Determination of Henry’s constant, the dissociation constant, and the buffer capacity of the bicarbonate system in ruminal fluid

Hille, Katharina T.; Hetz, Stefan K.; Rosendahl, Julia; Braun, Hannah-Sophie; Pieper, Robert; Stumpff, Friederike

doi:10.3168/jds.2015-9486

Cited by 12 publications

(19 citation statements)

References 39 publications

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“…2 by assuming equilibrium with CO 2 (g) at the local atmospheric pressure of 0.64 atm. The Bunsen absorption coefficient for CO 2 in rumen fluid was set to be 0.234 volume/(volume atm) (Hille et al, 2016 ).…”

Section: Methodsmentioning

confidence: 99%

Supersaturation of Dissolved Hydrogen and Methane in Rumen of Tibetan Sheep

et al. 2016

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Hydrogen (H2) is an essential substrate for methanogens to produce methane (CH4), and also influences pathways of volatile fatty acids (VFA) production in the rumen. Dissolved H2 (H2 (aq)) is the form of H2 available to microbes, and dissolved CH4 (CH4 (aq)) is important for indicating methanogens activity. Rumen H2 (aq) concentration has been estimated by assuming equilibrium with headspace gaseous H2 (H2 (g)) concentration using Henry's law, and has also been directly measured in the liquid phase in some in vitro and in vivo experiments. In this in vivo study, H2 (aq) and CH4 (aq) concentration measured directly in rumen fluid and their corresponding concentrations estimated from their gaseous phase concentrations, were compared to investigate the existence of equilibrium between the gas and liquid phases. Twenty-four Tibetan sheep were randomly assigned to two mixed diets containing the same concentrate mixed with oat grass (OG diet) or barley straw (BS diet). Rumen gaseous phase and contents were sampled using rumenocentesis and oral stomach tubing, respectively. Rumen H2 (aq) and CH4 (aq) concentration and VFA profile differed between sheep fed OG and BS diets. Measured H2 (aq) and CH4 (aq) concentration were greater than H2 (aq) and CH4 (aq) concentrations estimated using gas concentrations, indicating lack of equilibrium between gas and liquid phase and supersaturation of H2 and CH4 in rumen fluid. As a consequence, Gibbs energy changes (ΔG) estimated for various metabolic pathways were different when calculated using dissolved gases concentrations directly measured and when using dissolved gases concentrations assuming equilibrium with the gaseous phase. Dissolved CH4, but not CH4 (g), was positively correlated with H2 (aq). Both H2 (aq) and H2 (g) concentrations were positively correlated with the molar percentage of butyrate and negatively correlated with the molar percentage of acetate. In summary, rumen fluid was supersaturated with both H2 and CH4, and H2 (aq) was closely associated with the VFA profile and CH4 (aq) concentration. The assumption of equilibrium between dissolved gases and gaseous phase affected ΔG estimation.

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Section: Methodsmentioning

confidence: 99%

Supersaturation of Dissolved Hydrogen and Methane in Rumen of Tibetan Sheep

et al. 2016

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“…Gaseous CO 2 (gCO 2 ) was calculated as the total dissolved gas extracted minus dCH 4 extracted, assuming that rumen gases would be composed of CO 2 and CH 4 . Total dissolved CO 2 (dCO 2 ) concentration in the original rumen fluid (C TdCO 2 , mol/l) was calculated by combining equations from Wang et al (16) and Hille et al (24) , and expressed as follows:…”

Section: Sample Analysismentioning

confidence: 99%

Molecular hydrogen generated by elemental magnesium supplementation alters rumen fermentation and microbiota in goats

Wang

Zhang

et al. 2017

Br J Nutr

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We tested the hypotheses that supplementation of a diet with elemental Mg increases ruminal dissolved H2 (dH2) in rumen fluid, which in turn alters rumen fermentation and microbial community in goats. In a randomised block design, twenty growing goats were allocated to two treatments fed the same basal diet with 1·45 % Mg(OH)2 or 0·6 % elemental Mg. After 28 d of adaptation, we collected total faeces to measure total tract digestibility, rumen contents to analyse fermentation end products and microbial groups, and measured methane (CH4) emission using respiration chambers. Ruminal Mg2+ concentration was similar in both treatments. Elemental Mg supplementation increased dH2 at 2·5 h post morning feeding (+180 %, P<0·001). Elemental Mg supplementation decreased total volatile fatty acid concentration (-8·6 %, P<0·001), the acetate:propionate ratio (-11·8 %, P<0·03) and fungal copy numbers (-63·6 %, P=0·006), and increased propionate molar percentage (+11·6 %, P<0·001), methanogen copy numbers (+47·9 %, P<0·001), dissolved CH4 (+35·6 %, P<0·001) and CH4 emissions (+11·7 %, P=0·03), compared with Mg(OH)2 supplementation. The bacterial community composition in both treatments was overall similar. Ruminal dH2 was negatively correlated with acetate molar percentage and fungal copy numbers (P<0·05), and positively correlated with propionate molar percentage and methanogen copy numbers (P<0·05). In summary, elemental Mg supplementation increased ruminal dH2 concentration, which inhibited rumen fermentation, enhanced methanogenesis and seemed to shift fermentation pathways from acetate to propionate, and altered microbiota by decreasing fungi and increasing methanogens.

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“…Previously, BC has been investigated as an important factor influencing beer fermentations (Li, Liu, Kang, & Zheng, ), fermentation disorders in ruminant animals (Hille et al., ) water quality (Van Vooren, Van De Steene, Ottoy, & Vanrolleghem, ), and the BC of whey in cheese‐making (Hill, Irvine, & Bullock, ). However, the use of BC to estimate the pH of food ingredient mixtures or determine the influence food ingredients on equilibrium pH of acid or acidified foods has not been previously reported.…”

Section: Resultsmentioning

confidence: 99%

Modeling the buffer capacity of ingredients in salad dressing products

Longtin

Price

Mishra

et al. 2020

Journal of Food Science

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The pH of most acid food products depends on undefined and complex buffering of ingredients but is critically important for regulatory purposes and food safety. Our objective was to define the buffer capacity (BC) of ingredients in salad dressing products. Ingredients of salad dressings were titrated individually and in combination using concentrations typical of dressing products. Titration curves from pH 2 to 12 were generated with sodium hydroxide and hydrochloric acid, which were then used to generate BC curves. A matrix of concentration and pK values for a series of monoprotic buffers approximated the pH of each ingredient. Some buffer series required anion or cation corrections for accurate pH prediction, possibly due to the presence of salts of acid or bases. Most buffers had BC values less than 10-fold the BC of acetic acid (0.25 β) typically in dressing formulations and had little influence on the final product pH of the dressings tested. Unexpectedly, we found that sugars in dressing formulations, including sucrose or corn syrup, exhibited buffering at pH values greater than 11 (0.035 β and 0.059 β, respectively), which was likely due to weakly acidic hydroxyl groups on the sugar molecules. However, the concentration and pK for buffers above pH 11 or below pH 2 were difficult to quantify due to the BC of water. The BC data may help to quantify the effects of salad dressing ingredients on the final product pH and benefit regulatory agencies and manufacturers in assessing product pH and safety.

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Determination of Henry’s constant, the dissociation constant, and the buffer capacity of the bicarbonate system in ruminal fluid

Cited by 12 publications

References 39 publications

Supersaturation of Dissolved Hydrogen and Methane in Rumen of Tibetan Sheep

Supersaturation of Dissolved Hydrogen and Methane in Rumen of Tibetan Sheep

Molecular hydrogen generated by elemental magnesium supplementation alters rumen fermentation and microbiota in goats

Modeling the buffer capacity of ingredients in salad dressing products

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