| Summary: | A method for the assessment of volatile compounds in dairy products
was developed using solvent desorption dynamic headspace sampling. The
method was first applied to assay for diacetyl and acetoin in buttermilk.
Major buttermilk volatiles recovered included diacetyl, acetic acid, and
acetoin. Normalized detector responses were linear over the range of
concentrations tested for diacetyl and acetoin. The method enabled
quantitative estimation of diacetyl and acetoin in <30 min, including sample
preparation time.
Next, the ability of stabilizing and emulsifying agents to inhibit the
release of diacetyl from a model dairy matrix was examined using modified
purge parameters. Stabilizers (guar, xanthan, and carrageenan) and
emulsifiers (lecithin, carboxymethyl cellulose, and Tween 80) were
examined for their effects on headspace available diacetyl at 0.05, 0.10, and 0.20% (wt/wt) in a 5% milkfat model system. Guar gum and carrageenan
exhibited similar diacetyl release inhibition when corrected for viscosity.
Xanthan gum exhibited the greatest decrease in headspace available diacetyl
after correction for viscosity at increasing gum levels. Tween 80 imparted no
significant viscosity and had no effect on recoverable diacetyl. Lecithin had
no effect on viscosity, however it did inhibit the release of diacetyl as a
function of lecithin level. Carboxymethyl cellulose increased viscosity and
inhibited diacetyl release.
Finally, a rapid dynamic headspace sampling technique was evaluated
for its ability to differentiate between Cheddar cheese samples for volatile
aroma compounds. Seven samples of Cheddar cheese were examined
ranging in flavor from mild to extra sharp. A total of 14 volatile compounds
were tentatively identified with published retention indices and retention
times of known standards. Major volatiles recovered were 2-butanol,
acetoin, propanoic acid, butyric acid, and caproic acid. Other identified
compounds were 2-butanone, diacetyl, ethyl butyrate, 1-butanol, ethyl
caproate, hexanol, acetic acid, 2,3-butanediol, and octanoic acid.
The application of solvent desorption dynamic headspace sampling of
dairy volatiles is a simple, rapid method for the determination of volatile
compounds previously shown to influence flavor and aroma of dairy
products. This research was conducted to demonstrate the optimized
application of this technology to tracking dairy products aroma compounds. === Graduation date: 1996
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