Preventing toxin formation by proteolytic Clostridium botulinum is critical for food safety but remains a challenge for example when developing or reformulating various products including sodium-reduced or nitrite-free foods. Validated predictive food microbiology models can support this process by identifying combinations of product characteristics and storage conditions that prevent growth and toxin formation. An existing cardinal parameter growth and growth boundary model (Koukou et al., 2022b), including the effect of 11 environmental factors and their interactions, was extended to predict time-to-toxicity (TTT) for proteolytic C. botulinum. Data from 962 published TTT experiments were compiled to evaluate performance for different versions of this model. Product characteristics, storage conditions and TTT were collected for meat, poultry, vegetables, seafood, dough, processed cheese, other cheeses and uncategorized foods. These data, with 648 TTT positive and 314 TTT negative, covered a wide range of environmental factors and included responses for 138 proteolytic C. botulinum strains. Model performance was evaluated using percentages of fail-dangerous, fail-safe and correct predictions along with bias and accuracy factors for predicted and observed TTT. Model performance was markedly different for non-dairy and dairy foods. For non-dairy foods and within a wide range of applicability, including 494 TTT-responses, the new and extensive Koukou-TTT-model had 0.2% fail-dangerous TTT predictions and bias/accuracy factors of 0.53/2.5. For dairy products (n = 312), including processed and other cheeses, the Koukou-TTT-model provided 26.0% fail-dangerous TTT predictions. This unacceptable model performance was primarily due to calcium complexation with citric and lactic acids which reduced the inhibiting effect of these organic acids in the studied dairy foods. The Koukou-TTT-model was modified to predict the effect of total, rather than undissociated, concentrations of citric and lactic acids in dairy foods. This modified model predicted 144 TTT-responses with 0.0% fail-dangerous TTT predictions and bias/accuracy factors of 0.37/4.42. The original and the modified growth and growth boundary Koukou-models can be used, within defined and wide ranges of applicability, to determine combinations of product characteristics and storage conditions where growth and TTT for proteolytic C. botulinum are prevented in meat, poultry, vegetables, seafood, dough and dairy products.

Listeriosis cases continue to rise due to Listeria monocytogenes contaminated ready-to-eat foods. Recent studies show that L. monocytogenes persistence in food processing environments is poorly explained by biocide tolerance but strongly linked to biofilm, equipment design, and repeated introduction from raw materials. Daily cleaning and sanitation practices can reset levels but cannot be relied on to eliminate the bacterium. Producers can in some cases control L. monocytogenes through in-package inactivation, e.g., by heat. However, for many products, efficient L. monocytogenes management can be achieved by adjusting preservation methods and/or shelf-life. Design of suitable approaches to stabilize products against listerial growth is now facilitated by validated predictive models and software. We suggest a voluntary label to communicate the safety of stabilized products to consumers. To decrease future outbreaks, implicated products should be characterized and evaluated using validated predictive models to adjust declared shelf-life and/or preservation to avoid unacceptable L. monocytogenes growth.

The aims of this study were firstly, to determine if the removal of heads and storage in a modified atmosphere (MA) extended the sensory shelf-life of chilled shell-on cooked Northern shrimp (Pandalus borealis). Secondly, the safe shelf-life of products was determined in regard to Listeria monocytogenes. Shrimp were kept whole or as tails (head region removed) at 5°C in laminar-film-bags with or without MA (40% CO2/60% N2) for 21 days. Analyses included changes in sensory properties (shelf-life), headspace CO2/O2, drip loss, pH, microbiota, total volatile nitrogen (TVN), trimethylamine-oxide (TMAO), and trimethylamine (TMA). Shrimp tails stored in MA reached the end-of-sensory-shelf-life after 21 days, followed by 18 days for whole shrimp in MA, and 14 and 11 days, respectively, for shrimp tails and whole shrimp without MA. For all four treatments, aerobic plate counts reached >8 log CFU/g at the time of sensory spoilage with Carnobacterium spp. and Pseudoalteromonas spp. dominating for shrimp with or without MA, respectively. Sensory spoilage coincided with TVN levels of 32–41 mg-N/100 g for shrimp in MA, while higher levels (66–143 mg-N/100 g) were observed for shrimp without MA. Pseudoalteromonas spp. had the strongest spoilage potential and likely contributed to the observed conversion of TMAO to TMA in shrimp stored without MA. Safe shelf-life was studied by testing the growth rate of L. monocytogenes, and the applicability of existing models to predict its growth. At 2°C–15°C, L. monocytogenes grew faster in whole shrimp than in shrimp meat. Moreover, the studied predictive model slightly underestimated growth of the pathogen. Taken together, our results show that to avoid unacceptable growth of L. monocytogenes, the safe shelf-life should be limited to less than 10 days at 5°C in MA for these ready-to-eat, cooked shell-on Northern shrimp products. Extension of product shelf-life would require research into stabilization of the products to inhibit the growth of L. monocytogenes.

Performance was evaluated for two extensive models to predict growth and growth boundaries of mesophilic and psychrotolerant Bacillus cereus in dairy products. Both models incorporated the inhibitory effect of 11 environmental factors and of their interactions. The two models were calibrated and evaluated using data from 66 and 67 new challenge tests, respectively, conducted with various types of well-characterized dairy products. Additionally, the mesophilic model was evaluated using 139 growth responses from literature (growth/no-growth, lag time, and μmax values) for 24 different B. cereus strains. The psychrotolerant model was evaluated using 109 growth responses from published studies and including data for 26 strains in dairy products. The predictive performance of the evaluated models was compared with four existing models for mesophilic B. cereus and four different models for psychrotolerant B. cereus. The new mesophilic model had good performance and predicted growth responses in new challenge tests, with bias-/accuracy-factor values of 1.13/1.49 and 80% correct, 17% fail-safe, and 3% fail-dangerous growth/no-growth predictions. With literature data for mesophilic B. cereus, predictions were good with bias-/accuracy-factor values of 0.97/1.36 and 91% correct, 9% fail-safe, and 0% fail-dangerous predictions. The evaluated psychrotolerant model also exhibited good performance in predicting growth responses for new challenge tests, with bias-/accuracy-factor values of 1.07/1.38 and 84% correct, 14% fail-safe, and 2% fail-dangerous predictions for growth/no-growth responses. With literature data for psychrotolerant B. cereus, this model did not acceptably predict growth rates at temperatures <10°C. Therefore, the temperature term of the model was expanded at temperatures from 1°C to 10°C. The performance of the updated psychrotolerant model was markedly improved, achieving bias-/accuracy-factor of 1.07/1.80, and 91% correct, 9% fail-safe, and 0% fail-dangerous predictions. The two new and extensive models offer significant advantages over existing models by including the growth inhibiting effects of more environmental factors and their interactions, resulting in un-biased predictions for a wider range of dairy matrices. These validated models can support management of mesophilic and psychrotolerant B. cereus growth in diverse dairy products, contribute to risk assessments and to optimization of combinations of relevant growth-inhibitory factors during product formulation and innovation.

Malta produces approximately 15,000 tons of bluefin tuna every year and by-products are estimated to account for 55% of the harvest. Maltese tuna farmers established a company that processes these by-products into fish meal and oil that are sold to the pet food industry. In this study, the logistic of tuna farming and management in Malta was analysed and the environmental impact of the activity was estimated. The biomass quality and the preservation state of tuna head and liver were assessed. The head had the highest ash content (1.68 f 0.02%) while the liver had the highest protein content (16.18 f 0.02%) and the highest crude fat, (34.87 f 0.76%). The highest concentration of oil was found in the head's skin (50.07 f 0.84%). The predominant saturated fatty acids (SFAs) were c14:0, c16:0, and c18:0. Monounsaturated FAs (MUFAs) were the major fatty acids present in all samples, with the highest values in the tuna head. The oxidation levels found in the by-products upon arrival at the processing plant don't compromise their quality. No histamine formation was predicted. The Life Cycle Assessment estimated that the environmental score of the activity is 105 points per ton of fishmeal and 25 kg of oil produced (2.82 tCO2 eq). It is concluded that the processing of tuna by-products in Malta is a sustainable alternative to traditional disposal methods and their quality is high enough to be used as a source of proteins and lipids in farmed-animals feed.

Guidelines for combinations of product characteristics to prevent unacceptable growth of Bacillus cereus in foods are lacking, and models are therefore valuable for predicting these responses. B. cereus isolates of dairy origin were used to generate a comprehensive dataset to develop two cardinal parameter growth and growth boundary models for mesophilic and psychrotolerant B. cereus, respectively. Each model incorporated the inhibitory effect of 11 environmental factors, i.e., temperature, pH, NaCl/aw, organic acids (acetic, benzoic, citric, lactic, and sorbic), phosphate salts (orthophosphate, diphosphate, and triphosphate), and the effect of interactions between these factors. Cardinal parameter values for mesophilic and psychrotolerant strain cocktails were estimated using 231 and 203 maximum specific growth rates (μmax values), respectively, generated in a standard liquid laboratory medium (BHI broth). Furthermore, an additional 113 and 100 μmax values were generated for the two strain cocktails using a dairy-specific liquid medium (an ultra-filtration permeate from whey) to evaluate growth responses obtained in BHI broth. Cardinal parameter values for the two extensive growth boundary models were selected conservatively using data from BHI broth or UF permeate, such that the widest growth range was obtained for each environmental factor. The studied cocktail of six vegetative mesophilic B. cereus isolates exhibited greater acid tolerance in UF permeate than in BHI broth with lower pHmin (pHmin values of 4.75 versus 4.98), higher minimum inhibitory concentrations (MIC) of undissociated lactic acid (MICu,LAC of 2.99 versus 2.34 mM) and total citric acid (MICT,CAC of 169.1 versus 82.5 mM). The psychrotolerant B. cereus strain cocktail also had lower pHmin and higher values for MICLAC and MICT,CAC in UF permeate than in BHI broth. The remaining cardinal parameter values were determined from growth rates in BHI broth. The two new models can predict the combined effect of storage temperature and a wide range of dairy product characteristics, including combinations of organic acids and phosphate melting salts. These growth and growth boundary models can support the evaluation and management of the two B. cereus subgroups in various dairy products. However, product validation of the two predictive models is required to determine their performance and range of applicability.

Listeria monocytogenes presents a significant concern for the food industry due to its ability to persist in the food processing environment. One of the factors contributing to its persistence is decreased sensitivity to disinfectants. Our objective was to assess the diversity of L. monocytogenes sensitivity to food industry disinfectants by testing the response of 1,671 L. monocytogenes isolates to quaternary ammonium compounds (QACs) and 414 isolates to peracetic acid (PAA) using broth microdilution and growth curve analysis assays, respectively, and to categorize the isolates into sensitive and tolerant. A high phenotype-genotype concordance (95%) regarding tolerance to QACs was obtained by screening the genomes for the presence of QAC tolerance-associated genes bcrABC, emrE, emrC, and qacH. Based on this high concordance, we assessed the QAC genes' dissemination among publicly available L. monocytogenes genomes (n = 39,196). Overall, QAC genes were found in 23% and 28% of the L. monocytogenes collection in this study and in the global data set, respectively. bcrABC and qacH were the most prevalent genes, with bcrABC being the most detected QAC gene in the USA, while qacH dominated in Europe. No significant differences (P > 0.05) in the PAA tolerance were detected among isolates belonging to different lineages, serogroups, clonal complexes, or isolation sources, highlighting limited variation in the L. monocytogenes sensitivity to this disinfectant. The present work represents the largest testing of L. monocytogenes sensitivity to important food industry disinfectants at the phenotypic and genomic level, revealing diversity in the tolerance to QACs while all isolates showed similar sensitivity to PAA. Contamination of Listeria monocytogenes within food processing environments is of great concern to the food industry due to challenges in eradicating the isolates once they become established and persistent in the environment. Genetic markers associated with increased tolerance to certain disinfectants have been identified, which alongside other biotic and abiotic factors can favor the persistence of L. monocytogenes in the food production environment. By employing a comprehensive large-scale phenotypic testing and genomic analysis, this study significantly enhances the understanding of the L. monocytogenes tolerance to quaternary ammonium compounds (QACs) and the genetic determinants associated with the increased tolerance. We provide a global overview of the QAC genes prevalence among public L. monocytogenes sequences and their distribution among clonal complexes, isolation sources, and geographical locations. Additionally, our comprehensive screening of the peracetic acid (PAA) sensitivity shows that this disinfectant can be used in the food industry as the lack of variation in sensitivity indicates reliable effect and no apparent possibility for the emergence of tolerance.

Pandalus borealis is a commercially important wild-caught shrimp species with more than 250,000 tons/year being processed into a wide range of products. This review discusses the biology of P. borealis in relation to catch, processing and characteristics of seafood products including sensory and safe shelf-life. Biochemical, chemical, physiochemical and microbial spoilage reactions are discussed to establish (i) indices of spoilage for instrumental shelf-life determination, (ii) kinetic models for shelf-life prediction and (iii) preservation procedures for shelf-life extension. Free amino acids in P. borealis confer a unique sweet taste to products and polyunsaturated fatty acids contribute to good nutritional properties. Spoilage of frozen P. borealis products is caused by oxidation of lipids and shelf-life can be markedly extended by glazing with brines containing antioxidants. Spoilage of chilled products is due to high concentrations of bacteria and their formation of volatile amines that can be used as indices of spoilage. Developed predictive growth models facilitate design of new brined shrimp recipes with low salt and high pH to maintain desirable nutritional and flavor properties, while also inhibiting growth of Listeria monocytogenes and Clostridium botulinum during chilled storage. Future research should focus on sustainable processing and optimal use of the entire animal as food.

Pathogenic Bacillus cereus s.l. can survive cooking of starchy foods and grow at chilled storage temperatures, highlighting foods with extended chilled shelf life as a risk factor. Some food administrations encourage use of predictive microbiology to support decisions of safe shelf lives. Therefore, the present study embarked on identifying a model from literature and/or expanding an existing model to enable accurate predictions of growth and no-growth responses of relevant B. cereus s.l. in starchy ready-to-eat and ready-to-cook foods when stored at temperatures at or below 12°C. The study focused on isolates belonging to psychrotolerant or mesophilic-psychrotolerant intermediary thermotypes in panC-groups II, IV, V, or VI and generated data for growth kinetics for various pH (4.8-7.8), aw (0.935-0.999) and storage temperatures (6.0-11.7°C) in 42 starchy foods (bulgur, couscous, pasta, potatoes, rice) and eight composite foods containing at least one starchy ingredient. Using 21 of the growth kinetics obtained for starchy foods, the five best performing of 10 available growth models were selected for improvement by product calibration and/or expansion with terms to consider the effect of interactions between temperature, pH and aw. Of 410 updated models, nine showed promising performance and were evaluated using the remaining 21 growth kinetics obtained in starchy foods. Two models could be considered validated for these products with Bf /Af -values of 0.87/1.21 and 1.01/1.32, respectively. Both models provided ≥75% correct predictions of the growth/no-growth responses and did not provide any fail-dangerous predictions. Further evaluation of these models for predictions of maximum specific growth rates (μmax , h-1) and growth/no-growth responses for a broader range of starchy foods used 33 challenge tests from the scientific literature and eight challenge tests from the present study, and remarkably showed that the performance of both models was poor for composite protein-rich starchy foods with Bf -values ≤0.64 and Af -values ≥1.96, meaning these models should not be used for such products as μmax might be under-predicted creating unsafe situations. However, for other starchy foods, one of the validated models was found to be acceptable on the safe side with Bf - and Af -values of 1.34 and 1.57, respectively.

Immediately after the harvest of lumpfish (Cyclopterus lumpus) roe in artic regions, a common practice is to preserve the fresh roe in brine to produce a salted intermediate product (SIP), which can be transported and stored refrigerated for up to 1 year prior to retail processing. Because the roe is susceptible to microbial growth and lipid oxidation, the brines have been composed of mixes of salt (>10%) and benzoic acid to manage the quality and safety of the SIP. However, a demand for reducing the use of salt and benzoic acid is appearing on the European market. Therefore, the aim of this study was to evaluate the effect of five different brines comprised of combinations of salt, organic acids, and antioxidants on controlling microbial and chemical changes of the SIP, to be able to avoid the use of benzoic acid and reduce the salt content. Freshly harvested roe was mixed with brines to obtain 7 or 10% (w/w) NaCl and combinations of acetic, benzoic and/or lactic acids with or without addition of VivOx 7.5 (IFF Inc.) or Herbalox D-450 (Kalsec Inc.) as antioxidants. Brined roes were stored refrigerated (1.94°C ± 0.56°C) with sampling after 50, 80, 120, 210, 288 and 353 days. Regardless of the treatment applied, aerobic viable counts increased to >6.1 log CFU/g after 120 days of storage and the microbiota in all treatments became dominated by Debaromyces hansenii as identified using MALDI-TOF and metagenome sequencing. The addition of antioxidants reduced the formation of lipid hydroperoxides and thiobarbituric acid reactive substances. Both Herbalox and VivOx reduced the formation of 1-penten-3-ol, whereas VivOx increased the formation of pentanal in the roe. Concentrations of 2-methyl-butanol and 3-methyl-butanol were markedly reduced by treatments that included benzoic acid, which may be related to differences in the activity of the microbiota. Herbalox was more efficient than VivOx in reducing oxidative changes whereas the effect of organic acids on oxidative alterations remained inconclusive. In conclusion, it was possible to reduce the salt content and avoid the use of benzoic acid without affecting the microbial and oxidative stability of the SIP as well as its safety.

Listeria monocytogenes is an important human pathogen with a high mortality rate. Consumption of contaminated ready-to-eat food is the main mode of transmission to humans. Disinfectant-tolerant L. monocytogenes have emerged, which are believed to have increased persistence potential. Elucidating the mechanisms of L. monocytogenes disinfectant tolerance has been the focus of previous studies using pure cultures. A limitation of such approach is the difficulty to identify strains with reduced susceptibility due to inter-strain variation and the need to screen large numbers of strains and genes. In this study, we applied a novel metagenomic approach to detect genes associated with disinfectant tolerance in mixed L. monocytogenes planktonic communities. Two communities, consisting of 71 and 80 isolates each, were treated with the food industry disinfectants benzalkonium chloride (BC, 1.75 mg/L) or peracetic acid (PAA, 38 mg/L). The communities were subjected to metagenomic sequencing and differences in individual gene abundances between biocide-free control communities and biocide-treated communities were determined. A significant increase in the abundance of Listeria phageassociated genes was observed in both communities after treatment, suggesting that prophage carriage could lead to an increased disinfectant tolerance in mixed L. monocytogenes planktonic communities. In contrast, a significant decrease in the abundance of a high-copy emrC-harbouring plasmid pLmN12-0935 was observed in both communities after treatment. In PAA-treated community, a putative ABC transporter previously found to be necessary for L. monocytogenes resistance to antimicrobial agents and virulence, was among the genes with the highest weight for differentiating treated from control samples. The undertaken metagenomic approach in this study can be applied to identify genes associated with increased tolerance to other antimicrobials in mixed bacterial communities.

Prevalence, toxin gene profiles, lactose fermentation, and growth responses of B. cereus sensu lato subgroups in various dairy and dairy alternative products and ingredients were studied to identify relevant isolates for challenge testing and model development to predict and manage growth responses. Out of 71 examined products or ingredients, 51 B. cereus s.l. isolates were obtained from 35 positive samples (49% prevalence). These 51 isolates along with 18 additional dairy isolates and 12 B. cereus s.l. reference strains were identified using MALDI-TOF. The 81 isolates were further characterized by panC sequencing, testing for cold shock and toxin genes (cspA; hbl, nhe, CytK and ces), lactose fermentation, and study of growth rates (µmax) under various conditions (45 °C, 10 °C, 6% NaCl, pH 5.1), resulting in 298 µmax-values. These conditions were selected to differentiate mesophilic and psychrotolerant strains and to identify tolerant isolates. Dairy powders (83%), pasteurized upconcentrated cheese whey (43%), and cheeses (42%) had the highest prevalences of B. cereus s.l. and the highest concentrations in positive samples (5-100 CFU/g or ml). The panC groups II, III, IV, VI, and VIII were detected among the dairy isolates, with 97% harboring one or more toxin genes. Lactose fermentation was observed in 42% of isolates, with lactose-fermenting B. cereus s.l. isolates of panC groups III and IV dominant in dairy powders. Growth rates of B. cereus s.l. varied considerably, among and within panC groups of the dairy isolates. Based on the highest growth rates at 45 °C, 10 °C, 6% NaCl, pH 5.1, panC group membership, toxin genes profiles, and lactose fermentation ability, two cocktails of "mesophilic" or "psychrotolerant" isolates were selected. These strain cocktails can be used in future challenge testing and predictive food microbiology studies to evaluate and manage the growth of B. cereus s.l. in dairy products and ingredients.

Listeria monocytogenes continues to be a problem in ready-to-eat foods. Tolerance and adaptation to biocides have been proposed to contribute to the persistence of L. monocytogenes in the food processing industry. This study aimed to determine if the sensitivity to common biocides varies among 240 L. monocytogenes isolates. The impact of residual organic matter (soils), biofilm, and ability to adapt to biocides was also evaluated. Food and food processing related isolates of L. monocytogenes (n = 240) were whole genome sequenced and assigned to sequence types (n = 53) and clonal complexes (n = 32). Isolates were screened for genetic elements associated with biocide tolerance and tested for their minimum inhibitory concentration (MIC) to benzalkonium chloride (BC), peracetic acid (PAA), sodium hypochlorite (SH) and ethanol (ET). Biocide tolerance under soiled conditions, in biofilm and in a broth suspension test (BST) was further tested for 19 representative isolates. Adaptation to sub-MICs of BC, PAA or SH (18 days, 15 C) was tested for 15 isolates. MIC for PAA (62 mg/L) showed no variation, while for SH (47-94 mg/L) and ET (4.7-9.4% v/v) values differed 2 x among isolates. For BC, an 8 x difference (0.3-2.5 mg/L) was observed. Eighty-seven of 88 BC tolerant isolates (MIC of 2.5 mg/L) harbored known BC tolerance genes. Soiled conditions increased MIC-values 8-33 x for BC and 8 x for SH but not for PAA and ET. Biofilm increased minimum bactericidal concentrations 4-8 x for BC but not for PAA and SH. Survival of isolates with BC tolerance genes was not significantly (p > 0.05) improved in BSTs with PAA, SH or BC. Lineage I isolates (n = 7 of 19) showed significantly (p < 0.05) better survival than lineage II isolates (n = 12) when exposed to PAA (100 mg/L) in BSTs. Adaptation to BC (8 x MIC increase) occurred exclusively for originally sensitive isolates, while no adaptation to SH and PAA were observed. In conclusion, L. monocytogenes isolates showed limited variation in sensitivity to biocides in MIC assays. However, lineage I isolates were less sensitive to PAA than lineage II isolates in BSTs. The efficacy of SH and BC were affected by residual organic matter and/or biofilm, demonstrating the need for proper cleaning prior to biocide use with PAA being less perturbed.

Cold-smoked (CS) salmon contains high levels of sodium salts, and excess dietary sodium intake is associated with an array of health complications. CS salmon may also represent a food safety risk due to possible presence and growth of the foodborne pathogen Listeria monocytogenes which may cause fatal human infections. Here we determine how reformulated CS salmon using commercial sodium-reduced salt replacers containing KCl (e.g., Nutek, Smart Salt, SOLO-LITE) and acetate-based preservative salts (Provian K, proviant NDV) affect sensory properties, quality, and microbial safety. Initial sensory screening of sodium-reduced CS salmon was followed by L. monocytogenes growth analyses in selected variants of reformulated CS salmon, and finally by analyses of CS salmon variants produced in an industrial smokehouse. Projective mapping indicated overall minor sensory changes in sodium-replaced samples compared with a conventional product with NaCl. Growth of L. monocytogenes was temperature-dependent (4 °C vs. 8 °C storage) with similar growth in sodium-reduced and conventional CS salmon. The addition of 0.9% of the preservative salts Provian K or Provian NDV gave up to 4 log lower L. monocytogenes counts in both sodium-reduced and conventional cold-smoked salmon after 29 days of chilled storage. No changes in pH (range 6.20–6.33), aw levels (range 0.960–0.973), or weight yield (96.8 ± 0.2%) were evident in CS salmon with salt replacers or Provian preservative salts. Analyses of CS salmon produced with selected mineral salt and preservative salt combinations in an industrial salmon smokery indicated marginal differences in sensory properties. Samples with the preservative salt Provian NDV provided L. monocytogenes growth inhibition and low-level total viable counts (<2.8 log/g) dominated by Photobacterium and Carnobacterium during storage. Production of sodium-reduced CS salmon with inhibiting salts provides a simple method to achieve a healthier food product with increased food safety.

The growth inhibiting effect of lactic acid bacteria (LAB) on non-proteolytic Clostridium botulinum was studied. LAB had no significant effect on growth of C. botulinum and their effect was not included in the model to be evaluated. An available cardinal parameter growth and growth boundary model for non-proteolytic C. botulinum (Koukou et al., 2021; https://doi.org/10.1016/j.ijfoodmicro.2021.109162) was evaluated using a total of 822 time-to-toxin (TTT) formation data extracted from the scientific literature for seafood, poultry, vegetables and meat products. These data included smoked products and food stored in air, vacuum or modified atmosphere packaging (MAP) with added CO2. The available extensive model predicted TTT formation without bias (Bf-TTT value = 0.99) and with a reasonable accuracy (Af-TTT value = 1.76). The model was successfully validated for seafood and poultry products. This study substantially increased the range of applicability of the available growth and growth boundary model for non-proteolytic C. botulinum. The performed evaluation showed this model can be used to predict environmental conditions to prevent growth in seafood and poultry products including smoked fish and MAP foods. It is expected that this validated model will contribute to product development and innovation including new sodium reduced foods.

An extensive cardinal parameter growth and growth boundary model for C. sporogenes, as a surrogate for proteolytic C. botulinum, was developed to include the inhibitory effect of 11 environmental factors. 626 maximum specific growth rates (μmax) in broth were generated to determine cardinal parameter values for the growth inhibiting effect of temperature, pH, NaCl/water activity (aw), organic acids (acetic, benzoic, citric, lactic, sorbic) and phosphate melting salts (ortho-, di- and tri-phosphates). μmax-values for C. sporogenes growing in well-characterized processed cheeses were used for product calibration (n = 10) and for product evaluation of the developed broth-model (n = 29). 112 growth/no-growth responses and including 104 μmax-values from the scientific literature for 58 different isolates of proteolytic and toxigenic C. botulinum (Group I) were used for further model evaluation. The developed model had less bias and a higher percentage of correct predictions than available models and was acceptable for processed cheese and good for meat products. The new and extensive model can predict combinations of environmental factors that prevent growth of C. sporogenes and of proteolytic C. botulinum. These predictions are expected to facilitate development or re-formulation of processed cheese and meat products where growth is prevented.

A new cardinal parameter growth and growth boundary model for non-proteolytic C. botulinum was developed and validated for fresh and lightly preserved seafood and poultry products. 523 growth rates in broth were used to determine cardinal parameter values and terms for temperature, pH, NaCl/water activity, acetic, benzoic, citric, lactic and sorbic acids. The new growth and growth boundary model included the inhibiting interactive effect between these factors and it was calibrated using growth curves from 10 challenge tests with unprocessed seafood. For model evaluation, 40 challenge tests with well characterized fresh and lightly preserved seafood were performed. Comparison of these observed growth curves and growth rates (μmax-values) predicted by the new model resulted in a bias factor (Bf) of 1.12 and an accuracy factor (Af) of 1.40. Furthermore, the new model was evaluated with 94 growth rates and 432 time to toxin formation data extracted from the scientific literature for seafood, poultry, meat, pasta and prepared meals. These data included responses for 36 different toxigenic strains of non-proteolytic C. botulinum. The obtained Bf-/Af-values were 0.97/2.04 for μmax-values and 0.96/1.80 for time to toxin formation. The model correctly predicted 93.8% of the growth responses with 5.6% being fail-safe and <1% fail-dangerous. A cocktail of four non-toxin producing Clostridium spp. isolates was used to develop the new model and these isolates had more than 99.8% 16S rRNA gene similarity to non-proteolytic C. botulinum (Group II). The high number of environmental factors included in the new model makes it a flexible tool to facilitate development or reformulation of seafood and poultry products that do not support the growth of non-proteolytic C. botulinum. Further, evaluation of the new model with well characterized products is desirable particularly for meat, vegetables, pasta and prepared meals as well as for dairy products that was not included in the present study.

The annual global catch of Atlantic cod (Gadus morhua L.) is above 1,000,000 tons, and a large proportion is preserved and sold as frozen products. In Greenland, a new innovative fishing method centred on capture-based aquaculture has been developed. To compare the new fishing and processing method with the conventional method, the texture, colour, water holding capacity, salt soluble proteins and sensory properties of fillets were evaluated during 12 months of frozen storage. High quality life (HQL) and practical storage life (PSL) were determined for each fishing and processing method based on sensory evaluation, and by using water holding capacity and the salt soluble protein fraction as indices of quality. Capture-based aquaculture fishing and related processing increased frozen storage durability regarding texture attributes, blood content and sensory properties compared to the conventional method. Lowering the storage temperature to -40 degrees C increase the HQL to > 12 months compared to a HQL of 4-6 months at -20 degrees C.

Predictive microbiology has been suggested as a possible alternative to traditional microbiological assessment of food safety and quality. The effect of various environmental factors on growth of microorganisms has since been quantified in laboratory media and kinetic models have been developed. For most fish products the microorganisms responsible for spoilage, however, are not known and the spoilage microflora are also likely to change when storage conditions (e.g. temperature and atmosphere) are changed over wide ranges. This dynamic nature of the microbial spoilage process indicate that the spoilage domains of specific spoilage organisms must be determined before kinetic models can be developed. The present paper shows how quantitative comparisons of results from product and model system experiments have led to the conclusion that Photobacterium phosphoreum is responsible for spoilage of chilled packed cod. A simple model for the effect of CO, on this organism has been developed and found valid for accurate prediction of microbial spoilage. The square root model was found to be appropriate for predicting the effect of temperature on shelf life of superchilled and packed fresh fish and a new empirical model has been developed for the effect of temperature (O°C to 30°C) on the shelf life of fish from warm tropical waters.

Excessive sodium (Na) intake has been associated with high blood pressure and cardiovascular diseases. Therefore, sodium reduction is a public health challenge worldwide. The aim of this study was to develop smoked salmon with a reduced Na content. Sodium chloride (NaCl) was replaced by potassium chloride (KCl) at 25% and 50% (molar replacement) and studied in combination with two smoking procedures (natural wood and liquid smoke) as well as two smoking temperatures (18-19 °C or 56 °C). Smoked salmon samples were characterized by physicochemical, sensory and microbiological analyses. No major differences were observed regarding physicochemical properties in the studied treatments. Smoked samples with 50% of NaCl replaced by KCl were slightly more bitter than those with 25% whereas samples with 25% of replacement did not show differences to those with non-reduced Na content (5 g of added NaCl per 100 g of salmon). Molar Na:K ratio decreased from 4,3 in controls to 1,4 and 0,6 in samples with a NaCl reduction level of 25% and 50% respectively. Microbiological assessment indicates that 2-week shelf-life would be appropriate and safe in terms of accomplishment of the EU regulation, taking into account foreseeable storage temperatures (up to 8 °C). Thus, it is possible to achieve a reduction of 25-50% of NaCl in smoked salmon by replacing NaCl by KCl and considerer this product as a "source" of K.