Breath hydrogen and methane expiration in men and women after oat extract consumption

CH3SH and H2S Sensing Properties of V2O5/WO3/TiO2 Gas Sensor

Resistive-type semiconductor-based gas sensors were fabricated for the detection of methyl mercaptan and hydrogen sulfide. To fabricate these sensors, V2O5/WO3/TiO2 (VWT) particles were deposited on interdigitated Pt electrodes. The vanadium oxide content of the utilized VWT was 1.5, 3, or 10 wt.%. The structural properties of the VWT particles were investigated by X-ray diffraction and scanning electron microscopy analyses. The resistance of the VWT gas sensor decreased with increasing methyl mercaptan and hydrogen sulfide gas concentrations in the range of 50 to 500 ppb. The VWT gas sensor with 3 wt.% vanadium oxide showed high methyl mercaptan and hydrogen sulfide responses and good gas selectivity against hydrogen at 300 °C.

Mixed-Potential Gas Sensors Using an Electrolyte Consisting of Zinc Phosphate Glass and Benzimidazole

Mixed-potential gas sensors with a proton conductor consisting of zinc metaphosphate glass and benzimidazole were fabricated for the detection of hydrogen produced by intestinal bacteria in dry and humid air. The gas sensor consisting of an alumina substrate with platinum and gold electrodes showed good response to different hydrogen concentrations from 250 parts per million (ppm) to 25,000 ppm in dry and humid air at 100-130 °C. The sensor response varied linearly with the hydrogen and carbon monoxide concentrations due to mass transport limitations. The sensor responses to hydrogen gas (e.g., -0.613 mV to 1000 ppm H₂) was higher than those to carbon monoxide gas (e.g., -0.128 mV to 1000 ppm CO) at 120 °C under atmosphere with the same level of humidity as expired air.

Isomaltodextrin, a highly branched α-glucan, increases rat colonic H2 production as well as indigestible dextrin

Colonic hydrogen (H2) protects against inflammation-induced oxidative stress. We examined the effect of a new highly branched α-glucan, isomaltodextrin (IMD), on colonic H2 production in rats. Rats were fed a 16.7% IMD, 8.8% indigestible dextrin (ID), or 10.4% high amylose cornstarch diet (Expt. 1), were fed diets containing 3.3–16.7% IMD (Expt. 2), or were fed diets containing 16.7% IMD or 5.2% fructooligosaccharide (FOS) (Expt. 3), for 14 days. Compared with the control group, feeding IMD or other α-glucans dose dependently and significantly increased H2 excretion and portal H2 concentration. The ability of IMD to increase H2 production was not inferior to that of FOS. The cecal Firmicutes/Bacteroidetes ratio in the IMD group was 5–14% of that in the control group. The cecal abundance of bifidobacteria was significantly greater in the IMD group than in the control group. Taken together, IMD, as well as other α-glucans, significantly increased colonic H2 production in a dose-dependent manner.

Sensing properties of Pd-loaded Co3O4 film for a ppb-level NO gas sensor

We prepared 0.1 wt%–30 wt% Pd-loaded Co₃O₄ by a colloidal mixing method and investigated the sensing properties of a Pd-loaded Co₃O₄ sensor element, such as the sensor response, 90% response time, 90% recovery time, and signal-to-noise (S/N) ratio, toward low nitric oxide (NO) gas levels in the range from 50 to 200 parts per billion. The structural properties of the Pd-loaded Co₃O₄ powder were investigated using X-ray diffraction analysis and transmission electron microscopy. Pd in the powder existed as PdO. The sensor elements with 0.1 wt%–10 wt% Pd content have higher sensor properties than those without any Pd content. The response of the sensor element with a 30 wt% Pd content decreased markedly because of the aggregation and poor dispersibility of the PdO particles. High sensor response and S/N ratio toward the NO gas were achieved when a sensor element with 10 wt% Pd content was used.

Thermal balance analysis of a micro-thermoelectric gas sensor using catalytic combustion of hydrogen

A thermoelectric gas sensor (TGS) with a combustion catalyst is a calorimetric sensor that changes the small heat of catalytic combustion into a signal voltage. We analyzed the thermal balance of a TGS to quantitatively estimate the sensor parameters. The voltage signal of a TGS was simulated, and the heat balance was calculated at two sections across the thermoelectric film of a TGS. The thermal resistances in the two sections were estimated from the thermal time constants of the experimental signal curves of the TGS. The catalytic combustion heat Q_catalyst required for 1 mV of ΔV_gas was calculated to be 46.1 μW. Using these parameters, we find from simulations for the device performance that the expected Q_catalyst for 200 and 1,000 ppm H₂ was 3.69 μW and 11.7 μW, respectively.

Consumption of Cross-Linked Resistant Starch (RS4(XL)) on Glucose and Insulin Responses in Humans

Objective. The objective was to compare the postprandial glycemic and insulinemic responses to nutrition bars containing either cross-linked RS type 4 (RS4_XL) or standard wheat starch in normoglycemic adults (n = 13; age = 27 ± 5 years; BMI = 25 ± 3 kg/m²). Methods. Volunteers completed three trials during which they consumed a glucose beverage (GLU), a puffed wheat control bar (PWB), and a bar containing cross-linked RS4 (RS4_XL) matched for available carbohydrate content. Serial blood samples were collected over two hours and glucose and insulin concentrations were determined and the incremental area under the curve (iAUC) was calculated. Results. The RS4_XL peak glucose and insulin concentrations were lower than the GLU and PWB (P < .05). The iAUC for glucose and insulin were lower following ingestion of RS4 compared with the GLU and PWB trials. Conclusions. These data illustrate, for the first time, that directly substituting standard starch with RS4_XL, while matched for available carbohydrates, attenuated postprandial glucose and insulin levels in humans. It remains to be determined whether this response was due to the dietary fiber and/or resistant starch aspects of the RS4_XL bar.

Mid-infrared trace gas analysis with single-pass fourier transform infrared hollow waveguide gas sensors

A hollow core optical fiber gas sensor has been developed in combination with a Fourier transform infrared (FT-IR) spectrometer operating in the spectral range of 4000-500 cm(-1), enabling continuous detection of small volume gas-phase analytes such as CH(4), CO(2), C(2)H(5)Cl, or their mixtures at trace levels. Ag/Ag-halide hollow core optical fibers simultaneously serve as an optical waveguide for broad-band mid-infrared radiation and as a miniaturized absorption gas cell. Specifically, carbon dioxide, methane, and ethyl chloride as well as binary mixtures in a carrier gas were analyzed during exponential dilution experiments. In the studies reported here, the integration of an optical gas sensor with FT-IR spectroscopy provides excellent detection limits for small gas volumes ( approximately 1.5 mL) of individual analytes at a few tens of parts per billion (ppb, vol/vol) for carbon dioxide and a few hundreds of ppb (vol/vol) for methane. Furthermore, the broad-band nature of the radiation source and of the hollow core optical waveguide provides the capability of multi-constituent analysis in mixtures.

Pinto bean consumption changes SCFA profiles in fecal fermentations, bacterial populations of the lower bowel, and lipid profiles in blood of humans

Beans improve serum lipids and may reduce the risk of colon cancer by increasing colonic SCFA formation. We assessed whether pinto bean consumption affects in vitro fecal bacterial fermentation and production of SCFA, colonic bacterial populations, and serum lipids. Adults grouped as premetabolic syndrome (pre-MetSyn) (n = 40) or controls (n = 40) were randomly assigned to consume either a bean entrée [1/2 cup (130 g) of dried, cooked pinto beans] or an isocaloric chicken soup entrée daily for 12 wk. Measurements included in vitro fecal fermentation of various resistant starch substrates, fecal bacterial speciation, and blood lipids. When expressed as a difference between baseline and treatment, propionate production from fecal material fermented in vitro with bean flour was higher (P < 0.02) in volunteers consuming beans than in those consuming soup. During the treatment period alone, bean consumption did not affect propionic acid production with any substrate but lowered (P < 0.02) butyric acid production when cornstarch was the substrate. In all volunteers, bean consumption decreased fecal production of isovaleric (P < 0.05) and isobutyric (P < 0.002) acids from cornstarch by as much as 50%. Of the bacterial populations tested, only Eubacterium limosum was affected by bean consumption and was approximately 50% lower than in those consuming soup. Beans lowered serum total cholesterol (P < 0.014) by approximately 8% in the controls and 4% in the pre-MetSyn group. Bean consumption lowered serum HDL-cholesterol (P < 0.05) and LDL-cholesterol (P < 0.05) in both groups without affecting serum triglycerides, VLDL cholesterol, or glucose. This study provides evidence that bean consumption can improve lipid profiles associated with cardiovascular disease, but does not clearly confer health benefits related to colon cancer risk.

The effect of beta-glucan on the glycemic and insulin index

OBJECTIVE

To determine the effects of oat products with increasing beta-glucan content on the glycemic (GI) and insulin indexes (II) of oat products, and to establish the effect of physical properties of beta-glucan on these physiological responses.

DESIGN

Test group (n=10) randomly attended to three glucose tolerance tests and glycemic response tests for four oat bran products.

SETTINGS

Functional Foods Forum and the Department of Food Chemistry, University of Turku, and the Department of Food Technology, University of Helsinki.

SUBJECTS

One male and nine female volunteers were recruited from university students and staff, and all completed the study.

INTERVENTIONS

GI and II of different products were calculated for each subject using the average of parallel glucose tolerance tests and the subsequent glycemic/insulinemic responses for each product. Average indexes for products were calculated according to the individual data.

RESULTS

The glycemic responses to oat products with increasing amounts of beta-glucan had lower peak values than the reference glucose load. The amount of extractable beta-glucan had a high correlation between the glycemic and insulinemic response.

CONCLUSION

In addition to the total amount of beta-glucan in oat products, the amount of extractable beta-glucan in oat products explains the magnitude of the decrease in glycemic responses to carbohydrate products.

Evaluation of the pulsed discharge helium ionization detector for the analysis of hydrogen and methane in breath

Under the appropriate separation conditions the pulsed discharge helium ionization detector (PDHID) was used to detect hydrogen and methane separated from the matrix components of human breath samples. The sensitivity of this method is over an order of magnitude better than published methods using a flame ionization detector (FID) and a thermal conductivity detector (TCD), and has the further advantage of detecting both analytes with only one detector. Limits of detection were 0.3 ppmv for both hydrogen and methane and the method had a linear dynamic range (LDR) of three orders of magnitude (0.3-400 ppm, v/v). The PDHID was also compared to the FID and the TCD in regard to selectivity, sensitivity and reproducibility for high-speed gas chromatography (HSGC). It was shown that the PDHID is as sensitive as the FID for fast separations but is limited by the difficulty of resolving analyte peaks from O2 and N2. The PDHID was at least three orders of magnitude more sensitive than the TCD for all of the analytes examined.

Carbohydrate digestion in humans from a beta-glucan-enriched barley is reduced

Obese and diabetic patients may benefit from foodstuffs that are poorly absorbed and/or digested at a slower rate. Prowashonupana (PW) is a cultivar of barley, whose grains are enriched in beta-glucans, and thus may be less digestible than standard barley (barley cultivar (BZ) 594.35.e). To test this, both kinds of barley were grown in a chamber into which (13)CO(2) was injected. On two occasions, 10 healthy hydrogen (H(2))-producing adults consumed in random order one 35-g portion of each of the cooked, dehulled (13)C-enriched grains. CO(2) production was measured in a whole-body direct calorimeter, and H(2) and (13)CO(2) were measured in breath at baseline and intermittently for 450 min. The percentage of the (13)C dose recovered in breath was calculated. Results were compared by repeated measures analysis of variance (ANOVA). The percentage of the (13)C dose oxidized was greater after BZ than after PW consumption (P < 0.05). The area under the curve for H(2) was greater after PW (mean +/- SD, 8658 +/- 6582) than after BZ (5178 +/- 4759) intake (P < 0.05), whereas there was no difference in CO(2) production. We conclude that absorption of PW is significantly lower than that of BZ, making the modified barley appropriate for obese and diabetic patients.

Methane and hydrogen exhalation in normal children and in lactose malabsorption

Methane (CH4) and hydrogen (H2) are gases produced in the colon by the breakdown of carbohydrates, due to the action of anaerobic methanogenic bacteria. No papers have been published in pediatrics concerning these gases production and exhalation. Understanding of the pattern of H2, CH4, carbon dioxide (CO2), butyrates, indolellipsis,etc., production and exhalation, which may differ in gastrointestinal diseases, may be helpful as far as the diagnosis and treatment of some gastrointestinal conditions is concerned. Exhalation of H2, CH4 and CO2 by breath air was studied in basal conditions in 338 normal infants and in 27 lactose malabsorbers. Moreover, stools collected and stored for 10-12 h in anaerobic and aerobic conditions were incubated in anaerobiosis at 38 degrees C. After a 4-h incubation period, H2, CH4 and CO2 were determined.

RESULTS

Methane production is independent of hydrogen production; the number of children producing CH4 increases from 0% at 12 months of age to 44% at the age of 9 years. In lactose malabsorption, we found 26 children producing increased quantities of H2 and no methane, and only one producing methane but no hydrogen, which proves that methanogenic bacteria are independent of H2-producing bacteria, and that CH4 determination is compulsory in the study of lactose malabsorption. The incubation of stools in an anaerobic milieu at 38 degrees C for 4 h, in an attempt to imitate the human colon, showed a great production of methane and less of H2 in the stools collected and stored in anaerobic conditions. The same incubation method was applied to the stools collected and stored in aerobic conditions: production of H2 and CH4 was much lower than in the collected and stored anaerobic group. The appearance of CH4 in the stools of the aerobic group proves that methanogenic bacteria are, to a small degree, resistant to oxygen.

CONCLUSIONS

The study of gas exhalation in pediatrics merits more study by researchers, with a view to defining a special pattern of gas production in pathological conditions. The anaerobic stool incubation method is a good model for studying gas production under the effect of different diets and the gas production pattern in gastrointestinal diseases.

Measurement for breath concentration of hydrogen and methane in horses

This study concerns the establishment of a simple testing method for breath concentration of hydrogen and methane in horses. Twenty-eight healthy thoroughbreds and 24 Arabians were used. Breath samples were collected using one-minute closed circulatory respiration through an aluminum bag filled with 10 liters of pure oxygen, which was mounted on the subjects by means of a face mask. Breath samples obtained, were analyzed by gas chromatography. A significant correlation in both hydrogen and methane levels was observed for samples collected at separate times. These findings confirmed the usefulness of our approach for testing breath concentrations of hydrogen and methane in horses.