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Rapid Commun Mass Spectrom

Title:		Temperature-dependent Henry's Law constants of 4-alkyl branched-chain fatty acids and 3-methylindole in an oil-air matrix and analysis of volatiles in lamb fat using selected ion flow tube mass spectrometry
Author(s):		Castada HZ; Polentz V; Barringer S; Wick M;
Address:		"Department of Food Science and Technology, The Ohio State University, Columbus, OH, 43210, USA. Department of Animal Sciences, The Ohio State University, Columbus, OH, 43210, USA"
Journal Title:		Rapid Commun Mass Spectrom
Year:		2017
Volume:		31
Issue:		24
Page Number:		2135 - 2145
DOI:		10.1002/rcm.8007
ISSN/ISBN:		1097-0231 (Electronic) 0951-4198 (Linking)
Abstract:		"RATIONALE: 4-Alkyl branched-chain fatty acids and 3-methylindole are characteristic flavor compounds associated with sheep meat. Determining their partitioning behavior between the gas and condensed phase and ultimately developing a correlation between the compound's headspace concentration and sensory descriptive grouping are important for high-throughput characterization and grading classification. METHODS: The headspace concentrations of 3-methylindole, 4-methyloctanoic acid, 4-ethyl-octanoic acid, and 4-methylnonanoic acid above corn-oil-based standard solutions and lamb fat samples were measured using selected ion flow tube-mass spectrometry (SIFT-MS). The standard solutions were equilibrated at 80, 100, 110 and 125 degrees C while the fat samples were equilibrated at 125 degrees C. Statistical evaluation, linear and polynomial regression analyses were performed to establish the compound-specific and temperature-dependent Henry's Law constants, enthalpy (DeltaH) and entropy (DeltaS) of phase changes. RESULTS: The Henry's Law constants (k(H)(cp) ) were calculated from the regression analysis with a high degree of confidence (p < 0.05) and linearity (r(2) > 0.99). The k(H)(cp) increased with increase in equilibrium temperature. The empirical calculation of DeltaH and DeltaS at different temperatures confirmed the temperature-dependence of the Henry's Law constants. The headspace concentrations of the lamb-flavor compounds were determined above actual lamb fat samples and the corresponding condensed-phase concentrations were successfully derived. CONCLUSIONS: The temperature-dependent Henry's Law constants, DeltaH, and DeltaS of phase changes for 3-methylindole, 4-methyloctanoic acid, 4-ethyloctanoic acid, and 4-methylnonanoic acid in an air-oil matrix were empirically derived. The effectiveness of SIFT-MS for the direct, real-time, and rapid determination of key flavor compounds in lamb fat samples was established"
Keywords:		Animals Caprylates/analysis/*chemistry Dietary Fats/analysis Linear Models Mass Spectrometry Pheromones/analysis/*chemistry Sheep Skatole/analysis/*chemistry Thermodynamics;
Notes:		"MedlineCastada, Hardy Z Polentz, Victoria Barringer, Sheryl Wick, Macdonald eng England 2017/10/08 Rapid Commun Mass Spectrom. 2017 Dec 30; 31(24):2135-2145. doi: 10.1002/rcm.8007"