In-milk inactivation of Escherichia coli O157:H7 by the environmental lytic bacteriophage ECPS-6

Shiga toxin-producing Escherichia coli is a common foodborne pathogen which transmission includes dairy products. In the search for novel biocontrol methods, bacteriophages have become important candidates for the eradication of foodborne pathogens. The aim of this study was to evaluate the bacteriophage-mediated reduction of E. coli O157:H7 in raw and filtered milk. Laboratory-scale tests showed that the bacteriophage ECPS-6 efficiently adsorbed to E. coli O157: H7 cells. Furthermore, ECPS-6 remained stable when heated at 70°C for 20 min and in a wide pH range from 3.0 to 11.0. The trials on contaminated milk were performed using filtered and unfiltered raw milk contaminated with 1 × 10⁵ CFU × ml⁻¹ of E. coli O157: H7. Bacteriophage was added at multiplicity of infection (MOI) 5 and 50. The ECPS-6 reached the highest lytic activity at MOI = 5 (25°C) which resulted in 4.74 Log₁₀ CFU × ml⁻¹ and 7.3 Log₁₀ CFU × ml⁻¹ reduction after 10 days for both tested strains, respectively. Under refrigerated conditions (4°C) the quantity of E. coli decreased to 1.5 Log₁₀ CFU × ml⁻¹ and 3.04 Log₁₀ CFU × ml⁻¹ for these strains, respectively. Usage of MOI = 50 for the treatment unfiltered milk led to the reduction of E. coli O157:H7 A-2 below the detection limit after 6 hr.     

The Influence of Selected Osmotic Dehydration and Pretreatment Parameters on Dry Matter and Polyphenol Content in Highbush Blueberry (Vaccinium corymbosum L.) Fruits

The paper presents an assessment of the influence of selected highbush blueberry pretreatment methods and parameters on the process of osmotic dehydration conducted in 65 °Brix sucrose solution for 5 to 240 min at 30–70 °C. The pretreatment methods used included: fruit immersion in boiling water (15 s) and in 0.5 % NaOH solution (15 s at 95 °C), exposure to ultrasound at atmospheric pressure (vibration frequency of 35?±?5 kHz, 500 W, for 15 min.) and at low pressure (0.92 kg?cm^?1), and enzymatic processing; pectinase (enzyme activity of 46,000 PGU/mL; 0.6 mL/90 g of fruits; 30 min at approx. 22 °C) and lipase (enzyme activity of 750 PGU/mL; 0.7 mL/90 g of fruits; 30 min at approx. 22 °C) were used. Dehydration was also conducted in the presence of pectinolytic enzymes. The dehydrated material was analyzed in terms of the content of dry matter, total polyphenols, and particular polyphenols using high performance liquid chromatography. It was observed that dehydration was much more intensive at 60 and 70 °C, but such temperatures led to substantial losses of phenolic compounds (by 15–30 % after 2-h dehydration) and unfavorable changes in the texture of the final product. A promising method of pretreatment is fruit immersion in solutions containing pectinolytic and lipolytic enzymes, which increase dry matter content by 26 % (after 1 h of dehydration at 30 °C) with a low loss of phenolic compounds (4 %). Among the identified anthocyanins, the greatest retention during dehydration at various temperatures was displayed by petunidin-3-galactoside (over 80 % after 1 h of dehydration) and petunidin-3-glucoside (over 78 %).     

Novel adhesive system based on 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and hyperbranched polyglycerols

Two hyperbranched polyglycerols bearing 1,1,1-tris(hydroxymethyl)propane or Bisphenol A core and terminal hydroxyl functionality were examined as components of novel wood adhesive systems. Two 1,3-dimethylol-4,5-dihydroxyethyleneurea resins (DMDHEU) were used as crosslinkers. Shear strength tests revealed that the adhesives containing up to 75 wt% of renewable glycerol-derived polyglycerols retained performance comparable to that of neat DMDHEU. The results give way to extending the area of application of hyperbranched polyglycerols in the field of wood adhesives.     

An Improved Silver Ion HPLC Combined with Capillary Gas Chromatography of cis/trans Fatty Acids in Alimentary Fats and Human Milk Fat

A technique of analysis is described using a silver ion-loaded HPLC (Ag⁺/HPLC) column, gradient elution, and a laser light scattering detector followed by capillary gas chromatography (GC) for the determination of the fatty acid methyl ester (FAME) composition of rapeseed oil, the respective hydrogenated fat, some dietary fats, and human milk fat. With the use of Ag⁺/HPLC, FAMEs were separated into the following classes: saturated, trans-monounsaturated, cis-monounsaturated, trans–trans-di-unsaturated, trans–cis-di-unsaturated, cis–cis-di-unsaturated, and higher unsaturated FAMEs. Within each class, partial separation of positional isomers was also possible. Fractions of the eluate containing trans and cis C18:1 were separately collected and re-analyzed by GC in order to quantitate the positional isomers eight trans and nine cis in rapeseed oil and in human milk fat. The profiles of eight trans positional isomers in human milk fat and in hydrogenated rapeseed oil were alike but entirely different from that of six C18:1 trans isomers in bovine milk fat. Out of nine C18:1 cis isomers found in hydrogenated fat, only C18:1-9c and C18:1-11c were found in both human and bovine milk fat which may indicate some discrimination which occurs for certain isomers in fatty acid metabolism.     

The influence of brewing method on bioactive compounds residues in spent coffee grounds of different roasting degree and geographical origin

The content of bioactive compounds in spent coffee grounds (SGC) was studied. SGC were obtained from Coffea arabica beans of different roasting degrees (light and dark) and different geographical origins (Nicaragua, Columbia and Mexico) processed using four brewing methods (mocha, filtered, drip and infusion). The highest caffeine and chlorogenic acid contents were determined in filtered spent coffee extracts. All extracts of light roasted spent coffee grounds showed lower browning index levels in comparison to that from dark roasted spent coffee grounds. Generally, the highest content of total polyphenolic compounds and highest antioxidant capacity were determined in extracts prepared in drip. In conclusion, the results obtained in this study indicate that the spent coffee grounds produced of domestic levels, especially those obtained from filter coffeemaker, could be considered as a good source of natural antioxidants.     

Interactions between fecal bacteria,bile acids and components of tomato pomace

Food Science and Biotechnology - The tomato pomace obtained during processing as a residue of tomato processing from large industry. The interactions between tomato pomace and fecal bacteria, bile...