Impact of sourdough on the texture of bread

Sourdough has been used since ancient times and its ability to improve the quality and increase the shelf-life of bread has been widely described. During sourdough fermentation, lactic acid bacteria (LAB) produce a number of metabolites which have been shown to have a positive effect on the texture and staling of bread, e.g. organic acids, exopolysaccharides (EPS) and/or enzymes. EPS produced by LAB have the potential to replace more expensive hydrocolloids used as bread improvers. Organic acids affect the protein and starch fractions of flour. Additionally, the drop in pH associated with acid production causes an increase in the proteases and amylases activity of the flour, thus leading to a reduction in staling. While improving the textural qualities of bread, sourdough fermentation also results in increased mineral bioavailability and reduced phytate content. In this review we will be discussing the effect of sourdough on wheat and rye bread as well as the potential of sourdough to improve the quality of gluten-free bread.

Shelf Life and Safety Concerns of Bakery Products—A Review

Bakery products are an important part of a balanced diet and, today, a wide variety of such products can be found on supermarket shelves. This includes unsweetened goods (bread, rolls, buns, crumpets, muffins and bagels), sweet goods (pancakes, doughnuts, waffles and cookies) and filled goods (fruit and meat pies, sausage rolls, pastries, sandwiches, cream cakes, pizza and quiche). However, bakery products, like many processed foods, are subject to physical, chemical and microbiological spoilage. While physical and chemical spoilage limits the shelf life of low and intermediate moisture bakery products, microbiological spoilage by bacteria, yeast and molds is the concern in high moisture products i.e., products with a water activity (a(w)) > 0.85. Furthermore, several bakery products also have been implicated infoodborne illnesses involving Salmonella spp., Listeria monoctyogenes and Bacillus cereus, while Clostridium botulinum is a concern in high moisture bakery products packaged under modified atmospheres. This extensive review is divided into two parts. Part I focuses on the spoilage concerns of low, intermediate and high moisture bakery products while Part II focuses on the safety concerns of high moisture bakery products only. In both parts, traditional and novel methods of food preservation that can be used by the bakery industry to extend the shelf life and enhance the safety of products are discussed in detail.

Food safety knowledge of consumers and the microbiological and temperature status of their refrigerators

The objectives of this study were to examine domestic food safety knowledge levels of consumers, establish the levels and incidence of bacterial contamination and operational temperatures in domestic refrigerators, and identify areas in which consumer food safety education is necessary in Ireland. A food safety knowledge questionnaire applied to a representative sample of households (n = 1,020) throughout the island of Ireland found the gaps in consumer food safety knowledge. Analysis of swab samples (n = 900) recovered from the domestic refrigerators in these households showed average total viable counts of 7.1 log CFU/cm2 and average total coliform counts of 4.0 log CFU/cm2. Analysis of swab samples also detected the incidence of Staphylococcus aureus (41%), Escherichia coli (6%), Salmonella enterica (7%), Listeria monocytogenes (6%), and Yersinia enterocolitica (2%). Campylobacter jejuni and E. coli O157:H7 were not detected in domestic refrigerators. The temperature profiles of a subset of the sampled refrigerators (100) were monitored for 72 h, and 59% were found to operate, on average, at temperatures above the recommended 5 degrees C. Knowledge and temperature survey results varied considerably, but consumers who scored better in terms of basic food safety knowledge had reduced levels of bacterial contamination in their refrigerators and reported a reduced incidence of food-associated illnesses. This study confirms the effect of basic food hygiene knowledge on hygienic practice and identifies specific areasfor emphasis in the development and delivery of effective food safety risk communication messages to consumers.

Determination of bisphenol A in canned vegetables and fruit by high performance liquid chromatography

A high performance liquid chromatography (HPLC) method was developed for the determination of bisphenol A (BPA) that had migrated into canned fruit and vegetables. BPA was extracted with acetonitrile from the solid portion of canned food, and with an OASIS HLB cartridge from the aqueous portion, respectively. Both extracts were cleaned up on a Florisil cartridge. The HPLC separation was carried out on a Wakosil II 3C18 RS column (4.6 x 150 mm) with acetonitrile-water (40:60, v/v) as a mobile phase with a flow rate of 0.8 ml/min. BPA was detectable by UV detector at 228 nm and determined with the similarity of chromatographic peak spectrum by multiwavelength detector (similarity index was 0.99 or above). The quantification limits were 10 ng/g for the solid portion and 5 ng/ml for the aqueous portion, respectively. BPA was mainly detected in the solid portion of canned food and found at the maximum level of 11 micrograms per can. To verify migration into the solid portion of canned food, a partitioning experiment was carried out.

Fish silage: a review

Based on a review of various production principles of fish silage, this paper discusses the prospects of introduction of this method, as an alternative to fish meal, to utilize low value fish and waste products, particularly in developing countries. The paper covers the biochemistry, microbiology, and nutritional aspects of fish silage, as well as production technology and economy.

Tin in canned food: a review and understanding of occurrence and effect

Tinplate is light gauge, steel sheet or strip, coated on both sides with commercially pure tin and has been used for well over a hundred years as a robust form of food packaging. Altogether, about 25,000 million food cans are produced and filled in Europe per annum, about 20% of these having plain internal (unlacquered) tin-coated steel bodies. Worldwide, the total for food packaging is approximately 80,000 million cans. Tinplate is also extensively used for the production of beverage cans. Europe produces and fills over 15,000 million tinplate beverage cans per annum all of which are internally lacquered. The use of tinplate for food and beverage packaging, will result in some tin dissolving into the food content, particularly when plain uncoated internal surfaces are used. The Provisional Tolerable Weekly Intake for tin is 14 mg/kg body weight and recommended maximum permissible levels of tin in food are typically 250 mg/kg (200 mg/kg UK) for solid foods and 150 mg/kg for beverages. However, the question arises as to whether evidence exists that such elevated levels of tin in food in any way constitute a risk to human health. This review considers the factors affecting the dissolution of tin, the reported measurements/surveys of actual levels of tin in canned foods and the studies and reports of acute (short term) toxicity relating to the ingestion of elevated levels of tin in food products. Chronic studies are mentioned, but are not covered in detail, since the review is mainly concerned with possible effects from the ingestion of single high doses. From published data, there appears to be a small amount of evidence suggesting that consumption of food or beverages containing tin at concentrations at or below 200 ppm has caused adverse gastrointestinal effects in an unknown but possibly small proportion of those exposed. However, the evidence supporting this assertion is derived from reports of adverse effects which offer data that are limited, incomplete or of uncertain veracity. Clinical studies provide greater confidence regarding the effects of exposure concentration and dose, but few relevant studies have been made. Adverse gastrointestinal effects were observed in limited clinical studies at concentrations of 700 ppm or above, although no adverse gastrointestinal effects were also reported in two studies at higher concentrations. Overall, therefore, the published data do not present a particularly comprehensive profile on the toxic hazard to man of acute exposure to divalent inorganic tin. A food survey suggested that the contents of almost 4% of plain internal tinplate food cans contain over 150 mg/kg of tin and over 2.5 million such cans are consumed every year in the UK alone. Despite this, in the last 25 years, there have been no reports of acute effects attributable to tin contamination in the range 100-200 ppm. These facts strongly suggest that there is little evidence for an association between the consumption of food containing tin at concentrations up to 200 ppm and significant acute adverse gastrointestinal effects. Clearly though, only further clinical studies will generate unequivocal evidence that current legislative limits provide safe levels for adults in the general population.

The relationship of broiler breast meat color and pH to shelf-life and odor development

Experiments were conducted to compare the shelf-life of dark-colored and light-colored broiler breast meat. In each of three trials, 100 breast fillets were obtained from a commercial processing plant and subjectively categorized as "dark" or "light". The 100 fillets were then objectively evaluated for C.I.E. color values (lightness, redness, and yellowness). The fillets were separated into five storage groups, with each group containing 10 dark and 10 light fillets, and the fillets were held at 3 C for 0, 3, 6, 9, and 12 d. On each sampling day, fillets were evaluated in duplicate for psychrotrophic plate count (PPC), capacitance detection time (CDT), pH, and subjective odor evaluation. Dark fillets had significantly (P < 0.05) lower lightness values (L*), higher redness values (a*), lower yellowness values (b*), and higher pH values. Regression coefficients for odor scores resulted in darker fillets having significantly (P < 0.05) higher slopes than lighter-colored fillets even though intercept values were similar. Significant correlations existed between pH and color as well as odor, CDT, and PPC. These data suggest that darker broiler breast meat fillets have a shorter shelf-life than lighter breast fillets; the shorter shelf-life may be due to differences in pH.

Behavior of Escherichia coli O157:H7 in leafy vegetables

Leafy vegetables, including lettuce and spinach, have been implicated in several outbreaks of foodborne disease caused by Escherichia coli O157:H7, a pathogen of increasing public health significance because of the severity of the gastrointestinal illness and long-term, chronic sequelae that can result from infection. A definitive association between the consumption of leafy vegetables and human disease provides implicit evidence of transfer from animal sources to field crops and retail commodities, including minimally processed or fresh-cut products. Understanding the behavior of E. coli O157:H7 in leafy vegetables during production, after harvest, in storage, during processing, and in packaged fresh-cut products is essential for the development of effective control measures. To this end, previous research on the fate of the species at each step in the production of market-ready leafy vegetables is reviewed in this study. Several critical gaps in knowledge are identified, notably uncertainty about the location of contaminating cells on or in plant tissues, behavior in packaged products stored at low temperatures, and the influence of environmental stresses on growth and infectivity.

Use of time-temperature integrators and predictive modelling for shelf life control of chilled fish under dynamic storage conditions

A systematic approach for fish shelf life modelling and Time Temperature Integrator (TTI) selection in order to plan and apply an effective quality monitoring scheme for the fish chill chain was developed. The temperature behaviour of the natural microflora of the Mediterranean fish boque (Boops boops) was studied and growth of the specific spoilage bacteria Pseudomonas spp. and Shewanella putrefaciens was modelled and correlated to organoleptic shelf life. Arrhenius and square root functions were used to model temperature dependence of maximum growth rates. Bacterial growth and shelf life models were validated under dynamic storage conditions with independent variable temperature experiments. The response of several TTIs from similar storage experiments was also modelled. The reliability of the TTI monitoring was cumulatively expressed by the error in the TTI derived effective temperature (Teff) for different variable temperature distributions. Teff was directly translated to shelf life of the fish.

Protective cultures inhibit growth of Listeria monocytogenes and Escherichia coli O157:H7 in cooked, sliced, vacuum- and gas-packaged meat

Contamination of cooked meat products with Listeria monocytogenes poses a constant threat to the meat industry. The aim of this study was therefore to investigate the use of indigenous lactic acid bacteria (LAB) as protective cultures in cooked meat products. Cooked, sliced, vacuum- or gas-packaged ham and servelat sausage from nine meat factories in Norway were inoculated with 10(3) cfu/g of a mixture of three rifampicin resistant (rif-mutant) strains of L. monocytogenes and stored at 8 degrees C for four weeks. Growth of L. monocytogenes and indigenous lactic acid flora was followed throughout the storage period. LAB were isolated from samples where L. monocytogenes failed to grow. Five different strains growing well at 3 degrees C. pH 6.2, with 3% NaCl, and producing moderate amounts of acid were selected for challenge experiments with the rif-resistant strains of L. monocytogenes. a nalidixic acid/streptomycin sulphate-resistant strain of Escherichia coli O157:H7 and a mixture of three rif-resistant strains of Yersinia enterocolitica O:3. All five LAB strains inhibited growth of both L. monocytogenes and E. coli O157:H7. No inhibition of Y. enterocolitica O:3 was observed. A professional taste panel evaluated cooked, sliced, vacuum-packaged ham inoculated with each of the five test strains after storage for 21 days at 8 degrees C. All samples had acceptable sensory properties. The five LAB strains hybridised to a 23S rRNA oligonucleotide probe specific for Lactobacillus sakei. These indigenous LAB may be used as protective cultures to inhibit growth of L. monocytogenes and E. coli O157:H7 in cooked meat products.

Emerging fermentation technologies: Development of novel sourdoughs

The increasing knowledge of sourdough fermentation generates new opportunities for its use in the bakery field. New fermentation technologies emerged through in depth sourdough research. Dextrans are extracellular bacterial polysaccharides produced mainly by lactic acid bacteria (LAB). These bacteria convert sucrose thanks to an inducible enzyme called dextransucrase into dextran and fructose. The structure of dextran depends on the producing micro-organism and on culture conditions. Depending on its structure, dextran has specific properties which lead to several industrial applications in different domains. The use of dextran is not widely spread in the bakery field even if its impact on bread volume and texture was shown. A new process has been developed to obtain a sourdough rich in dextran using a specific LAB strain able to produce a sufficient amount of HMW dextran assuring a significant impact on bread volume. The sourdough obtained permits to improve freshness, crumb structure, mouthfeel and softness of all kinds of baked good from wheat rich dough products to rye sourdough breads. From fundamental research on dextran technology, a new fermentation process has been developed to produce an innovative functional ingredient for bakery industry.

Survival and growth of Escherichia coli O157:H7 inoculated onto cut lettuce before or after heating in chlorinated water, followed by storage at 5 or 15 degrees C

This study determined the effects of mild heat and chlorine treatment followed by storage for up to 18 days at 5 degrees C or 7 days at 15 degrees C on the survival and growth of Escherichia coli O157:H7 inoculated onto fresh-cut iceberg lettuce. The efficacy of treatment with 20 ppm chlorine in killing the pathogen on lettuce at 50 degrees C was determined. Treatment of lettuce with 20 ppm chlorine at either 20 or 50 degrees C did not result in significantly greater reductions in populations of E. coli O157:H7 compared to respective treatments in water without chlorine. The pathogen steadily decreased in viability on treated lettuce throughout subsequent storage at 5 degrees C for 18 days. The population increased by 2.3 to 3.2 log10 CFU/g within 2 days, then continued to increase at a slower rate through 7 days of storage at 15 degrees C. At 4 and 7 days, significantly (alpha = 0.05) higher populations were reached on lettuce that had been treated at 50 degrees C, compared to respective samples that had been treated at 20 degrees C, regardless of the presence of 20 ppm chlorine in the treatment water. Treatment of lettuce with 20 ppm chlorine at 50 or 20 degrees C before or after inoculation with E. coli O157:H7 did not have a marked influence on behavior of the pathogen during subsequent storage at 5 or 15 degrees C.

Evaluation of the role of Carnobacterium piscicola in spoilage of vacuum- and modified-atmosphere-packed cold-smoked salmon stored at 5 degrees C

The microflora on spoiled cold-smoked salmon often consists of a mixture of lactic acid bacteria (LAB) and Gram-negative bacteria. To elucidate the role of the different groups, a storage trial was carried out in which nisin and CO2 were used for the selective inhibition of the two bacterial groups. The shelf-life of vacuum-packed cold-smoked salmon, recorded by sensory evaluation, was four weeks at 5 degrees C and the microflora was composed of LAB (10(6)-10(7) cfu/g) with an associate Gram-negative flora in varying levels (10(5)-10(7) cfu/g). The addition of nisin and/or a CO2-atmosphere increased the shelf-life to five or six weeks and limited the level of LAB to about 10(4)-10(6), 10(3)-10(6) and 10(2)-10(4) cfu/g, respectively. CO2-atmosphere +/- nisin inhibited the growth of Gram-negative bacteria, whereas nisin had no effect on these in vacuum packages. The Gram-negative flora on vacuum-packed salmon was dominated by a Vibrio sp., resembling V. marinus, Enterobacteriaceae (Enterobacter agglomerans, Serratia liquefaciens and Rahnella aquatilis) and occasionally Aeromonas hydrophila. Irrespective of the addition of nisin and/or CO2-atmosphere, the LAB microflora was dominated by Carnobacterium piscicola, which was found to account for 87% of the 255 LAB isolates characterized. Whole-cell-protein patterns analysed by SDS-PAGE confirmed the Carnobacterium species identification. The spoilage potential of C. piscicola isolates was further studied by inoculation of approx. 10(6) cfu/g in cold-smoked salmon stored at 5 degrees C. The salmon did not spoil within 4 weeks of storage in vacuum- or CO2-atmosphere, and it is concluded that despite high levels (> 10(7) cfu/g) of C. piscicola, sensory rejection was caused by autolytic changes. This was supported by the development of soft texture and sour, rancid and bitter off-flavours at the point of spoilage, irrespective of the length of shelf-life and low or high total counts of LAB and Gram-negative bacteria.

Nutritional improvement of plant foods by non-thermal processing

As a result of the increasing consumer demand for minimally-processed fresh-like food products with high sensory and nutritional qualities, there is a growing interest in non-thermal processes for food processing and preservation. Key advanced technologies such as high-pressure processing, pulsed electric fields, dense gases and ultrasound are being applied to develop gentle but targeted processes to further improve the quality and safety of processed foods. These technologies also offer the potential for improving existing processes as well as for developing new process options. Furthermore, by adding new process dimensions (such as hydrostatic pressure, electric fields, ultrasonics, supercritical CO2) to the conventional process variables of temperature and time, they facilitate enlargement of the availability of unit operations. These operations might be applied effectively in unique combination processes, or as subsequent processing tools in more-targeted and subsequently less-intensive processes for food preservation and modification than the currently-applied processes.

Research of quality indices for cold-smoked salmon using a stepwise multiple regression of microbiological counts and physico-chemical parameters

AIMS

The aim of the study was to assess the relationships between the remaining shelf-life (RSL) of cold-smoked salmon and various microbiological and physico-chemical parameters, using a multivariate data analysis in the form of stepwise forward multiple regression.

METHODS AND RESULTS

Thirteen batches of French cold-smoked salmon were analysed weekly during vacuum-packed storage at 5 degrees C for their lipid, water, salt, phenol, pH, total volatile basic nitrogen (TVBN) and trimethylamine contents, total psychrotrophic count, lactic acid bacteria, lactobacilli, B. thermosphacta, Enterobacteriaceae and yeast counts. At the sensory rejection time, the flora was dominated by lactobacilli, lactobacilli/Enterobacteriaceae or Carnobacteria/B. thermosphacta. Shelf-life was very variable (1->6 weeks) and was related to the initial Enterobacteriaceae load (P < 0.05), depending on hygienic conditions in the smokehouse. High correlations existed between the RSL and lactobacilli count (P < 0.01), yeast count (P < 0.05) and TVBN concentration (P < 0.01). A polynomial fitting the RSL as a function of those three factors was proposed (R(2) = 0.80). Assuming that lactobacilli count could not exceed 109 cfu g-1, a minimum of 36 mg-N 100 g-1 was necessary for a product to be rejected, with a yeast count of 104 cfu g-1.

CONCLUSION

Estimation of cold-smoked salmon quality is possible by measuring three parameters: lactobacilli and yeast counts and TVBN concentration.

SIGNIFICANCE AND IMPACT OF THE STUDY

The technical content is important for the smoked salmon industry and for development of quality standards for cold-smoked salmon.

Field evaluation of the application of time temperature integrators for monitoring fish quality in the chill chain

The applicability of time temperature integrators (TTI) as effective tools of chill chain monitoring was assessed. Validated kinetic models of pseudomonads growth of Mediterranean, marine-cultured chilled gilt-head seabream (Sparus aurata) and full knowledge of the response of suitable enzymatic TTI are the basis of the TTI application algorithm. This scheme was evaluated through a controlled field test of exported fish, from harvest to final consumption. Response of TTI attached on different locations of packages was compared to actual temperature recording. Data that could not be obtained during the actual field test, such as microbiological or sensory tests of fish at intermediate points of the chain, were measured in a replicate laboratory study, simulating the handling of products and the real time-temperature profiles of the field test. The conducted field tests showed the applicability and usefulness of TTI monitoring of the fish chill chain, elucidating also the practical difficulties and limitations, that need to be addressed for expanding TTI use as a reliable management tool.

Egg handling and storage

The temperature and relative humidity of storage, as well as the gaseous environment, interact with the fertile egg over time during storage in such a way as to affect the success of incubation either negatively or positively. This interaction occurs both above and below the "physiological zero", at which embryonic metabolism is minimal. This interaction below physiological zero implies that certain physical aspects of the egg must be affected by the environmental conditions. As the eggshell is a relatively fixed component, changes in albumen, shell membranes, cuticle, yolk, or embryo proper must account for these time- and environment-related effects. It is concluded that the major contributor is the albumen, as it is obviously the most dynamic component below physiological zero and is strategically positioned.

Diversity of Listeria monocytogenes isolates from cold-smoked salmon produced in different smokehouses as assessed by Random Amplified Polymorphic DNA analyses

One hundred and forty-eight Listeria monocytogenes isolates originating from vacuum packed cold-smoked salmon produced in 10 different Danish smokehouses were compared by Random Amplified Polymorphic DNA (RAPD) profiling. A total of 16 different reproducible RAPD profiles were obtained using a standardised RAPD analysis by four primers separately. The grouping of the 148 strains was exactly the same for the four primers used. For a sub-set of 20 strains typed by Pulsed Field Gel Electrophoresis (PFGE), only one strain was allocated into a different group as compared to the grouping by RAPD typing. Different RAPD types dominated in products from different smokehouses. Some identical RAPD types were isolated in several smokehouses. In each of four smokehouses, one particular RAPD type could be repeatedly isolated from products. Each smokehouse/product carried its own specific RAPD type and this may indicate a possible persistence of closely related strains of L. monocytogenes in smokehouses.

Microbiological quality and shelf life prediction of chilled fish

A number of storage experiments have been carried out with whole cod and vacuum-packed cod fillets stored in ice. The microbiological quality of the fish was determined on the basis of detection time estimated rapidly by conductance assays in a TMAO-containing medium at 25 degrees C. Detection time and sensory data have been incorporated into a predictive linear model to estimate the remaining shelf life of the products. It is concluded that the shelf life of iced whole cod can be predicted using this model but not that of vacuum-packed fillets because of the greater variability of bacterial activity in packaged fish.

Multiple compound quality index for cold-smoked salmon (Salmo salar) developed by multivariate regression of biogenic amines and pH

Production of biogenic amines during chill storage of 12 lots of cold-smoked salmon was studied. These data allowed for a multiple compound quality index to be developed by multivariate regression (partial least square regression). The quality index was based on concentrations of cadaverine, histamine, putrescine, and tyramine and pH and showed good correlation with sensory assessments. Biogenic amines were indicators of spoilage rather than casual agents of spoilage off-flavors. Four different biogenic amine profiles were found at the time of spoilage in cold-smoked salmon. These were the results of differences in the spoilage microflora. Histamine was detected above regulatory limits but below toxic levels. Measurements of salt and dry matter for calculation of water phase salt could be substituted by rapid water activity measurements.

Target selection in designing pasteurization processes for shelf-stable high-acid fruit products

This study is focused on the search for targets and criteria for the design of pasteurization processes for high-acid shelf-stable fruit products, such as juices, nectars, pastes, purees, concentrates, jams, jellies, etc. First, an overview of pasteurization is presented and then, frequently used targets for pasteurization processes are reviewed Enzymes naturally present in fruits, in decreasing order of heat resistance, were pectinesterase, peroxidase, and polyphenoloxidase, and they may be used as pasteurization targets. The heat resistance of each enzyme is strongly dependent on its fruit origin. The most heat resistant micro-organisms capable of spoiling high acid fruit products include ascospores of Neosartorya fischeri, Byssochlamys nivea, Talaromyces flavus, Eupenicillium javanicum, and Byssochlamys fulva moulds, as well as bacterial spores of Clostridium butyricum, Bacillus coagulans, and Bacillus megaterium. These micro-organisms, spores, and enzymes were, in general, less heat resistant than the spores of a particular spoilage micro-organism named Alicyclobacillus acidoterrestris, which has been causing problems in the fruit industry. Therefore, the use of Alicyclobacillus acidoterrestris spores as a reference micro-organism in the design of pasteurization processes for high-acid shelf-stable fruit products is suggested.

Tracking spoilage bacteria in commercial poultry processing and refrigerated storage of poultry carcasses

Four trials were conducted to examine the effect of commercial processing and refrigerated storage on spoilage bacteria in the native microflora of broiler carcasses. Prescalded, picked, eviscerated, and chilled carcasses were obtained from a commercial processing facility, and psychrotrophs in the bacterial flora were enumerated on Iron Agar, Pseudomonas Agar, and STAA Agar. The size of the population of spoilage bacteria on processed carcasses stored at 4 degrees C for 7, 10, or 14 days was also determined. Bacterial isolates were identified and dendrograms of the fatty acid profiles of the isolates were prepared to determine the degree of relatedness of the isolates. Findings indicated that although some processing steps increased the level of carcass contamination by selected bacteria, the number of spoilage bacteria recovered from processed carcasses was significantly (P< or = 0.05) less than the number of bacteria recovered from carcasses entering the processing line. Acinetobacter and Aeromonas spp. were the primary isolates recovered from carcasses taken from the processing line. During refrigerated storage, there was a significant (P < or =0.05) increase in the population of bacteria on the carcasses, and Pseudomonas spp. were the predominant bacteria recovered from these carcasses. Dendrograms of the fatty acid profiles of the isolates indicated that bacterial cross-contamination of carcasses occurs during all stages of processing and that some bacteria can survive processing and proliferate on carcasses during refrigerated storage. Furthermore, cross-contamination was detected between carcasses processed on different days at the same facility. Findings indicate that although poultry processing decreases carcass contamination by psychrotrophic spoilage bacteria, significant levels of bacterial cross-contamination occur during processing, and bacteria that survive processing may multiply on the carcasses during refrigerated storage.

Research on factors allowing a risk assessment of spore-forming pathogenic bacteria in cooked chilled foods containing vegetables: a FAIR collaborative project

Vegetables are frequent ingredients of cooked chilled foods and are frequently contaminated with spore-forming bacteria (SFB). Therefore, risk assessment studies have been carried out, including the following: hazard identification and characterisation--from an extensive literature review and expertise of the participants, B. cereus and C. botulinum were identified as the main hazards; exposure assessment--consisting of determination of the prevalence of hazardous SFB in cooked chilled foods containing vegetables and in unprocessed vegetables, and identification of SFB representative of the bacterial community in cooked chilled foods containing vegetables, determination of heat-resistance parameters and factors affecting heat resistance of SFB, determination of the growth kinetics of SFB in vegetable substrate and of the influence of controlling factors, validation of previous work in complex food systems and by challenge testing and information about process and storage conditions of cooked chilled foods containing vegetables. The paper illustrates some original results obtained in the course of the project. The results and information collected from scientific literature or from the expertise of the participants are integrated into the microbial risk assessment, using both a Bayesian belief network approach and a process risk model approach, previously applied to other foodborne hazards.

Determinant parameters and components in the storage of virgin olive oil. Prediction of storage time beyond which the oil is no longer of "extra" quality

This work studies the changes in the quality indices standardized by the European Union, together with the evolution of the oxidative stability and sterols, polyphenols, alpha-tocopherol, pigments, and fatty acids contents throughout the storage of Picual and Hojiblanca olive cultivar "extra" virgin olive oils at 2 degrees C + darkness and 30 degrees C + illumination. Only two quality indices (K(270) and sensory evaluation) indicate the loss of the extra quality of the oil during storage, and there is an excellent correlation between initial stability and the time to reach the limit of K(270) > 0.25 (after which the oil quality is no longer of "extra" quality). This time can be predicted with an error of <10%, which is of great commercial interest and previously unknown. Also unknown until now is that the changes in polyphenols, pigments, and alpha-tocopherol with storage time follow first-order kinetics.