The effects of a biocide and a surfactant on the detachment of Pseudomonas fluorescens from glass surfaces

Application of antimicrobial chemicals is a general procedure in the cleaning and disinfection of food-contacting surfaces. Adhesion to glass surfaces and chemically induced detachment of Pseudomonas fluorescens ATCC 13525(T) were studied in situ, under flow conditions, in a well-controlled parallel plate flow chamber (PPFC). Ortho-phthalaldehyde (OPA) and cetyltrimethyl ammonium bromide (CTAB) were applied separately, at several concentrations, to attached bacteria and their subsequent detachment was monitored. Following treatments the remaining adhered bacteria were characterized in terms of viability and cell size. Simultaneously, the planktonic cell surface was characterized in order to correlate PPFC results with thermodynamic approaches for adhesion evaluation, and surface free energy of chemically treated cells with adhesion strength. About 2.8x10(6) cells/cm(2) adhered to the glass surface after 30 min of bacterial flow, although thermodynamic analyses evidenced unfavourable adhesion. The independent application of OPA and CTAB promoted bacterial detachment to a small extent (16% of total cells). The remaining adhering bacteria were totally non-viable for OPA> or =0.75 mM and CTAB> or =0.25 mM, showing a lack of correlation between bacterial viability and detachment. The cellular size decreased as attachment proceeded and with chemical treatment. Both chemicals altered the cell surface properties, increasing the cell-glass adhesion strength, and promoting the emergence of polar characteristics. The overall results emphasize that OPA and CTAB were markedly ineffective in removing glass-attached P. fluorescens, demonstrating that bacteria can be non-viable but remain strongly attached to the adhesion surface.     

Rheological and thermal properties of an enteral nutrition formula for nutritional support patients using a combined mixture of gelatin and maltodextrin

Enteral nutrition is a type of nutritional support that provides the necessary sources of energy and protein for patients who suffer from dysphagia, chronic disease, and loss of appetite. In this study, a gelatin-maltodextrin binary biopolymer system has been incorporated into a semi-solid formula. The I-optimal combination design approach was used to create 19 formulations, and the dynamic rheological properties, dynamic laser scattering, and zeta potential responses were evaluated over 30 days of storage at 5°C. Solid viscoelastic behavior has been approved since G′ > G″ in the frequency sweep test with no cross-over point. Maltodextrin may interfere within the gelatin network, and increasing the maltodextrin to gelatin (from 0.14 to 1) may lead to a wider linear viscoelastic (LVE) strain range (2.16%), a lower storage modulus at LVE (52%), a lower yield stress (46%), and a lower glass transition temperature (34%). The presence of maltodextrin may reduce the temperature of the sol-to-solid transformation by 48% and enhance its flexibility. In contrast, increasing the gelatin-to-maltodextrin ratio following melting at 37°C led to an increase in the cumulant mean and polydispersity index, indicating a relatively unstable system. The range of zeta potential values between −4.4 and 1.7 mV confirmed a tendency toward coagulation. Microscopic images revealed instability because of irregular or compact chains formed in the gelatin matrix by using higher amounts of maltodextrin. Finally, the best formula had the best rheological stability and was suitable for tube-feeding patients, with a gelatin-to-maltodextrin ratio of 4.35:3.64% w/w on day 17.4.     

Removal of pharmaceuticals in sewage treatment plants in Italy

A listing of "priority pharmaceuticals" for human use in Italy resulted in the selection of 26 pharmaceuticals, belonging to 11 therapeutic classes. They were analyzed by liquid chromatography-tandem mass spectrometry, their occurrence was assessed in six sewage treatment plants (STPs), and the loads and the removal rates (RR) were studied. Total loads ranged from 1.5 to 4.5 g/day/1000 inhabitants in influents and 1.0 and 3.0 g/day/1000 inhabitants in effluents. Total RR in STPs were mostly lower than 40%. Pharmaceuticals could be divided into three groups according to their behavior in STPs: one group with RR higher in summer than in winter, one group with RR similar in summer and winter, and a last group not removed. Last, we studied the distribution and fate of residual pharmaceuticals in the surface waters receiving the effluents of the STPs and identified degradation and sorption as the major factors affecting attenuation. Ciprofloxacin, ofloxacin, sulfamethoxazole (antibiotics), atenolol (cardiovascular drug), ibuprofen (antiinflammatory), furosemide, hydrochlorothiazide (diuretics), ranitidine (gastrointestinal drug), and bezafibrate (lipid regulator) were the most abundant residual drugs, thus those of environmental concern.     

Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese

Ricotta Salata is a traditional ripened and salted whey cheese made in Sardinia (Italy) from sheep's milk. This product is catalogued as ready‐to‐eat food (RTE) since it is not submitted to any further treatment before consumption. Thus, foodborne pathogens, such as Listeria monocytogenes, can represent a health risk for consumers. In September 2012, the FDA ordered the recall of several batches of Ricotta Salata imported from Italy linked to 22 cases of Listeriosis in the United States. This study was aimed at evaluating the presence and virulence properties of L. monocytogenes in 87 samples of Ricotta Salata produced in Sardinia. The ability of this product to support its growth under foreseen packing and storing conditions was also evaluated in 252 samples. Of the 87 samples 17.2% were positive for the presence of L. monocytogenes with an average concentration of 2.2 log₁₀ cfu/g. All virulence‐associated genes (prfA, rrn, hlyA, actA, inlA, inlB, iap, plcA, and plcB) were detected in only one isolated strain. The Ricotta Salata samples were artificially inoculated and growth potential (δ) was assessed over a period of 3 mo. The value of the growth potential was always >0.5 log₁₀ cfu/g under foreseen packing and storing conditions. This study indicates that Ricotta Salata supports the L. monocytogenes growth to levels that may present a serious risk to public health, even while stored at refrigeration temperatures.     

PCR amplification of 18S rRNA,single cell protein production and fatty acid evaluation of some naturally isolated microalgae

Microalgae were isolated during a screening program from soil samples collected from paddy-fields of Fars province, south of Iran. The protein content was assayed by the Kochert method. Total genomic DNA were isolated and used for PCR amplification of the 18S rRNA gene. The sequences were determined for 12 species of microalgae. Some bioinformatic tools were used for more investigation on these biologic data. Total lipids from five microalgal species were extracted and used for determination of different types of fatty acids by gas chromatography–mass spectrometry method. In our experiments the green algae yielded a maximum protein of about 42% ± 1.64. The DNA sequences were published in the NCBI under specific accession numbers. The composition of fatty acids was mainly, myristic acid, palmitic acid, oleic acid, α-linolenic acid, and γ-linolenic acid.     

Investigation of food products containing garlic or onion for a false positive sulphite response by LC-MS/MS

ABSTRACT

In the US, sulphites must be declared on the label if they are present in concentrations greater than 10 mg/kg (determined as) SO₂ because an allergic-like response has been reported in a small subset of the population upon consumption of sulphite-containing products. The most widely used method for sulphite determination, the optimised Monier-Williams (OMW), produces false positive results with vegetables from the Allium (garlic) and Brassica (cabbage) genera due to extraction conditions that are thought to cause endogenous sulphur compounds to release SO₂. Recently, an LC-MS/MS method was developed for sulphites but has only been tested with samples that are 100% Allium or Brassica. Since regulatory samples may contain these vegetables as ingredients, additional investigations were necessary to determine the potential extent of false positives. Four blank matrices, chips, phyllo shells, hummus, and quinoa were spiked with various concentrations of onion and garlic powders. The sulphite concentrations were determined using an LC-MS/MS method. The matrix is extracted with a buffered formaldehyde solution, converting free and reversibly bound sulphite to the stable formaldehyde adduct, hydroxymethylsulfonate (HMS). It was determined that even at concentrations up to 8% garlic powder or 2% onion powder, the measured sulphite concentration was below the 10 mg/kg SO₂ labelling threshold. Commercial dried garlic powders were evaluated to determine the variation in responses that might be encountered in future regulatory samples. Recovery studies were conducted to determine if these methods would detect added sulphite. The ability to eliminate false positives due to these ingredients will result in a greater reliability in the accurate determination of added sulphite to ensure compliance with labelling requirements.     

Protective effect of ω-3 polyunsaturated fatty acids (PUFA) on sodium nitrite induced nephrotoxicity and oxidative damage in rat kidney

Sodium nitrite (SNT) widely used as a curative agent in meat processing industry possesses cell-transforming mutagenic and cytogenic properties. Dietary omega-3 polyunsaturated fatty acids (ω-3 PUFA) has been shown to reduce the severity of certain types of cancers, cardiovascular and renal diseases. The present study examined whether feeding of fish oil (FO)/flaxseed oil (FXO) has protective effect against SNT-induced toxicity. SNT significantly altered the activities of serum creatinine (Crt), blood urea nitrogen (BUN), metabolic and brush border membrane (BBM) enzymes. SNT caused significant imbalances in the antioxidant system associated with increased lipid peroxidation (LPO). Feeding of FO and FXO with SNT ameliorated the changes in various parameters caused by SNT. Nephrotoxicity parameters lowered and enzyme activities of carbohydrate metabolism, BBM and radioactively labeled inorganic phosphate (³²Pi) transport were improved to near control values. The results of the present study suggest that ω-3 PUFA-enriched FO and FXO from sea-foods and plant sources respectively are similarly effective in reducing SNT-induced nephrotoxicity and oxidative damage.