Extraction,optimisation and characterisation of phenolics from Thymus vulgaris L.: phenolic content and profiles in relation to antioxidant,antidiabetic and antihypertensive properties

The objectives of this study were to examine varying extraction conditions of Thymus vulgaris L. as related to phenolic content and profiles of the extracts and their antioxidant, antihypertensive and antidiabetic properties. Phenolics were extracted under various conditions pertaining to free and bound phenolics, solvent type and combination of extraction time and temperature, and these extracts were evaluated in terms of their antioxidant activities and inhibitory activities of angiotensin‐converting enzyme (ACE), α‐glucosidase and α‐amylase. The acetone–water solvent mixture (1:1; v/v) produced the extract with the greatest phenolic content, antioxidant activity and inhibitory activities of ACE and α‐glucosidase. The optimal extraction temperature for maximum phenolic content and antioxidant activity associated with methanol extraction was 60 °C, whereas a lower temperature at 40 °C was required to maximise inhibitory activities for ACE, α‐glucosidase and α‐amylase. An inverse relationship was seen between antioxidant and glucosidase inhibitory activities vs. the ACE and α‐amylase inhibitory activities, which suggests the need for extractions to be directed to specific bioactivities of thyme extracts. Generally, the results indicate major differences in phenolic profiles among the tested extraction conditions with thymol as the predominant phenolic seen in most extractions, while gallic acid, rosmarinic acid or diosmin also predominated in other extracts. Extracts with the same predominant phenolic compound and similar phenolic content showed major disparities in their ACE, glucosidase and α‐amylase inhibitory activities, indicating that the major phenolic profiles of thyme extracts may not be necessarily related to the degree of inhibition of ACE, glucosidase and α‐amylase enzymes.     

The effects of temperature,chlorine and acids on the survival of Listeria and Salmonella strains associated with uncooked shrimp carapace and cooked shrimp flesh

The purpose of this study was to assess the influence of the association of Listeria and Salmonella with shrimp surfaces on the effects of temperature, chlorine and acids on their survival. Planktonic, attached and colonized cells of Listeria monocytogenes Scott A, L. monocytogenes V7, Salmonella Senftenberg 1734b and S. Typhimurium ATCC 14028 were challenged with high (50°, 60° and 70 °C) and low (4 °C) temperature, 100 ppm sodium hypochlorite solution, and acetic, hydrochloric and lactic acids (pH 4.0). Attached and colonized Listeria and Salmonella showed significantly greater (p < 0.05) resistance to heat (∼1.3–2.6 fold increase in D-values), hypochlorite (∼6.6 ≥ 40.0 fold) and acids (∼4.0–9.0 fold) than their planktonic counterparts. There were no significant differences (p > 0.05) in the survival of planktonic, attached or colonized cells of Listeria and Salmonella stored under refrigerated conditions. The association of Listeria and Salmonella with shrimp surfaces enhances their resistance to heat, chlorine and acids. Both attachment to, and subsequent colonization of, shrimp surfaces by pathogens may reduce the efficacy of methods used in their control. Strategies to reduce attachment of these pathogens to shrimp are required to assure safety of this product.     

The effect of multiple yeasts co-inoculations on Sauvignon Blanc wine aroma composition,sensory properties and consumer preference

Consumer acceptance testing has been only recently applied in wine research, to assess wine sensory attributes that affect hedonic liking. The aim of this study was to investigate the effect of Saccharomyces yeast co-inoculations on wine volatile composition and sensory profiles, and to determine if differences were sufficient enough to affect consumer acceptance. Fermentations were conducted using two- and three-yeast co-inoculations, and single strains. Yeast inocula differed substantially in volatile thiols and other flavour compounds, and in their sensory properties. Wines from four yeast inocula which showed large sensory differences were subjected to consumer testing by 120 consumers, with differences in overall liking found. Four clusters of consumers were identified, with one group strongly preferring the two-yeast co-inoculated wine with an intermediate sensory profile, while another group favoured the wine made using the three-yeast co-inoculation. This study has demonstrated that the yeast inoculum used to conduct fermentation affects consumer acceptance.     

Dimensions of depressive symptoms and smoking cessation.

Because different psychopathologic components of depressive symptoms may have distinct etiologies, examining their differential effects on smoking cessation may elucidate mechanisms underlying the smoking-depression relationship. Negative affect (NA), somatic features (SF), low positive affect/anhedonia (PA), and interpersonal disturbance (IP) have been identified as unique dimensions of depression that can be measured using the Center for Epidemiologic Studies Depression Scale (CESD). This study examined common and unique associations between CESD subscales and baseline smoking characteristics, nicotine withdrawal, and relapse in 157 participants enrolled in a smoking cessation trial for heavy social drinkers. Each dimension was univariately associated with negative and positive reinforcement smoking motives. Only SF had unique relations with tolerance smoking motives and univariate associations with nicotine dependence severity. Only PA predicted cessation-related changes in withdrawal symptoms on quit day. Analyses predicting abstinence at 8, 16, and 26 weeks post quit date showed that NA, SF, and PA each univariately predicted relapse, ps< or =.0083. Only low PA predicted poorer outcomes incrementally to the other dimensions, even when controlling for level of nicotine dependence, smoking frequency, and history of major depression, p = .0018. Interventions targeting anhedonia and low positive affect may be useful for smokers trying to quit.     

Occurrence, synthesis, and mammalian cell cytotoxicity and genotoxicity of haloacetamides: an emerging class of nitrogenous drinking water disinfection byproducts

The haloacetamides, a class of emerging nitrogenous drinking water disinfection byproduct (DBPs), were analyzed for their chronic cytotoxicity and for the induction of genomic DNA damage in Chinese hamster ovary cells. The rank order for cytotoxicity of 13 haloacetamides was DIAcAm > IAcAm > BAcAm > TBAcAm > BIAcAm > DBCAcAm > CIAcAm > BDCAcAm > DBAcAm > BCAcAm > CAcAm > DCAcAm > TCAcAm. The rank order of their genotoxicity was TBAcAm > DIAcAm approximately equal to IAcAm > BAcAm > DBCAcAm > BIAcAm > BDCAcAm > CIAcAm > BCAcAm > DBAcAm > CAcAm > TCAcAm. DCAcAm was not genotoxic. Cytotoxicity and genotoxicity were primarily determined by the leaving tendency of the halogens and followed the order I > Br > > Cl. With the exception of brominated trihaloacetamides, most of the toxicity rank order was consistent with structure-activity relationship expectations. For di- and trihaloacetamides, the presence of at least one good leaving halogen group (I or Br but not Cl) appears to be critical for significant toxic activity. Log P was not a factor for monohaloacetamides but may play a role in the genotoxicity of trihaloacetamides and possible activation of dihaloacetamides by intracellular GSH and -SH compounds.     

Alternate and new brominated flame retardants detected in U.S. house dust

Due to the voluntary withdrawals and/or bans on the use of two polybrominated diphenyl ether (PBDE) commercial mixtures, an increasing number of alternate flame retardant chemicals are being introduced in commercial applications. To determine if these alternate BFRs are present in indoor environments, we analyzed dust samples collected from 19 homes in the greater Boston, MA area during 2006. Using pure and commercial standards we quantified the following brominated flame retardant chemicals using GC/ECNI-MS methods: hexabromocyclododecane (sigma HBCD), bis(2,4,6,-tribromphenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), and the brominated components found in Firemaster 550 (FM 550): 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB) and (2-ethylhexyl)tetrabromophthalate (TBPH), the latter compound being a brominated analogue of di(2-ethylhexyl)phthalate (DEHP). The concentrations of all compounds were log-normally distributed and the largest range in concentrations was observed for HBCD (sum of all isomers), with concentrations ranging from <4.5 ng/g to a maximum of 130,200 ng/g with a median value of 230 ng/g. BTBPE ranged from 1.6 to 789 ng/g with a median value of 30 ng/g and DBDPE ranged from <10.0 to 11,070 ng/g with a median value of 201 ng/g. Of the FM 550 components, TBB ranged from <6.6 to 15,030 ng/g with a median value of 133 ng/g; whereas TBPH ranged from 1.5 to 10,630 ng/g with a median value of 142 ng/g. Furthermore, the ratio of TBB/TBPH present in the dust samples ranged from 0.05 to 50 (average 4.4), varying considerably from the ratio observed in the FM 550 commercial mixture (4:1 by mass), suggesting different sources with different chemical compositions, and/or differential fate and transport within the home. Analysis of paired dust samples collected from different rooms in the same home suggests HBCD, TBB, and TBPH are higher in dust from the main living area compared to dust collected in bedrooms; however, BTBPE and DBDPE levels were comparable between rooms. This study highlights the fact that numerous types of brominated flame retardants are present in indoor environments, raising questions about exposure to mixtures of these contaminants.     

Phthalate esters in human milk: concentration variations over a 6-month postpartum time

The present study investigated the levels of phthalate esters in a total of 86 human milk samples collected among 21 breast-feeding mothers over a 6-month postpartum time. Di(2-ethylhexyl) phthalate (DEHP) was the predominant ester with the arithmetic mean value of 222 ng g(-1) (range: 156-398 ng g(-1), 95% confidence limit), followed by dibutyl phthalate (DBP), 0.87 (range: 0.62-1.2) ng g(-1). Diethyl phthalate (DEP), with a mean of 0.31 ng g(-1), was detected in only a small number of samples. Weak correlations between lipid content and levels of phthalate esters were observed. The levels of phthalate esters in human milk fluctuated over the 6-month period; this may indicate a need for multiple sample collection, to calculate average concentrations over the feeding period. Multiple sample collection would provide a better estimate of the exposure of breast-fed infants to phthalate in human milk. For infants relying on breast-feeding, the mean daily intake over the first 6-month period considering a 7 kg infant consuming 750 g of milk was estimated at 167 microg d(-1) for DEHP and less than 1 microg d(-1) for DBP and DEP. While the nutritional and social benefits of breast-feeding are well established, the potential transfer of phthalate esters from mothers to breast-fed infants should also be recognized.     

Effect of vanillin, ethyl vanillin, and vanillic acid on the growth and heat resistance of Cronobacter species

Preservatives could be part of an effective intervention strategy for the control of Cronobacter species in foods, but few compounds with the desired antimicrobial properties have been identified to date. We examined the antibacterial activity of vanillin, ethyl vanillin, and vanillic acid against seven Cronobacter spp. in quarter-strength tryptic soy broth with 5 g/liter yeast extract (TSBYE) adjusted to pH 5.0, 6.0, and 7.0 at 10, 21, and 37°C. All compounds exhibited pH- and temperature-dependant bacteriostatic and bactericidal activity. MICs of vanillin and ethyl vanillin consistently increased with decreasing pH and temperature, but vanillic acid had little activity at pH values of 6.0 and 7.0. The MICs for all temperatures, pH values, and bacterial strains tested were 2 mg/ml ethyl vanillin, 3 mg/ml vanillin, and >8 mg/ml vanillic acid. MBCs also were influenced by pH, although significantly higher concentrations were needed to inactivate the bacteria at 21°C than at 10 or 37°C. Survivor curves for Cronobacter sakazakii strains at the MBCs of each compound revealed that all treatments resulted in immediate loss of cell viability at 37°C. Measurements of propidium iodide uptake indicated that the cell membranes were damaged by exposure to all three compounds. The thermal resistance of C. sakazakii was examined at 58°C in TSBYE supplemented with MBCs of each compound at pH 5.0 and 6.0. D-values at pH 5.0 were reduced from 14.56 ± 0.60 min to 0.93 ± 0.01, 0.63 ± 0.01, and 0.98 ± 0.02 min for vanillin, ethyl vanillin, and vanillic acid, respectively. These results suggest that vanillin, ethyl vanillin, and vanillic acid may be useful for the control of Cronobacter spp. in food during preparation and storage.     

Survivability of Salmonella and Shigella spp. in sodium lauryl sulfate and tween 80 at 22 and 40 degrees C

Fresh produce has been implicated in several foodborne disease outbreaks. A primary site of contamination during production and handling is the surface of produce. One approach to reducing contamination is to treat fresh produce with rinsing agents. Studies have examined the efficacies of detergents and other rinses in recovering pathogens from produce surfaces. The determination of how these detergents affect bacterial cells may aid in understanding the mechanisms behind their removal. This study examines the survivability of Salmonella and Shigella in two detergents. A 0.1% sodium lauryl sulfate (SLS) solution, a 0.1% Tween 80 solution, and water were inoculated with a cocktail of stationary-phase organisms (3 log CFU/ml) and incubated for up to 32 h at 22 degrees C and 40 degrees C. Samples were taken over time and plated on tryptic soy agar supplemented with 50 ppm of nalidixic acid. Salmonella survived in all solutions and exhibited significant growth in water (0.8 log CFU/ml at 22 degrees C and 1.9 log CFU/ml at 40 degrees C) and Tween 80 (1.0 log CFU/ml at 40 degrees C). Shigella survived in all solutions at 22 degrees C and exhibited a growth level of 2.0 log CFU/ml in SLS. Shigella also survived in all solutions at 40 degrees C, although its populations decreased significantly in Tween 80 over time. Elevated temperatures may allow Tween 80 to kill Shigella spp. over time. Overall, the detergents tested were not detrimental to the cells; therefore, if these solutions were to be used as produce rinse agents, they would aid in removal of organisms from surfaces rather than kill the cells.     

Tribromopyrrole,brominated acids,and other disinfection byproducts produced by disinfection of drinking water rich in bromide

Using gas chromatography/mass spectrometry (GC/MS), we investigated the formation of disinfection byproducts (DBPs) from high bromide waters (2 mg/L) treated with chlorine or chlorine dioxide used in combination with chlorine and chloramines. This study represents the first comprehensive investigation of DBPs formed by chlorine dioxide under high bromide conditions. Drinking water from full-scale treatment plants in Israel was studied, along with source water (Sea of Galilee) treated under carefully controlled laboratory conditions. Select DBPs (trihalomethanes, haloacetic acids, aldehydes, chlorite, chlorate, and bromate) were quantified. Many of the DBPs identified have not been previously reported, and several of the identifications were confirmed through the analysis of authentic standards. Elevated bromide levels in the source water caused a significant shift in speciation to bromine-containing DBPs; bromoform and dibromoacetic acid were the dominant DBPs observed, with very few chlorine-containing compounds found. Iodo-trihalomethanes were also identified, as well as a number of new brominated carboxylic acids and 2,3,5-tribromopyrrole, which represents the first time a halogenated pyrrole has been reported as a DBP. Most of the bromine-containing DBPs were formed during pre-chlorination at the initial reservoir, and were not formed by chlorine dioxide itself. An exception wasthe iodo-THMs, which appeared to be formed by a combination of chlorine dioxide with chloramines or chlorine (either added deliberately or as an impurity in the chlorine dioxide). A separate laboratory study was also conducted to quantitatively determine the contribution of fulvic acids and humic acids (from isolated natural organic matter in the Sea of Galilee) as precursor material to several of the DBPs identified. Results showed that fulvic acid plays a greater role in the formation of THMs, haloacetic acids, and aldehydes, but 2,3,5-tribromopyrrole was produced primarily from humic acid. Because this was the first time a halopyrrole has been identified as a DBP, 2,3,5-tribromopyrrole was tested for mammalian cell cytotoxicity and genotoxicity. In comparison to other DBPs, 2,3,5-tribromopyrrole was 8x, 4.5x, and 16x more cytotoxic than dibromoacetic acid, 3-chloro-4-(dichloromethyl)-5-hydroxy-2-[5H]-furanone [MX], and potassium bromate, respectively. 2,3,5-Tribromopyrrole also induced acute genomic damage, with a genotoxic potency (299 microM) similar to that of MX.