Aims:  Adhesion of a micro‐organism to a cell surface is often considered to be the first step in pathogenesis. Inhibiting this process may have therapeutic effects in vivo. This study investigates the inhibitory effects of various bovine whey products on the association of Salm. Typhimurium, E. coli O157:H7 and C. malonaticus (formerly Enterobacter sakazakii) to the human CaCo‐2 cell line. Invasion of CaCo‐2 cells by Salm. Typhimurium and C. malonaticus was also examined. Methods and Results:  Infection assays were performed by incubating pathogenic acteria with CaCo‐2 cells in the presence of untreated (UT) or enzyme‐modified (EM) whey products. Associated micro‐organisms were directly quantified by plate counts. Invasion of CaCo‐2 cells by Salm. Typhimurium and C. malonaticus in the presence/absence of test materials was also quantified using gentamicin protection assays. At a concentration of 40 mg ml−1, some UT whey products reduced association and invasion, but this effect was enhanced following hydrolysis with porcine pancreatic lipase. Conclusions:  Both UT and EM sweet whey protein concentrates (WPCs) were found to be particularly effective inhibitors of association and invasion. All EM whey products significantly (P < 0·05) inhibited invasion of C. malonaticus into epithelial cells, causing a 2‐log reduction in the quantity of these micro‐organisms internalized. Significance and Impact of the Study:  The present study suggests that whey products can inhibit association to and invasion of CaCo‐2 cells by selected micro‐organisms and may be useful in the treatment and/or prevention of foodborne infections.

The aim of this study was to investigate the inhibitory effect of various dairy powders and milk constituents on the adhesion of a clinical isolate of Streptococcus mutans to hydroxylapatite (HA), an analogue of tooth enamel. Adhesion of a microorganism to a cell surface such as epithelial cells or tooth enamel is considered to be the first step in pathogenesis. Inhibiting this process may have therapeutic effects in vivo. The adherence assays were performed by incubating S. mutans with HA in the presence of each test material for 45 min, followed by centrifugal separation of the HA. Unbound bacteria were then quantified using a fluorescent dye. Sweet and Acid WPC80, buttermilk powder and cream powder were found to very effectively inhibit adherence of S. mutans to phosphate-buffered saline coated HA (PBS-HA). Sodium caseinate and the casein fractions a-,b-and j-casein were also found to show high levels of anti-adhesive activity. A selection of test materials were assessed using saliva-coated HA (S-HA), and similar trends were observed. The results suggest commercial dairy powders, and certain milk proteins, can inhibit adhesion of S. mutans to HA and may have potential to control dental caries.

21In recent years, there has been considerable interest in non-thermal milk processing. The 22 objective of the present study was to assess the efficacy of two non-thermal technologies 23 (manothermosonication; MTS, and pulsed electric fields; PEF) in comparison to thermal 24 pasteurisation, by assessing the microbiological quality of each of these milk samples post-25 processing. Homogenised milk was subjected to MTS (amplitude; 27.9 µm, pressure; 225 26 kPa) at two temperatures (37°C or 55°C), before being immediately treated with PEF 27 (electric field strength; 32 kV/cm, pulse width; 10 µs, frequency; 320 Hz). Thermal

24In recent years, there has been an increased interest in food processing technologies that 25 could lessen the thermal impact on food products. In the present study, thermosonication 26 (TS) and pulsed electric fields (PEF), applied individually or in combination (TS/PEF), 27were investigated to determine their effects on inactivation and sub-lethal injury of 28Pseudomonas fluorescens and Escherichia coli. TS was applied at a low (L) and high 29 (H) wave amplitude (L; 18.6µm, H; 27.9µm, respectively), while PEF was applied at a 30 low and high electrical field strength (L; 29kVcm -1 , H; 32kVcm -1 , respectively). In 31 addition, the inhibitory effects of TS/PEF combined were assessed. For P. fluorescens, 32 when applied individually, TS and PEF resulted in ≤9% and ≤47% inactivation, 33 respectively, with 8% sub-lethal injury following PEF treatment. However, TS/PEF 34 treatment caused ≤48% inactivation and ≤34% sub-lethal injury, respectively. For E. 35 coli, TS caused ≤6% inactivation, and ≤2% sub-lethal injury, while PEF treatment alone 36 caused inactivation and sub-lethal injury of 86% and 29%, respectively. TS/PEF caused 37 a maximum of 66% inactivation, while sub-lethally injuring approximately 26% of the 38 of E. coli population. The present study confirms the ability of TS and PEF to inactivate 39 microorganisms, but shows that some bacteria were not killed, but sub-lethally injured. 40 41

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