Volatile compounds produced during deodorization of soybean oil and their flavor significance

Abstract

Freshly deodorized soybean oil has a characteristic nutty flavor but often yields no detectable headspace volatiles. The cause of this flavor was investigated by deodorizing soybean oil in an apparatus with a double cold trap that allowed the volatile compounds formed from the initial decomposition of hydroperoxides to be collected separately from those produced during the normal deodorization process. The chief volatile components from the normal deodorization process were hydrocarbons, which contributed little to no odor to the oil. The compounds with the greatest odor were carbonyls, especially heptanal and cis‐4‐heptenal. Although these components should accumulate at some steady‐state concentration in an oil during its deodorization, none seemed to account for the flavor of the deodorized oil. By using a particle detector, it was shown that small particles could be generated in the human mouth that could provide a mechanism to bring oil with nonvolatile flavor components into contact with the olfactory organ. Attempts to separate possible nonvolatile flavors in deodorized oil from triacylglycerides by chromatography on alumina or reaction with 2,4‐dinitrophenylhydrazine were unsuccessful. Possibly, the flavor is caused by the glycerol esters themselves.

Comparison of Flavor Volatiles and Some Functional Properties of Different Soy Protein Products

“…These compounds have been reported as the products of lipoxygenase catalyzed oxidation of polyunsaturated fatty acids [27,28]. Benzaldehyde, n-hexanol, and other minor components were also reported to be present in soy extract [8,9,29,30]. Flavor volatiles content, which was represented by total peak areas, of EWHT, OBA/PL-less and CE was less than that of AP and OBA/PL.…”

A RESEARCH NOTE: THE ROLE OF PARTICLES IN THE PERCEPTION OF FLAVORS1

“…These results are consistent with the hypothesis that particles generated when the tongue is drawn away from the palate or when the lips are parted can influence flavor perception. Kao et al (1998) detected particles 0.5 to 5 pM in diameter, although smaller particles also may be generated which were undetectable by their instrument. Presumably these particles consist of saliva in which food flavors may be dissolved, emulsified, or suspended.…”

“…and demonstrated the ability of particles to transport, amplify, and alter the perception of environmental odors. Recently Kao et al (1998) detected bursts of particles 0.5 to 5-pM in diameter in the human oral cavity using a light-scattering instrument when the lips were parted or the tongue was pulled away fiom the oral palate. Kao et al( 1998) were unable to find components in freshly deodorized soybean oil that would account for its customary nutty flavor.…”

“…Recently Kao et al (1998) detected bursts of particles 0.5 to 5-pM in diameter in the human oral cavity using a light-scattering instrument when the lips were parted or the tongue was pulled away fiom the oral palate. Kao et al( 1998) were unable to find components in freshly deodorized soybean oil that would account for its customary nutty flavor. They suggested that particles formed in the oral cavity could transport entrained triglycerides to the olfactory epithelium, and that the triglycerides themselves might be responsible for the nutty flavor.…”

“…

Oral particles are produced when the tongue is pulled away ffom the palate and when the lips are parted (Kao et al 1998). To explore the role of oral particles on flavor perception, experiments were designed to compare the perception of some foodflavors under conditions that produce and do not produce oral particles.

…”