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The major aim of the study was to establish the routes via which spoilage associated psychrotrophic bacteria contaminate poultry products at a large processing plant located in Belgium. Environmental samples were collected consisting of samples of air and swabs of food contact surfaces. Product samples were also collected consisting of modified atmosphere packaged (MAP) chicken wings and legs, which were analyzed microbiologically on the same day they were produced as well as after their sell-by date. Psychrotrophic bacteria from these samples were subsequently clustered and identified by means of MALDI-TOF MS and 16S rRNA gene sequencing. Carnobacterium maltaromaticum was determined to dominate the spoilage flora of both wings and legs. Other psychrotrophic bacteria able to grow on MRS which were identified on expired wings and legs included Carnobacterium divergens, Brocothrix thermosphacta, Lactobacillus curvatus, and Lactobacillus brevis. These were determined to arise from food contact surfaces such as cutting blades, leg hooks, Ertalon and polyurethane conveyor belts, working tables, and the hands of the operators. Importantly, it was determined that cleaning and disinfection was largely inadequate. Air was also determined to be an important vector of psychrotrophic bacteria in the processing environment, potentially contaminating the products directly or indirectly.

International audience; Aspergillus fischeri ascospores are known as potential spoilage microorganisms of pasteurized fruit products due to their high incidence in fruits, the ability to survive pasteurization and to grow in acidic conditions. This study aimed to develop a quantitative microbial spoilage risk assessment (QMSRA) model approach to estimate the spoilage risk of packaged strawberry purees due to A. fischeri under various scenarios regarding product formulation, processing and storage conditions. The development of the risk assessment comprised three steps: (1) initial contamination level of raw material by ascospores (N-0), (2) inactivation of ascospores during thermal processing (N-p) and (3) determination of the number of ascospores which are able to survive thermal processing and develop visible mycelia (D = 2 mm) during storage (N-f). Data of visible growth (t(v), days) comprised distributions previously obtained as function of water activity (a(w)) (0.860-0.985), oxygen (0-21%), temperature (8-30 degrees C) and pasteurization (95-105 degrees C/15 s). The simulations were performed in triplicate with 100,000 iterations using the software R. The outcome "spoilage risk" was defined as the probability of having at least one ascospore (N-f) capable of forming visible colonies in 100 g-pack strawberry puree within the typical use-by dates. Overall, high probabilities of spoilage were estimated for purees pasteurized at milder treatments at 85 degrees C/15-60 s (67%) and 90 degrees C/15-60 s (>= 40%) stored at ambient temperature (22 degrees C). The spoilage risk was only effectively reduced (0.02%) by increasing pasteurization conditions to 95 degrees C for at least 45 s. Moreover, the microbial stability of such purees, i.e., spoilage risk < 0.001% (=less than 1 spoilage pack out of 105 produced units) was predicted to occur for purees treated at 100 degrees C/15 s or stored at chilled conditions (

The major aims of this study were to assess inter- and intra-species variability of heat resistant moulds (HRMs), Byssochlamys fulva and Byssochlamys nivea, with regards to (i) heat resistance and (ii) effect of heat treatment intensity on subsequent outgrowth. Four-week-old ascospores were suspended in buffered glucose solution (13° Brix, pH 3.5) and heat treated in a thermal cycler adjusted at 85 °C, 90 °C and 93 °C. Two variants of the Weibull model were fitted to the survival data and the following inactivation parameters estimated: b (inactivation rate, min-1), n (curve shape) and δ (the time taken for first decimal reduction, min). In addition to the assessment of heat resistance, outgrowth of Byssochlamys sp. from ascospores heated at 70 °C, 75 °C, 80 °C, 85 °C and 90 °C for 10 min and at 93 °C for 30 and 70 s was determined at 22 °C for up to 30 days. The Baranyi and Roberts model was fitted to the growth data to estimate the radial growth rates (μmax, mm.day-1) and lag times (λ, days). Inter-species variability and significant differences (p < 0.05) were observed for both inactivation and growth estimated parameters among B. fulva and B. nivea strains. The effect of heat treatment intensity on outgrowth of B. fulva strains was more apparent at the most intense heat treatment evaluated (90 °C/10 min), which was also the condition in which greater dispersion of the estimated kinetic parameters was observed. On the other hand, B. nivea strains were more affected by heating, resulting in greater variability of growth parameters estimated at different heating intensities and in very long lag phases (up to 25 days). The results show that inter- and intra-species variability in the kinetic parameters of Byssochlamys sp. needs to be taken into account for more accurate spoilage prediction. Furthermore, the effect of thermal treatments on subsequent outgrowth from ascospores should be explored in combination with other relevant factors such as °Brix and oxygen to develop thermal processes and storage conditions which can prevent the growth of HRMs and spoilage of heat treated food products.

The objective of this study was to evaluate the combined effects of heat treatment intensity and pH on the activation/inactivation of ascospores of Byssochlamys nivea and their subsequent outgrowth. D-values were evaluated at 85, 90 and 95 °C, whilst activation/inactivation and outgrowth were determined by a full factorial study incorporating (i) heat treatments ranging from no heat treatment to 10 min at 55–90 °C and (ii) pH values ranging from 4 to 6. The estimated D-values were independent of pH and ranged from 1.1 to 1.2 min at 90 °C to 15–16 min at 85 °C. Optimal heat activation was observed when the ascospores were heated for 10 min at 75 °C. Whilst heat activation (10 min at 65–75 °C) did not have a significant effect (p > 0.05) on the lag phase of B. nivea relative to native ascospores, significantly (p

This review addresses the recent advances of the application of essential oils (EOs) in in vitro systems and in bread systems for the reduction of fungal spoilage. Given the number of research articles concerning the use of EOs as potential antifungal food preservatives, it is generally accepted that they must be given further attention for use in specific food matrices. However, despite the numerous articles stating the antifungal effect of EOs, very few report the actual application in bread or other bakery products and the impact addition can have on dough and bread production, physico-chemical, microbiological and sensorial quality. Advances have been made in the area of food preservation, but further research is necessary to fully comprehend the mode of action and to establish actual food applications of EOs in the bread and bakery industry.

The major objective of this study was to assess the application of commercially available ‘clean label’ fermentates as preservatives in dressings. This study was performed in two parts. In the first, the inhibitory activities of the reference preservative (potassium sorbate) and selected fermentates – MicroGARD® 200, Nabitor, Nabitor WS, Biogard ND, Defence AM-P and Polyfence™ 35TD - towards Zygosaccharomyces bailii were assessed as a function of pH (3.5–5.0) on Sabouraud agar. In the second part, challenge, shelf-life and sensorial tests were used to determine the potential of selected fermentates to replace potassium sorbate in dressings. All preservatives had significant (p

Heat-resistant moulds (HRMs) pose great challenges to processors of fruit-based products due to their thermal resistance and ability to grow across a broad range of conditions. Therefore, the quantification of the effect of inhibitory factors (conditions) on the growth of HRMs is very important to be used to prevent spoilage during shelf-life. This study assessed the minimum temperature and maximum sugar content (°Brix) for the growth of six HRMs (Byssochlamys spp. and Neosartorya spp.) previously isolated from fruit products. In addition, the time to form a visible colony (tv, days) was determined to assess biological variability of individual ascospores within same population. Heat activated ascospores (10 min at 80 °C) were spread plated (±100 spores) on acidified Potato Dextrose Agar (aPDA, pH 3.5) plates from which the °Brix was adjusted with fructose-glucose (1:1) to levels between 44 and 59 °Brix followed by incubation at 30 °C. To assess the effect of temperature, inoculated plates of aPDA were incubated at 4, 7, 8, 10, 12 and 14 °C. Three replicates (= 3 aPDA plates) were prepared per condition evaluated. The number of visible colonies were counted daily for up to two months. Probability distribution functions were then fitted in @Risk to the cumulative tv's. With regards to cold tolerance, B. nivea was the most cold sensitive as it had the least ability to germinate and form visible colonies at low temperatures (no growth when T ≤ 10 °C). On the other hand, N. hiratsukae was the most cold tolerant, being able to form visible colonies at temperatures ≥ 7 °C. Likewise, B. nivea was the most sensitive to increased °Brix values, whilst N. udagawae was able to grow out at the highest °Brix evaluated (59°/aw = 0.86). The tolerance of potential spoilage HRMs to high sugar levels and their ability to grow under chilled conditions represent a challenge for the microbial stability of high-sugar fruit products. Differences in individual tv's were mostly observed under conditions at the growth/no growth regions. For instance, individual tv's of B. nivea ascospores ranged from 24 to 46 days at 12 °C and those of N. udagawae ranged from 20 to 45 days at 59°Brix. The tv's data from each HRM and condition evaluated were then fitted to different statistical distributions (Exponential, Normal, Lognormal, Weibull, Logistic or Pareto) to allow the use of the obtained data in further Quantitative Microbial Spoilage Risk Assessment work for pasteurized fruit products.

This study aims to assess, by means of a full factorial design, the effect of storage temperature (10-30 °C), water activity (aw, 0.87-0.89), headspace oxygen (O2) level (0.15-0.80%) and pasteurization intensity (95 °C-105 °C/15sec) on the time to visible growth (tv, days) of Aspergillus fischerianus on acidified Potato Dextrose Agar (aPDA, pH 3.6) for up to 90 days. Moreover, in order to validate the results obtained on aPDA, 12 conditions were selected and assessed in concentrate strawberry-puree based medium. Overall, storage temperature had the greatest effect on the tv of A. fischerianus on the evaluated conditions. At 10 °C, no visible growth was observed over the 90 day incubation period, whilst visible mycelia (diameter ≥ 2 mm) were present in 37% and 89% of the conditions at 22 °C and 30 °C, respectively. Pasteurization intensity had only a minor effect on the outgrowth of A. fischerianus. Growth inhibition was observed when aw was reduced to 0.870 ± 0.005 in combination with very low headspace O2 levels (0.15% ± 0.10) in both, aPDA and concentrate strawberry-based media, regardless of the incubation temperature and heat pasteurization intensity. Overall, longer tv's were required when incubation was done at 22 °C compared to 30 °C. Ultimately, the effect of O2 (0.05 and 1%) and pasteurization intensity (95 °C and 105 °C/15sec) were evaluated on totally 22 fruit purees (un-concentrates and concentrates) over a 60 day storage period. None of the concentrates purees (aw ≤0.860) evaluated in this study supported the growth of A. fischerianus. On the other hand, A. fischerianus growth inhibition was only observed when the O2 levels were ≤0.05% on un-concentrates fruit purees (aw ≥ 0.980) stored at ambient temperature (22 °C). Combination of multiple stress factors effectively inhibited growth of A. fischerianus. In general, storage of fruit purees at low temperatures (

The major objective of this study was to assess the potential of commercially available ‘clean label’ fermentates to replace the preservative function of propionate in bread. This study was performed in two parts. In the first part of the study the inhibitory activities of selected fermentates, FA (cultured corn syrup and citric acid), FB (cultured wheat solids), FC (cultured dextrose) and FD (cultured dextrose), towards Penicillium chrysogenum and Penicillium paneum were assessed as a function of pH (4.5–6.5) on malt extract agar (MEA). In the second part of the study, challenge, shelf-life and sensorial tests were used to determine the suitability of these fermentates to replace calcium propionate in bread. All the fermentates evaluated in this study had appreciable inhibitory activities towards P. chrysogenum and P. paneum . As expected the antifungal activity of the fermentates was greater the lower the pH of the growth medium. Additionally, P. paneum was generally more tolerant to the fermentates than P. chrysogenum . The challenge and sensorial tests showed that bread prepared with FA (1.3%), FB (2%) and FC (1.3 and 2%) were as microbiologically stable and sensorially acceptable as the reference. Therefore, fermentates can be used as ‘label friendly’ preservatives in bread products.

This study had the major objective of evaluating the food safety knowledge, attitudes and practices of consumers and vendors of street foods in Ho Chi Minh City (MCMC), Vietnam. There were three main surveys performed in this study. A total of 120 consumers and 40 street food vendors from four districts [Binh Thanh (BT), Thu Duc (TD), district 3 (D3) and district 8 (D8)] in HCMC contributed to the study on a voluntary basis. The surveyed consumers had adequate levels of food safety knowledge and attitudes. No significant difference (p > 0.05) occurred between the food safety knowledge levels of the consumers on the basis of gender. However, significant differences (p 0.05) were observed in the food safety knowledge levels of the vendors on the basis of gender and age. However, significant differences (p

The major objective of this study was to assess the antifungal activities of commercially available 'clean label' fermentates and their potential to replace the preservative function of sorbate and propionate in cake. This study was performed in two parts. In the first part of the study the inhibitory activities of selected fermentates - FA, FB, FC and FD - towards Aspergillus tritici and Aspergillus amstelodami were assessed as a function of pH (5.0-6.5) on malt extract agar (MEA). In the second part of the study, challenge, shelf-life and sensorial tests were used to determine the suitability of these fermentates to replace potassium sorbate and calcium propionate in quarter pound cake. All the fermentates evaluated in this study all had significant (p0.05) inhibitory activities towards A. tritici and A. amstelodami within the recommended dosage range for application in bakery products. In all cases, the inhibitory activity of the fermentates increased with a decrease in the pH and an increase in concentration. FC was generally the most inhibitory whilst FD was the least inhibitory. Significant (p0.05) synergistic interactions were determined to occur between the effects of pH and concentration for all fermentates evaluated in this study. The sensorial tests with FC showed that cakes produced with ≤1% FC (on basis of the batter) did not differ significantly (p0.05) in flavour from the reference cake (0.5% calcium propionate and 0.54% potassium sorbate). However, the challenge and shelf-life tests showed that cakes produced with ≤1% FC were not as microbiologically shelf-stable as the reference cake, especially when sliced. Therefore, it can be concluded that whilst fermentates have appreciable antifungal effects, their use could potentially result in reduced shelf-stabilities. Robust challenge and shelf-life tests would be recommended before the marketing of cakes were propionate and/or sorbate has been replaced to ensure accurate shelf-lives are stated.

This study investigated the continuous dosing of chlorine to the wash water by means of a pump to maintain antimicrobial levels of free chlorine in the wash water during the washing of 12 batches of Pangasius fillets. In comparison to the control (no chlorination), total psychrotrophic bacteria were reduced by between 2 and 4 log CFU/100 ml. After the final batch was washed, total chlorine and organic matter in the water sampled had accumulated to 482.9 ± 17.0 ppm and 4447.5 ± 187.4 mg O 2 /L, respectively. However, only 8.9 ± 1.3 μg/L of trihalomethanes was formed in the chlorinated wash water whereas no trihalomethanes were detected in the washed Pangasius fillets after rinsing. It was concluded that the Pangasius fillets washed in chlorinated water continuously dosed with chlorine were safe for human consumption even after a throughput of 12 batches. However, the organoleptic properties of Pangasius fillets washed in the final batch differed significantly from those washed earlier batches.

This study evaluated the effect of both gaseous and dissolved oxygen (O2) concentration (0 - 21%) on the growth of six heat-resistant moulds (HRMs) (Neosartorya and Byssochlamys spp.) previously isolated from high-acid fruit products. The study was performed in acidified potato dextrose agar (aPDA) with all six HRMs and with B. fulva and N. fischeri in strawberry, apple and orange juice-based media. At ≥ 0.15% O2, visible growth of the HRMs occurred within 3-6 days. Complete inhibition on aPDA did not occur even at very low levels of dissolved O2 (ca. 0.01% O2). With the exception of B. fulva, decrease of the O2 concentration to ≤0.03% resulted in significantly (p

Heat-resistant moulds (HRMs) are well known for their ability to survive pasteurization and spoil high-acid food products, which is of great concern for processors of fruit-based products worldwide. Whilst the majority of the studies on HRMs over the last decades have addressed their inactivation, few data are currently available regarding their contamination levels in fruit and fruit-based products. Thus, this study aimed to quantify and identify heat-resistant fungal ascospores from samples collected throughout the processing of pasteurized high-acid fruit products. In addition, an assessment on the effect of processing on the contamination levels of HRM in these products was carried out. A total of 332 samples from 111 batches were analyzed from three processing plants (=three processing lines): strawberry puree (n = 88, Belgium), concentrated orange juice (n = 90, Brazil) and apple puree (n = 154, the Netherlands). HRMs were detected in 96.4% (107/111) of the batches and 59.3% (197/332) of the analyzed samples. HRMs were present in 90.9% of the samples from the strawberry puree processing line (1–215 ascospores/100 g), 47.0% of the samples from the orange juice processing line (1–200 ascospores/100 g) and 48.7% of samples from the apple puree processing line (1–84 ascospores/100 g). Despite the high occurrence, the majority (76.8%, 255/332) of the samples were either not contaminated or presented low levels of HRMs ( 0.05). On the contrary, a significant reduction (p

This study evaluated the effect of residual O2 level (0% to 5%) on microbial growth and volatile metabolite production on par-fried French fries packaged in a modified atmosphere with 60% CO2 (rest N2 ) at 4 °C. The results obtained showed that the initial headspace (IH) O2 level had an effect on growth of Leuconostoc mesenteroides on French fry simulation agar, whereby growth was slightly faster under 5% O2 . In terms of quantity, ethanol, 2-methyl-1-propanol, and dimethyl disulphide were the most significant volatile metabolites produced by L. mesenteroides. The production of ethanol by L. mesenteroides was highest on simulation agar packaged under low IH O2 levels (0% to 1%), indicating that the fermentative metabolism was induced under these conditions. In agreement with the results observed on the simulation medium, growth of native lactic acid bacteria was faster under an IH O2 level of 5%. In addition, ethanol, 2-methyl-1-propanol, and dimethyl disulphide were also quantitatively the most important volatile metabolites. However, in contrast, greater quantities of ethanol and dimethyl disulphide were produced on par-fried French fries packaged under 5% O2 . This was attributed to the limited growth of the native flora on the par-fried French fries under residual O2 levels of 0% and 1%. Although some significant differences (P < 0.05) occurred between the French fries packaged in 0%, 1%, and 5 % residual O2 during storage, all products were considered to be acceptable for consumption. The results of this study can be used to optimize the shelf-life of packaged chill stored potato products.

Adsorption and desorption isotherms for whole black peppercorns ( Piper nigrum L.) were developed at 22, 30 and 37 °C using standard static gravimetric method. The sorption isotherms exhibited a type III behaviour according to Brunauer-Emmett-Teller (BET) classifications. The equilibrium moisture content (EMC) decreased with increasing temperature at a particular water activity (a w ). Hysteresis existed over the entire a w range at 30 and 37 °C. At 22 °C, an intersection of the curves was found at a w closer to 0.75. The goodness of fit of the models was evaluated using several statistical indices and residual plots. The Guggenheim-Anderson-de Boer (GAB) and Peleg models were determined to best describe the experimental sorption data. The monolayer moisture content ( M 0 ) were 4.78, 3.56 and 3.49 g/100 g at 22, 30 and 37 °C for adsorption. The maximum isosteric heat of sorption was 28.1 and 73.3 kJ/mol for adsorption and desorption, respectively. The net isosteric heat of sorption and sorption entropy increased with increase in EMC; both curves dropped off exponentially after M 0 . The Gibbs free energy change for adsorption ranged from 100.6 to 9370.6 J/mol. The black peppercorns can be stored at 22, 30 and 37 °C, by reducing their MC to 10, 8 and 7 g/100 g, respectively, with a w below 0.60.

This study evaluated the decontamination of Pangasius fillets in chlorine or peracetic acid treated wash water. First, the decontamination efficacy of the washing step with chlorinated water applied by a Vietnamese processing company during trimming of Pangasius fillets was evaluated and used as the basis for the experiments performed on a laboratory scale. As chlorine was only added at the beginning of the batch and used continuously without renewal for 239 min; a rapid increase of the bacterial counts and a fast decrease of chlorine in the wash water were found. This could be explained by the rapid accumulation of organic matter (ca. 400 mg O 2 /L of COD after only 24 min). Secondly, for the experiments performed on a laboratory scale, a single batch approach (one batch of wash water for treating a fillet) was used. Chlorine and PAA were evaluated at 10, 20, 50 and 150 ppm at contact times of 10, 20 and 240 s. Washing with chlorine and PAA wash water resulted in a reduction of Escherichia coli on Pangasius fish which ranged from 0–1.0 and 0.4–1.4 log CFU/g, respectively while less to no reduction of total psychrotrophic counts, lactic acid bacteria and coliforms on Pangasius fish was observed. However, in comparison to PAA, chlorine was lost rapidly. As an example, 53–83% of chlorine and 15–17% of PAA were lost after washing for 40 s (COD = 238.2 ± 66.3 mg O 2 /L). Peracetic acid can therefore be an alternative sanitizer. However, its higher cost will have to be taken into consideration. Where (cheaper) chlorine is used, the processors have to pay close attention to the residual chlorine level, pH and COD level during treatment for optimal efficacy.

The major objective of this study was to evaluate the effect of water soluble fat replacers on the growth of bacteria of importance to processed meats. The first part of the study evaluated the effect of water soluble fat replacers (Beneo™ GR, Beneo™ HPX, STA-LITE WSIII™, Fibersol-2 and Nutriose) on the growth of Lactobacillus sakei and Listeria monocytogenes . Fibersol-2 appears to have the greatest potential for replacing fat without compromising microbiological stability as increase in its water phase concentration resulted in a significant increase in the lag phases of both Lb. sakei and L. monocytogenes . On the other hand, Beneo™ GR stimulated the growth of L. monocytogenes , implying that its use could compromise microbiological safety. In the second part of the study pork liver pate and low fat pate (30% less fat) were challenged with L. monocytogenes . The low fat pate was determined to be microbiologically less stable than the reference pate. This was a result of the low fat pate having significantly higher water activity and pH values than those of the reference pate. The results of this study are of importance to the meat processing industry to make more informed decisions when reducing and/or replacing fat.

This study had the major objective of determining the food safety knowledge, attitudes and practices of vendors and consumers of street food in Port-au-Prince, Haiti. Haiti currently has no food safety legislation in place. 160 consumers and 80 vendors from four different communes (Tabarre, Delmas, Petion-ville and downtown Port-au-Prince) volunteered to participate in the study. In general, consumers and vendors exhibited average food safety knowledge and attitude levels. Gender, training, level of education and location did not have a significant effect (p

Preservation of emulsions relies on factors including pH, temperature, structure and the application of carboxylic acid preservatives, such as sorbic and benzoic acid. Organic acid preservatives tend to migrate to the lipid phase of emulsions. Taking into account the fact that organic acid in the aqueous phase is solely responsible for antimicrobial activity, this partitioning behavior is considered as a loss of preservative. The influence of microstructure properties on sorbic acid distribution and preservation effect was investigated in model food systems comprising of aqueous phase, and liquid oil and solid fat as lipid phase, which represent major constituents of water-oil emulsions. The aqueous phase of the food model systems was comprised of Yeast Nitrogen Broth (YNB) in phosphate buffer and buffered at pH 4.5, 5.5, 6.5. Sorbic acid (100 mg/L) in the form of potassium sorbate was added to the aqueous phase. Candida guilliermondii (2 log CFU/mL) was inoculated in the aqueous phase to resemble industrial post-contamination CFU levels. Growth parameters, generation time (GT) and lag phase (λ) of C. guilliermondii in the aqueous phase of the food model systems were quantified during 1 month at 7 °C and maximum 80 h at 22 °C. HPLC analyses were performed to evaluate total sorbic acid content in each food model system. Sorbic acid inhibited growth of C. guilliermondii in YNB + SA at pH 4.5 at 7 °C and 22 °C. The presence of liquid oil caused partitioning of sorbic acid into the lipid phase in YNB + SA|oil at pH 4.5 at 7 °C and 22 °C, reducing its inhibitory effect. Adding solid fat into the model food systems significantly prolonged lag phase duration in the YNB + SA|oil + fat system at pH 4.5 at 22 °C and growth was inhibited at 7 °C. HPLC analysis showed a final aqueous sorbic acid concentration of 34 mg/L and 44 mg/L in YNB + SA|oil system at pH 4.5 at 7 °C and 22 °C after 1 month and 168 h, respectively. In YNB + SA|oil + fat system at pH 4.5, 87 mg/L of aqueous sorbic acid was measured after 1 month at 7 °C and 168 h at 22 °C, indicating that the presence of solid fat retards sorbic acid partitioning. Results show that structural components such as liquid oil and solid fat have an effect on the aqueous sorbic acid concentration and its preservation effect. The presence of solid fat reduces the tendency of sorbic acid to partition into the lipid phase, which is reflected in the inhibitory effect of sorbic acid on C. guilliermondii.

The major objectives of this study were to determine the incidence of psychrotolerant spore formers from REPFEDS marketed in Belgium, and their diversity and characteristics. Spore formers in general were found as spores on 38.3% of the food samples and in 85% food products types evaluated. 76% of the food samples containing spore formers had spores before enrichment. A total of 86 spore formers were isolated from the samples. 28 of 86 bacterial spore formers (32.6%) were capable of vegetative growth at 7 °C. 96% (27/28) of these psychrotolerant spore formers were determined to belong to Bacillus or related genera. According to a (GTG)5-PCR analysis, 24 of these 28 isolates were genetically distinct from each other. 10.7% (3/28) of the bacilli were determined to belong to the Bacillus cereus group, namely B. cereus (chicken curry and Edam cheese) and Bacillus mycoides (Emmental cheese). Almost half of the bacilli (12/27) were putatively identified as Bacillus pumilus, which occurs ubiquitously in nature and has been associated with outbreaks of foodborne disease. Only one psychrotolerant clostridium, Clostridium tyrobutyricum, was isolated in the study. The results of this study show the highly diverse ecology and spoilage potential of psychrotolerant spore formers in REPFEDs marketed in Belgium.

Pangasius hypophthalmus (referred to as Pangasius or tra fish in Vietnam) has become highly appreciated by consumers in the European Union, USA, Japan, etc. and is of worldwide economic importance. Therefore, the microbial quality and safety of Pangasius fish processed for export was assessed by means of a microbial assessment scheme throughout the entire production process. A total of 144 samples were collected from various processing steps and analyzed. It was determined that the microbial safety and quality of the products was not guaranteed as the contamination levels remained high throughout processing. Escherichia coli, Staphylococcus aureus and Vibrio cholerae were present on the hands of food operators, particularly those in the packaging area. Moreover, the presence of Listeria monocytogenes (1 positive out of 9 samples) and V. cholerae (4/9) on the final products was likely a result of inadequate hygiene practices in the processing environment. Also discussed in this paper are the results of a self-assessment questionnaire, which provide insight into the performance of the food safety management system currently implemented at the company. These data are of major importance in order to contribute valuable information to the local and international trade point of view in general and to the intended customers in particular.

The objective of the study was to evaluate the combined effects of pasteurization intensity (no heat treatment and 10 min at 70, 80 and 90 °C), water activity (aw) (0.960-0.990), pH (5.5-7.0) and storage temperature (7 and 10 °C) on the survival and outgrowth of psychrotolerant spores of Bacillus cereus FF119b and Bacillus pumilus FF128a. The experiments were performed in both artificial media and a validation was performed on real food products (cream, béchamel sauce and mixed vegetable soup). It was determined that in general, heat treatments of 10 min at 70 °C or 80 °C activated the spores of both B. cereus FF119b and B. pumilus FF128a, resulting in faster outgrowth compared to native (non-heat treated) spores. A pasteurization treatment of 10 min at 90 °C generally resulted in the longest lag periods before outgrowth of both isolates. Some of the spores were inactivated by this heat treatment, with more inactivation being observed the lower the pH value of the heating medium. Despite this, it was also observed that under some conditions the remaining (surviving) spores were actually activated as their outgrowth took place after a shorter period of time compared to native non-heated spores. While the response of B. cereus FF119b to the pasteurization intensity in cream and béchamel sauce was similar to the trends observed in the artificial media at 10 °C, in difference, outgrowth was only observed at 7 °C in both products when the spores had been heated for 10 min at 80 °C. Moreover, no inactivation was observed in cream or béchamel sauce when the spores were heated for 10 min at 90 °C in these two products. This was attributed to the protective effect of fat in the cream and the ingredients in the béchamel sauce. The study provides some insight into the potential microbial (stability and safety) consequences of the current trend towards milder heat treatments which is being pursued in the food industry.

The effect of initial headspace (IH) O2 level on the shelf-life of fresh-cut pineapple was evaluated in this study. The results showed that although the IH O2 level had a minor effect on the growth of Candida argentea, Candida sake and Meyerozyma caribbica on pineapple agar, the quantities of the volatile organic metabolites produced by these yeasts was generally smaller the lower the IH O2 level. The only exception was the production of ethyl acetate by C. argentea, which was higher at low IH O2 levels. In triangle tests performed with trained panellists, pineapple cubes packaged in an IH of 5% O2 were determined to be significantly different (P < 0.05) to those packaged in 21% O2 from day 5 of storage. Preference was shown for the pineapple cubes packaged in an IH of 5% O2. The results imply that packaging in an IH O2 level of 5% could be used to extend the shelf-life of fresh-cut pineapple.

Fresh-cut fruit such as pineapple have a very limited shelf-life. The study aims at prolonging the shelf-life of fresh-cut pineapple by means of modified atmospheres (MAs). The effect of MAs combining high O2 (21–70%) and CO2 (21–50%) levels on microbial spoilage and sensory quality of fresh-cut pineapple was therefore evaluated. In the first part of the study, the behaviour of two spoilage yeasts (Candida sake and Candida argentea) and one lactic acid bacterium (Leuconostoc citreum), which had previously been isolated from spoiled commercial fresh-cut pineapple cubes, were monitored on pineapple agar separately. In the second part of the study, the shelf-life of commercial fresh-cut pineapple cubes packaged in selected MAs was evaluated at 7 °C. The results showed that MAs combining high O2 and high CO2 levels had a large inhibitory effect on the growth and volatile metabolite production of C. sake and C. argentea on pineapple agar. A MA with 50% O2 and 50% CO2 was in both cases the most inhibitive. Although MAs induced the production of ethyl acetate by the yeasts, the quantity of ethyl acetate was much lower in high O2 and high CO2 than that in air due to lower yeast population density in MAs. With regards to growth, L. citreum was not sensitive to high O2 and CO2 levels. The fresh-cut pineapple packaged in air had deteriorated and were not acceptable any more by day 7, while those packaged in 50% O2 combined with 50% CO2, which also retarded the growth of aerobes and yeasts on pineapple cubes during storage, were still acceptable. It can be concluded that a MA with 50% O2 and 50% CO2 shows the best potential for extension of the shelf-life of fresh-cut pineapple.

The growth-inhibiting effects of simple and commercial salt replacers on the growth of Listeria monocytogenes were determined in broth at 7C. The divalent chlorides, CaCl2 and MgCl2, had the largest antilisterial activities at equivalent water phase concentrations or molalities followed by NaCl ≈ KCl and MgSO4 in decreasing order of antilisterial effect. Additional antilisterial activities other than their water activity depressing effects were observed for CaCl2 and MgCl2. Challenge tests performed on cooked ham and white sauce showed that reduction of NaCl levels by ≤28 and 33%, respectively, did not affect the stability of these products to L. monocytogenes. It can be concluded from the study that changes in the stability to L. monocytogenes are most likely to occur when NaCl is fully reduced and/or replaced or partially replaced by either CaCl2 (increased stability) or MgSO4 (reduced stability). Practical Applications The association of high dietary NaCl levels to hypertension and cardiovascular diseases has led to concerted efforts in the food industry to reduce NaCl levels. To date, several studies have been performed, which have focused primarily on addressing the sensorial, technological and shelf life aspects, with far less emphasis being placed on the food safety aspects. The results of this study provide much needed insight into the potential food safety consequences of reduction and/or replacement of NaCl in food products.

The ability of the meat isolate Staphylococcus sciuri I20-1 to inhibit food-borne pathogens in view of its application as a functional starter culture for the production of clean-label fermented meats was investigated. The strain produced a heat-stable antibacterial compound of a proteinaceous nature that was released following primary metabolite production kinetics. Its specific inhibitory spectrum included different strains of Staphylococcus aureus and both vegetative cells and spores of Clostridium botulinum . These two species pose potential biosafety hazards, in particular when producing fermented meats with a mild pH and without added nitrate and nitrite salts. Up till now, starter-culture based strategies to restrain S. aureus and C. botulinum have barely been explored in fermented meats, in contrast to the frequently investigated use of antilisterial cultures of lactic acid bacteria. When added to a fermented sausage model, S. sciuri I20-1 acted as a persistent culture throughout the fermentation process, during which it was able to produce its antibacterial compound in situ . In co-culture experiments, an immediate two-log inactivation of a S. aureus strain was found, even before production of the antibacterial compound could be detected. This was probably due to an instant pH-driven desorption of the antibacterial molecules from the producer cells when added to the meat batter. However, a sub-population of S. aureus that was resistant to the antibacterial compound was able to grow out to the same final counts as in the control experiment performed with a non-inhibitory strain of S. sciuri . This finding is indicative of the potential pitfalls when extrapolating promising in vitro results to the true complexity of fermented food matrices.

This study evaluated the effect of modified atmospheres (MAs) with different O(2) concentrations on microbial growth and volatile metabolite production in gray shrimp (Crangon crangon) during storage at 4 °C. Eight MAs were evaluated in total. Four of the MAs evaluated were without CO(2): 0/0/100, 0/10/90, 0/30/70, 0/50/50 (% CO(2)/O(2)/N(2)) whilst the other four MAs all contained 50% CO(2): 50/0/50, 50/10/40, 50/30/20, 50/50/0 (% CO(2)/O(2)/N(2)). Volatile spoilage metabolites were identified by thermal desorption GC-MS and quantified during storage by selective ion flow tube mass spectrometry (SIFT-MS). In comparison to microbial growth observed with an atmosphere of 100% N(2), microbial growth was stimulated by the addition of O(2) in the MAP in the absence of CO(2.) Under these conditions the total psychrotrophic counts exceeded 7 log cfug(-1) after just 3 days of storage. However, in the presence of 50% CO(2) the total psychrotrophic count exceeded 7 log cfug(-1) after 5 days of storage. The combination of 50% CO(2) and 50% O(2) significantly inhibited microbial growth. For this MA condition, a diminishing effect on the production of metabolites was also observed, especially for amines and sulfur compounds, which constituted the major fraction of components causing the offensive odor.

In the presence of oxygen, ascorbic acid (AA) is readily degraded to dehydroascorbic acid (DHA), which is prone to further degradation, hereby losing its vitamin C activity. In this study, the influence of different initial headspace O 2 concentrations on the oxidation of AA and the subsequent formation and breakdown of DHA was investigated in a model fruit juice. Kinetic rate constants for solely AA degradation were estimated using zero and first order kinetics, while first order irreversible and reversible consecutive models were used to describe the degradation kinetics of AA combined with the oxidative formation and irreversible breakdown of DHA. A linear relationship was found between the first order AA degradation constants and the initial headspace oxygen concentrations. Further, a similar relationship was found for a commercial fruit juice. In this way a tool is provided to predict the AA content in fruit juices at different stages during storage, knowing the residual headspace oxygen concentration after packaging, the O 2 -permeability of the packaging material and the initial AA and DHA concentration.

Pichia anomala, Hyphopichia burtonii and Saccharomycopsis fibuligera are spoilage yeasts causing chalk mould defects on par-baked breads packaged under modified atmosphere. The first objective of this study was to identify yeasts isolated from spoiled par-baked breads by means of a RAPD protocol and to determine the dominant spoilers amongst identified strains. The second objective was to determine the effects of water activity (aw) and pH value on the growth rates and lag phase durations of P. anomala, H. burtonii and S. fibuligera. 95% of the yeasts tested were identified as P. anomala and 5% as S. fibuligera, H. burtonii was not detected. In order to investigate the effect of aw and pH the growth of the three yeasts was tested within an aw range of 0.88–0.98 and a pH range of 2.8–8.0. P. anomala was able to grow from pH 2.8 to 8 without a clear optimum. S. fibuligera and H. burtonii showed a pH optimum for growth of 5. The optimum water activity for growth was different for the three strains and varied between 0.96 and 0.98. These growth data were further used to develop secondary models that describe the relationship between aw and the radial or colony growth rate (g, mm/d) or the lag phase duration (λ, d). The identification of the spoilage organisms and a good understanding of the effects of aw and pH on the growth behavior is essential for future development of adequate conservation strategies against chalk mould defects.

The effect of NaCl and various NaCl replacers (CaCl(2), MgCl(2), KCl and MgSO(4)) on the growth of Penicillium roqueforti and Aspergillus niger was evaluated at 22 degrees C. In addition, challenge tests were performed on white bread to determine the consequences of NaCl reduction with or without partial replacement on the growth of P. roqueforti. From the results obtained it can be concluded that at equivalent water phase concentrations the isolates exhibited differing sensitivities to the salts evaluated with NaCl and MgCl(2) having the greatest inhibitory action on the growth of A. niger and P. roqueforti, respectively. MgSO(4) had the least antifungal activity. At equivalent molalities, CaCl(2) had in general the largest antifungal activity. Although the water activity (a(w)) lowering effects of the compounds studied play a large role in explaining the trends observed, at equivalent water phase concentrations MgCl(2) was found to have a smaller inhibitory effect on A. niger than that expected from its a(w) depressing effect. The challenge tests revealed that no difference occurred in the growth of P. roqueforti on standard white bread, bread with 30% less NaCl and bread in which 30% of the NaCl has been partially replaced by a mixture of KCl and Sub4Salt. These results are of importance in assessing the possible microbiological consequences of NaCl reduction or replacement in bread and similar bakery products.

The shelf life of a food product is largely determined by its chemical and microbiological stability. In this respect, the gas composition surrounding a packaged product plays a major role. Modified Atmosphere Packaging (MAP) is a packaging technique that usually reduces the headspace oxygen to a preferable minimum for most food products. Besides the residual oxygen, the O 2 -permeability of the packaging material is also important, as it determines the amount of oxygen permeating into the package during storage. This paper describes the development of a practical software simulation tool to predict the amount of oxygen permeating into the headspace during storage for a variety of multilayer packaging configurations. The simulation tool gives access to simulation models for mono- and multilayer films, trays covered with top foils and bottles with caps. The user can compose his/her own (multilayer) packaging material and check the oxygen ingress over time for different temperature conditions for all packaging configurations. Industrial relevance The software simulation tool is of industrial relevance to food companies, as they can use it to select or compare different films, but also to underpin their choice for a certain packaging material with regard to the sensitivity of the food product to oxygen and the desirable shelf life. The simulation program also provides food companies with information about the influence of storage conditions, like time and temperature, on the ingress of oxygen in their food package throughout the storage-distribution chain. On the other hand, it can also be used by packaging suppliers to predict the oxygen permeability in the optimization process of new films and as a client support tool.

The relationship between water activity ( a w ) and concentration of NaCl, sucrose and various simple and commercial salt, sugar and fat replacers was determined. The model originally developed by Favetto and Chirife (1985) and extended by Roa and Tapia (1998) was successfully used to model the relationship between a w and molality of the binary and multi-component aqueous solutions. These models were then reparameterized to enable the a w to be modeled as function of the water phase concentrations of binary and multi-component solutions. This reparameterization enables the modeling of the a w depressing effects of compounds for which sufficient data required to calculate the molecular weight cannot be obtained. Both models were successfully used to predict the a w of some food products including meat and fish products and mayonnaises with average deviations of 0.0052 from the measured a w , and bias and accuracy factors of 0.995 and 1.0057, respectively.

The exposure to fumonisins from the maize harvest of 2006 (before and after sorting and storage) for 67 families was assessed along with its statistical association with agronomic practices in Rombo, Tanzania. Fumonisins were determined by high-performance liquid chromatography (HPLC) and exposure estimated based on 60 kg body weight and maize intake of 356 g per person day-1. Based on contamination in the unsorted maize, exposure for 27% of the families would exceed the provisional maximum tolerable daily intake of 2 µg kg-1 body weight. The odds ratio of fumonisin exposure from maize hybrid 614 (H614) were: two times higher compared with non-H614 maize (p = 0.089); and five times higher when the maize was grown without fertilizer (p = 0.004). Sorting maize before storage reduced the percentage of families with unacceptable exposures to 6%. Therefore, the results imply that planting of the non-H614 seeds using fertilizers combined with pre-storage sorting of maize significantly minimizes fumonisins exposure in Rombo. A field experiment to verify these findings is needed.

Dendrograms generated after cluster analysis of the (GTG)5-PCR fingerprints of isolates from brand 1 to brand 6. (DOCX 197 kb)

Vietnamese catfish (Pangasius hypophthalmus) is highly appreciated in many European countries, the U.S., Canada, Japan etc. This paper presents an overview of the microbiota of frozen Vietnamese catfish products marketed in Belgium. Samples of Pangasius steaks, portions and fillets from six brands were collected from supermarkets located in Ghent, Belgium. The total psychrotrophic and mesophilic aerobic counts of the samples evaluated from each brand did not differ significantly (p > 0.05) and ranged from 3.8-5.2 log CFU/g and 3.8-4.8 log CFU/g, respectively. Lactic acid bacteria counts varied from 2.2 to 4.1 log CFU/g while the counts of presumptive Enterobacteriaceae ranged from 1.6 to 3.8 log CFU/g. A total of 132 isolates were collected from the plates used to enumerate the microbial parameters mentioned above. Fourteen different genera and 18 different species were identified by means of 16S rRNA gene sequencing. The most prevalent genera of Lactococcus (31.2 %), Staphylococcus (11.7 %), Serratia (10.4 %), Acinetobacter (9.1 %), Enterococcus (7.8 %) and Pseudomonas spp. (6.5 %) were identified by means of 16S rRNA gene sequencing. The results obtained provide an overview of the dominant microbiota on frozen Pangasius which is useful for the development of appropriate preservation techniques for thawed Pangasius products.

A dilution protocol originally developed for the isolation of single bacterial cells was modified to suite the specificities of fungal growth. The modified protocol was used to study the growth kinetics of single spores of Aspergillus flavus and Fusarium verticillioides on yellow dent corn meal. Both aw and temperature significantly influenced the distributions of the colony growth rates and lag phases and the rate at which individual spores of both isolates completed the lag period. An interaction between aw and temperature was noted on the spread of the distributions of these growth parameters. The histograms of the single spore colony growth rates and lag phases generally became wider the more compromising the conditions for growth became, indicating a greater variation in growth ability at these conditions. The rate at which the single spores passed through the lag phases generally decreased with decrease in temperature and/or aw, with an interaction again noted between these two factors on the rate. These results show the potential range and variability in growth of individual fungal spores at the lowest inoculum level possible.

The combined effects of water activity (a(w)) and ammonium/sodium bicarbonate on growth and mycotoxin production in corn by Fusarium and Aspergillus species were investigated. Interaction was observed between the salts and a(w) on the colony growth rates and lag phase durations of all isolates. Growth stimulation at low salt levels was observed only for the Fusarium isolates as the fastest growth of F. verticillioides and F. proliferatum occurred at levels of 0.1-0.2 and 0.5% ammonium and sodium bicarbonate, respectively. Although the complete inhibition of the growth of the Fusarium and Aspergillus isolates investigated took place at a level of 1% ammonium bicarbonate as much as 4% sodium bicarbonate failed to completely inhibit the growth of the Aspergillus isolates. Increase in concentration of either salt generally resulted in large reductions of both fumonisin B(1) and aflatoxin B(1) production. According to the sensorial analysis performed, corn treated with up to 1% ammonium bicarbonate was still acceptable for consumption, whereas corn treated with at least 2% sodium bicarbonate was determined to be sensorially unsuitable. Ammonium bicarbonate can be concluded to be more suitable for protecting stored corn from fungal contamination as it was capable of completely inhibiting both growth and mycotoxin production of the Fusarium and Aspergillus isolates of most importance to corn at levels that were still sensorially acceptable. Therefore ammonium bicarbonate could possibly be applied as a cheap and easy to apply treatment for use in resource limited developing countries.

The adsorption and desorption isotherms of yellow dent corn were determined at 25, 30 and 37 °C by the gravimetric method. The GAB, Oswin, Halsey, Henderson, Chung-Pfost and polynomial models were fitted to the experimental sorption data. The isotherms exhibited Type II behaviour and were temperature dependent as the equilibrium moisture content decreased with increase in temperature. Hysteresis was also observed at all temperatures investigated. According to the goodness of fit test applied, the GAB model best described the experimental data followed by the Oswin, Chung-Pfost, polynomial and Henderson models. The Halsey model was the least adequate. The monolayer moisture content was found to decrease with increasing temperature, and was higher for desorption than adsorption. The isosteric heat of sorption was determined using the Claussius–Clapeyron equation, and it was found to markedly decrease at the average temperatures investigated with increase in moisture content.

This study evaluated the effect of residual O2 level (0% to 5%) on microbial growth and volatile metabolite production on par-fried French fries packaged in a modified atmosphere with 60% CO2 (rest N2 ) at 4 °C. The results obtained showed that the initial headspace (IH) O2 level had an effect on growth of Leuconostoc mesenteroides on French fry simulation agar, whereby growth was slightly faster under 5% O2 . In terms of quantity, ethanol, 2-methyl-1-propanol, and dimethyl disulphide were the most significant volatile metabolites produced by L. mesenteroides. The production of ethanol by L. mesenteroides was highest on simulation agar packaged under low IH O2 levels (0% to 1%), indicating that the fermentative metabolism was induced under these conditions. In agreement with the results observed on the simulation medium, growth of native lactic acid bacteria was faster under an IH O2 level of 5%. In addition, ethanol, 2-methyl-1-propanol, and dimethyl disulphide were also quantitatively the most important volatile metabolites. However, in contrast, greater quantities of ethanol and dimethyl disulphide were produced on par-fried French fries packaged under 5% O2 . This was attributed to the limited growth of the native flora on the par-fried French fries under residual O2 levels of 0% and 1%. Although some significant differences (P0.05) occurred between the French fries packaged in 0%, 1%, and 5 % residual O2 during storage, all products were considered to be acceptable for consumption. The results of this study can be used to optimize the shelf-life of packaged chill stored potato products.

This study was undertaken to assess the microbiological quality of fresh-cut organic vegetables produced in Zambia. Fresh-cut organic mixed vegetables and green beans produced in Zambia were analysed for aerobic plate counts, coliforms, Enterobacteriaceae, Escherichia coli, Bacillus cereus, Clostridium perfringens, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, and yeast and mould counts. The study included 160 samples for most of the parameters. The vegetables were grown on farms meant primarily for the export market. The vegetables were treated/washed with 150 μg ml−1 chlorine solution at the processing plant prior to sampling. The aerobic plate count ranged between 3 log10 and 9.7 log10 CFU/g, with the highest count recorded for green beans. The largest grouping (26.1%) of vegetable samples fell between 3 and 4 log10 CFU/g. Coliform counts were between 1.0 log10 and 7.7 log10 CFU/g. The highest incidence level was 31.4% for total coliform counts between 3 log10 and 4 log10 CFU/g. E. coli was only detected on mixed vegetables in the range of 0.6 log10 to 3 log10 CFU/g, while Enterobacteriaceae counts ranged between 1.6 log10 and 9.8 log10 CFU/g with the highest counts being found on green beans. The highest incidence level was of 25.8% for counts within the same range as the aerobic plate counts. Yeast and mould counts showed the highest incidence level between 5 log10 and 6 log10 CFU/g with an overall range between 1.5 log10 and 5.6 log10 CFU/g. L. monocytogenes, Salmonella spp. and S. aureus were detected in 20%, 23.1% and 83.9% of samples, respectively . C. perfringens and B. cereus were not detected in any of the samples analysed.

The two major fumonisin-producing Fusarium species are Fusarium verticillioides and Fusarium proliferatum. The growth and fumonisin production of these two isolates on corn was studied at water activities (a(w)) between 0.860 and 0.975 and at temperatures between 15 and 30 degrees C. Growth rates (g, mm/day) were obtained by linear regression during the linear phase of growth. In general, growth rates for both isolates increased significantly (P < 0.05) with increases in a(w) and temperature. Both fumonisin production and radial growth (mycelial development) for both isolates increased with a(w) at all temperatures investigated, but the effect of temperature on this relationship was not obvious. The effect of temperature on fumonisin production at high a(w) values optimal for growth was only marginal, whereas at lower a(w) values the effect of temperature was more pronounced, with more fumonisin production occurring at temperatures not optimal for growth. The optimum temperature for fumonisin production was between 15 and 25 degrees C. For F. proliferatum, the optimum temperature for growth at all a(w) values, 30 degrees C, resulted in the poorest fumonisin production. For both isolates, the slowest initial rate of fumonisin production was at 15 degrees C, the temperature at which the slowest growth rates were obtained.

There are numerous factors that can have an impact on the microbial ecology and quality of frozen Pangasius hypophthalmus fillets during processing in Vietnam. The presence of spoilage bacteria along the processing line can shorten the shelf-life of thawed frozen fish products. Therefore, the spoilage microbiota throughout the processing chain of two companies (BC: large scale factory, chlorine-based process, BW: large scale factory, water-based process and SC: small scale factory, chlorine-based process) was identified by culture-dependent techniques and 16S rRNA gene sequencing. The microbiological counts were observed to be insignificantly different ( p > 0.05) between BC and BW. Surprisingly, chlorine treated fillets from the SC line were revealed to have significantly higher microbial counts than potable water treated fillets at BW line. This was determined to be a result of temperature abuse during processing at SC, with temperatures even greater than 10 °C being recorded from skinning onwards. On the contrary, the microbiota related to spoilage for BC and BW lines was determined by 16S rRNA gene sequencing to be more diverse than that on the SC line. A total of 174 isolates, 20 genera and 38 species were identified along the processing chains. The genera Aeromonas , Acinetobacter , Lactococcus and Enterococcus were prevalent at various processing steps on all the processing lines evaluated. A diverse range of isolates belonging to the Enterobacteriaceae such as Providencia , Shigella , Klebsiella , Enterobacter and Wautersiella were isolated from fillets sampled on the SC line whereas Serratia was only observed on fillets sampled on the BC and BW lines. The results can be used to improve Good Manufacturing Practices for processed Pangasius fillets and to select effective measures to prolong the shelf-life of thawed Vietnamese Pangasius fillets products.

This study evaluated the potential of modified atmospheres (MAs) combining high oxygen (O₂) and high carbon dioxide (CO₂) levels to extend the shelf-life of fresh-cut honeydew melon. Firstly, the effect of MA on the growth and volatile organic metabolite production of Candida sake, Leuconostoc mesenteroides and Leuconostoc gelidum, which had all been previously isolated from spoiled commercial fresh-cut honeydew melon, was evaluated separately on honeydew melon agar at 7 °C. Additionally, the effect of selected MAs on the microbial, physico-chemical and sensory quality of commercial fresh-cut honeydew melon cubes was evaluated at 7 °C. The results showed that MAs with high O₂ and high CO₂ levels greatly retarded the growth, CO₂ and volatile metabolite production (i.e. ethanol, 2-methyl-1-butanol, ethyl acetate, phenylacetic acid, nonanal) of C. sake on honeydew melon agar; especially MAs consisting of 50% O₂+50% CO₂ and 70% O₂+30% CO₂. In contrast, the MAs evaluated only had a minor effect on the growth and volatile metabolite production of L. mesenteroides and L. gelidum. Overall, the effect of MAs on colour, juice leakage, juiciness, and firmness of fresh-cut honeydew melon was small during storage. Sensory preference was generally for fresh-cut honeydew melon cubes packaged in MA of 50% O₂+50% CO₂. These were still acceptable on day five of storage and had appreciably lower populations of yeasts and lactic acid bacteria, lower quantities of volatile organic compounds, but slightly stronger colour oxidation compared to honeydew melon that was packaged in air. Additionally, most of the samples packed in air had blown by day five due to the large quantity of CO₂ production during storage. Therefore, 50% O₂+50% CO₂ is a potential MA solution for extending the shelf-life of fresh-cut honeydew melon.

Consumers are switching to fresh, minimally processed foods, creating challenges. The shift in food production from local to global has led to a complex logistics chain. These trends and challenges have induced the development of packaging materials with better barrier properties, and active and intelligent packaging. A recent trend is for the sustainability of food packaging. Modifi ed atmosphere or vacuum packaging gives a longer shelf life by reducing the growth of spoilage microorganisms and/or oxidation processes. This chapter focuses on modifi ed- atmosphere packaging (MAP). The effects of high and low O 2 , elevated CO 2 concentrations and equilibrium modifi ed- atmosphere packaging are considered. The infl uence on food infectants, toxin- producing bacteria and mycotoxins is discussed. Recent studies on MAP have had contradictory results, mostly from differences in experimental design and materials.

The major objective of this study was to evaluate and model the combined effect of the water activity (a(w)) and pH of the heating menstrum on the heat resistance of spores of a psychrotolerant Bacillus cereus strain isolated from béchamel sauce. Two models, a quadratic polynomial equation and a reparameterized function, were assessed for their ability to describe the combined influence of a(w) and pH on the D(85°C)-values of the B. cereus isolate in tryptone soy broth. The performance of the models was validated by challenging the models with data independently collected in broth and béchamel sauce. Both models were found to adequately describe the validation data obtained in broth. However, it was determined that in béchamel sauce the predictions of the polynomial function not only showed bias (bias factor = 1.156) but were also fail-dangerous, as they deviated from the validation data by 17.2%. The reparameterized function was determined to be a good predictor of the D(85°C)-values in béchamel sauce as it showed no bias (bias factor = 1.033) and its predictions differed by only 7.9% from the validation data. The reparameterized function can be used to provide estimates of the minimum processing conditions required to achieve desired levels of spore inactivation within the a(w) and pH ranges studied and to determine the potential changes in heat resistance of B. cereus spores when a(w) and pH are changed, for example, during product reformulation. As validation of heat resistance models is rarely performed, let alone in actual food products, the models evaluated and validated in this study (in particular the reparameterized function) are of immediate relevance to the food industry.

The major objectives of this study were to determine the incidence, diversity and characteristics of Bacillus cereus group spp. isolated from food products marketed in Belgium. The food products investigated in this study included cooked pasta, lasagna, bechamel sauce, bolognaise sauce, fresh minced beef, fresh-cut vegetables and raw basmati rice. B. cereus group spp. were detected in 56.3% (324 of 575) of the samples giving rise to 380 strains. The highest incidence (100%) occurred in the raw basmati rice. Although only 10 (2.6%) of the 380 isolates were determined to be psychrotolerant (able to grow at ≤7°C), 25 (6.2%), 189 (49.7%) and 334 (87.9%) isolates were able to grow at mild temperature abuse conditions of 8°C, 9°C and 10°C, respectively. The large diversity of the isolates obtained (overall and between isolates obtained from the same product type) was highlighted by the results of the (GTG)(5) PCR fingerprinting of 80 selected isolates. Sixty-one of these 80 isolates belonged to 15 distinct clusters (≥85% Pearson correlation) whereas the remaining 19 were each clustered separately. Further diversity was also found in the distribution of toxin genes as 16 different profiles were observed in the 80 selected isolates. Whilst none of 80 selected strains harboured the ces gene required for the production of the emetic toxin cereulide, 42 strains (52.5%) carried all seven genes required for the production of the diarrhoeal enterotoxins: haemolytic BL, non-haemolytic enterotoxin and cytotoxin K. The results of this study highlight not only the omnipresence but also the highly diverse ecology of B. cereus spp. within and across several food product types available on the retail market in Belgium. They should also provide the impetus for more studies to enable detailed risk assessment studies to be performed.

The growth inhibiting effects of NaCl and selected simple salt replacers (CaCl(2), MgCl(2), KCl and MgSO(4)) on the growth of Lactobacillus sakei were studied in de Man Rogosa Sharpe broth at 7 degrees C over a water phase concentration of 0 to 6.4%. The divalent chloride salts (CaCl(2) in particular) generally had the largest antimicrobial activities at equivalent water phase concentrations, molalities or water activity (a(w)) values. MgSO(4) had not only the least antimicrobial activity but also the smallest a(w) depressing capacity. The results also showed that the antimicrobial effects of CaCl(2) were not fully accounted for by its a(w) depressing effects. Challenge tests performed on cooked ham and white sauce showed that reduction of NaCl levels by 28 and 33%, respectively, had no influence on the microbial stability of these products to L. sakei. Ultimately the study concluded that the microbiological consequences of the full or partial replacement of NaCl on the growth of L. sakei largely depend on the initial level of NaCl, the level of replacement and the nature of the salt replacer used. Altered stability to L. sakei is most likely given a high initial NaCl level, combined with a large level of partial replacement with either CaCl(2) (increased stability) or MgSO(4) (reduced stability) as the replacer.

Feeding children with maize may expose them to fumonisins (FBs). This study assessed FB exposure for infants consuming maize in Tanzania by modeling maize consumption data (kg/kg body weight (bw)/day) with previously collected total FB contamination (microg/kg) patterns for sorted and unsorted maize harvested in 2005 and 2006. Consumption was estimated by twice conducting a 24 h dietary recall for 254 infants. The exposure assessment was performed with the @RISK analysis software. Of the infants, 89% consumed maize from 2.37 to 158 g/person/day (mean; 43 g/person/day +/- 28). Based on the contamination for sorted maize; in 2005, the percentage of infants with FB exposures above the provisional maximum tolerable daily intake (PMTDI) of 2 microg/kg (bw) (26% (95% confidence interval (CI); 23-30)) was significantly higher than the level of 3% (90% CI; 2-12) in 2006. Pooling the datasets for sorted maize from the two seasons resulted in a seemingly more representative risk (10% (95% CI; 6-17)) of exceeding the PMTDI. However, infants who might have consumed unsorted maize would still be at a significantly higher risk (24% (95% CI; 15-34)) of exceeding the PMTDI. Sorting and other good maize management practices should be advocated to farmers in order to minimize FB exposure in rural areas.