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BACKGROUND: Studies have shown that the consumption of apples has a beneficial effect on cardiovascular diseases and some cancers, largely as a result of their micronutrient and phytoconstituent contents. Apple peel not only contains more polyphenols than the flesh, but also is likely to contain pesticide residues. The present study aimed to compare the contents of certain micronutrients and residual pesticide levels in peeled and unpeeled apples. RESULTS: Peeled apples contained fewer pesticide residues at lower concentrations than unpeeled apples. However, whether samples were peeled or not, the exposure values for pesticide residues in apples never exceeded the acceptable daily intake (ADI), but ranged between 0.04% and 2.10% of the ADI in adults for food intake estimated at the 95th percentile (277 g per person per day). Determination of polyphenol, fibre, magnesium and vitamin C levels showed that the nutritional differences observed between peeled and unpeeled apples were marginal. CONCLUSION: The consumption of apples, such as the apples tested in the present study, results in an exposure to pesticides that is low for unpeeled apples, and lower for peeled apples. Moreover, there was no significant loss of nutritional value from eating peeled apples based on the nutrients investigated. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Fatty acids of two mesophilic and one psychrotrophic strains of the foodborne pathogen Bacillus cereus were analyzed by gas chromatography coupled to mass spectrometry during growth at cold (10 and 12°C) vs. optimal (30°C) temperatures and during the whole growth process (6–7 sampling times) from lag to stationary phase. In all these strains, a sequential change of fatty acids during cold growth was observed. Fatty acids were modified as soon as the end of lag, with an increase of the short-chain fatty acids (less than 15 carbons), particularly i13. These short-chain fatty acids then reached a maximum at the beginning of growth and eventually decreased to their initial level, suggesting their importance as a rapid cold adaptation mechanism for B. cereus. In a second step, an increase in Δ5,10 di-saturated fatty acids and in monounsaturated fatty acids in Δ5 position, at the expense of unsaturation in Δ10, started during exponential phase and continued until the end of stationary phase, suggesting a role in growth consolidation and survival at cold temperatures. Among these unsaturated fatty acids, those produced by unsaturation of n16 increased in the three strains, whereas other unsaturated fatty acids increased in some strains only. This study highlights the importance of kinetic analysis of fatty acids during cold adaptation. [ABSTRACT FROM AUTHOR]

Bacterial adaptation is characterized by a lag-phase during which cells do not multiply and modify their physiology to cope with the constraints of their environment. Our aim was to determine a sequence of events during the lag-phase of growth at low temperature and pH for three Bacillus cereus strains. The onsets of expression of two genes, essential for stress adaptation (cshA coding for a RNA helicase) or involved in the transition between lag and exponential phase (abrB coding for a transition regulator), were determined using fluorescent transcriptional reporter systems. Regardless of the stressing conditions and the tested strains, cshA promoter was active very early, while the biomass increased and always before the first cell division. At 12°C and pH 7.0, onset of cshA promoter activity occurred between 3 h and 7 h, while bacterial counts started between 12 h and 13 h. At pH 5.0 and at 20°C or 30°C, onset of cshA promoter activity occurred before 1 h and earlier than at pH 7.0. In contrast, the onset of abrB promoter activity depended on the strain and stressing conditions. In the ATCC 14579 strain, onset of abrB promoter activity always started between 30 min and 3 h, before biomass increased and cell division occurred. For the other strains, it took place along with the first cell division at 12°C, but much later during growth in the other tested conditions. [ABSTRACT FROM AUTHOR]

Bacterial spores are resistant to physical and chemical insults, which makes them a major concern for public health and industry. Spores help bacteria to survive extreme environmental conditions that vegetative cells cannot tolerate. Spore resistance and dormancy are important properties for applications in medicine, veterinary health, food safety, crop protection and other domains. The resistance of bacterial spores results from a protective multilayered structure and from the unique composition of the spore core. The mechanisms of sporulation and germination, the first stage after breaking of dormancy, and organization of spore structure have been extensively studied in Bacillus species. This review aims to illustrate how far the structure, composition and properties of spores are shaped by the environmental conditions in which spores form. We look at the physiological and molecular mechanisms underpinning how sporulation media and environment deeply affect spore yield, spore properties like resistance to wet heat and physical and chemical agents, germination and further growth. For example, spore core water content decreases as sporulation temperature increases, and resistance to wet heat increases. Controlling the fate of Bacillus spores is pivotal to controlling bacterial risks and process efficiencies in, for example, the food industry, and better control hinges on better understanding how sporulation conditions influence spore properties. [ABSTRACT FROM AUTHOR]

Abstract: The 3‐component hemolysin BL (Hbl) and non‐hemolytic enterotoxin (Nhe) are probably associated with Bacillus cereus diarrheal outbreaks. In this study, toxin transcription of 18 biochemically positive isolates isolated from 80 beef burgers containing different percentage of meat (30, 60, and 90%) were evaluated using PCR method. Bacterial growth curves were further obtained by Bioscreen C to predict B. cereus population of uncooked and fried burgers kept at refrigerator and at room temperatures. The results showed that 22.5% of beef burgers (18 of 80 burgers) were contaminated with B. cereus where 14/18 and 5/18 of the samples contaminated to B. cereus with Nhe and Hbl genes, respectively. No significant growth was observed in burgers stored at 4 °C, although after 8 hr the uncooked burgers and within 10 hr the fried burgers stored at 20 °C were considered as spoiled by reaching B. cereus counts of >106 cfu/g. Practical applications: Bacillus cereus is recognized as a causative agent of emetic and diarrheal foodborne poisoning. To differentiate the encoding chromosomal genes of Nhe (i.e., nheA, nheB, and nheC) and Hbl (i.e., hblC, hblD, and hblA), multiplex PCR was quite selective to perform. [ABSTRACT FROM AUTHOR]

Background Spore-forming bacteria are a major cause of food spoilage and food poisoning. Spores that resist physical and chemical treatments used in the food industry may germinate and multiply. Spore germination, outgrowth and growth constitute a complex and highly heterogeneous process. Scope and approach Various techniques and methods can be used to observe the germination, outgrowth and early multiplication process of spore-forming bacteria and/or to quantify the impact of environmental conditions on its progress over time within a spore population. These techniques can be classified by different criteria: (i) the scale of analysis, from populations or cells to molecules, and (ii) the number of analyzed objects (cells) and (iii) the potential of the method to describe and/or quantify the impact of lethal or sub-lethal treatments or environmental conditions. Such treatments are applied to a spore population or a single spore and take into account parameters at the cellular level (growth capacity, morphological properties) to molecular level (proteomics, transcriptomics, spore molecular composition). Key findings and conclusion A better understanding and quantification of the germination, outgrowth and growth process require the implementation of several complementary methods. Methods providing information at single and population levels, as well as at molecular and cellular levels, are essential to assess and control the fate of spore-forming bacteria development in food systems. [ABSTRACT FROM AUTHOR]

The resistance to pulsed light ( PL) of spores of Bacillus subtilis strain 168 and of strains with mutations increasing sensitivity to UV-C or affecting spore structure was evaluated and compared to resistance to continuous UV-C and moist heat, in order to reveal original mechanisms of inactivation by PL. Spores of B. subtilis strain 168 (1A1) and eight mutant strains ( sspA, sspB, ssp AB, cotA, gerE, cotE, uvrA and recA) were exposed to PL (up to 1.77 J cm−2), continuous UV-C (up to 147 mJ cm−2) and moist heat at 90°C. Spores of the strains lacking proteins linked to coat formation or structure ( cotA, gerE and cotE) were markedly more sensitive to PL than 1A1, while their sensitivity to continuous UV-C or to moist heat was similar to the one of strain 1A1. Coat proteins had a major contribution to the resistance of B. subtilis spores to PL irradiation characterized by short-time and high-energy pulses of white light in the wavelengths 200-1100 nm. In contrast the role of coat proteins to UV-C or to moist heat resistance was marginal or null. [ABSTRACT FROM AUTHOR]

Fermentation can contribute to improve functional aspects of foods. The first goal of this study was to determine amongst apple, grape and orange juices, the one with the best bacterial growth performance during fermentation by Lactobacillus strains from commercial and artisanal food origins, at 40 °C for 48 h. The juice with the highest bacterial growth was evaluated for bacteria viability during 4 weeks of cold storage, superoxide dismutase (SOD) activity and folates production analyzed through HPLC/fluorimetry. Acceptability of fermented juice was appraised through hedonic analysis. Lactobacilli counts were the highest in apple and the lowest in orange juices at t = 48 h. In most cases, bacteria counts were higher in fermented (5.5 to 9.5 log CFU/ml) than in supplemented apple juices (4.2 to 5.7 log CFU/ml), at the 4th week of cold storage. SOD activity was significantly increased in all apple juices fermented by commercial Lactobacilli strains. Folates were produced in apple juices fermented by Lactobacillus plantarum and Lactobacillus rhamnosus . Apple juice was the best substrate for Lactobacillus growth and, considering bacterial viability and overall acceptance by the panelists, Lactobacillus acidophilus L10 was the most suitable strain for apple juice fermentation. [ABSTRACT FROM AUTHOR]

The photoprotective potential of fungus pigments was investigated by irradiating conidiospores of three Aspergillus niger strains possessing the same genetic background, but differing in their degree of pigmentation with pulsed light ( PL) and monochromatic (254 nm) UV-C radiation. Spores of A. niger MA93.1 and JHP1.1 presenting, respectively, a fawn and a white pigmentation were more sensitive to PL and continuous UV-C radiation than the wild-type A. niger strain N402 possessing a dark pigment. Both spores of the dark A. niger N402 and the fawn-color mutant were equally resistant to moist heat at 56°C while spores of the white-color mutant were highly sensitive. These results indicate that melanin protects pigmented spores of A. niger from PL. [ABSTRACT FROM AUTHOR]

Abstract: The growth rates of strains covering the seven major phylogenetic groups of Bacillus cereus sensu lato (as defined by Guinebretiere et al., 2008) at a range of temperature (7 °C–55 °C), pH (4.6–7.5) and a w (0.929–0.996, with 0.5%–10% NaCl as humectant) were determined. Growth rates were fitted by non-linear regression to determine the cardinal parameters T min, Topt, T max, pHmin, pHopt, a wmin and μ opt. We showed that cardinal parameters reflected the differences in the temperature adaptation observed between B. cereus phylogenetic groups I to VII. The ability of growing at low pH (up to 4.3) or low a w (from a w 0.929 and up to 10% NaCl) varied among strains. The strains of groups III and VII, the most tolerant to heat, were also the most adapted to high NaCl (all strains growing at 8% NaCl) and the ones of groups I and VI the least adapted (no growth at 7% NaCl). All strains of groups II and VII were able to grow at pH 4.6, and only a few strains of group VI. Phenotypic differences between the two psychrotrophic groups II and VI were revealed by contrasted acid and salt tolerance. The cardinal values determined in this work were validated by comparing with cardinal parameters of a panel of strains published elsewhere and with predictions of growth in a range of foods. [Copyright &y& Elsevier]

The pulsed light produced by xenon flash lamps was applied to 65 to 67 °Brix sugar syrups artificially contaminated with suspensions of Saccharomyces cerevisiae and with spores of Bacillus subtilis, Geobacillus stearothermophilus, Alicyclobacillus acidoterrestris, and Aspergillus niger. The emitted pulsed light contained 18.5% UV radiation. At least 3-log reductions of S. cerevisiae, B. subtilis, G. stearothermophilus, and A. acidoterrestris suspended in 3-mm-deep volumes of sugar syrup were obtained with a fluence of the incident pulsed light equal to or less than 1.8 J/cm², and the same results were obtained for B. subtilis and A. acidoterrestris suspended in 10-ram-deep volumes of sugar syrup. A. niger spores would requfle a more intense treatment; for instance, the maximal log reduction was close to 1 with a fluence of the incident pulsed light of 1.2 J/cm². A flowthrough reactor with a flow rate of 320 ml/min and a flow gap of 2.15 mm was designed for pulsed light treatment of sugar syrup. Using this device, a 3-log reduction of A. acidoterrestris spores was obtained with 3 to 4 pulses of incident pulsed light at 0.91 J/cm² per sugar syrup volume. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial spores (= endospores) are common contaminants in foods. Sources of contamination in the food chain may include soil, faeces, animal feeds and food ingredients and processing chain themselves. Sporulation may occur in very diverse environments. The environment of sporulation has a strong influence on spore properties relevant for food quality and safety. [Copyright &y& Elsevier]

Abstract: Consequences of climate change on the ecology of pathogens are difficult to forecast. However changes affecting microorganisms will likely involve already known evolution or adaptation mechanisms. Bacillus cereus is a frequent cause of foodborne poisonings and is known as a soil borne bacterium. B. cereus may represent an interesting model to study the impact of climate change on foodborne pathogens. The B. cereus group (or B. cereus sensu lato) displays a wide diversity of strains recently distributed in seven major phylogenetic groups. B. cereus growth domains range from psychrotrophic to nearly thermophilic. Current climate selects B. cereus distribution: psychrotrophes are more common in cold areas, while mesophiles prevail in tropical soils. In response to external signals, B. cereus may adapt to changing environments by varied mechanisms. Some illustrations of the signal transduction systems (two-component systems, alternative σ factors) and of the mechanisms of B. cereus adaptation to major environmental factors (temperature, carbon source, redox potential and pH) are proposed. The environment of sporulation has an impact on spore properties; heat resistance is positively correlated with sporulation temperature. Surveillance needed to detect changes in the epidemiology of B. cereus foodborne poisonings as a consequence of climate change is discussed. [Copyright &y& Elsevier]

Transposon mutagenesis of Bacillus cereus ATCC 14579 yielded cold-sensitive mutants. Mutants of genes encoding enzymes of the central metabolism were affected by cold, but also by other stresses, such as pH or salt, whereas a mutant with transposon insertion in the promoter region of BC0259 gene, encoding a putative DEAD-box RNA helicase displaying homology with Escherichia coli CsdA and Bacillus subtilis CshA RNA helicases, was only cold-sensitive. Expression of the BC0259 gene at 10 °C is reduced in the mutant. Analysis of the 5′ untranslated region revealed the transcriptional start and putative cold shock-responsive elements. The role of this RNA helicase in the cold-adaptive response of B. cereus is discussed. [ABSTRACT FROM AUTHOR]

Abstract: One hundred representative strains of Bacillus cereus were selected from a total collection of 372 B. cereus strains using two typing methods (RAPD and FT-IR) to investigate if emetic toxin-producing hazardous B. cereus strains possess characteristic growth and heat resistance profiles. The strains were classified into three groups: emetic toxin (cereulide)-producing strains (n =17), strains connected to diarrheal foodborne outbreaks (n =40) and food–environment strains (n =43), these latter not producing the emetic toxin. Our study revealed a shift in growth limits towards higher temperatures for the emetic strains, regardless of their origin. None of the emetic toxin-producing strains were able to grow below 10 °C. In contrast, 11% (9 food–environment strains) out of the 83 non-emetic toxin-producing strains were able to grow at 4 °C and 49% at 7 °C (28 diarrheal and 13 food–environment strains). non-emetic toxin-producing strains. All emetic toxin-producing strains were able to grow at 48 °C, but only 39% (16 diarrheal and 16 food–environment strains) of the non-emetic toxin-producing strains grew at this temperature. Spores from the emetic toxin-producing strains showed, on average, a higher heat resistance at 90 °C and a lower germination, particularly at 7 °C, than spores from the other strains. No difference between the three groups in their growth kinetics at 24 °C, 37 °C, and pH 5.0, 7.0, and 8.0 was observed. Our survey shows that emetic toxin-producing strains of B. cereus have distinct characteristics, which could have important implication for the risk assessment of the emetic type of B. cereus caused food poisoning. For instance, emetic strains still represent a special risk in heat-processed foods or preheated foods that are kept warm (in restaurants and cafeterias), but should not pose a risk in refrigerated foods. [Copyright &y& Elsevier]

Food raw materials used in refrigerated processed foods of extended durability (REPFEDs) manufactured in France were surveyed for Clostridium botulinum types A, B and E using PCR–Enzyme-linked Immunosorbent assay (PCR–ELISA) and mouse bioassay for detection respectively of cells and toxins in enrichment broth. Portions of 25 to 50 g of food were analysed. A total of 8 out of the 102 samples of fish and shellfish, 12 out of the 143 samples of meat and poultry, 1 out of the 62 samples of aroma, sauce and gravy, 4 out of the 25 samples of thickening agents, 3 out of the 26 samples of dehydrated dairy ingredients, and none of the 65 samples of spices, herbs and dehydrated mushroom were positive for C. botulinum in PCR–ELISA, i.e., 6.6% of all the samples tested. The 28 positive samples comprised 10 type A, 10 type B, 4 with both types A and B, and 4 undetermined by PCR typing. No sample positive for type E was detected. Of the 28 samples positive in PCR–ELISA, 15 were also positive in the mouse bioassay. The MPN count was between 1 and 3 C. botulinum/kg of food, which is similar to or in the lower range of values reported in the literature. [Copyright &y& Elsevier]

The growth of proteolytic Clostridium botulinum from spore inocula and changes in spore counts in mushroom, broccoli, and potato purées were monitored. Four strains of proteolytic C. botulinum types A and B were inoculated separately at approximately 10[sup 4] spores per ml in nutrient broth and vegetable purées incubated at 15, 20, and 30°C for up to 52 days. The times for the cell populations to increase 1,000-fold (T[sub 1,000]) in the tested vegetables (1 to 5 days at 30°C, 3 to 16 days at 20°C, 7 to >52 days at 15°C) were similar to those for meat or fish. Only temperature significantly influenced growth rate. In contrast, the lag phase depended on the strains and media tested, in addition to temperature. Lag times and T[sub 1,000]s for proteolytic C. botulinum were longer for potato and broccoli purées than for mushroom purée. These differences were not related to different phs or redox potentials. The germination level, evaluated as the decrease in the spore count, was low. The addition of a germinant mixture (L-cysteine, L-alanine, and sodium lactate) to some strains inoculated in vegetable purées resulted in an increase in germination, suggesting a lack of germination-triggering agents in the vegetable purées. [ABSTRACT FROM AUTHOR]

Bacillus cereus and Geobacillus stearothermophilus are spore-forming bacteria of concern for the quality and safety of cocoa-based foods, because of their frequent occurrence in raw materials and the capability of spores to withstand heat processing. Cocktails of spores of B. cereus and G. stearothermophilus strains were separately inoculated on cocoa beans and nibs and roasted using a laboratory equipment at 110 °C, 125 °C and 140 °C for up to 600 min to simulate an industrial roasting process. The period of time needed for the first log-reduction δ for the spores of the cocktail of B. cereus in cocoa nibs at 110 °C, 125 °C and 140 °C were 92.2 min, 30.5 min, and 17.2 min, respectively. In cocoa beans at 110 °C, 125 °C and 140 °C δ -values were 148.5 min, 55.9 min, and 23.3 min. The δ -values for the spores of the cocktail of G. stearothermophilus in cocoa nibs at 110 °C, 125 °C, and 140 °C were 105.0 min, 39.6 min and 30.4 min, respectively, and 183.6 min, 76.2 min and 49.1 min in cocoa beans at the same temperatures, respectively. The a w of cocoa nibs and cocoa beans ranged between 0.687 and 0.753 before roasting, and between 0.355 and 0.528 after roasting, respectively. The roasting process on beans or nibs applied in the cocoa industry may have a limited effect on the inactivation of naturally present spore-forming bacteria. • The fate of B. cereus and G. stearothermophilus during cocoa roasting was studied. • Roasting at 110, 125 and 140 °C was applied in inoculated cocoa beans and nibs. • Heat-resistance of both bacteria was poorly affected by temperature increase. • Heat-resistance in cocoa beans/nibs exceed values reported in aqueous environment. • Differences in resistance between both bacteria during roasting were marginal. [ABSTRACT FROM AUTHOR]

Abstract: Microbial contamination on surfaces of food processing equipment is a major concern in industries. A new method to inoculate a single-cell layer (monolayer) of microorganisms onto polystyrene was developed, using a deposition with an airbrush. A homogeneous dispersion of Bacillus subtilis DSM 402 spores sprayed on the surface was observed using both plate count and scanning electron microscopy. No clusters were found, even with high spore concentrations (107 spores/inoculated surface). A monolayer of microorganisms was also obtained after deposition of 10μL droplets containing 3×104 spores/spot on polystyrene disks, but not with a higher spore concentration. Pulsed light (PL) applied to monolayers of B. subtilis spores allowed log reductions higher than 6. As a consequence of clusters formation in spots of 10μL containing more than 3×105 spores, log reductions obtained by PL were significantly lower. The comparative advantages of spot and spray depositions were discussed. [Copyright &y& Elsevier]

Abstract: The optimal growth rate µ opt of Listeria monocytogenes in minimally processed (MP) fresh leafy salads was estimated with a hierarchical Bayesian model at (mean±standard deviation) 0.33±0.16 h−1. This µ opt value was much lower on average than that in nutrient broth, liquid dairy, meat and seafood products (0.7–1.3 h−1), and of the same order of magnitude as in cheese. Cardinal temperatures T min, T opt and T max were determined at −4.5±1.3 °C, 37.1±1.3 °C and 45.4±1.2 °C respectively. These parameters were determined from 206 growth curves of L. monocytogenes in MP fresh leafy salads (lettuce including iceberg lettuce, broad leaf endive, curly leaf endive, lamb''s lettuce, and mixtures of them) selected in the scientific literature and in technical reports. The adequacy of the model was evaluated by comparing observed data (bacterial concentrations at each experimental time for the completion of the 206 growth curves, mean log10 increase at selected times and temperatures, L. monocytogenes concentrations in naturally contaminated MP iceberg lettuce) with the distribution of the predicted data generated by the model. The sensitivity of the model to assumptions about the prior values also was tested. The observed values mostly fell into the 95% credible interval of the distribution of predicted values. The µ opt and its uncertainty determined in this work could be used in quantitative microbial risk assessment for L. monocytogenes in minimally processed fresh leafy salads. [Copyright &y& Elsevier]

Abstract: The effect of sporulation temperature on Bacillus cereus spore germination triggered by the nutrient germinants inosine and l-alanine was investigated. The germination (expressed as % A 600nm fall) of heat-activated spores of B. cereus strain ATCC14579 produced at 20 and 37°C, and of psychrotrophic strains LM9 and D15 produced at 15 and 37°C was followed in a germination buffer containing inosine at concentrations between 0.01 and 10mmoll−1, or l-alanine between 1 and 100mmoll−1. Spores wet-heat resistance at 90°C was also determined. Spores of the three strains produced at the lowest temperatures generally showed a higher germination capacity in response to both inosine and in l-alanine than those produced at 37°C, and were also more susceptible to heat. Low sporulation temperature is confirmed as a detrimental factor to B. cereus spore wet-heat resistance, and conversely gave spores with a sensitivity to the nutrient germinants inosine and l-alanine higher than that of spores formed close to the maximal sporulation temperature. [Copyright &y& Elsevier]

The acid tolerance of foodborne pathogen Bacillus cereus TZ415 was examined. B. cereus was more tolerant to an acid challenge at pH 4.0 when cells were grown at low pH in regulated batch cultures of rich J Broth (JB) medium. The pH-inducible acid tolerance response (ATR) was maximal at pH 5.0, a sublethal growth condition inducing a remarkable cell elongation. During growth at regulated pH 7.0 and 6.0, B. cereus TZ415 became more acid sensitive from lag to stationary growth phase and the acid tolerance of cells reached its maximum level in late-stationary growth phase. The ATR induced at pH 5.5 and 5.0 was not affected by growth phase. Cellular protein profiles were analysed as a function of growth phase and medium pH. The Hemolysin BL (HBL) enterotoxin was only detected when cells were grown at pH 7.0. [Copyright &y& Elsevier]

Alkalization is a step of cocoa processing and consists of the use of alkali and high temperature to improve the sensorial and technological qualities of cocoa. Intense food processing can select spores, which can compromise safety and quality of the final product. Thus, the aim of this study was to evaluate the fate of B. cereus and G. stearothermophilus spores during the alkalization of pre-roasted (Pr) nibs (held at 120 °C) and unroasted (Ur) nibs (held at 90 °C) using potassium carbonate (0, 2, 4 and 6% w/w). In all conditions, log-linear inactivation kinetics with a tail was observed. The inactivation rate (k max) for B. cereus varied from 0.065 to 1.67 min−1, whereas the k max for G. stearothermophilus varied from 0.012 to 0.063 min−1. For both microorganisms, the lowest k max values were observed during Ur nibs alkalization. The carbonate concentration increase promoted k max values reduction. The highest tail values were observed for G. stearothermophilus in Ur nibs alkalization, reaching 3.04 log spores/g. Tail formation and low k max values indicated that cocoa alkalization does not cause significant reductions on bacterial spore population. Therefore, the microbiological control should be primarily ensured by the raw material quality and by avoiding recontamination in the cocoa chain. • Inactivation of SB in Pr (120 °C)/Ur (90 °C) with K 2 CO 3 (0–6%) were non log-linear. • Larger variations of k max for B. cereus than for G. stearothermophilus. • Pr nibs alkalization led to greater reduction of SB than Ur nibs alkalization. • For both SB, the lowest k max values were observed during Ur nibs alkalization. • Increase of K 2 CO 3 concentration led to reduction of k max values. [ABSTRACT FROM AUTHOR]

Fresh produce has been a growing cause of food borne outbreaks world-wide prompting the need for safer production practices. Yet fresh produce agrifood systems are diverse and under constraints for more sustainability. We analyze how measures taken to guarantee safety interact with other objectives for sustainability, in light of the diversity of fresh produce agrifood systems. The review is based on the publications at the interface between fresh produce safety and sustainability, with sustainability defined by low environmental impacts, food and nutrition security and healthy life. The paths for more sustainable fresh produce are diverse. They include an increased use of ecosystem services to e.g. favor predators of pests, or to reduce impact of floods, to reduce soil erosion, or to purify run-off waters. In contrast, they also include production systems isolated from the environment. From a socio-economical view, sustainability may imply maintaining small tenures with a higher risk of pathogen contamination. We analyzed the consequences for produce safety by focusing on risks of contamination by water, soil, environment and live stocks. Climate change may increase the constraints and recent knowledge on interactions between produce and human pathogens may bring new solutions. Existing technologies may suffice to resolve some conflicts between ensuring safety of fresh produce and moving towards more sustainability. However, socio-economic constraints of some agri-food systems may prevent their implementation. In addition, current strategies to preserve produce safety are not adapted to systems relying on ecological principles and knowledge is lacking to develop the new risk management approaches that would be needed. [ABSTRACT FROM AUTHOR]

Changes in vitamin C concentration along the processing chain of canned green beans were predicted with a probabilistic and modular process model using vitamin C concentrations in raw green beans, constants of chemical reactions (activation energy, reaction rates and diffusivity) and process descriptors (time and temperature, dissolved oxygen concentration). The model accounts for the statistical uncertainty and/or variability of these quantities. The initial vitamin C concentration in green beans, partly established with n = 65 proper vitamin C assays, was (mean [variability interval at 95%]) 17 mg vitamin. 100 g −1 [4.1, 30.3] and markedly decreased to 7.5 mg 100 g −1 [0.6, 14.9] after blanching, to 6.2 mg 100 g −1 [0.3, 12.5] after sterilization, and to 2.3 mg 100 g −1 [0, 5.6] after storage. The model predictions were globally on agreement with independent observations that include specific vitamins C assays (n = 26) at different steps of processing. [ABSTRACT FROM AUTHOR]

The Bacillus cereus spore surface layers consist of a coat surrounded by an exosporium. We investigated the interplay between the sporulation temperature and the CotE morphogenetic protein in the assembly of the surface layers of B. cereus ATCC 14579 spores and on the resulting spore properties. The cotE deletion affects the coat and exosporium composition of the spores formed both at the suboptimal temperature of 20°C and at the optimal growth temperature of 37°C. Transmission electron microscopy revealed that ΔcotE spores had a fragmented and detached exosporium when formed at 37°C. However, when produced at 20°C, ΔcotE spores showed defects in both coat and exosporium attachment and were susceptible to lysozyme and mutanolysin. Thus, CotE has a role in the assembly of both the coat and exosporium, which is more important during sporulation at 20°C. CotE was more represented in extracts from spores formed at 20°C than at 37°C, suggesting that increased synthesis of the protein is required to maintain proper assembly of spore surface layers at the former temperature. ΔcotE spores formed at either sporulation temperature were impaired in inosine-triggered germination and resistance to UV-C and H2O2 and were less hydrophobic than wild-type (WT) spores but had a higher resistance to wet heat. While underscoring the role of CotE in the assembly of B. cereus spore surface layers, our study also suggests a contribution of the protein to functional properties of additional spore structures. Moreover, it also suggests a complex relationship between the function of a spore morphogenetic protein and environmental factors such as the temperature during spore formation. [ABSTRACT FROM AUTHOR]

Hydrosols are hydrodistillation products of aromatic plants. They contain less than 1 g/L of dispersed essential oils giving organoleptic properties. Hydrosols are subjected to microbial proliferation. Reasons for spoilage have to be found in the nature of substrates supporting growth and of microbiological contaminants. The composition in essential oils and the microbiota of 22 hydrosol samples of Citrus aurantium L. ssp. amara L. (orange blossom), Rosa damascena Miller (rose D.), and Rosa centifolia L. (rose C.) flowers were analyzed to determine the factors responsible for decay. The median concentrations in essential oils were 677 mg/L for orange blossom hydrosols, 205 mg/L for rose D. hydrosols, and 116 mg/L for rose C. hydrosols. The dry matter content of these hydrosols varied between 4.0 mg/L and 702 mg/L, and the carbohydrate content varied between 0.21 mg/L and 0.38 mg/L. These non-volatile compounds were likely carried over during distillation by a priming and foaming effect, and could be used as nutrients by microorganisms. A microbial proliferation at ambient temperature and also at 5 °C has been observed in all studied hydrosols when stored in a non-sterile container. In contaminated hydrosols, maximal counts were about 7 log 10 CFU/mL, while the French pharmacopeia recommends a maximal total bacterial count of 2 log 10 CFU/mL. Neither yeast nor mold was detected. The isolated microbial population was composed of environmental Gram-negative bacteria, arranged in four major genera: Pseudomonas sp., Burkholderia cepacia complex, and presumably two new genera belonging to Acetobacteraceae and Rhodospirillaceae . Among those bacteria, Burkholderia vietnamiensis and Novosphingobium capsulatum were able to metabolize volatile compounds, such as geraniol to produce 6-methyl-5-hepten-2-one or geranic acid, or phenylethyl acetate to produce 2-phenylethanol. EO concentrations in hydrosols or cold storage are not sufficient to insure microbiological stability. Additional hurdles such as chemical preservatives or aseptic packaging will be necessary to insure microbial stability. [ABSTRACT FROM AUTHOR]

Spoilage of low-acid canned food during prolonged storage at high temperatures is caused by heat resistant thermophilic spores of strict or facultative bacteria. Here, we performed a bacterial survey over two consecutive years on the processing line of a French company manufacturing canned mixed green peas and carrots. In total, 341 samples were collected, including raw vegetables, green peas and carrots at different steps of processing, cover brine, and process environment samples. Thermophilic and highly-heat-resistant thermophilic spores growing anaerobically were counted. During vegetable preparation, anaerobic spore counts were significantly decreased, and tended to remain unchanged further downstream in the process. Large variation of spore levels in products immediately before the sterilization process could be explained by occasionally high spore levels on surfaces and in debris of vegetable combined with long residence times in conditions suitable for growth and sporulation. Vegetable processing was also associated with an increase in the prevalence of highly-heat-resistant species, probably due to cross-contamination of peas via blanching water. Geobacillus stearothermophilus M13-PCR genotypic profiling on 112 isolates determined 23 profile-types and confirmed process-driven cross-contamination. Taken together, these findings clarify the scheme of contamination pathway by thermophilic spore-forming bacteria in a vegetable cannery. [ABSTRACT FROM AUTHOR]

Geobacillus stearothermophilus is the main thermophilic spore former involved in flat sour spoilage of canned foods. Three typing methods were tested and applied to differentiate strains at intra-species level: panC sequence analysis, REP-PCR and M13-PCR. panC gene was highly conserved within the studied strains, suggesting a low intra-specific diversity. This was supported by REP-PCR primary assays and M13-PCR results. M13-PCR profile analysis succeeded in differentiating six closely related groups (at 79% threshold similarity) among 127 strains from a range of spoiled canned food products and from different canneries. Phenotypic traits were investigated among 20 selected strains representing groups and origins. Ranges of growth under different temperatures (from 40 °C to 70 °C), pH (from 5.0 to 6.5), NaCl concentrations (from 1 to 5%) and sporulation conditions poorly differed between strains, but wet heat resistance of spores showed a 20-fold variation between strains. Furthermore, in this study, strains that belonged to the same M13-PCR genetic group did not share phenotypic characteristics or common origin. The work emphasizes a low diversity within the G. stearothermophilus species but data from this study may contribute to a better control of G. stearothermophilus spoilage in canned food. [ABSTRACT FROM AUTHOR]

Abstract: Microbial spoilage of canned foods by thermophilic and highly heat-resistant spore-forming bacteria, such as Geobacillus stearothermophilus, is a persistent problem in the food industry. An incubation test at 55°C for 7days, then validation of biological stability, is used as an indicator of compliance with good manufacturing practices. We propose a microbial risk assessment model predicting the percentage of non-stability due to G. stearothermophilus in canned green beans manufactured by a French company. The model accounts for initial microbial contaminations of fresh unprocessed green beans with G. stearothermophilus, cross-contaminations in the processing chain, inactivation processes and probability of survival and growth. The sterilization process is modeled by an equivalent heating time depending on sterilization value F 0 and on G. stearothermophilus resistance parameter zT . Following the recommendations of international organizations, second order Monte-Carlo simulations are used, separately propagating uncertainty and variability on parameters. As a result of the model, the mean predicted non-stability rate is of 0.5%, with a 95% uncertainty interval of [0.1%; 1.2%], which is highly similar to data communicated by the French industry. A sensitivity analysis based on Sobol indices and some scenario tests underline the importance of cross-contamination at the blanching step, in addition to inactivation due to the sterilization process. [Copyright &y& Elsevier]

Abstract: The main human sources of carotenoids are fruits and vegetables. Some bacteria also synthesise carotenoids that can have peculiar chemical structures that raise the question of their bioavailability in humans. Bacillus indicus HU36 and Bacillus firmus GB1 strains contain glycosyl carotenoids that are partially acylated by linear fatty acids. The aim of the present study was to assess the bioaccessibility, the uptake efficiency and the tissue distribution of these bacterial carotenoids. β-carotene was used as a model carotenoid for comparisons. Results of in vitro digestion experiments showed that bioaccessibility of purified extracts of bacterial carotenoids was considerably higher (about 4.5 times as high) than that of pure β-carotene. Bacterial carotenoids were also bioaccessible when digested from their natural matrices, but about 2 times less than their purified extracts. Bacterial carotenoids were absorbed by Caco-2 with similar efficiency as β-carotene, i.e. about 10%. Bacterial carotenoids were recovered in significant amounts in their native chemical forms in plasma, liver and in adipose tissue of rats, which were force-fed for 3days with either bacterial carotenoid extracts or lyophilised bacteria. Bacterial carotenoids were found at higher concentrations in rat tissues than β-carotene, about 2–3 times for GB1 carotenoids and 9 times for HU36 carotenoids. They were also more recovered in adipose tissue than β-carotene. In conclusion, glycosyl carotenoids from the HU36 and GB1 Bacillus strains are readily bioavailable. This is due in part to their higher bioaccessibility but perhaps also due to their easier accumulation in tissues. [Copyright &y& Elsevier]

Abstract: Predicting microbial survival requires reference parameters for each micro-organism of concern. When data are abundant and publicly available, a meta-analysis is a useful approach for assessment of these parameters, which can be performed with hierarchical Bayesian modeling. Geobacillus stearothermophilus is a major agent of microbial spoilage of canned foods and is therefore a persistent problem in the food industry. The thermal inactivation parameters of G. stearothermophilus (Dref , i.e.the decimal reduction time D at the reference temperature 121.1°C and pH 7.0, zT and zpH ) were estimated from a large set of 430 D values mainly collected from scientific literature. Between-study variability hypotheses on the inactivation parameters Dref , zT and zpH were explored, using three different hierarchical Bayesian models. Parameter estimations were made using Bayesian inference and the models were compared with a graphical and a Bayesian criterion. Results show the necessity to account for random effects associated with between-study variability. Assuming variability on Dref , zT and zpH , the resulting distributions for Dref , zT and zpH led to a mean of 3.3min for Dref (95% Credible Interval CI=[0.8; 9.6]), to a mean of 9.1°C for zT (CI=[5.4; 13.1]) and to a mean of 4.3 pH units for zpH (CI=[2.9; 6.3]), in the range pH 3 to pH 7.5. Results are also given separating variability and uncertainty in these distributions, as well as adjusted parametric distributions to facilitate further use of these results in aqueous canned foods such as canned vegetables. [Copyright &y& Elsevier]