Wintertime organic aerosols in Christchurch and Auckland, New Zealand: contributions of residential wood and coal burning and petroleum utilization

Wintertime PM10 samples from two New Zealand cities (Christchurch and Auckland) have been characterized using gas chromatography - mass spectrometry for biomass burning tracers, hopanes, n-alkanes, fatty acids, n-alkanols and sugars. The aerosol samples of Christchurch, which were heavily influenced by residential wood and coal burning, showed substantially higher ambient concentrations for most of the organic compounds than those of Auckland, where major sources of aerosols were vehicular emissions and sea-salt. Mass ratios between the biomass burning tracers studied were found to be significantly different (e.g., beta-sitosterol to nssK+ ratios were more than three times higher in Christchurch than in Auckland), although levoglucosan to nssK+ ratios were similar at the both sites. We also estimated, for the first time using stereochemical configurations of hopanes, that 60% of fossil fuel emissions came from petroleum utilization with the remaining 40% being from coal burning in Christchurch. In contrast, contribution of coal burning was negligible in Auckland. Moreover, contributions of most biomass burning tracers to organic carbon (OC) were significantly higher in Christchurch than in Auckland. On the other hand, saccharides (excluding levoglucosan) and hopanes accounted for larger fractions of OC in Auckland. This study demonstrates that intensive wood and coal burning can significantly affect organic aerosol composition in an urban environment.     

Bioavailability of peptides from casein hydrolysate in vitro: Amino acid compositions of peptides affect the antioxidant efficacy and resistance to intestinal peptidases

Measurements of in vitro bioactivity to support health benefits of bioactive compounds should be accomplished with estimates of their bioavailability to bolster nutritional significance to health claims. In vitro bioavailability of casein and casein peptides (casein hydrolysate and four peptide fractions) measured by the amount of peptide nitrogen is discussed. Antioxidant activities during gastrointestinal digestion and Caco-2 cell absorption were investigated as indices of peptide degradation. The antioxidant capacities of Trolox equivalent and oxygen radicals were used for assessing antioxidant efficacy of surviving peptides. Results showed that casein hydrolysate improved bioavailability compared to casein. Amino acid composition of peptides affected the resistance of peptides to digestive enzymes and intestinal peptidases. The acidic peptide fractions had higher bioavailability and a higher residual ratio of antioxidant activity. The peptides in the digest and absorbate of acidic fraction F1 with the highest bioavailability (23.14%) and the residual ratio of antioxidant activity were identified, and 12 intact, absorbed peptides (IAP) were obtained. Eleven of twelve of the IAPs were from β-Casein, and their amino acid components were rich in acidic and hydrophobic amino acids. Identification of IAPs might provide insight into the mechanism of how peptide structure provides resistance against peptidases by Caco-2 cells.     

Short communication: Extended-spectrum cephalosporin-resistant Escherichia coli in colostrum from New Brunswick,Canada, dairy cows harbor blaCMY-2 and blaTEM resistance genes

Dairy calves are colonized shortly after birth by multidrug resistant (MDR) bacteria, including Escherichia coli. The role of dairy colostrum fed to calves as a potential source of MDR bacteria resistance genes has not been investigated. This study determined the recovery rate of extended-spectrum cephalosporin-resistant (ESC-R) E. coli in colostrum from cows. The ESC-R E. coli isolates were further investigated to determine their phenotypic antimicrobial resistance pattern and the genes conferring ESC-R. Fresh colostrum was collected from 452 cows from 8 dairy herds in New Brunswick, Canada. The ESC-R E. coli was isolated from the colostrum by using the VACC agar, a selective media for extended-spectrum β-lactamase producing Enterobacteriaceae. Minimum inhibitory concentration was determined for all the suspected ESC-R E. coli isolates using a commercial gram-negative broth microdilution method. Two multiplex PCR were conducted on all the suspected ESC-R E. coli isolates to determine the presence of the bla_CTX-M (groups 1, 2, 9, and 8/25) bla_CMY-2, bla_SHV, and bla_TEM resistance genes. The ESC-R E. coli were detected in 20 (4.43%) of the colostrum samples. At least 1 ESC-R E. coli isolate was detected in 6 (75%) of the dairy herds. All ESC-R E. coli had MDR profiles based on minimum inhibitory concentration testing. No bla_CTX-M groups genes were detected; however, the bla_CMY-2 gene was detected in 9 or 20 (45%) and bla_TEM was detected in 7 of 20 (35%) of the ESC-R E. coli. No ESC-R E. coli had both bla_CMY-2 and bla_TEM resistance genes. This is the first report of bla_CMY-2 and bla_TEM genes found in E. coli isolates cultured from dairy colostrum to our knowledge.     

Milk kefir enriched with inulin-grafted seed extract from white wine pomace: chemical characterisation,antioxidant profile and in vitro gastrointestinal digestion

An innovative functional food with symbiotic and functional potential was produced by combining probiotic milk kefir, and white grape-seed pomace obtained by UAE (ultrasound-assisted extraction) rich in catechin and glycosylated flavonoids. The milk kefir was fortified by adding, after 24 h of fermentation, a polymer of inulin grafted with seed extract. The inulin/grape extract-enriched polymer showed a higher antioxidant profile (P < 0.05). Simulated in vitro digestion demonstrated that 50 g of the kefir product would result in the delivery of antioxidants equivalent to 300 mg of ascorbic acid. The integrity of the intestinal barrier functions was not compromised by kefir treatments (at 10 μg mL^-1).     

Willingness to adopt a more plant-based diet in China and New Zealand: Applying the theories of planned behaviour,meat attachment and food choice motives

The purpose of this study is to explore the significant factors that drive consumers’ willingness to adopt a more plant-based diet, in both an Asian developing country (China) and a Western developed country (New Zealand), on the basis of three theories: meat attachment factors, the theory of planned behaviour and food choice motives. The data were collected through online surveys in China (n = 604) and New Zealand (n = 581). Confirmatory factor analysis and structural equation modelling were used for the data analysis. Consumers’ willingness to adopt a more plant-based diet was significantly linked to all the four meat attachment factors (Hedonism, Affinity, Entitlement and Dependence), four factors based on the Theory of Planned Behaviour (Subjective norms, Personal norms, Perceived behavioural control and Attitudes), and one food choice motive (Environmental concern). There were differences between China and New Zealand in the impact of the meat attachment factors and the theory of planned behaviour factors on the willingness to adopt a more plant-based diet.     

PCBs and OCPs in sediment cores from the Lower St. Lawrence Estuary, Canada: evidence of fluvial inputs and time lag in delivery to coring sites

Three sediment cores were collected along the longitudinal axis of the Laurentian Trough in the Lower St. Lawrence Estuary (LSLE) and an additional one at the junction of the Estuary and the Gulf of St. Lawrence. After core-slicing, each sediment layer was analyzed for polychlorinated biphenyls (PCBs) and some organochlorine pesticides (OCPs) including p,p'-dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB) and Mirex. 210Pb activity was also measured in these sediments, which allowed us to confirm that these cores were too much affected by the overall impact of surface mixing to be dated. Nevertheless, POP sedimentary profiles in cores from the LSLE upstream stations showed well-defined subsurface peak concentrations. Apparently, the peak inputs of POPs to these sediment cores had occurred after the years of maximum sales and production of these chemicals in North America, suggesting a time lag in the delivery of POPs to the LSLE sediments. Concentrations of POPs in the LSLE surface sediments as well as POP inventories in sediment cores decreased in the seaward direction, confirming that the head of the LSLE acts as a sink for sediments and associated constituents. Surface concentrations of sigmaPCBs, sigmaDDTs, and HCB in the most upstream core were on average similar to those reported in two fluvial lakes of the St. Lawrence River but were between 12 and 39 times lower than those from Lake Ontario. For Mirex, the surface concentration in that core was 5 and 130 times lower than the average values found in the fluvial lakes and Lake Ontario, respectively. Differences between Lake Ontario sediment cores and the most upstream core from the LSLE were much smaller on the basis of POP inventories than surface concentrations of POPs, but were still important. The total burdens of POPs in LSLE sediments below the 200 m isobath were 8704 kg for sigmaPCBs, 1825 kg for sigmaDDTs, 319 kg for HCB, and 27.5 kg for Mirex. These values represent between 1% and 10% of the total burdens of these POPs in Lake Ontario sediments. The estimated contribution of POPs by direct atmospheric deposition into the water column area of the LSLE represented at most 30% of the total sediment burdens of POPs in the LSLE, illustrating the importance of fluvial inputs.