Hurdle technology

Food-borne illness as an outcome after the ingestion of contaminated food products indicates a broad group of illnesses caused by pathogenic microorganisms, chemical and physical contaminants that can contaminate food at several points during production and preparation process. Although the research in this eld has been very intensive during the last decades with the same trend that will continue in future, and many preventive and control measures that have already been applied in the food industry, the number of food-borne illnesses stays at unacceptably high level (Havelaar et al., 2010). There are several reasons for this. First, advances in the food microbiology allowed more food-borne pathogens to be identied (e.g., Escherichia coli O157:H7, Listeria monocytogenes, and Cronobacter sakazakii). Some known pathogens have expressed unexpected characteristics regarding survival/growth and occurrence in food not commonly associated with the specic pathogen (e.g., E. coli O157:H7 was found in fresh produce, apple cider, and cookie dough). Additionally, consumers’ demands have changed; nowadays, consumers prefer more fresh-like food with unchanged natural properties with long shelf life, and demographic characteristics including age, gender, education, and income have also changed. All these factors create the environment where food producers and scientists are facing new challenges and constantly search for new and enhanced preservation treatments to improve microbial safety of food products

Exposure of microplastic at levels relevant for human health : cytotoxicity and cellular localization of polystyrene microparticles in four human cell lines

Microplastics (MPs), which are ubiquitous in our living environment, can enter into human body via diverse pathways such as food packaging, contaminated food and bottled mineral water. Therefore, it is essential to assess the risk of MPs daily human intake. Up to date, almost all of related publications used concentrations that are much higher than likely present in these sources. Thus, investigation at levels of MPs relevant for human health exposure can help us rationally understand the threats of MPs. This study is aimed to evaluate cytotoxicity and quantify the cellular uptake and localization of MPs within the concentration range reported in bottled mineral water in human cell lines. To this aim, four types of human cell lines derived from colon (Caco-2), liver (HepG2) and lung (A549 and BEAS-2B) were exposed to 2-µm fluorescent PS microspheres (1E+3-1E+7 particles/L). A series of cellular and biochemical assays (intracellular reactive oxygen species, mitochondrial membrane potential, sulforhodamine B and MTT assay) were conducted. To confirm the cellular uptake, the fluorescent cells containing PS were counted by flow cytometry to evaluate the probability of cells embedded PS under different concentrations. Furthermore, laser confocal scanning microscopy was used to observe the distribution and count the number of PS microspheres in four cell lines

Fibrinogen increases resveratrol solubility and prevents it from oxidation

The French paradox describes a lower incidence of cardiovascular problems despite a high intake of saturated fats. This phenomenon was associated with higher consumption of red wine, as it was later discovered that the presence of antioxidants, including resveratrol, have beneficial effects. We hypothesized that resveratrol may have a more direct role in protection from harmful oxidation, presumably through binding to important proteins of the blood coagulation process. Spectrofluorimetry demonstrated that resveratrol is capable of binding to fibrinogen, the main protein in the coagulation process, which is also important as a food additive. Various spectroscopic methods determined that binding does not cause fibrinogen unfolding or destabilization since protein melting temperature remains unchanged. A mutually protective effect against the free radical-induced oxidation of polyphenol and fibrinogen was found. The presence of fibrinogen caused only a negligible masking effect of the antioxidative abilities of resveratrol, measured by a reduction of hexacyanoferrate (III), while greatly increasing its solubility in an aqueous environment, thus increasing its potential bioavailability. Due to its interaction with fibrinogen, resveratrol may serve as an antioxidant at the site of injury. The antioxidative effect of resveratrol may also protect and thus keep the desired characteristics of fibrinogen during the application of this protein as a food additive

Inactivation of Salmonella , Listeria monocytogenes and Escherichia coli O157:H7 inoculated on coriander by freeze-drying and supercritical CO 2 drying

Coriander, either fresh or inoculated with three strains of Escherichia coli O157:H7, Salmonella or Listeria monocytogenes, was treated with supercritical CO2 (scCO(2), with and without drying) or freeze-dried. After drying in scCO(2) for 150 min at 80 bar and 35 degrees C, the aerobic plate count, yeasts and molds, and the Enterobacteriaceae were reduced by 2.80, 5.03, and 4.61 log CFU/g, respectively. The total count of mesophilic aerobic spores was not significantly reduced by the treatment. Freeze-drying induced lower reductions with 1.23, 0.87, and 0.97 log CFU/g, respectively. After treatment at 100 bar and 40 degrees C without drying, inoculated strains of E. coli O157:H7, Salmonella, and L. monocytogenes were inactivated by > 7.37, > 4.73 and 4.99 log CFU/g, respectively. After drying in scCO 2 for 150 min at 80 bar and 35 degrees C, the strains were reduced by > 5.18 log CFU/g. Freeze-drying resulted in lower reduction with maximum 1.53, 2.03, and 0.71 log CFU/g, respectively. This study indicated that scCO(2) can be used for drying while offering a good inactivation of E. coli O157:H7, Salmonella, and L. monocytogenes as well as most of the bacteria in the vegetative form naturally occurring on coriander. Industrial relevance: Although dried foods are considered microbiological stable foods and show adverse conditions to microbial growth, they may still host pathogenic microorganisms, which may proliferate upon sufficient rehydration. Highly contaminated commodities such as herbs and spices can pose a threat to consumer health if not processed carefully. There is therefore a need to develop or improve drying techniques which can provide dried foods while reducing the initial contamination to acceptable levels in a single process. CO2 is a cheap, accessible solvent, with a low critical point (31 degrees C, 73.8 bar). Moreover, in the supercritical region, CO, exhibits potent microbicidal properties. Therefore, supercritical CO2 drying could be a valuable alternative nonthermal technique for conventional drying methods, such as air-drying or freeze-drying, when medium to high value-added food products with high initial contamination are involved