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Ziziphus mauritiana (masau) fruits are consumed by many people in Zimbabwe. The fruits contribute significantly to people's diet when they are in season. The objective of this study was to determine the nutritional content of the fruits and, hence, quantify their contribution to the diet. Samples of masau were collected in two seasons (August 2006 and August 2007). Both macronutrients and micronutrients were determined using standard AOAC methods of analysis. Dry matter content ranged from 21.1+/-0.2 to 24.1+/-0.3 g 100 g(-1) of edible portion of the sweet and sour fruits, and 84.8+/-0.2 to 87.2+/-0.2 g 100 g(-1) for the dried fruit. Crude protein per 100g edible portion of dry weight ranged between 7.9+/-0.0 and 8.7+/-0.0 g, crude fat from 0.8+/-0.0 to 1.5+/-0.0 g, crude fibre from 4.9+/-0.0 to 7.3+/-0.0 g, ash between 3.0+/-0.0 and 4.3+/-0.0 g and carbohydrate between 79.5+/-0.0 and 83.2+/-0.0 g. The fruits were rich in vitamin C (15.0+/-0.0-43.8+/-0.02 mg 100 g(-1)) and the energy values ranged between 1516.0+/-1.73 and 1575.0+/-2.3 kJ 100 g(-1). Furthermore, the fruits contained (mg 100 g(-1) of dry weight) potassium from 1865.0+/-1.3 to 2441.0+/-1.1, calcium from 160.0+/-0.3 to 254.0+/-0.1, sodium between 185.0+/-0.1 and 223.0+/-0.2, magnesium between 83.0+/-0.0 and 150.0+/-0.13 and phosphorous from 87.0+/-0.1 to 148.0+/-0.5. Manganese and copper contents ranged between 0.7+/-0.03 and 1.6+/-0.03, while iron and zinc ranged between 2.1+/-0.43 and 4.3+/-0.1, and 0.6+/-0.0-0.9+/-0.0 mg 100 g(-1) of dry weight, respectively. The masau fruit is therefore a good potential source of carbohydrates, proteins and micronutrients, such as calcium, potassium, sodium, phosphorous, copper, iron, Vitamin C and zinc., Ziziphus mauritiana (masau) fruits are consumed by many people in Zimbabwe. The fruits contribute significantly to people's diet when they are in season. The objective of this study was to determine the nutritional content of the fruits and, hence, quantify their contribution to the diet. Samples of masau were collected in two seasons (August 2006 and August 2007). Both macronutrients and micronutrients were determined using standard AOAC methods of analysis. Dry matter content ranged from 21.1+/-0.2 to 24.1+/-0.3 g 100 g(-1) of edible portion of the sweet and sour fruits, and 84.8+/-0.2 to 87.2+/-0.2 g 100 g(-1) for the dried fruit. Crude protein per 100g edible portion of dry weight ranged between 7.9+/-0.0 and 8.7+/-0.0 g, crude fat from 0.8+/-0.0 to 1.5+/-0.0 g, crude fibre from 4.9+/-0.0 to 7.3+/-0.0 g, ash between 3.0+/-0.0 and 4.3+/-0.0 g and carbohydrate between 79.5+/-0.0 and 83.2+/-0.0 g. The fruits were rich in vitamin C (15.0+/-0.0-43.8+/-0.02 mg 100 g(-1)) and the energy values ranged between 1516.0+/-1.73 and 1575.0+/-2.3 kJ 100 g(-1). Furthermore, the fruits contained (mg 100 g(-1) of dry weight) potassium from 1865.0+/-1.3 to 2441.0+/-1.1, calcium from 160.0+/-0.3 to 254.0+/-0.1, sodium between 185.0+/-0.1 and 223.0+/-0.2, magnesium between 83.0+/-0.0 and 150.0+/-0.13 and phosphorous from 87.0+/-0.1 to 148.0+/-0.5. Manganese and copper contents ranged between 0.7+/-0.03 and 1.6+/-0.03, while iron and zinc ranged between 2.1+/-0.43 and 4.3+/-0.1, and 0.6+/-0.0-0.9+/-0.0 mg 100 g(-1) of dry weight, respectively. The masau fruit is therefore a good potential source of carbohydrates, proteins and micronutrients, such as calcium, potassium, sodium, phosphorous, copper, iron, Vitamin C and zinc.

Yeast strains were characterized to select potential starter cultures for the production of masau fermented beverages. The yeast species originally isolated from Ziziphus mauritiana (masau) fruits and their traditionally fermented fruit pulp in Zimbabwe were examined for their ability to ferment glucose and fructose using standard broth under aerated and non-aerated conditions. Most Saccharomyces cerevisiae strains were superior to other species in ethanol production. The best ethanol producing S. cerevisiae strains, and strains of the species Pichia kudriavzevii, Pichia fabianii and Saccharomycopsis fibuligera were tested for production of flavor compounds during fermentation of masau fruit juice. Significant differences in the production of ethanol and other volatile compounds during fermentation of masau juice were observed among and within the four tested species. Alcohols and esters were the major volatiles detected in the fermented juice. Trace amounts of organic acids and carbonyl compounds were detected. Ethyl hexanoate and ethyl octanoate were produced in highest amounts as compared to the other volatile compounds. S. cerevisiae strains produced higher amounts of ethanol and flavor compounds as compared to the other species, especially fatty acid ethyl esters that provide the major aroma impact of freshly fermented wines. The developed library of characteristics can help in the design of mixtures of strains to obtain a specific melange of product functionalities., Yeast strains were characterized to select potential starter cultures for the production of masau fermented beverages. The yeast species originally isolated from Ziziphus mauritiana (masau) fruits and their traditionally fermented fruit pulp in Zimbabwe were examined for their ability to ferment glucose and fructose using standard broth under aerated and non-aerated conditions. Most Saccharomyces cerevisiae strains were superior to other species in ethanol production. The best ethanol producing S. cerevisiae strains, and strains of the species Pichia kudriavzevii, Pichia fabianii and Saccharomycopsis fibuligera were tested for production of flavor compounds during fermentation of masau fruit juice. Significant differences in the production of ethanol and other volatile compounds during fermentation of masau juice were observed among and within the four tested species. Alcohols and esters were the major volatiles detected in the fermented juice. Trace amounts of organic acids and carbonyl compounds were detected. Ethyl hexanoate and ethyl octanoate were produced in highest amounts as compared to the other volatile compounds. S. cerevisiae strains produced higher amounts of ethanol and flavor compounds as compared to the other species, especially fatty acid ethyl esters that provide the major aroma impact of freshly fermented wines. The developed library of characteristics can help in the design of mixtures of strains to obtain a specific melange of product functionalities.

Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen- Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture-independent approaches (PCR-DGGE). A total of 190 microbial strains, comprising 109 bacteria and 81 yeasts and moulds, were isolated and identified on the basis of the sequences of their 16S rDNA (bacteria) and 26S rDNA and ITS regions (fungi). DGGE of DNA extracted from Daqu was used to complement the culture-dependent method in order to include non-culturable microbes. Both approaches revealed that Bacillus licheniformis was an abundant bacterial species, and Saccharomycopsis fibuligera, Wickerhamomyces anomalus, and Pichia kudriavzevii were the most common yeasts encountered in Fen- Daqu. Six genera of moulds (Absidia, Aspergillus, Mucor, Rhizopus, Rhizomucor and Penicillium) were found. The potential function of these microorganisms in starters for alcoholic fermentation is discussed. In general the culture-based findings overlapped with those obtained by DGGE by a large extent. However, Weissella cibaria, Weissella confusa, Staphylococcus saprophyticus, Enterobacter aerogenes, Lactobacillus sanfranciscensis, Lactobacillus lactis, and Bacillus megaterium were only revealed by DGGE. © 2012 Elsevier Ltd., Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen- Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture-independent approaches (PCR-DGGE). A total of 190 microbial strains, comprising 109 bacteria and 81 yeasts and moulds, were isolated and identified on the basis of the sequences of their 16S rDNA (bacteria) and 26S rDNA and ITS regions (fungi). DGGE of DNA extracted from Daqu was used to complement the culture-dependent method in order to include non-culturable microbes. Both approaches revealed that Bacillus licheniformis was an abundant bacterial species, and Saccharomycopsis fibuligera, Wickerhamomyces anomalus, and Pichia kudriavzevii were the most common yeasts encountered in Fen- Daqu. Six genera of moulds (Absidia, Aspergillus, Mucor, Rhizopus, Rhizomucor and Penicillium) were found. The potential function of these microorganisms in starters for alcoholic fermentation is discussed. In general the culture-based findings overlapped with those obtained by DGGE by a large extent. However, Weissella cibaria, Weissella confusa, Staphylococcus saprophyticus, Enterobacter aerogenes, Lactobacillus sanfranciscensis, Lactobacillus lactis, and Bacillus megaterium were only revealed by DGGE. © 2012 Elsevier Ltd.

Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen-Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture-independent approaches (PCR–DGGE). A total of 190 microbial strains, comprising 109 bacteria and 81 yeasts and moulds, were isolated and identified on the basis of the sequences of their 16S rDNA (bacteria) and 26S rDNA and ITS regions (fungi). DGGE of DNA extracted from Daqu was used to complement the culture-dependent method in order to include non-culturable microbes. Both approaches revealed that Bacillus licheniformis was an abundant bacterial species, and Saccharomycopsis fibuligera, Wickerhamomyces anomalus, and Pichia kudriavzevii were the most common yeasts encountered in Fen-Daqu. Six genera of moulds (Absidia, Aspergillus, Mucor, Rhizopus, Rhizomucor and Penicillium) were found. The potential function of these microorganisms in starters for alcoholic fermentation is discussed. In general the culture-based findings overlapped with those obtained by DGGE by a large extent. However, Weissella cibaria, Weissella confusa, Staphylococcus saprophyticus, Enterobacter aerogenes, Lactobacillus sanfranciscensis, Lactobacillus lactis, and Bacillus megaterium were only revealed by DGGE

We sampled a cocoa powder production line to investigate the impact of processing on the microbial community size and diversity at different stages. Classical microbiological methods were combined with 16S rRNA gene PCR-denaturing gradient gel electrophoresis, coupled with clone library construction, to analyze the samples. Aerobic thermoresistant spores (ThrS) (100°C; 10 min) were also isolated and characterized (identity, genetic diversity, and spore heat resistance), in view of their relevance to the quality of downstream heat-treated cocoa-flavored drinks. In the nibs (broken, shelled cocoa beans), average levels of total aerobic microorganisms (TAM) (4.4 to 5.6 log CFU/g) and aerobic total spores (TS) (80°C; 10 min; 4.3 to 5.5 log CFU/g) were significantly reduced (P <0.05) as a result of alkalizing, while fungi (4.2 to 4.4 log CFU/g) and Enterobacteriaceae (1.7 to 2.8 log CFU/g) were inactivated to levels below the detection limit, remaining undetectable throughout processing. Roasting further decreased the levels of TAM and TS, but they increased slightly during subsequent processing. Molecular characterization of bacterial communities based on enriched cocoa samples revealed a predominance of members of the Bacillaceae, Pseudomonadaceae, and Enterococcaceae. Eleven species of ThrS were found, but Bacillus licheniformis and the Bacillus subtilis complex were prominent and revealed great genetic heterogeneity. We concluded that the microbiota of cocoa powder resulted from microorganisms that could have been initially present in the nibs, as well as microorganisms that originated during processing. B. subtilis complex members, particularly B. subtilis subsp. subtilis, formed the most heat-resistant spores. Their occurrence in cocoa powder needs to be considered to ensure the stability of derived products, such as ultrahigh-temperature-treated chocolate drinks.

The aim of this research was to determine the decimal reduction times of bacteria present on chicken fillet in boiling water. The experiments were conducted with Campylobacter jejuni, Salmonella, and Escherichia coli. Whole chicken breast fillets were inoculated with the pathogens, stored overnight (4°C), and subsequently cooked. The surface temperature reached 70°C within 30¿sec and 85°C within one minute. Extremely high decimal reduction times of 1.90, 1.97, and 2.20¿min were obtained for C. jejuni, E. coli, and S. typhimurium, respectively. Chicken meat and refrigerated storage before cooking enlarged the heat resistance of the food borne pathogens. Additionally, a high challenge temperature or fast heating rate contributed to the level of heat resistance. The data were used to assess the probability of illness (campylobacteriosis) due to consumption of chicken fillet as a function of cooking time. The data revealed that cooking time may be far more critical than previously assumed

Environmental surfaces contaminated with pathogens can be sources of indirect transmission, and cleaning and disinfection are common interventions focused on reducing contamination levels. We determined the efficacy of cleaning and disinfection procedures for reducing contamination by noroviruses, rotavirus, poliovirus, parechovirus, adenovirus, influenza virus, Staphylococcus aureus, and Salmonella enterica from artificially contaminated stainless steel surfaces. After a single wipe with water, liquid soap, or 250-ppm free chlorine solution, the numbers of infective viruses and bacteria were reduced by 1 log10 for poliovirus and close to 4 log10 for influenza virus. There was no significant difference in residual contamination levels after wiping with water, liquid soap, or 250-ppm chlorine solution. When a single wipe with liquid soap was followed by a second wipe using 250- or 1,000-ppm chlorine, an extra 1- to 3-log10 reduction was achieved, and except for rotavirus and norovirus genogroup I, no significant additional effect of 1,000 ppm compared to 250 ppm was found. A reduced correlation between reduction in PCR units (PCRU) and reduction in infectious particles suggests that at least part of the reduction achieved in the second step is due to inactivation instead of removal alone. We used data on infectious doses and transfer efficiencies to estimate a target level to which the residual contamination should be reduced and found that a single wipe with liquid soap followed by a wipe with 250-ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested.

1 april 2011, Item does not contain fulltext, Stable high-hydrostatic-pressure (HHP)-resistant Listeria monocytogenes LO28 variants were previously isolated and characterized. These HHP variants were also more resistant to heat. In addition, nonlinear heat inactivation kinetics pointed toward the existence of heat-resistant variants, although these could not be isolated so far. In this study, we used kinetic modeling of inactivation curves of two isolated HHP variants and their wild type, and this revealed that the probability of finding resistant variants should depend on the nature of the inactivation treatment and the time of exposure. At specific heat and HHP conditions, resistant LO28 and EGDe variants were indeed isolated. Resistant LO28 variants were even isolated after a heat inactivation at 72 degrees C in milk, and these variants showed high resistance to standard pasteurization conditions. The increased resistance of part of the isolated LO28 and EGDe variants was due to mutations in their ctsR genes. For the variants whose ctsR genes and upstream regions were not altered, the mechanisms leading to increased resistance remain to be elucidated. This research showed the strength of kinetic modeling in unraveling the causes of nonlinear inactivation and facilitating the isolation of heat-resistant L. monocytogenes variants.

To establish a link between governmental food safety control and operational food safety management, the concepts of the Appropriate Level of Protection (ALOP) and the Food Safety Objective (FSO) have been suggested by international bodies as a means of making food safety control transparent and quantifiable. The purpose of this study was to investigate how the concepts of ALOP and FSO could be applied in practice. As a case study, the risk of severe listeriosis due to consumption of deli meat products in the Netherlands was taken. The link between these concepts was explored for two situations following a “top-down” approach, using epidemiological country data as a starting point, and a “bottom-up” approach, using data on the prevalence and concentration of the pathogen at retail as a starting point. Models based on both approaches were able to describe the link between ALOP and FSO and our results showed that meaningful estimations are feasible, although interpretations need to be made with care. For the top-down approach, the mean estimated value derived for ALOP was 3.2 cases per million inhabitants per year (95% CrI: 1.1-6.6). For the bottom-up approach, ALOP values ranged considerably, 4.7-55 (with 95% CrI ranging from 2.9-162), depending on the input parameters selected. The level of detail considered in the stochastic models considerably influenced the ALOP and FSO estimates. As best practice it is recommended to develop both approaches, although depending on the application context one may appear more appropriate than the other.

The microbiological criteria of commercial cocoa powder are defined in guidelines instituted by the cocoa industry. Twenty-five commercial samples were collected with the aim of assessing the compliance with the microbiological quality guidelines and investigating the occurrence and properties of aerobic Thermoresistant Spores (ThrS). Seventeen samples complied with the guidelines, but one was positive for Salmonella, five for Enterobacteriaceae and two had mould levels just exceeding the maximum admissible level. The treatment of the cocoa powder suspensions from 100 °C to 170 °C for 10 min, revealed the presence of ThrS in 36% of the samples. In total 61 ThrS strains were isolated, of which the majority belonged to the Bacillus subtilis complex (65.6%). Strains resporulation and spore crops inactivation at 110 °C for 5 min showed a wide diversity of heat-resistance capacities. Amplified fragment length polymorphism analysis revealed not only a large intraspecies diversity, but also different clusters of heat-resistant spore-forming strains. The heat-resistance of spores of six B. subtilis complex strains was further examined by determination of their D and z-values. We concluded that B. subtilis complex spores, in particular those from strain M112, were the most heat-resistant and these may survive subsequent preservation treatments, being potentially problematic in food products, such as chocolate milk

The quality of commercial cocoa beans, the principal raw material for chocolate production, relies on the combination of factors that include the type of planting material, the agricultural practices, and the post-harvest processing. Among these, the fermentation of the cocoa beans is still the most relevant since it is the process whereby the precursors of the cocoa flavor arise. The formation of these precursors depends on the activity of different microbial groups on the beans pulp. A comparison of fermentations in different countries showed that a well-defined microbial succession does not always take place and that the role of Bacillus spp. in this process remains unclear. Considering the overriding importance of the fermentation to achieve high quality commercial cocoa beans, we discuss the need of addressing the impact of the farming system, the ripeness state of the pods, and the role of microbial interactions on the fermentation in future research. In addition, the problem of high acidification cocoa beans, aspects dealing with the volatile fraction of the flavor, and the cocoa butter properties, all were identified as critical aspects that need further investigation. The standardization of the microbiological methods and the application of metagenomic approaches would magnify the knowledge in this domain.

Stable high-hydrostatic-pressure (HHP)-resistant Listeria monocytogenes LO28 variants were previously isolated and characterized. These HHP variants were also more resistant to heat. In addition, nonlinear heat inactivation kinetics pointed toward the existence of heat-resistant variants, although these could not be isolated so far. In this study, we used kinetic modeling of inactivation curves of two isolated HHP variants and their wild type, and this revealed that the probability of finding resistant variants should depend on the nature of the inactivation treatment and the time of exposure. At specific heat and HHP conditions, resistant LO28 and EGDe variants were indeed isolated. Resistant LO28 variants were even isolated after a heat inactivation at 72°C in milk, and these variants showed high resistance to standard pasteurization conditions. The increased resistance of part of the isolated LO28 and EGDe variants was due to mutations in their ctsR genes. For the variants whose ctsR genes and upstream regions were not altered, the mechanisms leading to increased resistance remain to be elucidated. This research showed the strength of kinetic modeling in unraveling the causes of nonlinear inactivation and facilitating the isolation of heat-resistant L. monocytogenes variants

The present work provides data on the microbial composition of Tayohounta, a product of natural fermentation of baobab seed kernels. Samples were collected from 3 different small scale producers from Benin at the end of the fermentation process. Microorganisms were enumerated and identified using phenotypic and molecular approaches. Tayohounta was also investigated using culture independent techniques, direct DNA extraction, polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE) and cloning. Isolated microorganisms were tested for their functionality in baobab seed kernels fermentation. Total viable counts were around 9 log cfu/g representing mainly Bacillus spp., whereas lactic acid bacteria (LAB) (8 log cfu/g), yeasts and moulds represent a smaller part of the total flora in all Tayohounta samples. Sequencing of clones of polymerase chain reaction (PCR) products of bacterial DNA directly extracted from Tayohounta revealed large differences between the products made by different producers. In all products, Bacillus licheniformis, B. pumilus, B. subtilis, B. thermoamylovorans and Lactobacillus fermentum were present. Other microorganisms (B. thuringiensis, Brevibacterium borstelensis, Enterococcus casseliflavus, E. durans, Lb. agilis, Pediococcus pentosaceus, Streptococcus equinus and Weissella confusa) were present occasionally. In experimental pure culture fermentations, B. subtilis showed little effect on pH, but degraded protein and caused a typical pungent smell typical of Tayohounta.

The public health effects of illness caused by foodborne pathogens in Greece during 1996–2006 was quantified by using publicly available surveillance data, hospital statistics, and literature. Results were expressed as the incidence of different disease outcomes and as disability-adjusted life years (DALY), a health indicator combining illness and death estimates into a single metric. It has been estimated that each year ˜370,000 illnesses/million inhabitants are likely caused because of eating contaminated food; 900 of these illnesses are severe and 3 fatal, corresponding to 896 DALY/million inhabitants. Ill-defined intestinal infections accounted for the greatest part of reported cases and 27% of the DALY. Brucellosis, echinococcosis, salmonellosis, and toxoplasmosis were found to be the most common known causes of foodborne illnesses, being responsible for 70% of the DALY. Overall, the DALY metric provided a quantitative perspective on the impact of foodborne illness that may be useful for prioritizing food safety management targets.

This research aims to test the absence (gamma hypothesis) or occurrence of synergy between two growth-limiting factors, i.e., pH and water activity (aw), using a systematic approach for model selection. In this approach, preset criteria were used to evaluate the performance of models. Such a systematic approach is required to be confident in the correctness of the individual components of the combined (synergy) models. With Bacillus cereus F4810/72 as the test organism, estimated growth boundaries for the aw-lowering solutes NaCl, KCl, and glucose were 1.13 M, 1.13 M, and 1.68 M, respectively. The accompanying aw values were 0.954, 0.956, and 0.961, respectively, indicating that equal aw values result in similar effects on growth. Out of the 12 models evaluated using the preset criteria, the model of J. H. T. Luong (Biotechnol. Bioeng. 27:280–285, 1985) was the best model to describe the effect of aw on growth. This aw model and the previously selected pH model were combined into a gamma model and into two synergy models. None of the three models was able to describe the combined pH and aw conditions sufficiently well to satisfy the preset criteria. The best matches between predicted and experimental data were obtained with the gamma model, followed by the synergy model of Y. Le Marc et al. (Int. J. Food Microbiol. 73:219–237, 2002). No combination of models that was able to predict the impact of both individual and combined hurdles correctly could be found. Consequently, in this case we could not prove the existence of synergy nor falsify the gamma hypothesis.