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Retronasal-olfactory und orosensory active modulators of fat taste of dietary oils
Project
Project code: keine Angaben
Contract period: 01.01.2009
- 31.12.2012
Purpose of research: Applied research
Activity-guided fractionation of extra virgin olive oil led to the identification of
free fatty acids di- and triglycerides as ingredients, which are able to induce a
fatty taste impression in a fatty acid-free, but lipid-like matrix (TFL-matrix). For the
first time, it was possible to show that fatty acids and triglycerides can be detected
by human subjects chemosensorially. In sensory tests the subjects described
unsaturated fatty acids with a fatty taste impression and in higher concentrations
as unpleasant raspy. The thresholds ranged between 0,1 bis 0,4 mmol/L for the
fatty taste. In contrast, saturated fatty acids and the fatty acid alcohols were only
described as raspy, whereas any fatty perception was lacking. Furthermore it
was demonstrated for the first time, that a lipid-like texture is necessary in order
to taste unsaturated fatty acids in a fatty way. These data support the idea that
the perception of fat taste by human subjects is due to a convergence of receptor-
mediated detection of free fatty acids and mechanosensory inputs.
Moreover, the activity of human lingual lipase was investigated using three different
analytical approaches. Independent on the method used, we were not able
to detect any significant release of free fatty acids from triglycerides when incubated
with human saliva. Compared to the lipase activity published for rodents,
our data indicate the absence or just a marginal activity of the human lingual
lipase; this was confirmed even by human in-mouth incubation experiments. Current
experiments are targeting the activity of the lingual lipase secreted from the
“van Ebner glands” of the foliate papillae to investigate a potential local concentration
gradient of the lipase in the area of the taste papillae, which might release
fatty acids from triglycerides in close proximity to the fatty acid receptors.
As there was no information available on the chemical composition and the structure
of the oral lipid film remaining after fatty food consumption, oral lipid films
were isolated with an aqueous ethanolic solution and analyzed by HPLC. Thereby,
it was obvious that the oral lipid films reflect the triglyceride pattern of the used
edible oil and that there is, apparently, no specificity at all in the formation of the
lipid films. In order to study the relevance of the lipid coating in fat perception
while consuming fatty food, in-mouth fluorescence measurements were developed
and applied on lipid films on the tongue; first data reveal large inter-individual
differences between the panellists with a thickness between 25-190 μm
shortly after the oil intake. Already after one minute the thickness of the lipid film
decreased by 50 % and reached a value of < 20 μm after about five minutes. Currently,
studies are conducted to correlate the perceived fat taste and the time-dependent
thickness of the oral lipid coating in human subjects.
Section overview
Subjects
- Physiology of Nutrition
- Food Chemistry
Collaborative Project
Saturated fat perception and regulation: approach to the development of reduced-fat foods
