Ellagitannin content and anti-enterohemorrhagic Escherichia coli activity of aqueous extracts derived from commercial pomegranate products.

This study compared the efficacy of aqueous extracts of commercially available pomegranate peel products and a juice powder in inhibiting the growth of two enterohemorrhagic Escherichia coli strains. Cell suspension of each E. coli strain (5 Log CFU/ml) was added into tryptic soy broth amended with 9 or 23% of each extract prepared with two different methods. After treatment for 5, 10, and 24 h at 25 °C, surviving E. coli cells were enumerated on tryptic soy agar to determine cell population reduction compared to the controls. The concentrations of six different ellagitannins and titratable activity in each treatment system were determined and correlated to E. coli cell population reduction. The extracts from three powdered pomegranate peels caused a significantly greater (p ≤ 0.05) reduction in E. coli population than the extract from the whole peel and juice powder. The higher dose of extracts resulted in a greater cell population reduction than the lower dose. The level of E. coli population reduction correlated positively with the total ellagitannins content (R2 0.67-0.98) and the titratable acidity (R2 0.69-0.98) in the treatment systems. The study suggests that pomegranate peels are promising natural additives or preservatives to control pathogens like EHEC.

The fate of enterohemorrhagic Escherichia coli on alfalfa and fenugreek seeds and sprouts as affected by ascaroside #18 treatments.

Alfalfa and fenugreek sprouts are healthy foods, but they are occasionally contaminated with bacterial pathogens and serve as vehicles for transmitting foodborne illnesses. This study examined the efficacy of ascaroside (ascr)#18 treatment for the control of enterohemorrhagic E. coli (EHEC) growth on sprouts. Commercial alfalfa and fenugreek seeds were decontaminated with 20,000 ppm of NaClO, and residual chlorine was neutralized with Dey-Engley broth. Decontaminated seeds were treated with 1 mM or 1 µM ascr#18, a plant immunity modulator, before being dried and mixed with sandy soil inoculated with E. coli F4546 or BAA-2326 at 104-105 CFU/g. The inoculated seeds were sprouted on 1% water agar at 25ºC for 7 days in the dark. Seed or sprout samples were collected on days 0, 1, 3, 5, and 7 for enumeration of bacterial populations. Data was fit into the general linear model and analyzed using Fisher's least significant different test of the statistical analysis software. Treatment with ascr#18 significantly (P ≤ 0.05) reduced the cell population of EHEC on sprouts. The mean EHEC populations in the 1 mM or 1 µM treatment groups were 3.31 or 1.56 log CFU/g lower compared to the control groups. Besides treatment, sprout seed type and sprouting time were also significant independent variables influencing the growth of EHEC, according to the results of type III error analysis. However, EHEC strain type was not a significant independent variable. The study suggests that ascr#18 could be potentially used to control EHEC contamination and improve the microbial safety of sprouts.

Pesticides residues in leafy green vegetables and irrigation waters in Accra, Ghana.

Pesticides are used in vegetable farming to control pests and diseases, reduce crop losses and improve yield. The study examined pesticide residues in irrigation waters and leafy green vegetables grown in some farming areas in Accra, Ghana. Three types of irrigation water sources (n = 23) and two exotic and four indigenous Ghanaian leafy vegetables (n = 34) from 10 farming areas in Accra, Ghana were collected and examined for 15 organochlorines, 13 organophosphorus and 9 synthetic pyrethroids pesticide residues using the modified QuEChERS procedure. Pesticide residues were detected on 50% (17/34) of the leafy vegetable and 52% (12/23) of the irrigation water samples analysed. Chlorpyrifos and deltamethrin were the most detected pesticide residues in the vegetables and irrigation water. About 26.5% of the vegetables contained pesticide residues exceeding the EU maximum residue limits, so vegetable farmers should be encouraged to comply with appropriate measures on pesticide use to enhance food safety.

Microencapsulated polyphenol extracts from Georgia-grown pomegranate peels delay lipid oxidation in salad dressing during accelerated and ambient storage conditions.

Lipid oxidation is a major cause of quality deterioration in salad dressings. This study evaluated the effect of incorporating microencapsulated polyphenol extracts via spray drying from pomegranate peels (MPP) to delay lipid oxidation in Italian-style salad dressings (ISD) during accelerated (55°C) and ambient (25°C) storage conditions. ISDs, prepared at high (5000 rpm) and low (250 rpm) shear rates conditions, were formulated with unencapsulated polyphenol extracts from pomegranate peels (PPP), MPP, and/or grape seed extract (GSE). Lipid oxidation in ISDs was evaluated by measuring peroxide value (PV), iodine value (IV), and TBARS, stored in accelerated and ambient conditions for 21 days and 8 weeks, respectively. Tannis in extracts were measured via HPLC-DAD and the total hydrolyzable tannin content of PPP and MPP was 283.09 and 427.74 (mg/g extract), respectively. Condensed tannins were not detected in PPP and MPP but were found in GSE (348.53 mg/g extract). Salad dressings prepared at high shear rates had significantly (p < .05) higher emulsion stability than those homogenized at low shear rates. Mixing conditions did not affect the lipid oxidative stability of IDSs. Salad dressing stored under accelerated storage had higher lipid oxidation (higher PV, lower IV, and higher TBARS) after 21 days than IDSs stored under ambient conditions for 8 weeks. ISDs prepared with MPPP showed significantly (p < .05) lower lipid oxidation than the other ISDs at the end of the shelf life studies. Results from the accelerated storage suggested that incorporating MPP could have extended the shelf life of IDSs by 20% compared to using unencapsulated polyphenol extracts. The study demonstrated that MPP delays lipid oxidation in ISDs during storage more effectively than unencapsulated extracts. MPP may serve as a natural and effective functional food ingredient for controlling lipid oxidation in high-lipid and acidified foods.

Efficacy of Ascaroside #18 Treatments in Control of Salmonella enterica on Alfalfa and Fenugreek Seeds and Sprouts.

A novel, natural, and effective antimicrobial intervention is in demand for improving the microbial safety of vegetable seeds/sprouts. This study assessed the efficacy of ascaroside treatment in the control of Salmonella enterica on alfalfa and fenugreek sprouts. Sanitized commercial seeds were treated with 1 mM or 1 µM ascaroside (ascr)#18, a plant immunity modulator (PIM) and dried for an hour before being inoculated with lyophilized S. Cubana or S. Stanley cells in sandy soil (104 CFU/g). Treated and untreated seeds were spouted on 1% water agar at 25°C in the dark. Seed or sprout samples were collected on days 0, 1, 3, 5, and 7, and the population of Salmonella was determined. Data were fit into the general linear arrangement, and means were separated using Fisher's least significant difference test. Seed type, strain type, treatment type, and sprouting time were significant factors (P ≤ 0.05) influencing Salmonella growth on sprouts. The populations of Salmonella were significantly higher on fenugreek than on alfalfa sprouts. S. Stanley had a significantly higher population than S. Cubana. The population of Salmonella increased from day 0 to day 3 and reached the peak population on Day 5. Treatments with both concentrations of ascaroside significantly decreased the populations of Salmonella compared to the controls. The mean Salmonella population reduction was ca. 4 or 1 log CFU/g by treatment with 1 mM and 1 µM of the PIM, respectively. Treatment with the PIM could be potentially used to improve the microbial safety of vegetable seeds and sprouts.

Microbial Load of Fresh Blueberries Harvested by Different Methods.

Currently, more and more growers are transitioning to the use of over-the-row machine harvesters for harvesting fresh market blueberries. This study assessed the microbial load of fresh blueberries harvested by different methods. Samples (n = 336) of 'Draper' and 'Liberty' northern highbush blueberries, which were harvested using a conventional over-the-row machine harvester, a modified machine harvester prototype, ungloved but sanitized hands, and hands wearing sterile gloves were collected from a blueberry farm near Lynden, WA, in the Pacific Northwest at 9 am, 12 noon, and 3 pm on four different harvest days during the 2019 harvest season. Eight replicates of each sample were collected at each sampling point and evaluated for the populations of total aerobes (TA), total yeasts and molds (YM), and total coliforms (TC), as well as for the incidence of fecal coliforms and enterococci. The harvest method was a significant factor (p < 0.05) influencing the TA and TC counts, the harvest time was a significant factor influencing the YM counts, while the blueberry cultivar was an insignificant (p > 0.05) factor for all three indicator microorganisms. These results suggest that effective harvester cleaning methods should be developed to prevent fresh blueberry contamination by microorganisms. This research will likely benefit blueberry and other fresh fruit producers.

Application of multiple occupational health risk assessment models in occupation health risk prediction of trichloroethylene in the electroplating and electronics industries.

Objectives. This study assessed the occupational health risks of work group exposure to trichloroethylene (TCE) in the electroplating and electronics industries in China. Methods. The UK Control of Substances Hazardous to Health (COSHH) Essential, the US Environmental Protection Agency (EPA) and the Singapore and the Chinese semiquantitative risk assessment models were used to assess the risks of TCE. Twenty degreasing groups and 14 cleaning groups were recruited in the companies selected. Results. The concentrations of TCE in 66.7% of the cleaning groups and 35.0% of the degreasing groups exceeded the permissible concentration time-weighted average (PC-TWA) in China, and the concentrations of TCE in 100.0% of the cleaning groups and 70.0% of the degreasing groups exceeded the permissible concentration short-term exposure limit (PC-STEL) in China. Over 60.0% of the work groups were evaluated at high risk and over half of the work groups were evaluated at high cancer risk by the risk assessment models. Conclusion. Most work groups exposed to TCE in the electroplating and electronics industries in China are at high risk. The cleaning groups may have a higher risk for TCE exposure. The Chinese exposure index method and the synthesis index method are more practical than the other methods.

Identification of the genetic elements involved in biofilm formation by Salmonella enterica serovar Tennessee using mini-Tn10 mutagenesis and DNA sequencing.

Biofilms are known to contribute to bacterial tolerance to desiccation and survival in low moisture foods. However, the molecular mechanisms underlying biofilm formation have not been fully elucidated. This study identified some of the genes that are implicated in biofilm formation by Salmonella enterica serovar Tennessee, the "peanut butter outbreak" strain. Mini-Tn10 mutagenesis was used in the study to generate random transposon insertion libraries. The ability of selected mutants in forming biofilms was compared with their wildtype parent using the crystal violet binding assay. Mutants forming significantly less (P ≤ 0.05) biofilm compared to their wildtype parent were selected for whole-genome sequencing. Mini-Tn10 insertion sites on mutant genomes were identified by comparing the acquired sequencing data with those in the Genbank using the BLAST search. In total, 56 mutants were obtained, and five were selected for further analysis according to the result of the biofilm assay. Sequencing analysis revealed that the mini-Tn10 interrupted the S. enterica genes that encode bacterial cell membrane lipoprotein, DNA topoisomerase III, attachment and invasion locus protein, bacteriocin immunity protein, and cell division protein. The information generated from the research should be useful in the control fo S. enterica in low-moisture foods and their production environments.

Effect of Pre-Exposure to Chlorine Dioxide on the Susceptibility of Fecal Coliforms to Antibiotics.

Adaptive exposure to sub-lethal concentrations of sanitizers was previously reported to offer cross-protection to bacteria against antibiotics. This study was undertaken to determine whether the pre-exposure of fecal coliforms to suboptimal concentrations of a chemical sanitizer, chlorine dioxide (ClO2), alters their susceptibility to certain antibiotics. Fecal coliforms isolated from fresh fruit packing facilities (n = 12) were adapted in ½ or » of the manufacturer-recommended concentration of ClO2. The susceptibility of the adapted and non-adapted cells to 13 different antibiotics was determined by observing the changes in their minimal inhibitory concentrations (MICs). The results showed that preadaptation to the suboptimal concentrations of ClO2, in general, either decreased or did not change the MICs of the antibiotics against selected fecal coliform isolates, with only two exceptions; preadaptation increased the MICs of kanamycin against two of the fecal coliform isolates, and of nalidixic acid against one of the fecal coliform isolates. The results suggest that the use of ClO2 has a relatively low risk of inducing the resistance of fecal coliforms to antibiotics.

Validating the Efficacy of Sanitation Methods Commonly Used by Ghanaian Households in Inactivating Artificially Inoculated Salmonella enterica on Leafy Green Vegetables.

ABSTRACT: Our previous survey revealed the poor microbial quality of leafy green vegetables and the presence of Salmonella on these vegetables grown and sold in Accra, Ghana. This study validated the efficacy of some cleaning and sanitation methods (tap water, salt solution, lemon juice, and vinegar) commonly used by Ghanaian households, by comparing them with the performance of several sanitation approaches used by the U.S. fresh produce industry (chlorine, peracetic acid, and ozonated water) in reducing Salmonella populations on leafy green vegetables. Cabbage and lettuce leaves inoculated with each of three Salmonella cocktails were treated with sterile water and the previously mentioned six sanitizers. The efficacies of the treatments were evaluated by using the standard plate count assay. The effect of the treatments on the sensory quality of treated vegetables was evaluated by a 97-member consumer panel in the United States. Treatments with citric and acetic acid were as effective as chlorine and peracetic acid in reducing Salmonella counts on vegetable leaves. Ozonated water was less effective than the two organic acids but equally as effective as treatment with the salt solution. Rinsing vegetables with water did not significantly reduce Salmonella counts (P > 0.05). Cabbage leaves treated with citric acid, vinegar, and water were more preferred (P ≤ 0.05) by the consumer panel, while chlorine-treated cabbage leaves were the least preferred. Lettuce samples treated with citric acid and water were more preferred, and salt-treated samples were least preferred. Among the vegetable sanitation methods used by Ghanaian households, treatments with citric and acetic acid are effective in inactivating Salmonella without adversely affecting the sensory quality of treated vegetables.

Lipid metabolism disorders associated with dioxin exposure in a cohort of Chinese male workers revealed by a comprehensive lipidomics study.

Dioxins, environmentally stable and ubiquitous, have been found to induce metabolic changes especially in lipids and be related to multiple diseases. However, limited study is available on lipid alternations related to human exposure to dioxins. This study aims to explore the serum lipidomic characterization and to understand the underlying mechanisms of adverse health risks associated with dioxin exposure. A lipidomic study integrating nontargeted lipidomics, and targeted free fatty acid (FFA) and acyl-coenzyme A (acyl-CoA) analyses were conducted to investigate the 94 serum samples from two groups of male workers with remarkably different dioxin concentrations. The obtained results exhibited distinct lipidomic signatures between the high and low exposed groups. A total of 37 lipids were identified with the significant changes. The results revealed that dioxin exposure caused accumulations of triglyceride (TG), ceramide (Cer) and sphingoid (So), remodeling of glycerophospholipid (GP), imbalanced FFA metabolism, as well as upregulation of platelet-activating factor (PAF). These findings implied the associations between dioxin exposure and potential adverse health risks including inflammation, apoptosis, cardiovascular diseases (CVDs), and liver diseases. This study is the first to explain the associations between dioxin exposure and health effects at the level of lipid metabolism.

Efficacy of commercial overhead washing and waxing systems on the microbiological quality of fresh peaches.

Overhead spray washing and waxing systems (WWS) are used commercially to reduce the risk of microbial contamination and improve the quality of fresh produce during packing. This study evaluated the microbiological quality of overhead spray water and spent peach wash water, as well as fresh peaches before and after they pass the WWS. Pre- and post-washed/waxed peach samples (n = 192) and overhead spray water and spent peach wash water samples (n = 54) were collected several times over the course of a processing day in three packing facilities located in the state of Georgia. Populations of total aerobes (TA), yeasts and molds (YM), and coliforms (TC) and the presence of thermotolerant coliforms (TTC) and enterococci (EC) were measured in collected samples. The average TA and TC counts and the incidences of TTC and EC were significantly higher (P < 0.05) on peach samples collected after the WWS compared to those collected before the WWS. Counts and incidences of TA, YM, and TC in spent peach wash water were significantly higher than in the overhead spray water where neither TTC nor EC was detected. Results suggest that the commercial washing and waxing systems had little effect in improving the microbiological quality of fresh peaches.

Influence of Bacterial Competitors on Salmonella enterica and Enterohemorrhagic Escherichia coli Growth in Microbiological Media and Attachment to Vegetable Seeds.

Interests in using biological agents for control of human pathogens on vegetable seeds are rising. This study evaluated whether probiotic bacterium Lactobacillus rhamnosus GG, bacterial strains previously used as biocontrol agents in plant science, as well as a selected plant pathogen could compete with foodborne human pathogens, such as Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC), for growth in microbiological media and attachment to vegetable seeds; and to determine whether the metabolites in cell-free supernatants of competitive bacterial spent cultures could inhibit the growth of the two pathogens. The results suggest that the co-presence of competitive bacteria, especially L. rhamnosus GG, significantly (p < 0.05) inhibited the growth of Salmonella and EHEC. Cell-free supernatants of L. rhamnosus GG cultures significantly reduced the pathogen populations in microbiological media. Although not as effective as L. rhamnosus GG in inhibiting the growth of Salmonella and EHEC, the biocontrol agents were more effective in competing for attachment to vegetable seeds. The study observed the inhibition of human bacterial pathogens by competitive bacteria or their metabolites and the competitive attachment to sprout seeds among all bacteria involved. The results will help strategize interventions to produce vegetable seeds and seed sprouts free of foodborne pathogens.

Improving the survival of Lactobacillus plantarum NRRL B-1927 during microencapsulation with ultra-high-pressure-homogenized soymilk as a wall material.

Probiotic foods and supplements have been shown to offer multiple potential health benefits to consumers. Dried probiotic cultures are increasingly used by the food industry because they are easily handled, transported, stored, and used in different applications. However, drying technologies often expose probiotic cells to extreme environmental conditions that reduces cell viability. Hence, this study aimed to evaluate the effect of using ultra high-pressure homogenization (UHPH) on soymilk's microencapsulating ability, and the resultant effect on the survivability of probiotic Lactobacillus plantarum NRRL B-1927 (LP) during drying. Liquid suspensions containing LP (~109 CFU/g of solids) were prepared by suspending LP cultures in soymilk which had been either treated with UHPH at 150 MPa or 300 MPa or left untreated. LP suspensions were then dried by concurrent spray drying (CCSD), mixed-flow spray drying (MXSD) or freeze-drying (FD). Cell counts of LP were determined before and after microencapsulation. Moisture, water activity, particle size and morphology of LP powders were also characterized. LP powders produced with 300 MPa treated soymilk had 8.7, 6.4, and 2 times more cell counts than those produced with non-UHPH treated soymilk during CCSD, MXSD, and FD, respectively. In the 300 MPa treated samples, cell survival (%) of LP during drying was the highest in MXSD (83.72) followed by FD (76.31) and CCSD (34.01). Using soymilk treated at higher UHPH pressures resulted in LP powders with lower moisture content, smaller particle sizes and higher agglomeration. LP powders produced via MXSD showed higher agglomeration and fewer signs of thermal damage than powders produced via CCSD. This study demonstrates that UHPH improves the effectiveness of soymilk as a microencapsulant for probiotics, creating probiotic powders that could be used in plant-based and non-dairy foods.

Antibiotic Resistance Profile of Salmonella enterica Isolated from Exotic and Indigenous Leafy Green Vegetables in Accra, Ghana.

ABSTRACT: Fresh produce-borne enteric bacterial pathogens that are resistant to antibiotics have posed serious challenges to food safety and public health worldwide. This study was conducted to evaluate the antibiotic resistance profiles of Salmonella enterica isolates (n = 33) recovered from exotic and indigenous leafy green vegetable samples (n = 328) collected from 50 vegetable farms in 12 farming areas and 37 vegetable sellers in four market centers in Accra, Ghana, from March 2016 to March 2017 and to determine the distribution of integrons among antibiotic-resistant isolates. The susceptibility of the Salmonella isolates to 12 antibiotics was assayed with the standard disk diffusion assay. The MICs of the five most resisted antibiotics were determined with a twofold macrodilution method. A PCR assay was used to detect the presence of integrons in Salmonella isolates, and PCR products with the amplified integron gene cassette were purified and sequenced with the Sanger sequencing technology. The Salmonella isolates used in the study were resistant to at least one tested antibiotic, and 30.3% (10 of 33) of the isolates were multidrug resistant. Most isolates (81.8%) were resistant to sulfisoxazole. The MICs of tetracycline, cefoxitin, streptomycin, ampicillin, and sulfisoxazole were 16, 32, 64, 64, and >1,024 µg/mL, respectively. Five patterns of multidrug resistance were observed among the Salmonella isolates, and the most common patterns were AAuFox (30.3%) and AAuFoxSSu (18.1%). One (3.0%) of the 33 Salmonella isolates tested positive for the class 1 integron, with a gene cassette of about 800 bp. Nucleotide sequencing revealed that this class 1 integron carried a single gene, dfrA7. Further studies are needed to determine whether the consumption of contaminated leafy green vegetables is a route for acquiring antibiotic-resistant Salmonella in Accra, Ghana.

Backward modeling of urinary test reliability for assessing PAH health risks: An approximation solution for naphthalene.

Urine sample tests are one of the most common methods of estimating human exposure to polycyclic aromatic hydrocarbons (PAHs) and assessing population health risks. To evaluate the reliability of the urine test and the impact of other PAH elimination routes on the health risk estimated by this test, we proposed a backward modeling framework integrating other common elimination routes of PAH metabolites to calculate the overall intake rate of the parent PAH based on the levels of corresponding main metabolites in urine. Due to limited biotransformation data, we selected naphthalene as an example to evaluate model performance and collected urine samples from 234 random adults in Shenzhen. The overall intake rates of naphthalene were then simulated and compared to current literature data. The simulated intake rates of naphthalene ranged from 3.70 × 10-3 mg d-1 to 1.95 mg d-1 and followed a lognormal distribution with a median value of 6.51 × 10-2 mg d-1. The results indicated that, if naphthalene exposure occurred only via food for the population of Shenzhen, the literature data fell within the most frequent interval [3.70 × 10-3, 4.45 × 10-2] but were lower than the simulated median value. However, if other exposure routes were considered, the allocation factor-adjusted literature data were close to the simulated median values. In addition, under normal physiological conditions, the simulated results were more sensitive to 1-hydroxynaphthalene (1-OHN) and 2-hydroxynaphthalene (2-OHN) levels in urine than other biometric variables, which is due to the limited load of 1-OHN and 2-OHN in human elimination routes. Furthermore, the suggested safety levels of 1-OHN and 2-OHN in urine to protect 99% of the general population of Shenzhen were 6.40 × 10-6 and 3.75 × 10-5 mg L-1, which could be used as regulatory indicators based on the high reliability of the model.

Quercetin inhibits TNF-α induced HUVECs apoptosis and inflammation via downregulating NF-kB and AP-1 signaling pathway in vitro.

BACKGROUND: Quercetin, a major flavonol, wildly exists in plantage, which has been reported to have an anti-apoptosis and anti-inflammation effects on vascular endothelial cells, but its underlying molecular mechanisms remain unclear. OBJECTIVE: The aim of this study was to investigate the mechanisms of how quercetin inhibits tumor necrosis factor alpha (TNF-α) induced human umbilical vein endothelial cells (HUVECs) apoptosis and inflammation. METHODS AND RESULTS: HUVECs were preconditioned with quercetin for 18 hours, and subsequently treated with TNF-α for 6 hours to induce apoptosis. The expression of intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), E-selectin, ß-actin mRNA was then detected by RT-PCR. Flow cytometry was used to estimate the apoptosis rates, and the expression of activator protein 1 (AP-1) and nuclear factor kappa B (NF-κB) was measured by Western blot. TNF-α induced elevated apoptosis rates and upregulation of VCAM-1, ICAM-1, and E-selectin were meaningfully reduced in HUVECs by pretreatment with quercetin. In addition, quercetin also inhibited the activation of AP-1and NF-κB. CONCLUSION: Results indicate that quercetin could suppress TNF-α induced apoptosis and inflammation by blocking NF-κB and AP-1 signaling pathway in HUVECs, which might be one of the underlying mechanisms in treatment of coronary heart disease.

Microencapsulation of Lactobacillus plantarum NRRL B-1927 with Skim Milk Processed via Ultra-High-Pressure Homogenization.

Several health benefits are associated with the consumption of probiotic foods. Lyophilized probiotic cultures are commonly used to manufacture probiotic-containing products. Spray drying (SDR) is a cost-effective process to microencapsulate probiotics. However, the high temperatures of the drying air in SDR can inactivate significant numbers of probiotic cells. Ultra-high-pressure homogenization (UHPH) processing can modify the configuration of proteins found in skim milk which may increase its protective properties as microencapsulating agent towards probiotic cells during SDR. The aim of this study was to evaluate the effect of microencapsulating probiotic Lactobacillus plantarum NRRL B-1927 (LP) with UHPH-treated skim milk after SDR or freeze drying (FD). Dispersions containing LP were made with either UHPH-treated (at 150 MPa or 300 MPa) or untreated skim milk and dried via concurrent SDR (CCSD), mixed-flow SDR (MXSD) or FD. Higher cell survival (%) of LP was found in powders microencapsulated with 150 MPa-treated skim milk than in those microencapsulated with non-UHPH-treated and 300 MPa-treated skim milk via FD followed by MXSD and CCSD, respectively. Increasing UHPH pressures increased the particle size of powders produced via CCSD; and reduced particle agglomeration of powders produced via MXSD and FD. This study demonstrated that UHPH processes improves the effectiveness of skim milk as a microencapsulating agent for LP, creating powders that could be used in probiotic foods.

Serum metabolic changes associated with dioxin exposure in a Chinese male cohort.

Dioxins, a group of persistent organic pollutants, have been proved to correlate with ranges of diseases by activating the aryl hydrocarbon receptor (AhR). However, previous dioxin toxicity studies primarily focused on the activation of AhR with signaling pathways at gene and protein levels. The investigation of underlying mechanisms at the metabolic level is still necessary. In this study, serum samples of 48 and 47 healthy participants with the highest and lowest dioxin levels based on quartile distribution of the serum dioxin concentrations of 215 male adults were selected for metabolomics analysis by using liquid chromatography coupled with orbitrap high-resolution mass spectrometry to investigate dioxin-related metabolic responses. The identified potential biomarkers included acylcarnitines, fatty acids and derivatives, glycerophospholipids, etc. suggested that metabolic pathways such as fatty acid ß-oxidation, essential fatty acid metabolism, arachidonic acid metabolism, glycerophospholipid and sphingolipid metabolism and purine metabolism were disturbed by dioxin exposure. The results indicated that people with high dioxin exposure levels were at the potential health risks of inflammation, liver and cardiovascular diseases. The metabolic findings may help understand the link between dioxin exposure and the diseases.

Interactions between fish isolates Pseudomonas fluorescens and Staphylococcus aureus in dual-species biofilms and sensitivity to carvacrol.

Biofilm formation is a frequent source of contamination of food products, which results in significant economic losses through microbial spoilage and poses serious health concerns. Little is known about the fate of Staphylococcus aureus in the dual-species biofilms with Pseudomonas fluorescens an important spoiler commonly found in aquatic products. This study evaluates the interactions between mono- or dual-species biofilms formed by P. fluorescens and S. aureus, as well as the sensitivity of the two tested strains to carvacrol. The biofilm cell population, expolysaccharide production, biofilm structures of P. fluorescens as mono- and dual-species with S. aureus at ratios of 1:1 and 1:0.01 were investigated with different concentrations of carvacrol (0, 0.4, 0.8 and 1.6 mM) in fish juice at 30 °C. The results show that the biofilm cell population of S. aureus in the dual-species was significantly lower (p < 0.05) than that in the mono-species, compared to no difference for P. fluorescens. In the co-culture the dominance of P. fluorescens inhibited the growing population of S. aureus in both planktonic and biofilm cells, however, two strains were stimulated to produce the large expolysaccharides and coaggregation, forming the complex spatial multibiofilm structures. The large increase in the dual-species biofilms was positively correlated with high quorum sensing autoinductor-2 (AI-2), and exogenous 4,5-dihydroxy-2,3-pentanedione (the AI-2 precursor, DPD), rather than C4-HSL, greatly stimulated the dual-species biofilm formation. In addition, carvacrol significantly reduced the tested biofilms and expolysaccharide secretion without affecting cell viability in a concentration-dependent manner, especially for S. aureus. Furthermore, the two strains as the dual-species biofilms exhibited lower sensitivity to carvacrol than the mono-culture, regardless of the level of inoculum of S. aureus, which was consistent with the decrease of AI-2 activity. The present study highlights that the interactions between P. fluorescens and S. aureus in dual-species biofilms promoted the large production of expolysaccharides and complex biofilm structures modulated by AI-2 signal, which results in the community-level resistance to carvacrol.