Virulence properties of Escherichia coli isolated from Australian dairy powder factory environments

A total of 298 environmental samples from 5 separate dairy powder factories (A–E) were analysed for the presence of Escherichia coli. E. coli was isolated from 80 of these samples to obtain 359 isolates. These isolates were tested for the presence of 12 virulence genes associated with enteropathogenic E. coli (EPEC), atypical EPEC, Shiga toxin (Stx)-producing E. coli (STEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC). A total of 4 isolates obtained from two different sampling points at Factory C were positive for the astA gene, indicative of EAEC. A further 2 isolates from one sample from Factory C were positive for the presence of eaeA and escV genes, indicative of atypical EPEC. No virulence genes were detected in the remaining 353 isolates. While E. coli was present within the environment of dairy powder processing factories the carriage of potential virulence genes was low.     

Degradation kinetics of tomato juice quality parameters by ozonation

Tomato juice samples were ozonated with control variables of ozone concentration (1.6–7.8 %w/w) and treatment time (0–10 min). Effects of ozone processing variables on quality parameters of pH, ^oBrix, titratable acidity (TA), cloud value, non-enzymatic browning, colour values ( L *, a *, and b *) and ascorbic acid (AA) content were determined. No significant changes ( P  > 0.05) in pH, ^oBrix, TA, cloud value and Non enzymatic browning (NEB) ( P  ≤ 0.05) were found with ozonation. L *, a * and b * colour values were significantly affected by ozone concentration and treatment time. A significant reduction of AA (96 %) was observed at an ozone concentration of 7.8%w/w and a treatment time of 10 min. Results presented in this study indicate that visual colour and nutritional quality is significantly affected during ozone processing. Thus, the effects of ozonation on the nutritional properties of tomato juice should be considered by processors prior to its adoption as a preservation technique.     

Evaluation of antioxidative and hypolipidemic properties of a novel functional diet formulation of Auricularia auricula and Hawthorn

Auricularia auricula and hawthorn are well known for both traditional food and folk medicine. To develop a novel healthy functional diet (FD), the formulation of A. auricula polysaccharide (AAP) and hawthorn flavones were postulated in present study. In vitro, FD significantly increased the radical-scavenging effects and inhibited LDL oxidation, compared with AAP. In vivo, the hyperlipidemic mice, induced by cholesterol-enriched diet, were provided either 150, 300, 450 mg/kg day of FD or 300 mg/kg day of AAP for 12 weeks to evaluate their expected hypolipidemic activity. Compared with CED, both FD and AAP groups could lower serum TC and atherogenic index (AI), improve serum and hepatic antioxidant status. Especially, formulating with hawthorn could enhance hepatic antioxidant status in dose-dependent manner, compared with AAP. Thus, it can be concluded that FD may act as a potent hypolipidemic and powerful antioxidant formulation via improving serum lipid profile and inhibiting lipid peroxidation in mice.Industrial relevanceWith the development of modern living standard, dyslipidemia has become one of major causes leading to antioxidant stress and atherosclerosis. It is of great significance to maintain the normal body functions by reducing the elevated serum cholesterol to an adequate level. In view of side effects of recent therapies, it is urgent to produce certain health-promoting functional diet against dyslipidemia. Therefore, we studied on a novel functional formulation diet (Auricularia auricula and Hawthorn) against hyperlipidemia, using the traditional both edible and medicinal herbs. The antioxidant and hypolipidemic properties are roundly evaluated in vitro and in vivo with the appropriate animal model. Our research also suggests the optimum dosage with potent nutritional property. It could provide the future practical application to produce this functional diet as an adjuvant dietetic food.     

Synergistic effect of high hydrostatic pressure treatment and food additives on the inactivation of Salmonella enteritidis

The synergistic effect of high hydrostatic pressure (HHP) treatment and food additives (FAs) on the inactivation of Salmonella enteritidis was investigated. At 1% concentrations, all of the FAs tested showed significant synergistic effects, and 9 of 30 FAs showed strong synergistic effects. Citric acid, adipic acid, C8-sugarester, C10-sugarester, tannin, nisin, wasabi extract, ε-polylysine, and protamine each showed a strong inactivation effect when administered alone at the 1% level. In the HHP treatment at 250 MPa for 30 min, the minimum effective concentrations of C8-sugarester, C10-sugarester, and protamine were 0.25, 0.125, and 0.06%, respectively. These results indicate that some FAs are useful for increasing the inactivation ratio of S. enteritidis in HHP treatment.     

Flavouring reduced fat high fibre cheese products with enzyme modified cheeses (EMCs)

Medium (13%) and low (2%) fat imitation cheeses (pH 6 or 5.5) were flavoured with 5% w/w EMC containing 16%, 28% or 47% total free fatty acids (low to high levels of hydrolysis, respectively) and were examined by a sensory panel. Aroma active short-chain free fatty acids were monitored using gas chromatographic techniques. Regardless of cheese pH or EMC composition, panellists ranked all medium-fat cheeses similarly. Low-fat cheeses flavoured (pH 6 or 5.5) with low or medium lipolysis EMC were described as ‘well-balanced’ and ‘cheesy’ and were significantly more preferred to cheeses containing high hydrolysis EMCs. Low-fat cheeses were least preferred of all cheeses because of ‘very intense’ bursts of off-flavours. Lower pH cheeses were softer and less melting. Higher fat levels in imitation cheese modulated a greater retention of fat-based flavour compounds and improved their release during consumption more than did lower fat levels.     

Investigation of imitation cheese matrix development using light microscopy and NMR relaxometry

The hydration of rennet casein and emulsification of fat were monitored throughout imitation cheese manufacture by monitoring changes in water mobility using NMR relaxometry and cheese microstructure by light microscopy. The changes in water mobility and microstructure observed are consistent with a four-stage model of protein hydration/matrix development in imitation cheese manufacture. These stages included the wetting and swelling of casein particles, the formation of a congealed matrix, the development of a more cohesive matrix and the formation of a homogeneous cheese mass. The initial two stages were dominated by protein–water and protein–protein interactions, while the latter stages were predominately governed by protein–fat and protein–water interactions. This study followed imitation cheese manufacture in situ by monitoring changes in viscosity, allowing a realistic insight into the development of an imitation cheese matrix.