Harshitha VSLP, Dutta Samit, P. Srilatha · Archives of Current Research International · 2025
Aims: This study aimed to standardize hot water and steam blanching for the processing of Spinach, assessing their effectiveness in peroxidase (POD) enzyme inactivation and their impact on key quality attributes including color, pH, total soluble solids (TSS), antioxidant activity, ascorbic acid, oxalate content and microbial quality. Study Design: A completely randomized design (CRD) was employed, utilizing one-way ANOVA and Duncan's multiple range (DMR) tests to evaluate and compare the effect of the blanching method on spinach quality. Place and Duration of Study: College of Food Processing Technology and Bioenergy, Anand Agricultural University, Anand, between March and Oct 2024. Methodology: Various hot water blanching parameters (70 °C and 90 °C for 30 s and 60 s) and steam blanching durations (60 s, 120 s, and 180 s) were tested. Peroxidase (POD) activity was analyzed to determine inactivation. Hot water at 90 °C for 30 s and steam for 180 s were identified as optimal. These optimal parameters were then used to assess their impact on various quality attributes. Results: Statistical analysis revealed that hot water blanching (90 °C, 30 s) and steam blanching (180 s) were equally effective in peroxidase (POD) inactivation, with residual activities of 9.79 ± 1.05% and 10.50 ± 0.72%, respectively. Greenness (a* value) improved from −6.51 ± 0.21 (fresh) to −9.86 ± 0.04 (hot water) and −7.15 ± 0.05 (steam). Total oxalate content decreased significantly, from 454.66 ± 45.79 mg/100 g (fresh) to 220.00 ± 44.00 mg/100 g (hot water) and 286.00 ± 22.00 mg/100 g (steam), representing a reduction of nearly 50%. Both blanching methods significantly increased pH and simultaneously reduced total soluble solids (TSS), antioxidant activity, ascorbic acid content, and microbial load. Conclusion: Blanching significantly enhanced spinach greenness and reduced anti-nutrients (oxalates) and microbial load. This study provides food processors with scientific evidence for standardizing blanching methods ensuring maximum enzyme inactivation with minimal nutrient loss, thus supporting production of minimally processed, nutrient-rich spinach products.
Cited by 0Open access
Farhad Jamali‐Hafshejani, Bahram Hosseinzadeh Samani, Kimia Taki et al. · Food Science & Nutrition · 2025
This study developed a nonthermal pasteurization method for heat-sensitive sour cherry juice using hurdle technology, combining atmospheric cold plasma (ACP) and pulsed electric field (PEF) to reduce microbial load while preserving bioactive compounds. The effects of PEF intensity (5-10 kV/cm), exposure time (5-35 s), argon-to-air ratio (0-1), and plasma jet-nozzle angle (0°-90°) on <i>Escherichia coli</i> inactivation in the ACP-PEF system were assessed. Exposure time was the dominant factor in <i>E. coli</i> reduction. Optimal conditions of PEF intensity of 10 kV/cm, 35 s exposure, 0.63 argon-to-air ratio, and 3.44° jet-nozzle angle yielded a 5.73-log <i>E. coli</i> reduction. Compared to individual PEF or ACP treatments, the combined system showed a synergistic effect, enhancing microbial inactivation. Compared to conventional thermal processing, ACP-PEF better preserved juice quality, with minimal changes in total phenolic compounds (TPC), anthocyanin content (TAC), ascorbic acid, and color indices. This integrated approach ensures effective microbial control while maintaining sour cherry juice's sensory and nutritional attributes, offering a promising alternative to traditional methods.
Cited by 4Open access
Rajka Božanić, Irena Jeličić, Mladen Brnčić et al. · SHILAP Revista de lepidopterología · 2012
Ultrasonication and thermo-sonication belong to alternative, non-thermal food processing methods. The aim of this study was to investigate the influence of different ultrasound power inputs (240 W, 320 W, 400 W) without and in combination with heat pre-treatment on microbial inactivation and sensory properties of rennet cheese whey in comparison with conventional pasteurization batch processes. Ultrasonication treatments had no impact on reduction of any group of studied microorganisms. Microbial inactivation caused by thermo-sonication treatments with pre-heating to 35 °C or 45 °C increased with nominal power input and/or exposure times and was probably due to the heat improved ultrasonic cavitation. Thermo-sonication treatments at nominal power input (400 W) and preheating to 55 °C were the most effective resulting in greater microbial reduction compared to that observed by simulating pasteurization processes, but occurred probably due to developed heat solely. Sensory properties after ultrasonication and thermo-sonication were considerably improved in comparison with that after simulated pasteurization processes. Mouth feel of whey samples was considerably better, there was no occurrence of sediment and colour remained unchanged in almost all samples.
Cited by 0Open access
Stephan Stöckel, Wilm Schumacher, Susann Meisel et al. · Applied and Environmental Microbiology · 2010
Micro-Raman spectroscopy is a fast and sensitive tool for the detection, classification, and identification of biological organisms. The vibrational spectrum inherently serves as a fingerprint of the biochemical composition of each bacterium and thus makes identification at the species level, or even the subspecies level, possible. Therefore, microorganisms in areas susceptible to bacterial contamination, e.g., clinical environments or food-processing technology, can be sensed. Within the scope of point-of-care-testing also, detection of intentionally released biosafety level 3 (BSL-3) agents, such as Bacillus anthracis endospores, or their products is attainable. However, no Raman spectroscopy-compatible inactivation method for the notoriously resistant Bacillus endospores has been elaborated so far. In this work we present an inactivation protocol for endospores that permits, on the one hand, sufficient microbial inactivation and, on the other hand, the recording of Raman spectroscopic signatures of single endospores, making species-specific identification by means of highly sophisticated chemometrical methods possible. Several physical and chemical inactivation methods were assessed, and eventually treatment with 20% formaldehyde proved to be superior to the other methods in terms of sporicidal capacity and information conservation in the Raman spectra. The latter fact has been verified by successfully using self-learning machines (such as support vector machines or artificial neural networks) to identify inactivated B. anthracis-related endospores with adequate accuracies within the range of the limited model database employed.
Cited by 53Open access
Micha Peleg · 2004
The standard methods of calculating microbial mortality and spore inactivation are based on the assumption that these processes follow a first-order kinetics. Consequently, assessment of the safety of a preservation process or of the efficacy of a disinfection method has usually been done on the basis ofD values: the time needed to reduce the number of targeted microbial cells or spores by a factor of 10. Similarly, traditional methods to establish the safety of thermal preservation processes for low-acid foods, which is mandated by regulating authorities, is based on ‘‘thermal death time’’: the time needed to reduce a population of C. botulinum spores by 12 orders ofmagnitude at a given temperature. Becausemost experimental survival data only cover five to eight orders of magnitude reduction, the thermal death time is calculated by extrapolation, assuming that a first-order inactivation kinetics holds over the entire 12-decade range. Since commercial sterilization usually involves heating and cooling and, hence, nonisothermal conditions, the degree of inactivation achieved is calculated by integration of the temporary effects over the pertinent temperature history or ‘‘profile.’’ The process lethality is assessed in terms of F0 values, calculated by (Teixeiva 1992, Jay 1996, Holdsworth 1997, Toledo 1998):F0 ¼ ðt 0Z dt ð1Þwhere Tref is a reference temperature and Z is the temperature span at which D itself is reduced by a factor of 10. Traditionally, D has been 250jF, or 121.1jC, for low-acid foods (see below).
Cited by 1
Sara Spilimbergo, Nicola Elvassore, Alberto Bertucco · Institutional Research Information System (Università degli Studi di Trento) · 2001
Abstract High-pressure treatments are receiving a great deal of attention for the inactivation of micro-organisms in foodstuff processing, pressure instead of temperature is used as stabilizing factor. In this context, high hydrostatic pressure treatment is the most studied alternative process, many works reported successful results in inactivating a wide range of micro-organisms under different operative conditions such as temperature, cycles of pressure, exposure time. Furthermore, a number of processes using high pressure treatment (HPT) has already been put into the market. Nevertheless this new technology presents the main limitation to be very expensive and difficult to control and manage because of the extremely high pressure employed, so that the widespread industrial diffusion in industry field appears cumbersome. The treatment with supercritical CO 2 could become a relevant alternative to HPT in the field of microbial inactivation of food as well as an innovative technique for the sterilization of thermally and hydrolytically sensitive polymeric materials in biomedical applications, such as polymeric particles for drug delivery or polymeric implants. It has been demonstrated that the effect of microbial inactivation assuring healthy food preservation is already consistent at pressures moderated (lower than 200 bar) when compared with those employed by traditional hydrostatic-pressure HPT methods (2000–7000 bar). In this work the anti-microbial potential of compressed CO 2 was investigated against gram-negative bacteria, gram-positive bacteria and spores; as model species, Pseudomonas aeruginosa , Bacillus subtilis and spores of B. subtilis were used. The experiments were performed in a semi-continous apparatus at different but mild operative conditions. Excellent results were obtained for micro-organisms, under appropriate conditions the survival ratio of bacteria could be reduced to about seven orders of magnitude. Inactivation of spores under the same conditions, found to be conflicting in open literature, was not satisfactory. Spore inactivation was possible by coupling combination of higher temperature and longer contact time conditions. The application of pressure cycles was also found to be beneficial.
Cited by 0
Jasjeet Kaur, Raghupathy Karthikeyan, Suresh D. Pillai · Journal of Environmental Science and Health Part A · 2015
In this study, bactericidal effects of 24 kHz ultrasound, ultraviolet (UV-C) irradiation, and titanium dioxide (TiO2) photocatalyst were studied on inactivation of Aeromonas hydrophila, an emerging pathogen listed on the US Environmental Protection Agency's (US EPA) candidate contaminant list. Metabolic activity (using the AlamarBlue dye) assays were performed to assess the residual activity of the microbial cells after the disinfection treatments along with culture-based methods. A faster inactivation rate of 1.52 log min(-1) and inactivation of 7.62 log10 was observed within 5 min of ultrasound exposure. Ultrasound treated cells repaired by 1.4 log10 in contrast to 5.3 log10 repair for UV-C treated cells. Ultrasound treatment significantly lowered the reactivation of Aeromonas hydrophila in comparison to UV-C- and UV-C-induced photocatalysis. Ultrasound appeared to be an effective means of inactivating Aeromonas hydrophila and could be used as a potential disinfection method for water and wastewater reuse.
Cited by 9
Anete Vircava, Ingus Skadiņš, Ģirts Smelters et al. · Results in Engineering · 2025
• New “effort” metric enables holistic optimization of HHP sterilization • Closed-loop ML simulations integrate data for efficient HHP process modeling • Optimized multi-pulsed HHP achieves sufficient microbial inactivation High hydrostatic pressure (HHP) is a nonthermal sterilization method with strong potential for application in liquid and gel-like materials. Compared with conventional heat- or chemical-based approaches, it offers the advantage of preserving material integrity while reducing energy consumption. In this study, we combined machine learning (ML) with sequential experimentation to optimize the key parameters of HHP treatment (pressure, holding time, and number of cycles) and introduced a new output descriptor, termed effort , which integrates these variables into a single measure of process efficiency. The experiments demonstrated that complete inactivation of Escherichia coli could be achieved at 200 MPa for 10 minutes with four pressure cycles, providing the same level of sterilization as 300 MPa with a single cycle, but requiring approximately 25–30% less energy. Energy analyses further revealed that increasing the pressure from 200 to 300 MPa raised energy consumption by about 70%, whereas applying multiple cycles at lower pressures achieved an equivalent level of microbial reduction with substantially lower resource use. By integrating Random Forest modeling with Monte Carlo simulations, we identified parameter regions (≥200 MPa, 2–4 cycles, 5–10 min) that consistently combined substantial microbial inactivation with low effort. This approach reduced the number of experiments needed by more than half compared with traditional trial-and-error methods. In summary, the results demonstrate that ML/DoE-integrated optimization of HHP enables reliable bacterial inactivation under milder conditions and with significantly reduced energy demand. The proposed framework, therefore, provides a practical pathway toward more efficient and sustainable sterilization processes, particularly for sensitive biomaterials.
Cited by 0Open access
Gary Amy, Christopher J. Douville, B. Daw et al. · Water Science & Technology · 2000
Ozonation has emerged as the most effective disinfectant for inactivation of Cryptosporidium, the controlling microorganism in drinking water treatment. However, ozonation of waters containing bromide also produces bromate ion, a regulated DBP, leading to possible tradeoffs between microbial and chemical risk. Since higher O3 doses will be necessary, even relatively low-bromide waters may become problematical. Whileeffective disinfection cannot be compromised, there are methods for controlling bromate, providing a means of reducing overall risk.
Cited by 10
Yangılar, Filiz, Oğuzhan, Pınar · DergiPark (Istanbul University) · 2015
Microbial inactivation modelling is located as an application of food preservation methods for preserved food safety and freshness. Thermal processes used for microbiological safety such as pasteurization, sterilization, drying and condensation are widespread. But, due to overheating in foods are caused loss of flavour, aroma, vitamin and textural structure in foods. Cold sterilization methods have been developed for the purpose of prevention and reduction of microorganisms in foods without spoilage the quality of the food. With this method, products are traded on at ambient temperature and thus both mentioned losses are minimized and freshness and naturality of products can be preserved. Cold plasma technique was emerged as an alternative to according to other the methods of inactivation due to advantages such as less power consumption, adversely affect the organoleptic characteristics of the product and providing a strong sterilization. In this review, the mechanism of cold plasma technique, the general properties, use of areas and the study done on this subject are given information.
Cited by 0
Peleg, Micha, Corradini, M.G. · ScholarWorks@UMassAmherst (University of Massachusetts Amherst) · 2003
AIM: To develop a method to calculate microbial survival parameters in water treated with a dissipating disinfectant and predict the inactivation patterns under different agent concentrations and decay rate regimes. METHODS AND RESULTS: It has been assumed that the survival curves of the organism, under (hypothetical) constant agent concentration conditions, follow the power law model log [N(t)/N0] = -btn with a concentration independent exponent, n. The concentration dependence of the 'rate parameter', b, has been assumed to obey a log logistic relationship. Under changing disinfectant concentration, the survival curve is constructed so that its local slope, i.e. momentary logarithmic inactivation rate of the organism, is the slope of the momentary 'constant concentration' curve at the momentary agent concentration, at the time which corresponds to the momentary survival ratio. The resulting differential equation was used to retrieve the survival parameters by numerical minimization procedures. Once these are calculated, the equation is solved numerically to produce the survival curve for almost any conceivable agent concentration history. The predictive ability of the method is demonstrated by using the survival parameters, calculated from published data obtained under one concentration profile, to predict survival curves under very different decay patterns. CONCLUSIONS: It is possible to calculate microbial survival parameters from data obtained in treatments where the unstable or volatile disinfectant progressively dissipates and use them to predict the outcome of different treatments. SIGNIFICANCE AND IMPACT OF THE STUDY: The proposed mathematical method will enable the prediction of microbial inactivation patterns in water treated with unstable and/or volatile chemical agents.
Cited by 0
Rizwan Ahmad, Mariam Tajammal, Amna Mahfooz et al. · Journal of medical & health sciences review. · 2025
Meat processing technologies play a critical role in ensuring the safety, quality and shelf-life of meat products. Traditional processing methods, including chilling, freezing, curing, smoking and thermal treatments have long been employed to reduce microbial contamination and extend storage life. However, these methods can adversely affect the sensory attributes and nutritional quality of meat. Emerging technologies such as high pressure processing (HPP), pulsed electric fields (PEF), ultrasonication, irradiation, cold plasma and ohmic heating, offer innovative approaches that can enhance microbial safety while better preserving meat quality. This review provides a comprehensive comparison of traditional and modern meat processing techniques, evaluating their effects on microbial inactivation, shelf-life extension, sensory characteristics and nutritional retention. Additionally, the review discusses the regulatory frameworks, industrial adoption challenges and future research trends associated with these technologies. By highlighting the strengths and limitations of both traditional and emerging approaches, this review aims to inform researchers, industry professionals and policymakers about optimal strategies for producing safe and high quality meat products.
Cited by 0Open access
Schijven, Jack, Pang, Liping, Ying, Guang-Guo · Figshare · 2019
The goal of this chapter is to provide the readers with useful information that can help with evaluating the microbial contamination risk of groundwater from faecal sources, determining safe setback distances and selecting suitable sites for wastewater reclamation. <br>Estimating microbial contamination risk in groundwater from faecal wastewater disposals requires knowledge of faecal pathogen loading, microbial attenuation in subsurface media and their transport pathways, which are the essential information required for Quantitative Microbial Risk Assessment (QMRA).<br>The chapter will outline the available indicators, surrogates, mathematical models, laboratory and field methods that are used for evaluating microbial subsurface transport, and summarise the current knowledge on the capacity of subsurface media in attenuating microbial contaminants. The usefulness and limitations of the exiting tools will be discussed to guild the end-users to find the right decisions about management, treatment and monitoring.<br>A number of useful tracers (salts, dyes, DNAs and emerging chemical tracers) for establishing flow connection, identifying and tracking the sources/pathways of faecal contamination in groundwater are described. Microbial tracers, microspheres and novel “micro mimics” (biomolecule-modified particles) to determine microbial attenuation and transport in porous media are discussed. Information on their applicability and representativeness are given, including their enumerable concentration range by detection methods. <br>Mathematical models are given to describe processes involved in microbial transport in subsurface media, including advection, dispersion, degradation (persistence/inactivation), attachment, detachment, straining and colloidal associated transport.<br>Laboratory methods are described for characterising the physiochemical properties of (bio)colloids, soil and aquifer media, determining microbial inactivation rates using incubation tests, examining particle attachment/detachment between water-solid interface in batch tests, and studying mechanisms and processes of microbial transport in porous media using column experiments. Relative attenuation of pathogens, indicators and surrogates determined from column studies in various porous media is summarised. <br>Field studies of microbial transport are discussed in investigating the impacts of preferential flow and heterogeneity of porous medium and (bio)colloid properties on microbial transport. This is followed by a summary of microbial removal rates and transport parameter values derived from field studies using indicators, surrogates and pathogens in soils, vadose zones, and groundwater (with links to other chapters). Based on microbial removal rates derived from field studies, suitable sites for wastewater reclamation are recommended. <br>One section presents model tools for calculation of protection zones/setback distances and for including river bank filtration (RBF) as part of QMRA. For RBF these tools are QMRAspot and QMRAcatch. <br>Finally, a selection of field studies covering developing and developed countries are described. These studies encompass relatively homogenous fine-grain aquifers (sandy aquifers) and heterogeneous aquifers (alluvial sandy gravels, karst, fractured rocks), focusing on cases of groundwater contamination by wastewater disposals.
Cited by 0Open access
Schijven, Jack, Pang, Liping, Ying, Guang-Guo · ESR Data and information Repository · 2019
The goal of this chapter is to provide the readers with useful information that can help with evaluating the microbial contamination risk of groundwater from faecal sources, determining safe setback distances and selecting suitable sites for wastewater reclamation. <br>Estimating microbial contamination risk in groundwater from faecal wastewater disposals requires knowledge of faecal pathogen loading, microbial attenuation in subsurface media and their transport pathways, which are the essential information required for Quantitative Microbial Risk Assessment (QMRA).<br>The chapter will outline the available indicators, surrogates, mathematical models, laboratory and field methods that are used for evaluating microbial subsurface transport, and summarise the current knowledge on the capacity of subsurface media in attenuating microbial contaminants. The usefulness and limitations of the exiting tools will be discussed to guild the end-users to find the right decisions about management, treatment and monitoring.<br>A number of useful tracers (salts, dyes, DNAs and emerging chemical tracers) for establishing flow connection, identifying and tracking the sources/pathways of faecal contamination in groundwater are described. Microbial tracers, microspheres and novel “micro mimics” (biomolecule-modified particles) to determine microbial attenuation and transport in porous media are discussed. Information on their applicability and representativeness are given, including their enumerable concentration range by detection methods. <br>Mathematical models are given to describe processes involved in microbial transport in subsurface media, including advection, dispersion, degradation (persistence/inactivation), attachment, detachment, straining and colloidal associated transport.<br>Laboratory methods are described for characterising the physiochemical properties of (bio)colloids, soil and aquifer media, determining microbial inactivation rates using incubation tests, examining particle attachment/detachment between water-solid interface in batch tests, and studying mechanisms and processes of microbial transport in porous media using column experiments. Relative attenuation of pathogens, indicators and surrogates determined from column studies in various porous media is summarised. <br>Field studies of microbial transport are discussed in investigating the impacts of preferential flow and heterogeneity of porous medium and (bio)colloid properties on microbial transport. This is followed by a summary of microbial removal rates and transport parameter values derived from field studies using indicators, surrogates and pathogens in soils, vadose zones, and groundwater (with links to other chapters). Based on microbial removal rates derived from field studies, suitable sites for wastewater reclamation are recommended. <br>One section presents model tools for calculation of protection zones/setback distances and for including river bank filtration (RBF) as part of QMRA. For RBF these tools are QMRAspot and QMRAcatch. <br>Finally, a selection of field studies covering developing and developed countries are described. These studies encompass relatively homogenous fine-grain aquifers (sandy aquifers) and heterogeneous aquifers (alluvial sandy gravels, karst, fractured rocks), focusing on cases of groundwater contamination by wastewater disposals.
Cited by 0Open access
T.A. Brinley, C.N. Dock, Vinh-Hien Truong et al. · Journal of Food Science · 2007
Continuous-flow microwave heating has potential in aseptic processing of various food products, including purees from sweetpotatoes and other vegetables. Establishing the feasibility of a new processing technology for achieving commercial sterility requires evaluating microbial inactivation. This study aimed to assess the feasibility of using commercially available plastic pouches of bioindicators containing spores of Geobacillius stearothermophilus ATCC 7953 and Bacillus subtilis ATCC 35021 for evaluating the degree of microbial inactivation achieved in vegetable purees processed in a continuous-flow microwave heating unit. Sweetpotato puree seeded with the bioindicators was subjected to 3 levels of processing based on the fastest particles: undertarget process (F(0) approximately 0.65), target process (F(0) approximately 2.8), and overtarget process (F(0) approximately 10.10). After initial experiments, we found it was necessary to engineer a setup with 2 removable tubes connected to the continuous-flow microwave system to facilitate the injection of indicators into the unit without interrupting the puree flow. Using this approach, 60% of the indicators injected into the system could be recovered postprocess. Spore survival after processing, as evaluated by use of growth indicator dyes and standard plating methods, verified inactivation of the spores in sweetpotato puree. The log reduction results for B. subtilis were equivalent to the predesigned degrees of sterilization (F(0)). This study presents the first report suggesting that bioindicators such as the flexible, food-grade plastic pouches can be used for microbial validation of commercial sterilization in aseptic processing of foods using a continuous-flow microwave system.
Cited by 20
D. T Ruong · 2007
Continuous-flow microwave heating has potential in aseptic processing of various food products, includ- ing purees from sweetpotatoes and other vegetables. Establishing the feasibility of a new processing technology for achieving commercial sterility requires evaluating microbial inactivation. This study aimed to assess the feasibility of using commercially available plastic pouches of bioindicators containing spores of Geobacillius stearothermophilus ATCC 7953 and Bacillus subtilis ATCC 35021 for evaluating the degree of microbial inactivation achieved in vegetable purees processed in a continuous-flow microwave heating unit. Sweetpotato puree seeded with the bioindicators was subjected to 3 levels of processing based on the fastest particles: undertarget process (F 0 approximately 0.65), target process (F 0 approximately 2.8), and overtarget process (F 0 approximately 10.10). After initial experiments, we found it was necessary to engineer a setup with 2 removable tubes connected to the continuous-flow microwave system to facilitate the injection of indicators into the unit without interrupting the puree flow. Using this approach, 60% of the indicators injected into the system could be recovered postprocess. Spore survival after processing, as evaluated by use of growth indicator dyes and standard plating methods, verified inactivation of the spores in sweetpotato puree. The log reduction results for B. subtilis were equivalent to the predesigned degrees of sterilization (F 0). This study presents the first report suggesting that bioindicators such as the flexible, food-grade plastic pouches can be used for microbial validation of commercial sterilization in aseptic processing of foods using a continuous-flow microwave system.
Cited by 0
Alberto Garre, M.H. Zwietering, Heidy M.W. den Besten · International Journal of Food Microbiology · 2022
Meta-regression models have gained in popularity during the last years as a way to create more generic models for Microbial Risk Assessments that also include variability. However, as with most meta-analyses and empirical models, systematic biases in the data can result in inaccurate models. In this article, we define experimental bias as a type of selection bias due to the practical limitations of microbial inactivation experiments. Conditions with extremely high D-values (i.e. slow inactivation) need very long experimental runs to cause significant reductions. On the other hand, when the D-value is extremely low, not enough data points can be gathered before the microbial population is below the detection limit. Consequently, experimental designs favour conditions within a practical experimental range, introducing a selection bias in the D-values. We demonstrate the impact of experimental bias in meta-regression models using numerical simulations. Models fitted to data with experimental bias overestimated the z-value and underestimated variability. We propose a rapid heuristic method to identify experimental bias in datasets, and we propose truncated regression to mitigate its impact in meta-regression models. Both methods were validated using simulated data. Thereafter the procedures were tested by building a meta-regression model for actual data for the inactivation of Bacillus cereus spores. We concluded that the dataset included experimental bias, and that it would cause an overestimation of the microbial resistance at high temperatures (>120 °C) for classical meta-regression models. This effect was mitigated when the model was built using truncated regression. In conclusion, we demonstrate that experimental bias could potentially result in inaccurate models for predictive microbiology. Therefore, checking for experimental bias should be a routine step in meta-regression modelling, and be included in guidelines on data analysis for meta-regression.
Cited by 12Open access
Ingrid Aguiló‐Aguayo, Lucía Plaza, Gloria Bobo et al. · 2017
Fresh apples and pears are good sources of antioxidants, fiber, and vitamin C, and for juice processors, it is of importance to maintain them during their processing and shelf life. Moreover, its microbial safety and stability should be guaranteed. For this reason, several researches have been carried out to optimize juice processing in order to avoid undesirable quality changes, increase yield production, and ensure microbial safety. In this chapter, conventional processing techniques are explained and compared to innovative technologies. The effect of novel and conventional thermal methods (pasteurization and HTST) on the nutritional content, quality-related enzymes, microbial inactivation, and organoleptic attributes is described. Innovative technologies include pulsed electric field, high hydrostatic pressure, ultrasounds, ultraviolet light-C, pulsed light, high-pressure homogenization, Ohmic heating, and the use of generally regarded as safe (GRAS) substances. Nonthermal technologies have demonstrated good results in preserving color and flavor characteristics and effectively reduced microbial loads.
Cited by 1
Gülsün Akdemir Evrendilek · 2016
The basic goal of food preservation technologies is to provide safer food products
with extended shelf life and inactivation of microorganisms or inhibition of microbial
growth. In order to inactivate microorganisms or prevent microbial growth, different preservation methods such as application of low or high temperature, reduction
of water activity, addition of preservatives, lowering pH, and modication of the
gas atmosphere in food packaging or the environment are applied (Blackburn and
McClure, 2002; Mohamed and Eissa, 2012). In most of the cases, the applied dose or
magnitude of these technologies should be very high to inactivate some microorganisms, which adversely affect the desired sensory and nutritional properties of foods.
Therefore, alternative or new technologies are in search for product commodities having the required level of microbial inactivation and good quality as well as better sensory characteristics. A new technology should have signicant impact on food quality,
while at the same time maintain the cost of technology within feasibility limits in
order to be qualied as an alternative method (Lado and Yousef, 2002; Mohamed
and Eissa, 2012). Several technologies based on the application of different forms of
energy or physical force such as pulsed electric eld (PEF), high hydrostatic pressure16.1 PEF Technology and Denition 393
16.2 PEF-Processing Systems 395
16.3 Inactivation Mechanisms of Bacteria and Enzymes 39816.3.1 Microbial and Enzyme Inactivation by PEF Processing 402
16.3.1.1 Inactivation of Microorganisms 402
16.3.1.2 Inactivation of Enzymes 42216.4 PEF Effects on Nutritional and Sensory Properties and Bioactive
Components 42216.5 Food Safety Issues of PEF-Processed Foods 430
16.6 Packaging of PEF-Processed Foods 432
16.7 Future Trends 433
References 434(HHP), ohmic heating, microwave, cold plasma, etc., have been developed that have
the capability of inactivating microorganisms at lower temperatures than typically
used in conventional heat treatments (Lado and Yousef, 2002; Mohamed and Eissa,
2012). Among the new technologies classied, nonthermal processes have gained
importance in recent years due to the increasing demand for foods with a high nutritional value and fresh-like characteristics, representing an alternative to conventional
thermal treatments, and PEF is an emerging technology that has been extensively
studied for nonthermal food processing, especially for low-viscosity, high-acidity
foods such as fruit juices and beverages and to lesser extent for milk (Garde-Cerdan
et al., 1997; Reina et al., 1998; Evrendilek et al., 2004a), yogurt drink (Evrendilek
et al., 2004b), yogurt-based products (Yeom et al., 2004), apple sauce, salad dressing,
soup (Vega-Mercado et al., 1996a,b; Mohamed and Eissa, 2012), liquid whole egg
(LWE), and liquid egg products (Martin-Belloso et al., 1997; Mohamed and Eissa,
2012; Hermawan et al., 2004).
Cited by 1
P. Sreedevi, P. Srinivasa Rao, P. Lalitha Kameswari · International Journal of Current Microbiology and Applied Sciences · 2017
The shelf-life of fresh sugarcane juice is limited due to enzymatic browning and microbial growth. Browning is caused by polyphenol oxidase (PPO) enzyme and the microbial spoilage occurs mainly due to yeasts and moulds, aerobic bacteria and coliforms. High pressure processing is one of the novel food preservation methods used as an alternative to thermal treatment. The impact of high pressure processing (HPP) conditions on physicochemical properties (colour, TSS, pH), PPO activity and microbial population of fresh sugarcane juice was studied. The samples were pressurized at 300 and 400 MPa for 10 to 25 minutes dwell time at ambient temperature (25±2 °C). At 300 MPa, the maximum of 3.3, 3.84 and 6.30 log10 cycles reduction was observed in total bacterial count, yeast & mould and coliforms respectively; whereas the numerals for those at 400 MPa were 4.44, 5.31& 6.30log10 cycles, respectively. The inactivation of PPO in sugarcane juice increased with increase in either pressure or dwell time. Maximum of 57% inactivation of PPO was obtained under 400 MPa pressure at 25 min. No significant changes (p>0.05) were observed in pH and °Brix and also the colour changes were not visually noticed (ΔE<2.5) for pressurized juice at different dwell times.
Cited by 8Open access