial and chemical risk assessment' was dedicated to training on predictive microbiology fundamentals, implementation of different modelling strategies, design of experiments and software tools such as MATLAB, GInaFiT and DMFit. The fellow performed MATLAB training on maximum specific growth rate (μmax) determination according to the Ratkowsky model. GInaFiT training on different models for bacterial inactivation and DMFit training on growth parameters of Vibrio parahaemolyticus were also carried out. Optical density measurements of V. parahaemolyticus bacterial cultures were performed. The obtained kinetics of optical density measurements were used to estimate μmax. Hereafter, Minimum inhibitory concentrations and non-inhibitory concentrations of aminoglycoside antibiotics were estimated based on the quantification of the fractional areas of the optical density vs time. It can be concluded that the results of the quantitative characterisation of V. parahaemolyticus are reliable and can be used for exposure assessments. Also, the turbidimetric assay can be applied for successful estimation of minimum inhibitory concentrations and non-inhibitory concentrations.

Quantitative tools in microbial and chemical risk assessment

The popularity of biological origin food protection substances is driven by demands from consumers for natural and clean label product, increasing various food-related safety and health concerns and sustainability issues. Lactic acid bacteria (LAB) are most promising because they are a large group of beneficial microorganisms commonly used in food protection due to their ability to inhibit the growth of pathogenic bacteria and enhance food safety. Extensive scientific research has been conducted to understand the mechanisms by which LAB exert their protective effects in various food systems. Even though LAB activity against various food pathogens and spoilers is distinguished, use of cell-free supernatant (CFS) is still under investigation. This report is dedicated to present how qualitative measures can elaborate in new bacteria-origin food additive investigation. As part of the EU-FORA programme, the fellow was involved in the risk assessment tasks and projects which include gaining basic knowledge in predicative microbiology fundamentals, including different types of modelling strategies; delivering essential understanding about experimental design, knowledge in three specific software tools (MATLAB, GInaFiT and DMFit) and gained overall understanding what are the main differences while modelling growth or inactivation models. Secondary activities were included as a way to expand competences beyond qualitative measures to overall all activities done regarding risk assessment and build a strong network of food safety experts and professionals to continue engaging in risk assessment beyond fellowship programme.

Disentangling the contributions of initial heterogeneities and dynamic stress adaptation to nonlinearities in bacterial survival curves

The deviations from log-linearity that are often observed in bacterial survivor curves can be explained using different arguments, both biological and experimental. In this study, we used Bacillus subtilis as a model organism to demonstrate that the generally accepted vitalistic arguments (initial heterogeneities in the stress resistance of the cells in the population) may fail to describe microbial inactivation in some situations. In this sense, we showed how dynamic stress acclimation during an isothermal treatment provides an alternative explanation for survivor curves with an upwards curvature. We also provided an innovative experimental approach based on preadaptation experiments to evaluate which hypothesis is more suitable for the bacterial response. Furthermore, we used our experimental results to define bounds for the possible stress acclimation that may take place during dynamic treatments, concluding that the magnitude of stress acclimation may be larger for dynamic treatments than for isothermal experiments. We also evaluated the contribution of the SigB general stress response system to heat resistance by comparing the heat survival of wt and the ΔsigB mutant. Both strains survived better in 51, 52.5 and 55 °C when cells were pre-adapted at 48 °C than non-pre-adapted cells. However, ΔsigB was less resistant to heat than wt due to the missing SigB general stress system. Although these conclusions were based on B. subtilis as a model organism, this study can be the first step towards the development of a novel methodology able to estimate dynamic effects using only isothermal experiments. This would improve the models developed within the predictive microbiology community, improving our ability to predict microbial inactivation during industrial treatments, which are most often dynamic.

High-pressure pulses for Aspergillus niger spore inactivation in a model pharmaceutical lipid emulsion

High hydrostatic pressure (HHP) is a non-thermal process widely used in the food industry to reduce microbial populations. However, rarely its effect has been assessed in products with high oil content. This study evaluated the efficacy of HHP (200, 250, and 300 MPa) at different temperatures (25, 35, and 45 °C) by cycles (1, 2, or 3) of 10 min in the inactivation of Aspergillus niger spores in a lipid emulsion. After treatments at 300 MPa for 1 cycle at 35 or 45 °C, no surviving spores were recovered. All treatments were modeled by the linear and Weibull models. The presence of shoulders and tails in the treatments at 300 MPa at 35 or 45 °C resulted in sigmoidal curves which cannot be described by the linear model, hence the Weibull + Tail, Shoulder + Log-lin + Tail, and double Weibull models were evaluated to elucidate the inactivation kinetics. The tailing formation could be related to the presence of resistance subpopulations. The double Weibull model showed better goodness of fit (RMSE <0.2) to describe the inactivation kinetics of the treatments with the higher spore reductions. HHP at 200-300 MPa and 25 °C did not reduce the Aspergillus niger spores. The combined HHP and mild temperatures (35-45 °C) favored fungal spore inactivation. Spore inactivation in lipid emulsions by HHP did not follow a linear inactivation. HHP at mild temperatures is an alternative to the thermal process in lipid emulsions.

The Attenuation of Microbial Reduction in Blueberry Fruit Following UV-LED Treatment

Ultraviolet-C (UV-C) irradiation is a well-recognized technology for improving blueberry postharvest quality, and previous literature indicates that it has the potential for dual-use as an antimicrobial intervention for this industry. However, the practicality and feasibility of deploying this technology in fresh blueberry fruit are significantly hindered by the shadowing effect occurring at the blossom-end scar of the fruit. The purpose of this study was to determine if treating the blueberry fruit within a chamber fitted with UV-Light Emitting Diodes (LEDs) emitting a peak UV-C at 275 nm could minimize this shadowing and result in improved treatment efficacy. Ten blueberry fruits were dip-inoculated with E. coli at a concentration of 10⁵ CFU/mL and irradiated within the system at doses of 0, 1.617, 3.234, 9.702, and 16.17 mJ/cm² (0, 30, 60, 180, and 300 s). Statistical analysis was performed to characterize the extent of microbial survival as well as the UV-C inactivation kinetics. A maximum of 0.91-0.95 log reduction was observed, which attenuated after 60 s of treatment. The microbial inactivation and survival were thus modeled using the Geeraerd-tail model in Microsoft Excel with the GInaFIt add-in (RMSE = 0.2862). Temperatures fluctuated between 23 ± 0.5°C and 39.5°C ± 0.5°C during treatment but did not statistically impact the treatment efficacy (P = 0.0823). The data indicate that the design of a UV-LED system may improve the antimicrobial efficacy of UV-C technology for the surface decontamination of irregularly shaped fruits, and that further optimization could facilitate its use in the industry.

A Systematic Quantitative Determination of the Antimicrobial Efficacy of Grape Seed Extract against Foodborne Bacterial Pathogens

Concerns regarding the role of antimicrobial resistance (AMR) in disease outbreaks are growing due to the excessive use of antibiotics. Moreover, consumers are demanding food products that are minimally processed and produced in a sustainable way, without the use of chemical preservatives or antibiotics. Grape seed extract (GSE) is isolated from wine industry waste and is an interesting source of natural antimicrobials, especially when aiming to increase sustainable processing. The aim of this study was to obtain a systematic understanding of the microbial inactivation efficacy/potential of GSE against Listeria monocytogenes (Gram-positive), Escherichia coli and Salmonella Typhimurium (Gram-negative) in an in vitro model system. More specifically, for L. monocytogenes, the effects of the initial inoculum concentration, bacterial growth phase and absence of the environmental stress response regulon (SigB) on the GSE microbial inactivation potential were investigated. In general, GSE was found to be highly effective at inactivating L. monocytogenes, with higher inactivation achieved for higher GSE concentrations and lower initial inoculum levels. Generally, stationary phase cells were more resistant/tolerant to GSE as compared to exponential phase cells (for the same inoculum level). Additionally, SigB appears to play an important role in the resistance of L. monocytogenes to GSE. The Gram-negative bacteria under study (E. coli and S. Typhimurium) were less susceptible to GSE as compared to L. monocytogenes. Our findings provide a quantitative and mechanistic understanding of the impact of GSE on the microbial dynamics of foodborne pathogens, assisting in the more systematic design of natural antimicrobial-based strategies for sustainable food safety.

Inactivation of Alicyclobacillus acidoterrestris spores, single or composite Escherichia coli and native microbiota in isotonic fruit-flavoured sports drinks processed by UV-C light

Pasteurized sports drinks and other fruit-based beverages are susceptible to deterioration due to thermal processing ineffectiveness to inactivate certain spoilage microorganisms, like Alicyclobacillus acidoterrestris. This represents a major challenge for the beverage industry. The goals of this study were to: i) investigate the UV-C inactivation (annular thin film unit, actinometrical delivered fluence: 795-1270 mJ/cm², 10-15 min, 20 °C, 1.8 L/h, Re_h = 391-1067, recirculation mode operation) and the evolution during refrigerated storage of A. acidoterrestris ATCC 49025 spores and single or composite Escherichia coli ATCC 25922 in isotonic sports drinks (ISDs) made from orange (orange-ISD, UVT% = 81) or orange-banana-mango-kiwi-strawberry-lemon juices (multi-fruit-ISD, UVT% = 91), compared to a turbid orange-tangerine juice (OT juice, UVT% = 40); ii) assess the effect of pH, °Brix, A_254nm, turbidity, colour and particle size of the ISDs and juice on microbial inactivation, iii) evaluate the evolution of native microbiota during cold storage, iv) investigate the Coroller, biphasic, Weibull, and Weibull-plus-tail models' ability to describe microbial inactivation and v) measure 5-hydroxymethylfurfural (HMF) formation. The modified biodosimetry method was used to calculate the germicidal UV-C fluences. Heat pasteurization (T-coil, 80 °C/6 min) was evaluated as the control treatment. UV-C was highly effective at inactivating E. coli as 4.1-5.1 and 4.5-5.6 log reductions were determined in the multi-fruit-ISD and orange-ISD, respectively, barely impacted by the background microbiota. No significant differences were recorded for the inactivation of E. coli in the UV-C and T-coil systems. Whereas, a significantly higher inactivation of A. acidoterrestris spores was achieved by UV-C (3.7-4.0 log reductions), compared to the negligible one achieved by the thermal treatment. Even though E. coli inactivation curves were similar in shape, UV-C was less effective when a cocktail of other E. coli strains was present. In comparison to the OT juice, the ISDs' inactivation kinetics were markedly different in shape, with a rapid decrease in population during the first minutes of treatment. The germicidal fluence (H_{d biod}) corresponding to A. acidoterrestris (19.1 mJ/cm²) was selected as it was higher than the one obtained for E. coli (11.0 mJ/cm²). UV-C induced 2.8- or 1.3 and 2.3- or 0.8 log-reductions of total aerobes or moulds and yeasts in the multi-fruit-ISD and orange-ISD, respectively. Compared to the other models, the Coroller and biphasic models showed a better fit and more accurate parameter estimates. UV-C-induced HMF production was not significant in the ISDs. The current study found that the UV-C treatment was more effective than typical heat pasteurization for inactivating A. acidoterrestris spores in isotonic drinks, following a similar trend for E. coli and native microbiota.

Evaluation of pathogen disinfection efficiency of electrochemical advanced oxidation to become a sustainable technology for water reuse

Water treatment and reuse is gaining acceptance as a strategy to fight against water contamination and scarcity, but it usually requires complex treatments to ensure safety. Consequently, the electrochemical advanced processes have emerged as an effective alternative for water remediation. The main objective here is to perform a systematic study that quantifies the efficiency of a laboratory-scale electrochemical system to inactivate bacteria, bacterial spores, protozoa, bacteriophages and viruses in synthetic water, as well as in urban wastewater once treated in a wetland for reuse in irrigation. A Ti|RuO₂-based plate and Si|BDD thin-film were comparatively employed as the anode, which was combined with a stainless-steel cathode in an undivided cell operating at 12 V. Despite the low resulting current density (<15 mA/cm²), both anodes demonstrated the production of oxidants in wetland effluent water. The disinfection efficiency was high for the bacteriophage MS2 (T99 in less than 7.1 min) and bacteria (T99 in about 30 min as maximum), but limited for CBV5 and TuV, spores and amoebas (T99 in more than 300 min). MS2 presented a rapid exponential inactivation regardless of the anode and bacteria showed similar sigmoidal curves, whereas human viruses, spores and amoebas resulted in linear profiles. Due the different sensitivity of microorganisms, different models must be considered to predict their inactivation kinetics. On this basis, it can be concluded that evaluating the viral inactivation from inactivation profiles determined for bacteria or some bacteriophages may be misleading. Therefore, neither bacteria nor bacteriophages are suitable models for the disinfection of water containing enteric viruses. The electrochemical treatment added as a final disinfection step enhances the inactivation of microorganisms, which could contribute to safe water reuse for irrigation. Considering the calculated low energy consumption, decentralized water treatment units powered by photovoltaic modules might be a near reality.

Chitosan enhances antibacterial efficacy of 405 nm light-emitting diode illumination against Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella spp. on fresh-cut melon

This study aimed to evaluate the influence of chitosan on the antibacterial efficacy of 405 nm LED illumination against Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes on fresh-cut melons. The antibacterial efficacy of LED illumination (a total dose of 1.3 kJ/cm²) with or without chitosan (0.5 and 1.0 %) against these three pathogens was determined at 4 and 10 °C, respectively. Non-illuminated and chitosan-treated fruits were stored in the dark for 36 h under the same temperature. Color changes, ascorbic acid content, and total flavonoid content of illuminated and non-illuminated fruits were also analyzed. The results showed that the populations of all three pathogens on the non-illuminated and chitosan-treated fruits remained unchanged during storage. Regardless of bacterial species and chitosan concentrations, LED illumination in combination with chitosan greatly reduced the bacterial populations by 1.5 - 3.5 log/cm², which was greater than LED illumination alone. Among the three pathogens, L. monocytogenes was the most susceptible to chitosan-mediated LED illumination. However, the whiteness index of illuminated fruits significantly increased by 1.3-fold compared to that of non-illuminated fruits, regardless of the presence of chitosan. Unlike color, no significant difference was observed in ascorbic acid and total flavonoid contents between illuminated and non-illuminated fruits. Although the fruit color was changed by LED illumination, these results indicate that adding chitosan could enhance the antibacterial efficacy of 405 nm LED illumination against major foodborne pathogens on fresh-cut melons without changing nutritional quality.

Comparison of microbial reduction effect of intense pulsed light according to growth stage and population density of Escherichia coli ATCC 25922 using a double Weibull model

This study evaluated how the efficacy of intense pulsed light (IPL) was influenced by biological factors such as the incubation time and the population of Escherichia coli. According to the 4D value, the microorganisms in the exponential phase were more susceptible to IPL (0.51 J/cm²), while those in the stationary phase were the most resistant (0.67 J/cm²). The microorganisms in the exponential phase could have more critical DNA damage. In addition, the degree of inactivation was affected by the microbial population. When the population was 10⁹ CFU/ml, a maximum 3.4-log reduction was observed after applying IPL at 12.5 J/cm². In contrast, a population with a density of 10¹⁰ CFU/ml showed maximally 0.13-log reduction when IPL was applied at 18.7 J/cm². This large difference might have been due to cell distribution and aggregation. The study is expected to contribute to the analytical confirmation of the microbial reduction mechanism through non-thermal technologies.

Modeling the UV-C Inactivation Kinetics and Determination of Fluence Required for Incremental Inactivation of Cronobacter spp

ABSTRACT

A study was undertaken to model the UV-C inactivation kinetics and determine the fluences required for the incremental inactivation of several strains of Cronobacter spp. suspended in clear phosphate-buffered saline (PBS). In total, 13 strains of Cronobacter spp. were individually suspended in PBS and treated with UV-C doses of 0, 2, 4, 6, 8, and 10 mJ cm-2 with a collimated beam device emitting UV-C at 253.7 nm. The log reduction from each treatment was identified using the plate count method and plotted against the UV-C dose and then curve fitted using several mathematical models. The UV-C dose required for incremental inactivation of each isolate was determined using both linear and nonlinear regression. For the 13 strains tested, a UV-C dose of 10 mJ cm-2 inactivated between 3.66 ± 0.101 and 5.04 ± 0.465 log CFU mL-1. The survival behavior of all strains was best fitted to the Weibull+tail model, with correlation coefficients between 97.17 and 99.71%, and was used to determine the fluences required for incremental inactivation. The UV-C fluences needed to inactivate 1 log (D10-value) of Cronobacter spp. in buffer were between 3.53 and 5.50 mJ cm-2, whereas a fluence greater than 6.57 mJ cm-2 was required to achieve a 4-log inactivation. A clear understanding of the UV-C dose-response of several strains of Cronobacter spp. lays the foundation to design effective UV-based disinfection systems.

HIGHLIGHTS

Novel pulsed infrared radiation: Effect on microbial, chemical, and sensory properties of saffron (Crocus sativus L.)

AIM

In this study, the effect of pulsed infrared (PIR) irradiation on saffron microbial, chemical, and sensory properties were evaluated.

METHODS AND RESULTS

The PIR power (250, 350, and 450W), the distance of sample with irradiation source (10, 20, and 30cm), irradiation time (0-20min), and PIR pulse (1, 2, and 3pulse/s) were investigated. Decontamination of total bacteria and total mold and yeast flora and microbial inactivation kinetics were determined. Saffron quality by FTIR and HPLC and sensory attributes were also measured. The highest reduction of the total bacterial count (2.203 Log₁₀ CFU/g) and total mold and yeast counts (2.194 Log₁₀ CFU/g) were obtained in Sargol Negin saffron at 350 W PIR power, 10 cm distance, 1.5 min treatment time, and 3 pulse/s. The Double Weibull model is the best-fit model for the prediction of the microbial population.

CONCLUSION

Until now, there have been no reports of application for PIR in food processing and decontamination. According to the results, it can be concluded that PIR can be used as a safe method of saffron processing.

SIGNIFICANCE AND IMPACT OF THE STUDY

Utilization of a proper decontamination method for spices especially saffron as the most expensive agricultural product is challengeable. It is recommended to use the PIR method for food processing because due to the reduction of microbial population, it can maintain foodstuff quality at an acceptable level.

Study of coliforms and Clostridium bacteria inactivation in wastewaters by a pilot photolysis process and by the maturation lagoons of a low-cost nature-based WWTP

The inactivation processes of coliform bacteria (total and fecal) and sulphito-reducing Clostridium bacteria (vegetative species and spores) in water maturation lagoon of a low-cost nature-based wastewater treatment plant using constructed wetlands and through processes of photolysis in a pilot photoreactor have been comparatively studied. The different inactivation mechanisms by photolysis of these bacteria have been studied following the criteria of different statistical and kinetic models. Clostridium disinfection treatments fit models in which two types of bacteria populations coexist, one sensitive (vegetative species) and the other (spores) resistant to the treatment, the sensitive one (94%) with an inactivation rate of k = 0.24 ± 0.07 min-1 and the resistant one (6%) with k = 0.11 ± 0.05 min-1. Total coliform photolytic disinfection also shows two populations with different physiological state. The time required to reduce the first logarithmic decimal cycle of the different types of bacteria (physiological states) are δ1 = 4.2 ± 0.9 and δ2 = 8.3 ± 1.1 min, respectively. For fecal coliform photolytic disinfection, only bacteria population, with k = 1.15 ± 0.19 min-1, is found. The results obtained confirm the photolytic disinfection processes and maturation lagoon are effective systems for Clostridia bacteria removal after water treatment by nature-based systems. Total removal of coliform bacteria is not achieved by maturation lagoons, but their reduction is significant using low doses of cumulative radiation.

Survival and inactivation kinetics of Salmonella enterica serovar Typhimurium in irradiated and natural poultry litter microcosms

The use of poultry litter as a biological soil amendment presents a risk for the preharvest contamination of fresh produce by Salmonella. In order to properly assess this risk, it is important to understand the factors influencing the persistence of Salmonella in poultry litter. This research was performed to investigate the influence of indigenous microflora on the survival of Salmonella Typhimurium in poultry litter. Microcosms of irradiated (sterilized) and natural poultry litter were inoculated with S. Typhimurium, adjusted to pH 8.0, 0.92 water activity (a_w), and stored at 30°C for 6 days. S. Typhimurium populations (log CFU g^-1) declined in both litter treatments and there were no significant differences (P > 0.05) in recovery between litter treatments on any sampling days (0 to 6). The pH of the natural litter significantly increased (P < 0.05) from 8.42 on day 0 to 9.00 on day 6. By day 6, S. Typhimurium populations in both litter treatments fell below the limit of detection (1 log CFU g^-1). The inactivation kinetics of S. Typhimurium in both litter treatments were described by the Weibull model. Under the experimental conditions (pH 8.0, 0.92 a_w, 30°C), the presence or absence of poultry litter microflora did not significantly influence the survival of S. Typhimurium. This study demonstrates that the mere presence of poultry litter microflora will not inhibit Salmonella survival. Instead, inhibitory interactions between various microorganisms in litter and Salmonella are likely dependent on more favorable environmental conditions (e.g., a_w, pH) for growth and competition.

Chlorinated cyanurates and potassium salt of peroxymonosulphate as antimicrobial and antibiofilm agents for drinking water disinfection

The understanding of microbial susceptibility to disinfectants is an important step to provide drinking water (DW) of adequate microbiological quality. In drinking water distribution systems (DWDS) the application of disinfectants is the main approach to control microorganisms. Although chlorine has been commonly used for DW treatment, the increase of microbial resistance and the production of harmful disinfection by-products promote the necessity to seek new alternatives. This study evaluated the antimicrobial activity of sodium dichloroisocyanurate (NaDCC), trichloroisocyanuric acid (TCCA), and pentapotassium bis(peroxymonosulphate) bis(sulphate) (OXONE) against two emerging pathogens isolated from DW, Acinetobacter calcoaceticus and Stenotrophomonas maltophilia. Free chlorine from calcium hypochlorite was used for comparison. The dose and time-responses against planktonic bacteria were performed as well as the assessment of the effects on membrane integrity. Moreover, the effects against 48 h-old biofilms formed on polyvinyl chloride and stainless steel were evaluated in terms of biofilm culturability and removal. Minimum bactericidal concentrations of 2.1 and 3.1 mg/L for NaDCC, 2.5 and 3.8 mg/L for TCCA, 340 and 690 mg/L for OXONE, and 0.80 and 1.0 mg/L for free chlorine alone were obtained against S. maltophilia and A. calcoaceticus, respectively. The kinetic modeling revealed that NaDCC and TCCA caused similar inactivation rates and the time for first log reduction by OXONE was less than 10 min, for both bacteria. All the disinfectants triggered significant bacterial cytoplasmic membrane destabilization, even at sub-lethal concentrations. A 30 min treatment with the disinfectants allowed a reduction in the biofilm culturability up to 5 log. OXONE was the disinfectant with the best efficiency against both bacterial biofilms. However, none of the disinfectants caused significant biofilm removal (reduction < 1 log cells/cm²). This study highlights NaDCC, TCCA, and OXONE as promising alternatives to free chlorine for DW disinfection, particularly for planktonic growth control and biofilm culturability reduction.

Antimicrobial Efficacy of Un-Ionized Ammonia (NH3) against Salmonella Typhimurium in Buffered Solutions with Variable pH, NH3 Concentrations, and Urease-Producing Bacteria

The presence of Salmonella in poultry litter, when used as a biological soil amendment, presents a risk for the preharvest contamination of fresh produce. Poultry litter is rich in organic nitrogen, and previous studies have suggested that ammonia (NH₃) in poultry litter may affect the survival of Salmonella. Salmonella enterica serovar Typhimurium was inoculated into buffer solutions to characterize the pH dependency, minimum antimicrobial concentration, and efficacy of NH₃ production. In solutions with 0.4 M total ammonia nitrogen (TAN) at various pH levels (5, 7, 8, and 9), significant inactivation of Salmonella only occurred at pH 9. Salmonella was reduced by ∼8 log CFU/mL within 12 to 18 h at 0.09, 0.18, 0.26, and 0.35 M NH₃. The minimum antimicrobial concentration tested was 0.04 M NH₃, resulting in an ∼7 log CFU/mL reduction after 24 h. Solutions with urea (1% and 2%) and urease enzymes rapidly produced NH₃, which significantly reduced Salmonella within 12 h. The urease-producing bacterium Corynebacterium urealyticum showed no antagonistic effects against Salmonella in solution. Conversely, with 1% urea added, C. urealyticum rapidly produced NH₃ in solution and significantly reduced Salmonella within 12 h. Salmonella inactivation data were nonlinear and fitted to Weibull models (Weibull, Weibull with tailing effects, and double Weibull) to describe their inactivation kinetics. These results suggest that high NH₃ levels in poultry litter may reduce the risk of contamination in this biological soil amendment. This study will guide future research on the influence of ammonia on the survival and persistence of Salmonella in poultry litter.

IMPORTANCE Poultry litter is a widely used biological soil amendment in the production of fresh produce. However, poultry litter may contain human pathogens, such as Salmonella, which introduces the risk of preharvest produce contamination in agricultural fields. Ammonia in poultry litter, produced through bacterial degradation of urea, may be detrimental to the survival of Salmonella; however, these effects are not fully understood. This study utilized aqueous buffer solutions to demonstrate that the antimicrobial efficacy of ammonia against Salmonella is dependent on alkaline pH levels, where increasing concentrations of ammonia led to more rapid inactivation. Inactivation was also demonstrated in the presence of urea and urease or urease-producing Corynebacterium urealyticum. These findings suggest that high levels of ammonia in poultry litter may reduce the risk of contamination in biological soil amendments and will guide further studies on the survival and persistence of Salmonella in poultry litter.

Combined Effect of Temperature and Relative Humidity on the Survival of Salmonella Isolates on Stainless Steel Coupons

The survival on stainless steel of ten Salmonella isolates from food factory, clinical and veterinary sources was investigated. Stainless steel coupons inoculated with Salmonella were dried and stored at a range of temperatures and relative humidity (RH) levels representing factory conditions. Viability was determined from 1 to 22 days. Survival curves obtained for most isolates and storage conditions displayed exponential inactivation described by a log-linear model. Survival was affected by environmental temperatures and RH with decimal reduction times (DRTs) ranging from <1 day to 18 days. At 25 °C/15% RH, all isolates survived at levels of 10³ to 10⁵ cfu for >22 days. Furthermore, temperatures and RH independently influenced survival on stainless steel; increasing temperatures between 10 °C and 37 °C and increasing RH levels from 30–70% both decreased the DRT values. Survival curves displaying a shoulder followed by exponential death were obtained for three isolates at 10 °C/70% RH. Inactivation kinetics for these were described by modified Weibull models, suggesting that cumulative injury occurs before cellular inactivation. This study highlights the need to control temperature and RH to limit microbial persistence in the food manufacturing environment, particularly during the factory shut-down period for cleaning when higher temperature/humidity levels could be introduced.

Pasteurization of fruit juices by pulsed light treatment: A review on the microbial safety, enzymatic stability, and kinetic approach to process design

Pulsed light (PL) is a polychromatic radiation-based technology, among many other non-thermal processing techniques. The microbiological lethality of the PL technique has been explored in different food matrices along with their associated mechanisms. Pasteurization of fruit juice requires a 5-log cycle reduction in the resistant pathogen in the product. The manufacturers look toward achieving the microbial safety and stability of the juice, while consumers demand high-quality juice. Enzymatic spoilage in fruit juice is also a crucial factor that needs attention. The retailers want the processed juice to be stable, which can be achieved by inactivating the spoilage enzymes and native microflora inside it. The present review argued about the potential of PL technology to produce a microbiologically safe and enzymatically stable fruit juice with a minimal loss in bioactive compounds in the product. Concise information of factors affecting the PL treatment (PLT), primary inactivation mechanism associated with microorganisms, enzymes, the effect of PLT on various quality attributes (microorganisms, spoilage enzymes, bioactive components, sensory properties, color), and shelf life of fruit juices has been put forward. The potential of PL integrated with other non-thermal and mild thermal technologies on the microbial safety and stability of fruit juices has been corroborated. The review also provides suggestions to the readers for designing, modeling, and optimizing the PLT and discusses the use of various primary, secondary kinetic models in detail that have been utilized for different quality parameters in juices. Finally, the challenges and future need associated with PL technology has been summarized.

Impact of factors affecting the efficacy of intense pulsed light for reducing Bacillus subtilis spores

This study investigated how the following four intense pulsed light (IPL) treatment factors affect the inactivation of Bacillus subtilis (KCCM 11,315) spores: distance between the sample and IPL lamp (8, 13, and 18 cm), pulse width (0.5, 1.3, and 2.1 ms), charging voltage (1000, 1200, and 1400 V), and processing time (10, 20, and 30 s). The results showed that all four factors considerably influenced the spore inactivation rate in different ways. Excluding processing time, which does not affect the pulse itself, the effect was largest for pulse width, followed by distance, and charging voltage. The optimal treatment condition that maximized the inactivation rate was a distance of 8 cm, a pulse width of 2.1 ms, a charging voltage of 1000 V, and a processing time of 30 s, which together produced a 6 log reduction. It revealed that individual factors need to be investigated together for achieving the optimal condition of IPL.

Sterilization of food packaging by UV-C irradiation: Is Aspergillus brasiliensis ATCC 16404 the best target microorganism for industrial bio-validations?

In food industries UV-C irradiation is used to achieve decontamination of some packaging devices, such as plastic caps or laminated foils, and of those smooth surfaces that can be directly irradiated. Since its effectiveness can be checked by microbial validation tests, some ascospore-forming molds (Aspergillus hiratsukae, Talaromyces bacillisporus, Aspergillus montevidensis, and Chaetomium globosum) were compared with one of the target microorganisms actually used in industrial bio-validations (Aspergillus brasiliensis ATCC 16404) to find the species most resistant to UV-C. Tests were carried out with an UV-C lamp (irradiance = 127 μW/cm²; emission peak = 253.7 nm) by inoculating HDPE caps with one or more layers of spores. Inactivation kinetics of each strain were studied and both the corresponding 1D-values and the number of Logarithmic Count Reductions (LCR) achieved were calculated. Our results showed the important role played by the type of inoculum (one or more layers) and by the differences in cell structure (thickness, presence of protective solutes, pigmentation, etc.) of the strains tested. With a single-layer inoculum, Chaetomium globosum showed the highest resistance to UV-C irradiation (1D-value = 100 s). With a multi-layer inoculum, Aspergillus brasiliensis ATCC 16404 was the most resistant fungus (1D-value = 188 s), even if it reached a number of logarithmic reductions that was higher than those of some ascospore-forming mycetes (Aspergillus montevidensis, Talaromyces bacillisporus) tested.

Prevalence and stability of SARS-CoV-2 RNA on Bangladeshi banknotes

Originating in December 2019 in China, SARS-CoV-2 has emerged as the deadliest pandemic in humankind's history. Along with direct contact and droplet contaminations, the possibility of infections through contaminated surfaces and fomites is investigating. This study aims to assess SARS-CoV-2 viral RNA's prevalence by real-time one-step reverse transcriptase PCR on banknotes circulating in Bangladesh. We also evaluated the persistence of the virus on banknotes spiked with SARS-CoV-2 positive diluted human nasopharyngeal samples. Among the 425 banknote samples collected from different entities, 7.29% (n = 31) were tested positive for targeted genes. Twenty-four positive representative samples were assessed for n gene fragments by conventional PCR and sequenced. All the samples that carry viral RNA belonged to the GR clade, the predominantly circulating clade in Bangladesh. In the stability test, the n gene was detected for up to 72 h on banknotes spiked with nasopharyngeal samples, and CT values increase significantly with time (p < 0.05). orf1b gene was observed to be less stable, especially on old banknotes, and usually went beyond detectable limit within 8 to 10 h. The stability of virus RNA well fitted by the Weibull model and concave curve for new banknotes and convex curve for old banknotes revealed. Handling banknotes is unavoidable; hence, these findings imply that proper hygiene practice is needed to limit SARS-CoV-2 transmission through banknotes.

Modeling Salmonella spp. inactivation in chicken meat subjected to isothermal and non-isothermal temperature profiles

Salmonella genus has foodborne pathogen species commonly involved in many outbreaks related to the consumption of chicken meat. Many studies have aimed to model bacterial inactivation as a function of the temperature. Due to the large heterogeneity of the results, a unified description of Salmonella spp. inactivation behavior is hard to establish. In the current study, by evaluating the root mean square errors, mean absolute deviation, and Akaike and Bayesian information criteria, the double Weibull model was considered the most accurate primary model to fit 61 datasets of Salmonella inactivation in chicken meat. Results can be interpreted as if the bacterial population is divided into two subpopulations consisting of one more resistant (2.3% of the total population) and one more sensitive to thermal stress (97.7% of the total population). The thermal sensitivity of the bacteria depends on the fat content of the chicken meat. From an adapted version of the Bigelow secondary model including both temperature and fat content, 90% of the Salmonella population can be inactivated after heating at 60 °C of chicken breast, thigh muscles, wings, and skin during approximately 2.5, 5.0, 9.5, and 57.4 min, respectively. The resulting model was applied to four different non-isothermal temperature profiles regarding Salmonella growth in chicken meat. Model performance for the non-isothermal profiles was evaluated by the acceptable prediction zone concept. Results showed that >80% of the predictions fell in the acceptable prediction zone when the temperature changes smoothly at temperature rates lower than 20 °C/min. Results obtained can be used in risk assessment models regarding contamination with Salmonella spp. in chicken parts with different fat contents.

Survival of Clostridioides difficile in finished dairy compost under controlled conditions

AIM

The survival of Clostridioides difficile (previously Clostridium difficile) vegetative cells and endospores was compared at different levels of indigenous microflora using autoclaved and unautoclaved dairy composts with different moisture contents (MCs).

METHODS AND RESULTS

Both types of composts adjusted to 20, 30 and 40% MCs were inoculated with a suspension of C. difficile that contained both vegetative cells (c. 5-6 log CFU per gram) and endospores (c. 5·0 CFU per gram), and then stored aerobically inside a humidity-controlled chamber at room temperature 22·5 ± 0·8°C for 1 year. The level of indigenous microflora was very stable during the storage after day 7 in both types of compost. The greatest reductions of C. difficile vegetative cell counts occurred during the first 24 h of storage in autoclaved and unautoclaved composts, which had 4·7 and 5·5 log CFU per gram with 20% MC, 1·8 and 2·1 log CFU per gram with 30% MC, and 2·3 and 1·3 log CFU per gram with 40% MC, respectively. Both MC and the duration of storage have significant (P < 0·05) effects on the survival of vegetative cells for first 120 days of storage. The slow inactivation of C. difficile vegetative cells at higher MCs during aerobic storage was confirmed by exponentially decaying modelling data during the early stage of aerobic exposure. The reduction of endospore counts (<1·0 log CFU per gram) during the storage for both types of compost at all MCs was not significant (P > 0·05) except for the autoclaved compost with 30% MC.

CONCLUSION

The highly resistant C. difficile endospores to the unfavourable environmental conditions survived for more than a year while vegetative cells died off exponentially upon the initial aerobic exposure.

SIGNIFICANCE AND IMPACT OF THE STUDY

The long-term survival of C. difficile endospores in contaminated compost may transmit the pathogen to fresh produce, animals or water in pre-harvest conditions.

Optimization of UV-C Processing of Donkey Milk: An Alternative to Pasteurization?

The effect of UV-C light technology on the inactivation of six foodborne pathogens inoculated in raw donkey milk was evaluated. Fresh raw donkey milk was artificially inoculated with the following foodborne pathogens-L. inoccua (NCTC 11288), S. aureus (NCTC 6571), B. cereus (NCTC 7464), Cronobacter sakazakii (NCTC 11467), E. coli (NCTC 9001), Salmonella enteritidis (NCTC 6676)-and then treated with UV-C doses of up to 1300 J/L. L. innocua was the most UV-C-resistant of the bacteria tested, requiring 1100 J/L for complete inactivation, while the rest of the bacteria tested was destructed in the range of 200-600 J/L. Results obtained from this study indicate that UV-C light technology has the potential to be used as a non-thermal processing method for the reduction of spoilage bacteria and foodborne pathogens that can be present in raw donkey milk.

Disentangling survival of Escherichia coli O157:H7 in soils: From a subpopulation perspective

Soil physicochemical properties and microbial community have been proved to be correlated to survival behaviors of Shiga toxin-producing Escherichia coli O157:H7, but the roles of biotic and abiotic factors in the different stages of inactivation process remain unclear. Here, fruit producing soils were collected, and soils physicochemical properties, bacterial and fungal community structure were characterized. Survival experiments were performed by inoculating E. coli O157:H7 in soils. Double Weibull survival model was found to better fit the experimental data, and two subpopulations with different capability on resistance to stress were identified. The sensitive subpopulation with smaller δ (time needed for first decimal reduction) (i.e., δ₁) died off faster compared to the more resistant subpopulation with greater δ (i.e., δ₂). Partial Mantel test revealed that ttd (time needed to reach detection limit) was jointly influenced by physical factors, chemical factors, and bacterial composition (P < 0.05); δ₁ was shaped by physical factors (P < 0.01) and additional bacterial composition (P < 0.05); and δ₂ was strongly steered by bacterial community (P < 0.001). Bacterial co-occurrence network analysis revealed that samples with lower δ₂ were coupled with higher network complexity and closer taxa relationship (e.g. higher average (weighted) degree, higher network diameter, higher graph density, and lower modularity), and vice versa. Taken together, the sensitive subpopulation had difficulty in adapting to coarse particles conditions, while resistant subpopulation might eventually succumb to the robust biodiversity. This study provides novel insights into the E. coli O157:H7 survival mechanism through subpopulation perspective and sheds light on the reduction of edaphic colonization by pathogens via agricultural management strategy.

Variability in microbial inactivation: From deterministic Bigelow model to probability distribution of single cell inactivation times

Phenotypic heterogeneity seems to be an important component leading to biological individuality and is of great importance in the case of microbial inactivation. Bacterial cells are characterized by their own resistance to stresses. This inherent stochasticity is reflected in microbial survival curve which, in this context, can be considered as cumulative probability distribution of lethal events. The objective of the present study was to present an overview on the assessment and quantification of variability in microbial inactivation originating from single cells and discuss this heterogeneity in the context of predicting microbial behavior and Risk assessment studies. The detailed knowledge of the distribution of the single cells' inactivation times can be the basis for stochastic inactivation models which, in turn, may be employed in a risk - based food safety approach.

Effect of peracetic acid on ascospore-forming molds and test microorganisms used for bio-validations of sanitizing processes in food plants

Industrial sterilization of packaging and filling machineries by peracetic acid (PAA) is a widespread practice. In our study we assessed the resistance to PAA of three ascospore-forming molds (Chaetomium globosum ATCC 6205; Talaromyces bacillisporus SSICA 10915; Aspergillus hiratsukae SSICA 3913) compared to that of Aspergillus brasiliensis ATCC 16404 and Bacillus atrophaeus DSM 675, that are currently used as test microorganisms during industrial bio-validations of food packaging and machineries. Tests were carried out at 40 °C using 1,000 mg/l of PAA, with or without a supporting material (aluminium, tin-plate, PET). At all conditions tested, a greater resistance to PAA was registered for C. globosum, followed by T. bacillisporus, A. hiratsukae, A. brasiliensis and B. atrophaeus. D-values of C. globosum varied from 23 to 68 min, whereas T. bacillisporus showed D-values from 83 to 352 s and A. hiratsukae showed D-values from 32 to 65 s. Surprisingly, both test microorganisms (A. brasiliensis and B. atrophaeus) proved less resistant than ascospore-forming molds tested, their D-values being always lower than 30 s. Cells treated without a supporting material proved more resistant than those deposited on plastic or metallic strips, with the exception of tin-plate, where results approaching those obtained without a supporting materials were obtained. Based on the results obtained in this paper, test microorganisms currently used for bio-validations in industrial plants and also heat-resistant strains proved sensibly less resistant to PAA than C. globosum. Therefore, for practical purposes C. globosum should be furtherly studied to understand if its use during bio-validations of sanitizing processes could lead to more performing results.

Effect of pilot-scale UV-C light treatment assisted by mild heat on E. coli, L. plantarum and S. cerevisiae inactivation in clear and turbid fruit juices. Storage study of surviving populations

Consumer growing demands for high-quality and safe food and beverages have stimulated the interest in alternative preservation technologies. Short-wavelength ultraviolet light (UV-C, 254 nm) has proven to be useful for the decontamination of a great variety of clear juices while improving their quality compared to traditional thermal treatments. Suspended solids and coloured compounds in turbid juices, diminish light transmission. The use of UV-C under a hurdle approach, may be a promising strategy for their treatment. The purpose of this study was to analyse Escherichia coli ATCC 25922, Saccharomyces cerevisiae KE 162 and Lactobacillus plantarum ATCC 8014 inactivation in clear pear juice (PJ), turbid orange-tangerine (OT) and orange-banana-mango-kiwi-strawberry (OBMKS) juices processed by single UV-C (390 mJ/cm², 20 °C) and UV-C assisted by mild heat (UV-C/H, 50 °C) at pilot-scale in a coiled tubing unit and stored under refrigeration (5 °C). Inactivation studies were also conducted in peptone water (PW) and model solution (MS). The adequacy of the Coroller, Weibull and Biphasic Plus Shoulder models was studied. UV-C was highly effective in PW, MS and PJ, achieving up to 5.5-6.3-4.7, 4.8-5.1-4.6 and 4.4-5.5 log reductions for L. plantarum, E. coli,and S. cerevisiae, respectively. Whereas, a moderate inactivation by single UV-C was recorded in the turbid blends, reducing up to 2.4-3.8-1.6 and 3.6-3.7-1.3 log-cycles in OT and OBMKS, respectively. When the UV-C/H treatment was applied, high bacterial inactivation was observed achieving 5.2-5.6, 6.3-6.6 and 5.5-6.7 log reductions in OT, OBMKS and PJ, respectively, while 4.6-4.9 log reductions were determined for the yeast in OBMKS and OT, respectively. Thus, additive inactivation effects between UV-C and H were observed. All the models tested gave useful information regarding the existence of microbial subpopulations with varying resistances. However, the cumulative Weibull distribution function was the most versatile one, fitting inactivation curves with different shapes. Additionally, the frequency distributions of resistances showed that UV-C/H not only increased the UV-C microbicidal effect but changed the distribution of inactivation times. Principal component analysis revealed that UV-C effectiveness was associated to low particle size, a⃰, turbidity and high UV-C transmittance. An increase on the inactivation of treated bacterial populations was recorded along storage, while no yeast recovery was observed, thus emphasizing the contribution of refrigerated storage to microbial inactivation. Microbial inactivation in clear and turbid juices achieved by UV-C (390 mJ/cm²) assisted by mild heat (50 °C) and subsequent refrigerated storage may represent an useful alternative for multiple applications in the juice industry.

Interaction between Fungal Communities, Soil Properties, and the Survival of Invading E. coli O157:H7 in Soils

Pathogens that invade into the soil cancontaminate food and water, andinfect animals and human beings. It is well documented that individual bacterial phyla are well correlated with the survival of E. coliO157 (EcO157), while the interaction betweenthe fungal communities and EcO157 survival remains largely unknown. In this study, soil samples from Tongliao, Siping, and Yanji in northeast China were collected and characterized. Total DNA was extracted for fungal and bacterial community characterization. EcO157 cells were spiked into the soils, and their survival behavior was investigated. Results showed that both fungal and bacterial communities were significantly correlated (p < 0.01) with the survival of EcO157 in soils, and the relative abundances of fungal groups (Dothideomycetes and Sordariomycetes) and some bacterial phyla (Acidobacteria, Firmicutes, gamma- and delta-Proteobacteria)weresignificantly correlated with ttds (p < 0.01). Soil pH, EC (electric conductance) salinity, and water-soluble nitrate nitrogen were significantly correlated with survival time (time to reach the detection limit, ttd) (p < 0.05). The structural equation model indicated that fungal communities could directly influence ttds, and soil properties could indirectly influence the ttds through fungal communities. The first log reduction time (δ) was mainly correlated with soil properties, while the shape parameter (p) was largely correlated with fungal communities. Our data indicated that both fungal and bacterial communities were closely correlated (p < 0.05)with the survival of EcO157 in soils, and different fungal and bacterial groups might play different roles. Fungal communities and bacterial communities explained 5.87% and 17.32% of the overall variation of survival parameters, respectively. Soil properties explained about one-third of the overall variation of survival parameters. These findings expand our current understanding of the environmental behavior of human pathogens in soils.

Modeling Salmonella Typhimurium Inactivation in Dry-Fermented Sausages: Previous Habituation in the Food Matrix Undermines UV-C Decontamination Efficacy

The effects of previous Salmonella Typhimurium habituation to an Italian-style salami concerning pathogen resistance against ultraviolet-C light (UV-C) treatment were modeled in order to establish treatment feasibility for the decontamination of dry-fermented sausage. S. Typhimurium following 24 h habituation in fermented sausage (habituated cells) or non-habituation (non-habituated cells) were exposed to increasing UV-C radiation treatment times. The Weibull model was the best fit for describing S. Typhimurium UV-C inactivation. Heterogeneity in UV-C treatment susceptibilities within the S. Typhimurium population was observed, revealing intrinsic persistence in a sub-population. UV-C radiation up to 1.50 J/cm2 was a feasible treatment for dry-fermented sausage decontamination, as the matrices retained instrumental color and lipid oxidation physiochemical characteristics. However, habituation in the sausage matrix led to a 14-fold increase in the UV-C dose required to achieve the first logarithm reduction (δ value) in S. Typhimurium population. The results indicate that, although UV-C radiation might be considered an efficient method for dry-fermented sausage decontamination, effective doses should be reconsidered in order to reach desirable food safety parameters while preserving matrix quality.

Comparative evaluation of approaches to modelling kinetics of microbial thermal death as in the case of Alicyclobacillus acidoterrestris

Microbial death kinetics modelling is an integral stage of developing the food thermal sterilisation regimes. At present, a large number of models have been developed. Their properties are usually being accepted as adequate even beyond boundaries of experimental microbiological data zone. The wide range of primary models existence implies the lack of universality of each ones. This paper presents a comparative assessment of linear and nonlinear models of microbial death kinetics during the heat treatment of the Alicyclobacillus acidoterrestris spore form. The research allowed finding that single-phase primary models (as adjustable functions) are statistically acceptable for approximation of the experimental data: linear – the Bigelow’ the Bigelow as modified by Arrhenius and the Whiting-Buchanan models; and nonlinear – the Weibull, the Fermi, the Kamau, the Membre and the Augustin models. The analysis of them established a high degree of variability for extrapolative characteristics and, as a result, a marked empirical character of adjustable functions, i.e. unsatisfactory convergence of results for different models. This is presumably conditioned by the particularity and, in some cases, phenomenology of the functions themselves. Consequently, there is no reason to believe that the heat treatment regimes, developed on the basis of any of these empirical models, are the most effective. This analysis is the first link in arguing the necessity to initiate the research aimed at developing a new methodology for determining the regimes of food thermal sterilisation based on analysis of the fundamental factors such as ones defined spore germination activation and their resistance to external impact.