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iStock/Erin McCarthy

Why Does Garlic Make Your Breath Smell So Bad?

iStock/Erin McCarthy
iStock/Erin McCarthy

Garlic is tasty, but its flavor comes at the cost of alienating your dinner partners with a distinct odor on your breath—and even your skin—when the meal is done. How do these innocent-looking little bulbs cause so much trouble?

Garlic breath isn’t so much garlic’s fault as our own. The chemicals responsible for the stink aren’t present in whole garlic cloves, but are only formed when the clove is damaged. Chopping or crushing garlic releases an enzyme called allinase, which converts odorless alliin molecules into pungent, sulfurous allicin.

Allicin is the major contributor to the aroma of fresh-chopped garlic and also gets the ball rolling on garlic breath. It’s unstable and quickly breaks down into several other smelly sulfur-containing compounds—including diallyl disulfide, allyl methyl sulfide, allyl methyl disulfide, and allyl mercaptan—that hang out in the air in your mouth and make your breath stink. 

Your body metabolizes most of these compounds within a few hours, but allyl methyl sulfide is slower to break down and stays in the body longer than the others—sometimes up to a day or two. From the gut, it slips into the bloodstream and moves freely about your body. It gets circulated to the lungs and shows up on your breath again, and also makes its way into your sweat and urine, giving them a garlicky odor.

Garlicky sweat can cause some other issues aside from the smell. Doctors in the UK reported the case of a patient who made china dolls and complained of black speckles showing up on the dolls’ heads after she handled them. The doctors found that the patient ate a lot of garlic and that her body wasn’t very good at metabolizing the various sulfur compounds, allowing them to be “excreted virtually unchanged in her sweat.” When she touched the dolls with sweaty hands, the garlic compounds reacted with flecks of iron in the clay the dolls were made from, resulting in black splotches. 

Now that you know what causes garlic breath, what can you do about it? Brushing your teeth after you eat garlic can rid your mouth of some of the smelly compounds, and you can also mask them with a stronger, more pleasant smell until they break down. There’s also some research that suggests that eating certain other foods—kiwi fruit, spinach, lettuce, parsley, basil, mushrooms, milk and rice—can help reduce garlic breath by degrading, trapping and/or deodorizing the sulfur compounds. 

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science
New Clear Coating for Everyday Objects Repels Practically All Liquids
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A new clear coating that is said to repel just about everything—peanut butter included—aims to halt the advance of sticky fingers. Developed by researchers at the University of Michigan, the substance can be applied to a variety of surfaces to keep them smudge- and crud-free, including smartphone and laptop screens, windows, walls, and countertops.

Researchers used algorithms to predict which substances would yield an efficient omniphobic coating, or in other words, something capable of repelling oils, alcohols, and other liquids while remaining durable and smooth. Made from a mix of fluorinated polyurethane and a fluid-repellent molecule called F-POSS, the coating can be “sprayed, brushed, dipped, or spin-coated onto a wide variety of surfaces, where it binds tightly,” according to the University of Michigan’s website.

The team’s findings were published in the March issue of the journal ACS Applied Materials Interfaces. Associate professor Anish Tuteja, who headed up the University of Michigan research team, says it could be a godsend for parents of young tots.

"I have a 2-year-old at home, so for me, this particular project was about more than just the science," Tuteja said in a statement. "We're excited about what this could do to make homes and daycares cleaner places, and we're looking at a variety of possible applications in industry as well."

The team is currently conducting follow-up tests to ensure the coating is nontoxic, but if all checks out, it could find its way into kindergarten classes and daycare centers within the next two years.

Child-proofing everyday objects for the sake of cleanliness isn’t its only potential application, though. The university notes that it could be beneficial to “all industries that depend on the condensation of liquids,” such as refrigeration, power generation, and oil refining.

In recent years, other researchers have set out to create omniphobic coatings, some of which have been successful. However, this undertaking is typically challenging and involves complex synthetic chemistry, according to Chemistry World.

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Food
Why You Never See Fresh Olives at the Grocery Store
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If given a choice, most grocery shoppers prefer fresh produce over something that's been pumped full of preservatives. Yet shoppers are almost never given that choice when it comes to olives. The small, meaty fruits can be found floating in brines, packed in cans, and stuffed with pimentos, but they're hardly ever shipped to the store straight off the tree. As the video series Reactions explains, there's a good reason for that.

In their natural state, because they contain high concentrations of a bitter-tasting compound called oleuropein, fresh olives are practically inedible. To make the food palatable, olive producers have to get rid of these nasty-tasting chemicals, either by soaking them in water, fermenting them in salt brine, or treating them with sodium hydroxide.

Because of its speed, food manufacturers prefer the sodium hydroxide method. Commonly known as lye, sodium hydroxide accelerates the chemical breakdown of oleuropein into compounds that have a less aggressive taste. While other processes can take several weeks to work, sodium hydroxide only takes one week.

Afterward, the olives are washed to remove the caustic lye, then packed with water and salt to extend their shelf life, giving them their distinct briny flavor.

For more on the chemistry of olives, check out the full video from Reactions below.

[h/t Reactions]

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