Is the smell of the quilt after drying it the smell of mites?

When it comes to the "sun smell" of quilts drying, the most widely circulated saying is:

The mites are burnt by high temperature, and the smell is produced by the protein being heated.

This statement has dissuaded many friends who are obsessed with the smell of quilts: when they think that the smell of the quilts they are obsessed with actually comes from the corpses of mites...

But we want to give you a reassurance:

The "sun smell" of the quilt may be related to mites, but the relationship is not that big.

01 Is the smell of the quilt related to mites? It may be related, but the relationship is not that big. There are three reasons:

1. The temperature is not high enough

The main basis for this statement is the unique smell emitted by the carbonization of protein of mites under high temperature.

So what is the normal temperature when drying quilts?

We specially found a sunny day, took our quilts to the rooftop, and sunbathed them for 2 hours.

Tests show that the surface temperature of the quilt is around 22°C.

This temperature is not even high enough to denature most proteins, let alone give off a burnt smell.

The test was conducted in winter, when the temperature was lower. But even in the hot summer, the temperature on the quilt surface was not high enough to cause protein to char.

There are two main types of mites that we come into contact with on a daily basis: dust mites and demodex mites.

Demodex mites live primarily in human hair follicles and sebaceous glands;

Dust mites mainly live in dust, long-used clothes, quilts, and carpets.

The mites on the quilt are mainly dust mites.

Dust mites look like this

Dust mites are similar to humans, with about 70-75% water, and the rest being protein and small amounts of other organic components.

In other words, if you expose the quilt to the sun for half a day, at best you can only dry out the water in the mites' bodies and kill them.

Not enough heat to allow its protein to develop flavor.

2. The taste is different

Even if dust mites produce an odor when exposed to heat, it is not quite the same as the "sun smell."

If you have no idea what burning protein smells like, take a strand of your hair and burn it with a lighter.

This is the unique smell of protein when it is heated, a slightly pungent burnt smell, often described as "burnt feathers".

The "sun smell" of the quilt after it has been dried in the sun is a warm, baked scent, which is obviously different from the smell of burnt protein.

3. Insufficient quantity

If you collect all the dust mites on the quilt, they would weigh only a few milligrams at most.

What's more, the protein content of these dust mites is not high.

Even if there is a smell, it is very subtle and difficult to smell.

To sum up, the smell of drying quilts has little to do with mites.

02 What does the smell of the quilt have to do with? What is that smell?

We searched for some information and found some relevant research:

They think it's most likely related to the light reaction.

During the study, in order to eliminate the influence of mites and detergents on odor, researchers used new, undyed cotton towels as research objects.

After washing the towel with deionized water, dry it in three simulated environments:

Outdoors in the sun

Outdoor shade

indoor

turn out:

Towels hung outdoors to dry all have a sun smell, but those hung indoors do not.

In other words, this smell has little to do with mites, and may be related to ultraviolet rays.

03 What is this smell? In order to further study what this smell is.

The researchers used a device to collect odor substances on the surface of towels for measurement.

turn out:

After being exposed to the sun, some substances that were not originally there appeared in the quilt, and the concentration of some substances increased.

Most of these substances are organic compounds such as aldehydes, ketones, carboxylic acids, such as methacrolein and 2-methylpropanal.

Most of them smell good and appear in many scenes, and some are even used as perfume ingredients.

You must be familiar with their taste:

2-Methylpropanal has a fruity, baking aroma. Methacrolein has a floral aroma. 2/3-Methylfuran has a chocolate flavor.

More importantly, these substances can be smelled by humans even in very small amounts.

Putting all these together, it is not difficult to understand why the smell of drying quilts makes people feel soothing and reassuring.

As for the source of these substances, researchers speculate that it is related to the photochemical reactions that occur when textiles are exposed to sunlight.

He used a diagram to describe how the scent is generated:

Ultraviolet rays catalyze a series of oxidation reactions in the substances on the surface of the towel, turning them into volatile organic compounds with unique odors, which together create the smell of the sun.

The researchers also inferred that similar phenomena would occur in many scenarios.

For example, after it rains, tree trunks that have been exposed to the sun will also emit a similar smell.

If we put it into the scene of drying quilts, this kind of sun smell is more likely to be:

The mixed smell is produced by the reaction of human sebum, dust, dyes, residual laundry detergent, and a small amount of mites (the contribution is unknown and the probability is extremely low) on the surface of the quilt.

You can also understand it as the smell of "human" after being exposed to the sun.

The above document is one of the more valuable conclusions we have found.

Of course, there is still a lot of research on the taste of the sun, and there is no final conclusion yet on what the real taste of the sun is.

But no matter what its source is, it has nothing to do with mites.

There is really no need to worry too much about the "burnt mite smell". Just sunbathe when you need to and sleep when you need to.

In addition, we would like to remind you:

① Although drying quilts in the sun cannot completely kill mites, exposing them to the sun more often can still effectively kill them.

Especially for those who are allergic to mites, they should dry their quilts frequently.

② The longer you expose your quilt to the sun, the better. Prolonged exposure to the sun can easily break the cotton fibers and make the quilt damp.

Generally, 2 hours of sun exposure in summer and 3 hours in winter are most suitable.

③When drying the quilt, the mites' desire to survive will make them move to a shady place consciously.

Therefore, the best way to dry a quilt is to dry the back side first (the side that touches the human body), then the front side, and finally pat it.

References:

[1] Cui Yubao. Biology, ecology and epidemiology of dust mites[J]. Foreign Medical Journal (Parasitic Diseases), 2004.

[2]Pugliese S, Jespersen MF, Pernov JB, et al. Chemical analysis and origin of the smell of line-dried laundry[J]. Environmental Chemistry, 17.