Passion fruit smell = underarm odor? You are not mistaken...

If a colleague suddenly told you that passion fruit smells like armpit odor, would you scold him or...

Once you have an association, you can never go back to the way it was before.

If it stinks, how can it be called passion fruit? However, more than one person thinks passion fruit stinks...

Are these two search results in conversation?

After learning about this, my colleagues immediately started arguing: some said boiled eggs smelled bad, some said boiled rice smelled like feet, and some said coriander smelled like bugs...

After checking the information, I want to say to these colleagues: Yes! You are not alone!

Passion fruit is not necessarily fragrant

The name of passion fruit makes people feel that it is "too fragrant", but among these "hundreds of scents", aren't there one or two that some people find stinky?

If you search for passion fruit and underarm odor in your browser, the first thing that comes into your view is people's complaints about Sauvignon Blanc wine. As a wine characterized by fruity aroma, Sauvignon Blanc has always been complained about having the smell of underarm odor. And passion fruit happens to be the typical smell of this wine.

“Am I the only one who thinks Sauvignon Blanc smells like underarm sweat?

This wine has a passion fruit smell, thanks to a substance called 3MHA (3-mercaptohexyl acetate) - a thiol compound, and thiol is the typical substance in underarm odor. Many studies have found that when the concentration of this "passion fruit smell" substance is high, its smell becomes sweat and cat urine...

Different thiols have different flavors | AEB USA/Youtube

Back to passion fruit itself, researchers have also conducted many experiments on how many kinds of aroma molecules passion fruit contains. As early as the last century, many studies have found that there are many kinds of sulfur-containing organic compounds in the volatile oil and juice of passion fruit. Most of these sulfur-containing organic compounds have the characteristic of being "unpleasant" at high concentrations.

Newly identified sulfur-containing esters have an unpleasant taste at high concentrations | Reference [2]

In addition, researchers found 2-methylbutylhexanoate in the volatile oil of yellow passion fruit. This substance contributes to the strongest smell of yellow passion fruit - the pungent smell of sweat.

Imagine: the pungent smell of sweat and stench mixed with the sourness of the fruit itself... Then you smell the passion fruit, do you suddenly feel that something is wrong with it?

Is sulfur the root of all odors?

Whenever we talk about bad smells, sulfur seems to be the inevitable "culprit". The bad smell of boiled eggs comes from hydrogen sulfide, the bad smell of garlic comes from sulfides and mercaptans, and the bad smell of onions, leeks and green onions is also inseparable from sulfides...

Most people are very sensitive to the smell of sulfur-containing substances, so sulfur-containing odorants are also added to odorless harmful gases to alert people to the leakage of harmful gases.

If you encounter some unpleasant smell and find "evidence" related to the presence of sulfur, then it basically really stinks. However, sulfur is not the "only standard answer" to explain other colleagues' taste associations.

Cilantro = Bugs

Chinese toon, coriander... It seems that these things with the word "fragrant" are always said to be smelly. Regarding the controversy over coriander, people who don't like it directly associate it with stink bugs. This is not intentional sarcasm, after all, the English word for coriander comes from the Greek word for stink bug.

Say No To Cilantro is a website that provides "No Cilantro" in various languages ​​(from left to right: Chinese, Spanish, Thai)丨SayNoToCilantro.com

The similarity between the smell of coriander and bed bugs comes from aldehydes. In the analysis of coriander odor substances, aldehydes occupy a large part of the "ranking list" of odor contributions. Bed bugs also release aldehydes, and people who are sensitive to aldehydes will find this smell very "pungent" and disgusting.

Some odor-active substances in fresh coriander (FD represents the aroma dilution factor, the larger the value, the more obvious the contribution to the odor) | Reference [8]

However, not all aldehydes are unpleasant. Eucalyptus essential oil and citrus essential oils contain relatively more aldehydes, and the "heady" smell given by these aldehyde molecules also brings a refreshing effect.

Cooked rice = foot odor

In the process of collecting strange smells, someone also suggested that the smell of cooked rice is like socks and foot odor. This immediately reminded me of the unforgettable memory of butyric acid leak in the laboratory next door when I was a graduate student: the whole laboratory building was filled with a strong sour smell for 3 consecutive days...

So if you mention foot odor to a chemistry student, he will immediately tell you: butyric acid.

Butyric acid is a well-known "foot odor substance" and its olfactory threshold is very low: even lower concentrations of butyric acid can be immediately felt by people.

Someone once tested the smell of four types of rice from different regions after cooking, and found butyric acid in all of them. At the same time, another study on the smell of cooked white glutinous rice pointed out that butyric acid is the substance with the highest odor activity value, which means that butyric acid contributes the most to the smell.

Although different types of rice have different characteristics, when you smell foot odor next to the rice cooker, the rice may really be to blame.

Amines

In addition to the above-mentioned substances, there is another category of "source of all odors": amines. You may have smelled the pungent smell of ammonia in high school chemistry experiments, but the lethality of amine compounds is far more than that. The main components of the pungent smell of fertilizers, urine and canned herring are amines.

In the laboratory, the smell of organic amines is even more terrible: propylamine, butylamine, trimethylamine, oleylamine, aniline, halogenated amines... Some of the smells are warm and unrestrained, while others are calm and heavy. When mixed together, they make people intoxicated and unforgettable (that is, they make them dizzy).

There are many other substances that have flavors, and their smells produce a variety of olfactory effects depending on their concentration and combination. At the same time, almost all kinds of fragrance substances with too high concentrations will cause people to feel uncomfortable. This may be the case of "all is lacking, and extremes are bound to be reversed."

People's sensitivity to smells also varies greatly, resulting in different olfactory experiences. Just like some people think they are seriously ill when they smell their own urine after eating asparagus, but some people cannot smell the pungent sulfur substances in "asparagus urine" at all.

So don’t force others to eat coriander, and don’t say that coriander stinks in front of people who like to eat it. After all, no one will ever be able to empathize with you (dog head).

Have you ever had a strange smell that everyone else finds nice but you just can’t accept?

References

[1] Barzantny, H., Brune, I., & Tauch, A. (2012). Molecular basis of human body odour formation: insights deduced from corynebacterial genome sequences. International journal of cosmetic science, 34(1), 2-11.

[2] Engel, KH, & Tressl, R. (1991). Identification of new sulfur-containing volatiles in yellow passionfruit (Passiflora edulis f. flavicarpa). Journal of Agricultural and Food Chemistry, 39(12), 2249-2252.

[3] Sahib, NG, Anwar, F., Gilani, AH, Hamid, AA, Saari, N., & Alkharfy, KM (2013). Coriander (Coriandrum sativum L.): A potential source of high-value components for functional foods and nutraceuticals-A review. Phytotherapy Research, 27(10), 1439-1456.

[4] Coetzee, C., & du Toit, WJ (2012). A comprehensive review on Sauvignon blanc aroma with a focus on certain positive volatile thiols. Food Research International, 45(1), 287-298.

[5] Troccaz, M., Borchard, G., Vuilleumier, C., Raviot-Derrien, S., Niclass, Y., Beccucci, S., & Starkenmann, C. (2009). Gender-specific differences between the concentrations of nonvolatile (R)/(S)-3-methyl-3-sulfanylhexan-1-Ol and (R)/(S)-3-hydroxy-3-methyl-hexanoic acid odor precursors in axillary secretions. Chemical senses, 34(3), 203-210.

[6] Jo, SH, Kim, KH, Kim, YH, Lee, MH, Ahn, JH, Szulejko, JE, ... & Kim, AYH (2013). Study of odor from boiled eggs over time using gas chromatography. Microchemical journal, 110, 517-529.

[7] Sahib, NG, Anwar, F., Gilani, AH, Hamid, AA, Saari, N., & Alkharfy, KM (2013). Coriander (Coriandrum sativum L.): A potential source of high-value components for functional foods and nutraceuticals-A review. Phytotherapy Research, 27(10), 1439-1456.

[8] Ma Mingjuan, Wang Dan, Xie Tian, ​​Chen Haitao, Sun Baoguo, Zhang Yuyu. Identification and analysis of key aroma components of fresh coriander[J]. Fine Chemicals, 2017, 34(08): 893-899.

[9] Maraval, I., Mestres, C., Pernin, K., Ribeyre, F., Boulanger, R., Guichard, E., & Gunata, Z. (2008). Odor-active compounds in cooked rice cultivars from Camargue (France) analyzed by GC− O and GC− MS. Journal of agricultural and food chemistry, 56(13), 5291-5298.

[10] Ajarayasiri, J., & Chaiseri, S. (2008). Comparative study on aroma-active compounds in Thai, black and white glutinous rice varieties. Agriculture and Natural Resources, 42(4), 715-722.

[11] Where does the smell of asparagus urine come from? https://www.guokr.com/article/440358/?ep=Cl97ZaWap%2C1850988623%2CCl97ZaWap%2C1850988623

Author: Yun Dongjun

Editor: Owl, Window Knocking Rain