Odor detection threshold

<h2 id="values">Values</h2>
<ul><li>The <a href="/facts/Odor_threshold_value/8F973zgo">threshold value</a> is the concentration at which an aroma or taste can be detected (air, water and fat).</li>
<li>The recognition threshold or arousal threshold of <a href="/facts/Olfactory_neurons/CcPIXqbU">olfactory neurons</a> is the concentration at which you can identify an odor (air, water and fat).</li>
<li>The <a href="/facts/Odour_activity_value/2k1GWFVv">odour activity value</a> is the concentration divided by the threshold.</li>
<li>The flavor impact is the value the rate of change in perception with concentration.</li>
<li>The flavor contribution of an aroma component in a mixture to the total profile can be calculated from the total odor units and the number contributed by that aroma chemical.</li></ul>
<h3>Odor detection value</h3>
Odor threshold value (OTV) (also aroma threshold value (ATV), Flavor threshold) is defined as the most minimal <a href="/facts/Concentration/wqBmz5od">concentration</a> of a substance that can be detected by a <a href="/facts/Human_nose/fmhw8BmP">human nose</a>. Some substances can be detected when their concentration is only few <a href="/facts/Milligram/lU2zbPk8">milligrams</a> per 1000 <a href="/facts/Tonnes/gMymLmWv">tonnes</a>, which is less than a <a href="/facts/Drop_(unit)/7SmVzPDu">drop</a> in an <a href="/facts/Olympic_swimming_pool/tzGgbDce">Olympic swimming pool</a>. Odor threshold value can be expressed as a concentration in water or concentration in air.
Two major types of flavor thresholds can be distinguished: the absolute and the difference threshold. The odor detection threshold and the odor recognition threshold are absolute thresholds; the first is the minimum concentration at which an odor can be detected without any requirements to identify or recognize the stimulus, while the second is the minimum concentration at which a stimulus can be identified or recognized.<a class="footnote-ref" id="fnref:2" href="#fn:2">2</a>
The odor threshold value of an odorant is influenced by the medium.
Examples of substances with strong odors:

<ul><li><a href="/facts/Grapefruit_mercaptan/mJgMfTXl">Grapefruit mercaptan</a> (OTV = 0.1 <a href="/facts/Parts_per_trillion/PozRuoLM">ppt</a>)<a class="footnote-ref" id="fnref:3" href="#fn:3">3</a></li>
<li><a href="/facts/Sotolon/dDMTyhbM">Sotolon</a> (OTV = 1 ppt)<a class="footnote-ref" id="fnref:4" href="#fn:4">4</a></li>
<li>(Z)-8-tetradecenal (OTV = 9 ppt in water)<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a></li>
<li><a href="/facts/Geosmin/MkP604Hv">Geosmin</a> (OTV = 10 ppt<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a>)</li>
<li><a href="/facts/Strawberry_furanone/rPEhVPI5">strawberry furanone</a> (OTV = 40 ppt)<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a></li>
<li><a href="/facts/Trimethylamine/cj1dWmJq">Trimethylamine</a> (OTV = 0.37 - 1.06 ppb) <a class="footnote-ref" id="fnref:8" href="#fn:8">8</a></li>
<li>p-<a href="/facts/Vinylguaiacol/Btk0Lg6L">vinylguaiacol</a> (OTV = 10 <a href="/facts/Parts_per_billion/PozRuoLM">ppb</a>)<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a></li></ul>
<h2 id="variables">Variables</h2>
Threshold in a food is dependent upon:

<ul><li>The threshold of the aroma in air.</li>
<li>Concentration in the food.</li>
<li>Solubility in oil and water.</li>
<li>Partition coefficient between the air and the food.</li>
<li>The <a href="/facts/PH/RnSv8D7y">pH</a> of the food. Some aroma compounds are affected by the pH: weak organic acids are protonated at low pH making them less soluble and hence more volatile.</li>
<li>Number and functionality of odorant receptors in the observer's nose.</li></ul>
The concentration of an odor above a food is dependent on its solubility in that food and its <a href="/facts/Vapor_pressure/whrEr96T">vapor pressure</a> and concentration in that food.

<h2 id="variation-by-individual">Variation by individual</h2>
A 2014 study found no significant differences between men and women, and between non-pregnant and pregnant individuals, despite the existence of anecdotal reports of <a href="/facts/Hyperosmia/K74lqTxj">hyperosmia</a> among the latter.<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a>
People with <a href="/facts/Multiple_Sclerosis/vghXl0IQ">Multiple Sclerosis</a> have been found to have higher olfactory thresholds. In scientific research, this is often represented by a lower threshold score, i.e. reversing the scale. Olfactory function is more impaired in patients with primary progressive MS than that in relapsing-remitting MS.<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a>

<h2 id="variation-among-species">Variation among species</h2>
Some species can detect odors that others cannot. It is widely believed that animals such as dogs and rodents have a superior sense of smell overall, however a 2017 paper disputed that, saying that "the absolute number of <a href="/facts/Olfactory_neuron/CcPIXqbU">olfactory neurons</a> is remarkably consistent across mammals".<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a>

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Olfactometer/4KuxnEnN">Olfactometer</a></li>
<li><a href="/facts/Taste_detection_threshold/cs01dIfn">Taste detection threshold</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">Lin, S (1977). "Tastes and Odors in Water Supplies - A Review" (PDF). Department of Registration and Education. 127: 1. <a href="https://www.isws.illinois.edu/pubdoc/C/ISWSC-127.pdf" target="_blank">https://www.isws.illinois.edu/pubdoc/C/ISWSC-127.pdf</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">L.J. van Gemert (2003) Flavour thresholds <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">Leffingwell & Associates. "Odor & Flavor Detection Thresholds in Water (In Parts per Billion)". Retrieved May 10, 2022. <a href="http://www.leffingwell.com/odorthre.htm" target="_blank">http://www.leffingwell.com/odorthre.htm</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">Leffingwell & Associates. "Odor & Flavor Detection Thresholds in Water (In Parts per Billion)". Retrieved May 10, 2022. <a href="http://www.leffingwell.com/odorthre.htm" target="_blank">http://www.leffingwell.com/odorthre.htm</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">PSabine, Widder; Symrise GmbH & Co. KG. "8-tetradecenal as fragrance and flavoring substance". Google Patents. Retrieved July 20, 2017. <a href="https://patents.google.com/patent/US7332468" target="_blank">https://patents.google.com/patent/US7332468</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">Polak et al find an average threshold of 9.5 ppt for the negative enantiomer of Geosmin, for the positive enantiomer it's 78 ppt. The range for both enantiomers is between 4 ppt to > 100 ppt across 50 human subjects. Polak, E.H.; Provasi, J. (1992). "Odor sensitivity to geosmin enantiomers". Chemical Senses. 17 (1): 23–26. doi:10.1093/chemse/17.1.23. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Leffingwell & Associates. "Odor & Flavor Detection Thresholds in Water (In Parts per Billion)". Retrieved May 10, 2022. <a href="http://www.leffingwell.com/odorthre.htm" target="_blank">http://www.leffingwell.com/odorthre.htm</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Leffingwell & Associates. "Odor & Flavor Detection Thresholds in Water (In Parts per Billion)". Retrieved May 10, 2022. <a href="http://www.leffingwell.com/odorthre.htm" target="_blank">http://www.leffingwell.com/odorthre.htm</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">H.H. Baek, K.R. Cadwallader (1999) Contribution of Free and Glycosidically Bound Volatile Compounds to the Aroma of Muscadine Grape Juice Journal of Food Science 64 (3), 441–444 doi:10.1111/j.1365-2621.1999.tb15059.x <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Cameron, E. L. (2014). "Pregnancy does not affect human olfactory detection thresholds". Chemical Senses. 39 (2): 143–150. doi:10.1093/chemse/bjt063. PMID 24302690. <a href="https://pubmed.ncbi.nlm.nih.gov/24302690/" target="_blank">https://pubmed.ncbi.nlm.nih.gov/24302690/</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">Schmidt, Felix A.; Maas, Matthew B.; Geran, Rohat; Schmidt, Charlotte; Kunte, Hagen; Ruprecht, Klemens; Paul, Friedemann; Göktas, Önder; Harms, Lutz (July 2017). "Olfactory dysfunction in patients with primary progressive MS". Neurology: Neuroimmunology & Neuroinflammation. 4 (4): e369. doi:10.1212/NXI.0000000000000369. PMC 5471346. PMID 28638852. <a href="https://nn.neurology.org/content/4/4/e369.full" target="_blank">https://nn.neurology.org/content/4/4/e369.full</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">"Not to be sniffed at: Human sense of smell rivals that of dogs, says study". TheGuardian.com. May 11, 2017. <a href="https://www.theguardian.com/science/2017/may/11/not-to-be-sniffed-at-human-sense-of-smell-rivals-that-of-dogs-says-study" target="_blank">https://www.theguardian.com/science/2017/may/11/not-to-be-sniffed-at-human-sense-of-smell-rivals-that-of-dogs-says-study</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
</ol>

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Odor detection threshold