Vapor pressures and gas-film coefficients for ketones

Rathbun, R.E.; Tai, D.Y.

doi:10.1016/0045-6535(87)90110-x

Cited by 8 publications

(6 citation statements)

References 16 publications

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“…For the series of methyl ketones, the headspace concentration in pure water (0% fat) decreased with increasing carbon length and decreasing volatility and molar concentration (Table ). The measured decrease in headspace concentration with increase in carbon chain is in contrast with increases reported in equilibrium systems but consistent with release data described by Rathbun and Tai using a dynamic two-film model.…”

Section: Resultssupporting

confidence: 89%

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In Vitro Measurement of Volatile Release in Model Lipid Emulsions Using Proton Transfer Reaction Mass Spectrometry

Frank

Appelqvist

Piyasiri

et al. 2012

J. Agric. Food Chem.

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The presence of fat in food plays an important role in the way aroma is released during consumption and in the creation of the overall sensory impression. Fat acts as a reservoir for lipophilic volatile compounds and modulates the timing and delivery of aroma compounds in a unique manner. Despite considerable research, reproducible in vitro methods for measuring the effect of fat on volatile release are lacking. An open in vitro cell was used to simulate the open human naso-oropharygeal system and was interfaced with a proton transfer reaction mass spectrometer (PTR-MS) to examine some of the fundamental effects of fat on dynamic volatile release in liquid fat emulsions. Lipid emulsions with various fat contents (0-20%) and droplet sizes (0.25, 0.5, and 5.0 μM) were spiked with flavor volatiles representing a range of lipophilicity (K(o/w) = 1-1380). Preloaded syringes of spiked emulsion were injected into the cell, and temporal changes in release were measured under dynamic conditions. Significant differences in release curves were measured according to the lipid content of emulsions, the vapor pressure, and K(o/w) values of the volatile compounds. With increasing addition of fat, the critical volatile release parameters, maximum concentration (I(max)), time to maximum concentration (T(max)), and the integrated area under the concentration curve (AUC), were affected. The in vitro curves were reproducible and in agreement with theory and correlated with the preswallow phase of in vivo release data. An exponential model was used to calculate changes in mass transfer rates with increased fat addition.

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Section: Resultssupporting

confidence: 89%

“… a Carbon chain number ( C ), molar concentration based on 2.5 mg/L added to water or emulsion (mol/L), octanal/water partition coefficient ( K o/w ), vapor pressure (VP), measured ion by PTR-MS ( m / z [M + H] + ). b Corvarrubias-Cervantes et al c Rathbun and Tai d Voilley et al …”

Section: Methodsmentioning

confidence: 99%

In Vitro Measurement of Volatile Release in Model Lipid Emulsions Using Proton Transfer Reaction Mass Spectrometry

Frank

Appelqvist

Piyasiri

et al. 2012

J. Agric. Food Chem.

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“… a Carbon chain number ( C ), molar concentration based on 25 mg/L added to water or emulsion (mol/L), octanol/water partition coefficient ( K o/w ), molecular weight (MW), boiling point (bp), vapor pressure (VP), measured ion by PTR-MS ( m / z M + H + ). b Corvarrubias-Cervantes et al c Rathbun and Tai d Voilley et al …”

Section: Methodsmentioning

confidence: 99%

Proton Transfer Reaction Mass Spectrometry and Time Intensity Perceptual Measurement of Flavor Release from Lipid Emulsions Using Trained Human Subjects

Frank

Appelqvist

Piyasiri

et al. 2011

J. Agric. Food Chem.

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The effect of the fat component of liquid emulsions on dynamic "in-nose" flavor release was examined using a panel of trained human subjects (n = 6), proton transfer reaction mass spectrometry (PTR-MS), and time intensity (TI) sensory evaluation. A rigorous breathing and consumption protocol was developed, which synchronized subjects' breathing cycles and also the timing of sample introduction. Temporal changes in volatile release were measured in exhaled nostril breath by real-time PTR-MS. Corresponding changes in the perceived odor intensity could also be simultaneously measured using a push button TI device. The method facilitated accurate examination of both "preswallow" and "postswallow" phases of volatile release and perception. Volatile flavor compounds spanning a range of octanol/water partition coefficient (K(o/w)) values (1-1380) were spiked into water (0% fat) or lipid emulsions with various fat contents (2, 5, 10, and 20% fat). Replicate samples for each fat level were consumed according to the consumption protocol by six subjects. Statistical comparisons were made at the individual level and across the group for the effects of changes in the food matrix, such as fat content, on both pre- and postswallow volatile release. Significant group differences in volatile release parameters including area under the concentration curve (AUC) and maximum concentration (I(max)) were measured according to the lipid content of emulsions and volatile K(o/w). In a second experiment, using single compounds (2-heptanone, ethyl butanoate, and ethyl hexanoate), significant decreases in both in-nose volatile release and corresponding perceived odor intensities were measured with increasing fat addition. Overall, the effect of fat on in vivo release conformed to theory; fat had little effect on compounds with low K(o/w) values, but increased for volatiles with higher lipophilicity. In addition, significant pre- and postswallow differences were observed in AUC and I(max), as a result of changing fat levels. In the absence of fat, more than half of the total amount of volatile was released in the preswallow phase. As the content of fat was increased in the emulsion systems, the ratio of volatile released postswallow increased compared to preswallow. These data may provide new insights into why low-fat and high-fat foods are perceived differently.

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“…Alternatively, it is possible that the (p o L,i (T j,i )) E values for 3-nitrophenol and 4-nitrophenol are in error. Indeed, it is undoubtedly true that some of the experimentally based p o L,i =f i (T ) expressions suffer from significant error: numerous prior parameter prediction studies have identified experimental data that likely are in error, e.g., see the comments by Rathbun (1987) on the likelihood of errors in the p o L data of Stull (1947) for 2-pentanone and other similar ketones.…”

Section: Methods Validation Of Simpol1 With a Test Set Of Compoundsmentioning

confidence: 99%

SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

Pankow¹,

Asher²

2007

Preprint

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Abstract. The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure pLo (atm) and enthalpy of vaporization ΔHvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10pL,io(T)=Σkνk,ibk(T) where νk,i is the number of groups of type k, and bk(T) is the contribution to log10 pL,io(T) by each group of type k. A zeroeth group is included that uses b0(T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C–C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk(T) is assumed to follow b(T)=B1/T+B2+B3T+B4lnT. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions pL,io=fi(T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict pLo values is examined using a test set of 161 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10pL,io(T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, pL,io(T) values are predicted to within a factor of 2. Because d(log10pL,io(T))/d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide predictions of ΔHvap,i based on structure.

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Vapor pressures and gas-film coefficients for ketones

Cited by 8 publications

References 16 publications

In Vitro Measurement of Volatile Release in Model Lipid Emulsions Using Proton Transfer Reaction Mass Spectrometry

In Vitro Measurement of Volatile Release in Model Lipid Emulsions Using Proton Transfer Reaction Mass Spectrometry

Proton Transfer Reaction Mass Spectrometry and Time Intensity Perceptual Measurement of Flavor Release from Lipid Emulsions Using Trained Human Subjects

SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

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