Rub an oregano leaf from your balcony pot between your fingertips, and a peppery, warm aroma rises up. It's the scent that belongs with pizza and tomato sauce. Thyme gives off the same fragrance. The compound behind it is called carvacrol, and a recent study looked at how it might be used to keep food fresh longer.
The Compound Behind the Scent: Carvacrol
Carvacrol is an aromatic compound found in oregano and thyme. Cooks have long noticed that meat and sauces made with these two herbs seem to spoil more slowly, and carvacrol is one reason why. In lab tests, it has curbed the growth of a range of bacteria. As antibiotic-resistant bacteria become more common, researchers have been looking to natural compounds like this one as alternatives to chemical preservatives.
Strongly scented compounds have a weakness, though. Carvacrol evaporates easily, and it breaks down when exposed to light, heat, and air. It's the same reason a picked leaf loses its fragrance if you leave it out too long. Added straight to food, its effect simply doesn't last.
Wrapped in a Tiny Shell
The researchers enclosed carvacrol in particles too small to see. The coating is a polymer called polyhydroxybutyrate (PHB), a material that breaks down on its own over time. Kept in the refrigerator, the particles stayed stable for more than 247 days. The shell is designed so the aroma doesn't escape all at once but seeps out slowly instead.
How fast it was released depended on the type of food. In fattier foods, carvacrol came out more slowly and over a longer stretch of time. That suggests the aroma and its preserving effect could last longer in foods that contain fat, such as sausage or cheese.
Fewer Bacteria, But Is It Safe for Us?
The particles reduced the numbers of two bacteria that cause food poisoning: Listeria and Staphylococcus aureus, better known as staph. Listeria is especially tricky to deal with because it can grow even at the cold temperatures inside a refrigerator, and the particles held it back as well. This isn't a powerful sterilizer that wipes bacteria out completely; it slows down how quickly they multiply.
In tests on human cells, more cells died as the concentration went up, while at moderate concentrations more than half the cells survived. The researchers also raised the possibility that the compound could suppress cancer cells, but that observation comes from cells in a lab dish. How it affects people when eaten, and how much is safe, has not been established yet, so it's too early to call it good for your health.
What to Try in Your Garden Today
Nano-shells belong in the lab, but the aroma that inspired them is something you can grow in a pot. Oregano and thyme thrive on a sunny windowsill and don't need frequent watering. Pinch off a few leaves and add them to a freshly made tomato sauce or a piece of grilled meat. Freshly picked leaves have a stronger scent than dried ones. If you ever find yourself wondering how fresh the banchan (Korean side dishes) in your fridge still are, start with the simple habit of adding these two herbs.
