Inhibition of microbial production of the malodorous substance isovaleric acid by 4,4' dichloro 2-hydroxydiphenyl ether (DCPP).

Human body malodour is a complex phenomenon. Several types of sweat glands produce odorless secretions that are metabolized by a consortium of skin-resident microorganisms to a diverse set of malodorous substances. Isovaleric acid, a sweaty-smelling compound, is one major malodorous component produced by staphylococci with the skin-derived amino acid L-leucine as a substrate. During wearing, fabrics are contaminated with sweat and microorganisms and high humidity propagates growth and microbial malodour production. Incomplete removal of sweat residues and microorganisms from fabrics during laundry with bleach-free detergents and at low temperatures elevate the problem of textile malodour. This study aimed to analyze the inhibitory effect of the antimicrobial 4,4' dichloro 2-hydroxydiphenyl ether (DCPP) on the formation of isovaleric acid on fabrics. Therefore, GC-FID- and GC-MS-based methods for the analysis of isovaleric acid in an artificial human sweat-mimicking medium and in textile extracts were established. Here, we show that antimicrobials capable to deposit on fabrics during laundry, such as DCPP, are effective in growth inhibition of typical malodour-generating bacteria and prevent the staphylococcal formation of isovaleric acid on fabrics in a simple experimental setup. This can contribute to increased hygiene for mild laundry care approaches, where bacterial contamination and malodour production represent a considerable consumer problem.

The egg and larval pheromone dodecanoic acid mediates density-dependent oviposition of Phlebotomus papatasi.

BACKGROUND: Gravid females assess the conditions of oviposition sites to secure the growth and survival of their offspring. Conspecific-occupied sites may signal suitable oviposition sites but may also impose risk due to competition or cannibalism at high population density or heterogeneous larval stage structure, respectively. Chemicals in the habitat, including chemicals emitted from other organisms, serve as cues for females to assess habitat conditions. Here, we investigated the attraction and oviposition preference of the Old World cutaneous leishmaniasis vector, Phlebotomus papatasi, to young and old conspecific stages, including eggs and evaluated the effect of a semiochemical associated with eggs and neonate larvae. METHODS: Attraction and oviposition preference of Ph. papatasi to each of various life stages (eggs, first-, second-, third-, fourth-instar larvae, pupae and male and female adults) was investigated using cage and oviposition jar behavioral assays. Identification of organic chemical compounds extracted from eggs was performed using GC-MS and chemicals were tested in the same behavioral assays in a dose-response manner. Behavioral responses were statistically analyzed using logistic models. RESULTS: Gravid Ph. papatasi females were significantly attracted to and preferred to oviposit on medium containing young life stages (eggs and first instars). This preference decreased towards older life stages. Dose effect of eggs indicated a hump-shaped response with respect to attraction but a concave-up pattern with respect to oviposition. Chemical analysis of semiochemicals from eggs and first-instar larvae revealed the presence of dodecanoic acid (DA) and isovaleric acid. Sand flies were attracted to and laid more eggs at the lowest DA dose tested followed by a negative dose-response. CONCLUSIONS: Findings corroborated our hypothesis that gravid sand flies should prefer early colonized oviposition sites as indicators of site suitability but avoid sites containing older stages as indicators of potential competition. Findings also supported the predictions of our hump-shaped oviposition regulation (HSR) model, with attraction to conspecific eggs at low-medium densities and switching to repellence at high egg densities. This oviposition behavior is mediated by DA that was identified from surface extracts of both eggs and first-instar larvae. Isovaleric acid was also found in extracts of both stages.

Short-chain fatty acids accompanying changes in the gut microbiome contribute to the development of hypertension in patients with preeclampsia.

Preeclampsia (PE) is regarded as a pregnancy-associated hypertension disorder that is related to excessive inflammatory responses. Although the gut microbiota (GM) and short-chain fatty acids (SCFAs) have been related to hypertension, their effects on PE remain unknown. We determined the GM abundance and faecal SCFA levels by 16S ribosomal RNA (rRNA) sequencing and gas chromatography, respectively, using faecal samples from 27 patients with severe PE and 36 healthy, pregnant control subjects. We found that patients with PE had significantly decreased GM diversity and altered GM abundance. At the phylum level, patients with PE exhibited decreased abundance of Firmicutes albeit increased abundance of Proteobacteria; at the genus level, patients with PE had lower abundance of Blautia, Eubacterium_rectale, Eubacterium_hallii, Streptococcus, Bifidobacterium, Collinsella, Alistipes, and Subdoligranulum, albeit higher abundance of Enterobacter and Escherichia_Shigella. The faecal levels of butyric and valeric acids were significantly decreased in patients with PE and significantly correlated with the above-mentioned differential GM abundance. We predicted significantly increased abundance of the lipopolysaccharide (LPS)-synthesis pathway and significantly decreased abundance of the G protein-coupled receptor (GPCR) pathway in patients with PE, based on phylogenetic reconstruction of unobserved states (PICRUSt). Finally, we evaluated the effects of oral butyrate on LPS-induced hypertension in pregnant rats. We found that butyrate significantly reduced the blood pressure (BP) in these rats. In summary, we provide the first evidence linking GM dysbiosis and reduced faecal SCFA to PE and demonstrate that butyrate can directly regulate BP in vivo, suggesting its potential as a therapeutic agent for PE.

Fate of 6:2 fluorotelomer sulfonic acid in pumpkin (Cucurbita maxima L.) based on hydroponic culture: Uptake, translocation and biotransformation.

6:2 fluorotelomer sulfonic acid (6:2 FTSA) is currently used as an alternative to perfluorooctanesulfonate (PFOS) and is widely detected in the environment. The uptake, translocation and biotransformation of 6:2 FTSA in pumpkin (Cucurbita maxima L.) were investigated by hydroponic exposure for the first time. The root concentration factor (RCF) of 6:2 FTSA was 2.6-24.2 times as high as those of perfluoroalkyl acids (PFAAs) of the same or much shorter carbon chain length, demonstrating much higher bioaccumulative ability of 6:2 FTSA in pumpkin roots. The translocation capability of 6:2 FTSA from root to shoot depended on its hydrophobicity. Six terminal perfluorocarboxylic acid (PFCA) metabolites, including perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), perfluorobutanoic acid (PFBA), perfluoropropionic acid (PFPrA) and trifluoroacetic acid (TFA) were found in pumpkin roots and shoots. PFHpA was the primary metabolite in roots, while PFBA was the major product in shoots. 1-aminobenzotriazole (ABT), a cytochromes P450 (CYPs) suicide inhibitor, could decrease the concentrations of PFCA products with dose-dependent relationships in pumpkin tissues, implying the role of CYP enzymes involved in plant biotransformation of 6:2 FTSA. This study indicated that the application of 6:2 FTSA can lead to the occurrence of PFCAs (C2-C7) in plants.

A Method for Controlled Odor Delivery in Olfactory Field-Testing.

A widely recognized limitation in mammalian olfactory research is the lack of current methods for measuring odor availability (i.e., the quantifiable amount of odor presented and thus available for olfaction) of training or testing materials during behavioral or operational testing. This research utilized an existing technology known as Controlled Odor Mimic Permeation Systems (COMPS) to produce a reproducible, field-appropriate odor delivery method that can be analytically validated and quantified, akin to laboratory-based research methods, such as permeation devices that deliver a stable concentration of a specific chemical vapor for instrumental testing purposes. COMPS were created for 12 compounds across a range of carbon chain lengths and functional groups in such a way to produce similar permeation rates for all compounds. Using detection canines as a model, field-testing was performed to assess the efficacy of the method. Additionally headspace concentrations over time were measured as confirmation of odor availability using either externally sampled internal standard-solid phase microextraction-gas chromatography-mass spectrometry (ESIS-SPME-GC-MS) or collection onto a programmable temperature vaporizing (PTV) GC inlet with MS detection. Finally, lifetime usage was considered. An efficient method for producing and measuring reliable odor availabilities across various chemical functional groups was developed, addressing a noted gap in existing literature that will advance canine and other nonhuman mammal research testing.

Matrix binding of T-2 toxin: structure elucidation of reaction products and indications on the fate of a relevant food-borne toxin during heating.

This study deals with the influence of food matrix components on the degradation of the mycotoxins T-2 toxin (T-2) and HT-2 toxin (HT-2) and with the binding of T-2 to starch during thermal food processing. Both mycotoxins were heated in a simulated food environment and subsequently analyzed via HPLC-HRMS to generate degradation curves and to draw conclusions regarding the thermal degradation under food processing conditions. Thermal degradation increased generally with increasing time and temperature with a maximum degradation rate of 93% (T-2) and 99% (HT-2). Furthermore, HRMS data were exploited to screen the samples for degradation products. In model heating experiments, T-2 was bound to 1-O-methyl-α-D-glucopyranoside, a model compound that was used to simulate starch. The formed reaction products were isolated and identified by NMR, giving detailed insights into a potential binding of T-2 to starch. In the next step, further model heating experiments were performed, which proved the covalent binding of T-2 to starch. Finally, the amount of matrix-bound T-2 was estimated roughly in a semi-quantitative approach in the model heating experiments as well as during cookie-making via GC-MS analysis of the isovaleric acid ester moiety of T-2, released after alkaline hydrolysis.

Short communication: Blood metabolites, body reserves, and feed efficiency of high-producing dairy cows that varied in ruminal pH when fed a high-concentrate diet.

Recent studies report considerable variation in ruminal pH for lactating dairy cows even when fed the same diet. We hypothesized that blood metabolites would be indicators of low ruminal pH, and hence could be used as predictors to help manage this variability. The objective of the study was to determine whether blood metabolite concentrations, body reserves, and feed efficiency were associated with ruminal pH in high-producing dairy cows fed a high-concentrate diet. Seventy-eight individually fed lactating dairy cows (days in milk = 103 ± 27; body weight = 638 ± 77 kg at the start; mean ± SD) were fed a diet consisting of 35% forage and 65% concentrate (dry matter basis). Cows were adapted for 14 d and then were sampled for 10 d. Ruminal pH was measured by rumenocentesis for all cows at the end of the study 4 h after feeding, and reticular pH was measured on a subsample of 14 cows via indwelling sensors for 5 consecutive days. Cows were classified according to rumenocentesis pH as high (pH ≥ 6.0; n = 26), medium (5.8 ≤ pH < 6; n = 21), and low (pH < 5.8; n = 31). Cows were also classified according to reticular pH as high if pH <5.8 persisted <330 min/d (an average of 78 min/d; n = 5) or low if duration of pH <5.8 was ≥330 min/d (an average of 920 min/d; n = 9). The classification based on rumenocentesis pH revealed that serum activity of aspartate aminotransferase (AST) was greater in cows with low ruminal pH (70.7 U/L) than cows with high (56.6 U/L) and medium (59.9 U/L) ruminal pH. Also, the blood urea nitrogen concentration was greater in cows with low ruminal pH (13.6 mg/dL) than cows with medium (12.2 mg/dL) and high (12.5 mg/dL) ruminal pH. Blood albumin concentration was greater for cows with low ruminal pH than for cows with medium and high ruminal pH. The classification based on reticular pH also resulted in a trend of greater AST activity and greater blood urea nitrogen concentration in the blood of cows with low pH. Regression analysis showed high serum concentration of AST was associated with high valerate concentration in ruminal fluid (R2 = 0.14), low rumenocentesis pH (R2 = 0.10), and low milk fat percentage (R2 = 0.06). Glucose, triglyceride, cholesterol, globulin, alkaline phosphates, and serum amyloid A did not differ among the different ruminal pH classes. Low pH cows (reticular and ruminal) had less backfat thickness measured via ultrasound, and cows with low ruminal pH tended to have greater milk:feed ratio. Results indicated that cows that differ in ruminal pH also had different concentrations of blood metabolites and backfat thickness, and AST activity in blood may be a plausible indicator of ruminal pH in dairy cows. Further studies on the applicability of AST in blood as a biomarker for detecting low ruminal pH in dairy cows are warranted.

Phenyl-γ-valerolactones and phenylvaleric acids, the main colonic metabolites of flavan-3-ols: synthesis, analysis, bioavailability, and bioactivity.

Covering: 1958 to June 2018 Phenyl-γ-valerolactones (PVLs) and their related phenylvaleric acids (PVAs) are the main metabolites of flavan-3-ols, the major class of flavonoids in the human diet. Despite their presumed importance, these gut microbiota-derived compounds have, to date, in terms of biological activity, been considered subordinate to their parent dietary compounds, the flavan-3-ol monomers and proanthocyanidins. In this review, the role and prospects of PVLs and PVAs as key metabolites in the understanding of the health features of flavan-3-ols have been critically assessed. Among the topics covered, are proposals for a standardised nomenclature for PVLs and PVAs. The formation, bioavailability and pharmacokinetics of PVLs and PVAs from different types of flavan-3-ols are discussed, taking into account in vitro and animal studies, as well as inter-individual differences and the existence of putative flavan-3-ol metabotypes. Synthetic strategies used for the preparation of PVLs are considered and the methodologies for their identification and quantification assessed. Metabolomic approaches unravelling the role of PVLs and PVAs as biomarkers of intake are also described. Finally, the biological activity of these microbial catabolites in different experimental models is summarised. Knowledge gaps and future research are considered in this key area of dietary (poly)phenol research.

Understanding the microbial basis of body odor in pre-pubescent children and teenagers.

BACKGROUND: Even though human sweat is odorless, bacterial growth and decomposition of specific odor precursors in it is believed to give rise to body odor in humans. While mechanisms of odor generation have been widely studied in adults, little is known for teenagers and pre-pubescent children who have distinct sweat composition from immature apocrine and sebaceous glands, but are arguably more susceptible to the social and psychological impact of malodor. RESULTS: We integrated information from whole microbiome analysis of multiple skin sites (underarm, neck, and head) and multiple time points (1 h and 8 h after bath), analyzing 180 samples in total to perform the largest metagenome-wide association study to date on malodor. Significant positive correlations were observed between odor intensity and the relative abundance of Staphylococcus hominis, Staphylococcus epidermidis, and Cutibacterium avidum, as well as negative correlation with Acinetobacter schindleri and Cutibacterium species. Metabolic pathway analysis highlighted the association of isovaleric and acetic acid production (sour odor) from enriched S. epidermidis (teen underarm) and S. hominis (child neck) enzymes and sulfur production from Staphylococcus species (teen underarm) with odor intensity, in good agreement with observed odor characteristics in pre-pubescent children and teenagers. Experiments with cultures on human and artificial sweat confirmed the ability of S. hominis and S. epidermidis to independently produce malodor with distinct odor characteristics. CONCLUSIONS: These results showcase the power of skin metagenomics to study host-microbial co-metabolic interactions, identifying distinct pathways for odor generation from sweat in pre-pubescent children and teenagers and highlighting key enzymatic targets for intervention.

GC-MS Analysis of Short-Chain Fatty Acids in Feces, Cecum Content, and Blood Samples.

Short-chain fatty acids, the end products of fermentation of dietary fibers by the gut microbiota, have been shown to exert multiple effects on mammalian metabolism. For the analysis of short-chain fatty acids, gas chromatography-mass spectrometry is a very powerful and reliable method. Here, we describe a fast, reliable, and reproducible method for the separation and quantification of short-chain fatty acids in mouse feces, cecum content, and blood samples (i.e., plasma or serum) using gas chromatography-mass spectrometry. The short-chain fatty acids analyzed include acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, and heptanoic acid.

Reliable GC Method for Related Substances in Divalproex Sodium Drug.

A specific GC method has been developed, optimized and validated for the determination of seven related substances namely N,N-dimethyl valpronamide, valeric acid, 2-methyl valeric acid, 2-ethyl valeric acid, 2-isopropyl valeric acid, 2-n-butyl valeric acid and 2-propyl-2-pentenoic acid in divalproex sodium (DPS) drug substance. Chromatographic separations of these seven impurities were achieved on DB-FFAP column (30 m × 0.53 mm, 1.0 µm), which consists nitroterephthalic acid modified polyethylene glycol material as stationary phase. DPS is a coordination complex of the sodium valproate and valproic acid (VPA). Nonanoic acid is used as internal standard. All the seven related substances, VPA and nonanoic acid were extracted into dichloromethane and monitored by GC with flame ionization detector. The performance of the developed method was assessed by evaluating specificity, linearity, sensitivity, precision, accuracy and robustness. Forced degradation experiments were conducted to evaluate the degradation behavior of DPS. The established limits of detection (LODs) and limits of quantification (LOQs) values for the related substances were in the ranges of 4-5 and 12-15 µg mL-1, respectively. Further, for VPA, LOD and LOQ values were 4 and 12 µg mL-1, respectively. The correction factors of these related substances with respect to VPA and lie between 0.92 and 1.44. The average recoveries were in the range of 92.4-108.4%.

Additive free preparative chiral SFC separations of 2,2-dimethyl-3-aryl-propanoic acids.

A series of racemic 2,2-dimethyl-3-aryl-propanoic acids were resolved by chiral supercritical fluid chromatography (SFC) without the use of an acidic additive, trifluoroacetic acid (TFA). The use of additive-free protic methanol as co-solvent in CO2 was expanded to successfully resolve other series of carboxylic acid containing racemates. Large-scale SFC of racemic acid 4, 3-(1-(4-fluorophenyl)-1H-indazol-5-yl)-2,2-dimethyl-3-phenylpropanoic acid, in methanol without TFA as additive on both Chiralpak AD-H and Chiralcel OJ-H will be discussed, along with impact on throughput and solvent consumption. Investigation of co-solvent effect on peak sharpening of acid racemate 20, 2-(2-chloro-9-fluoro-5H-chromeno[2,3-b]pyridin-5-yl)-2-methylpropanoic acid, without TFA further indicated that methanol in CO2 provided improved peak shape compared with isopropanol (IPA) and acetonitrile. Finally, we discuss the resolution of basic aromatic chiral amines without the addition of basic additives such as diethylamine (DEA) and application of this protocol for the large-scale SFC separation of weakly basic indazole-containing racemate 14, methyl 3-(1H-indazol-5-yl)-2,2-dimethyl-3-phenylpropanoate, in methanol without DEA.

Conversion of polyhydroxyalkanoates to methyl crotonate using whole cells.

Isolated polyhydroxyalkanoates (PHA) can be used to produce biobased bulk chemicals. However, isolation is complex and costly. To circumvent this, whole cells containing PHA may be used. Here, PHA containing 3-hydroxybutyrate and small amounts of 3-hydroxyvalerate was produced from wastewater and used in the conversion of the 3-hydroxybutyrate monomer to methyl crotonate. Due to the increased complexity of whole cell reaction mixtures compared to pure PHA, the effect of 3-hydroxyvalerate content, magnesium salts and water content was studied in order to evaluate the need for downstream processing. A water content up to 20% and the presence of 3-hydroxyvalerate have no influence on the conversion of the 3-hydroxybutyrate to methyl crotonate. The presence of Mg(2+)-ions resulted either in an increased yield or in byproduct formation depending on the counter ion. Overall, it is possible to bypass a major part of the downstream processing of PHA for the production of biobased chemicals.

Isovaleric acid in stool correlates with human depression.

OBJECTIVE: Human depression is a major burden, both on the individuals who suffer from the disease and on society at large. Traditionally, depression has been linked to psychological and biological causes, but there has been increasing interest in the gut-brain axis. In this regard, we have recently shown that specific bacteria are correlated with human depression, and we hypothesize that volatile fatty acids (VFAs) are mediators. METHODS: Here, we analyzed the direct correlation between VFAs, depression and cortisol in a cohort consisting of 34 depressed patients and 17 controls. RESULTS: We found statistically significant correlations between depression and the VFA isovaleric acid, as well as between isovaleric acid and cortisol. Furthermore, bacteria that previously have been identified as being correlated with depression were also correlated with isovaleric acid. Isovaleric acid showed a bimodal distribution in which the depressed patients were overrepresented in the high level group (P < 0.00005, binominal test). DISCUSSION: It has recently been shown that gut-derived VFAs can cross the blood-brain barrier, where isovaleric acid interferes with synaptic neurotransmitter release. The multiple correlation patterns, in addition to a potential mechanistic model, point towards a potential causal relationship between depression and isovaleric acid.

Determination of XLR-11 and its metabolites in hair by liquid chromatography-tandem mass spectrometry.

Analysis of drugs in hair is often used as a routine method to obtain detailed information about drug ingestion. However, few studies have been conducted on disposition of synthetic cannabinoids including cyclopropylindoles (UR-144 and XLR-11) and their metabolites in hair. XLR-11 has been widely abused in South Korea recently. Identification of metabolites in hair can be an important proof of synthetic cannabinoids use because it can exclude the possibility of passive smoke exposure. In this study, we described a quantitative analytical method of XLR-11 and its metabolites (UR-144, UR-144 N-5-hydroxypentyl metabolite, UR-144 N-4-hydroxypentyl metabolite, UR-144 N-pentanoic acid metabolite and XLR-11 N-4-hydroxypentyl metabolite) in hair by liquid chromatography with ESI-MS/MS. The target analytes were extracted with methanol from washed and cut hair samples and the extracts were evaporated, filtered and analyzed by LC-MS/MS with electrospray ion source in positive-ionization mode. JWH-018-d9 and JWH-018 N-5-hydroxypentyl metabolite-d5 were used as internal standards. Chromatographic separation was completed within 15 min. No interferences were detected in 10 blank hair samples. In intra- and inter-assay precision and accuracy study, CV (%) and bias (%) were below 12. The limit of detection (LOD) was 0.1∼2 pg/mg and the limit of quantification (LOQ) was 0.2-2 pg/mg, respectively. The validation results proved that the method was selective, accurate and precise with acceptable linearity within calibration range. No significant variation was observed by different sources of matrices. This method was applied to hair samples from 14 individual suspects of XLR-11 use. In this result, XLR-11, UR-144, UR-144 N-5-hydroxypentyl metabolite and UR-144 N-pentanoic acid metabolite, XLR-11 N-4-hydroxypentyl metabolite were detected. The concentration of XLR-11 as a parent drug was much higher than other metabolites. UR-144 N-5-hydroxy metabolite and UR-144 N-pentanoic acid were detected mainly in the authentic hair samples from suspected of XLR-11 use. UR-144 N-4- hydroxypentyl metabolite was not detected in all cases.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production by a moderate halophile Yangia sp. ND199 using glycerol as a carbon source.

Yangia sp. ND199, a moderate halophile isolated from mangrove soil sample in Vietnam, was found to accumulate poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from unrelated carbon sources in a medium with 4.5% (w/v) NaCl. Cultivation with glycerol as carbon source and yeast extract as nitrogen source resulted in maximum cell dry weight of 5.7 g/l and PHBV content of 52.8 wt% (containing 2.9 mol% of 3HV) after 40 h. The 3HV content of the PHBV was the highest during initial stages of copolymer production and decreased with increase in the copolymer amount with time, but was not affected by changing the pH of the culture medium. Only homopolymer poly(3-hydroxybutyrate) was synthesized when monosodium glutamate was used as the nitrogen source. Fed-batch cultivation of Yangia sp. ND199 with glycerol and yeast extract gave PHBV content and productivity of 53.2 wt% and 0.44 g/l/h, respectively, which were reduced to 40.6 wt% and 0.25 g/l/h, respectively, with crude glycerol as carbon source. Both the copolymer content and productivity were improved to 56 wt% and 0.61 g/l/h, respectively, by using 1:1 mixture of crude glycerol and high fructose corn syrup. This is the first report of PHBV production by a wild-type halophilic bacterium using glycerol as carbon source.

Determination of 2-, 3-, 4-methylpentanoic and cyclohexanecarboxylic acids in wine: development of a selective method based on solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry and its application to different wines and alcoholic beverages.

A method to analyse 2-methylpentanoic, 3-methylpentanoic and 4-methylpentanoic acids as well as cyclohexanecarboxylic acid has been developed and applied to wine and other alcoholic beverages. Selective isolation with solid phase extraction, derivatization with 2,3,4,5,6-pentafluorobenzyl bromide at room temperature for 30 minutes, and further analysis by gas chromatography-mass spectrometry in negative chemical ionization mode provides detection limits between 0.4 and 2.4 ng/L. Good linearity up to 3.6 µg/L, satisfactory reproducibility (RSD<10%) and signal recovery of around 100% represent a robust method of analysis. Concentration data of these analytes in wine and other alcoholic beverages are reported for the first time. The levels found ranged from the method detection limits to 2630 ng/L, 2040 ng/L and 3810 ng/L for 2-, 3- and 4-methylpentanoic acids, respectively, and to 1780 ng/L for cyclohexanecarboxylic acid. There are significant differences depending on the type of wine or beverage. Distilled beverages, beer and aged wines have higher contents in methylpentanoic and cyclohexanecarboxylic acids.

Characteristic odor components of volatile oil from the cultivation medium of Lactobacillus acidophilus.

Volatile oils obtained from both the liquid medium after incubation (MAI) and liquid medium before incubation (MBI) in the cultivation process of Lactobacillus acidophilus were isolated by hydrodistillation (HD) and analyzed to investigate the utility of the liquid waste. The composition of the volatile oils was analyzed by capillary gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). In total, 46 and 19 compounds were detected in the volatile oils from MAI (MAI oil) and MBI (MBI oil), respectively. The principle components of MAI oil were fatty acids, including pentanoic acid (12.75%), heptanoic acid (14.05%), and nonanoic acid (14.04%). The important aroma-active compounds in the oils were detected by GC-MS/Olfactometry (GC-O), and their intensity of aroma were measured by aroma extraction dilution analysis (AEDA). Pyrazines were determined as key aroma components; in particular, 2-ethyl-5-methylpyrazine was the most primary aroma-active compound in MAI oil. In addition, as the characteristic aroma-active compounds, 3-(methylthio)-propanal, trimethylpyrazine, and pentanoic acid were also detected in MAI oil. These results imply that the waste medium after incubation of L. acidophilus may be utilized as a source of volatile oils.

Effect of non-surgical periodontal treatment on short chain fatty acid levels in gingival crevicular fluid of patients with generalized aggressive periodontitis.

BACKGROUND AND OBJECTIVE: Short chain fatty acids (SCFAs) play important roles in periodontal diseases. However, the concentrations of SCFAs in gingival crevicular fluid of patients with aggressive periodontitis are not known. The aim of this intervention study was to investigate the influences of non-surgical periodontal therapy on levels of SCFAs in the gingival crevicular fluid of patients with generalized aggressive periodontitis (G-AgP), and analyze the concentrations of SCFAs in sites with or without the detected putative periodontal pathogens. MATERIAL AND METHODS: Eighty gingival crevicular fluid samples (four per subject) were collected on filter paper strips from patients with G-AgP (n = 20; mean age 24.5 years), before and at 2 wk, 2, 4 and 6 mo after non-surgical periodontal treatment. Eighty gingival crevicular fluid samples (four per subject) were collected from periodontally healthy controls (n = 20; mean age 26.2 years). Concentrations of formic acid, succinic acid, acetic acid, lactic acid, propionic acid, butyric acid and isovaleric acid from the supernatant of gingival crevicular fluid samples were measured by high performance capillary electrophoresis. Porphyromonas gingivalis, Treponema denticola, Aggregatibacter actinomycetemcomitans, Prevotella intermedia and Fusobacterium nucleatum from the precipitate of the same pretreatment samples of gingival crevicular fluids were analyzed by polymerase chain reaction amplification. RESULTS: The clinical parameters of patients with G-AgP during the 6 mo after non-surgical periodontal treatment were improved remarkably. The formic acid concentration increased significantly after treatment; the level of formic acid was lower in the P. gingivalis-, T. denticola-, P. intermedia- or F. nucleatum-positive sites compared with the negative sites. The concentrations of acetic acid, propionic acid and butyric acid reduced significantly after treatment and reached the lowest level at 2 wk post-treatment, although showed a tendency to increase after 2 mo post-treatment, and the three SCFA levels were significantly higher in P. gingivalis-, T. denticola-, P. intermedia- or F. nucleatum-positive sites compared with those in the negative sites. CONCLUSION: Non-surgical periodontal treatment resulted in a significant decrease of acetic acid, propionic acid, butyric acid levels and increase of formic acid level in gingival crevicular fluids in patients with G-AgP, accompanied by improvement in clinical parameters. A marked lower level of formic acid, as well as higher levels of acetic acid, propionic acid and butyric acid in gingival crevicular fluid of patients with G-AgP was consistent with periodontal pathogen infection.

Characterization of the key aroma compounds in beef extract using aroma extract dilution analysis.

Aroma extract dilution analysis (AEDA) of an ether extract prepared from beef extract (BE) and subsequent identification experiments led to the determination of seven aroma-active compounds in the flavor dilution (FD) factor range of 32-128. Omission experiments to select the most aroma-active compounds from the seven aroma compounds suggested that 2,3,5-trimethyl pyrazine, 1-octen-3-ol, 3-methylbutanoic acid, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were the main active compounds contributing to the aroma of BE. Aroma recombination, addition, and omission experiments of the four aroma compounds in taste-reconstituted BE showed that each compound had an individual aroma profile. A comparison of the overall aroma between this recombination mixture and BE showed a high similarity, suggesting that the key aroma compounds had been identified successfully.