YOKUU BLOG

WHY YOUR LAUNDRY STILL SMELLS (AND HOW TO FIX IT WITH PROBIOTICS)

You wash your clothes. You dry them. But they still smell kind of… off?

That lingering odour actually has a name: permastink. And no, it’s not your fault.

What is permastink?

Permastink refers to persistent odours that remain in textiles, especially synthetic fabrics, even after washing. It’s caused by microbial metabolism - in other words, the bacteria on your skin break down sweat into volatile organic compounds (VOCs) like isovaleric acid and methanethiol.

These compounds bind to the fibres of your clothes, particularly polyester and nylon, and resist removal during standard wash cycles. Over time, they build up and become harder to eliminate.

Why traditional detergents can’t solve it

Most conventional detergents are designed to make your laundry look and smell clean, but they don’t necessarily deal with the root cause. They often rely on perfumes to cover up smells, surfactants to lift surface dirt, and sometimes antibacterial agents to reduce microbial load.

But here’s the issue: these approaches don’t fully break down the molecules responsible for bad odour. And high-heat or aggressive washes can disrupt the microbiome of your laundry, making the problem worse over time. In fact, a 2025 study in BMC Biology showed that repeated washing can lead to the development of bacterial biofilms - sticky colonies of microbes that cling to fabric and protect odour-causing bacteria from being removed.

Why probiotics are a better approach

YOKUU’s probiotic laundry sheets use a biological solution to a biological problem.

Each sheet contains over 1 billion probiotic cleaning agents. These beneficial microbes get to work during the wash by breaking down the organic matter and VOCs that cause odour. They help rebalance the microbiome of your clothes, making it harder for smell-producing bacteria to thrive. They also prevent the formation of new biofilms by disrupting bacterial colonies before they take hold.

And they don’t stop after the spin cycle. The probiotics continue working while your clothes dry - or even while you wear them.

What this means in practice

You wash your clothes as usual. The probiotics activate in water, quietly and efficiently doing their job, and some of them remain on the fibres after rinsing. That’s a good thing - they keep working, keeping your fabrics fresher for longer.

An added bonus? These microbes also help keep your washing machine cleaner over time.

What the science says

Researchers have known for years that synthetic fabrics are more likely to hold onto odour-causing molecules. Their structure makes it easy for VOCs to bind, and hard for standard detergents to remove them. The 2017 Specialty Fabrics Review noted that simply killing bacteria isn’t enough - real odour removal requires breaking down the compounds themselves.

Meanwhile, the 2025 BMC Biology study showed that traditional detergent use can actually increase the genetic potential for odour and biofilm formation in textiles. In other words, washing the wrong way can make permastink worse.

Probiotic cleaning offers a more intelligent solution. By working with nature instead of against it, YOKUU’s laundry sheets provide a gentle, effective, and science-backed way to deal with stubborn odours - without bleach, or harsh chemical cleaners.

TLDR

Permastink happens when sweat and bacteria produce odour molecules that get trapped in synthetic fabrics. Regular detergent often masks, but doesn’t solve, the issue. YOKUU’s probiotic laundry sheets break down the source of the smell, rebalance the microbiome of your clothes, and keep working after the wash.

Still smell something? Not for long.

Discover more

  • WHY YOUR LAUNDRY STILL SMELLS (AND HOW TO FIX IT WITH PROBIOTICS)

    WHY YOUR LAUNDRY STILL SMELLS (AND HOW TO FIX I...

    You wash your clothes. You dry them. But they still smell kind of… off? That lingering odour actually has a name: permastink. And no, it’s not your fault.

    WHY YOUR LAUNDRY STILL SMELLS (AND HOW TO FIX I...

    You wash your clothes. You dry them. But they still smell kind of… off? That lingering odour actually has a name: permastink. And no, it’s not your fault.

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