In early summer, run your fingertips over sage leaves and the scent stays on your skin long afterward. But once the leaves are stripped, you're left with a heap of tough stems and twiggy branches, and most of it goes on the compost pile. One team of researchers took a second look at those leftovers, working with Greek sage (Salvia triloba), which is grown widely across the Mediterranean.
Not the Leaves, but What's Left Behind
After the harvest, the researchers gathered the stems and branches still in the field and heated them with microwaves to draw out their aromatic compounds. The usual method is to boil plant material in water for a long time and collect the steam. Microwave heating is faster and uses less heat. Even this discarded material produced a good yield of essential oil.
The Compounds Behind the Scent
When the team broke the oil down into its parts, thujone came out on top, at roughly a quarter of the total. Next came camphor and eucalyptol, the compound that gives eucalyptus its familiar smell. Rub a sage leaf between your fingers and you'll notice a cool, pungent aroma. These compounds produce it.
One caution: in large amounts, thujone can be hard on the nervous system, and Europe limits how much of it can go into food. Cooking with leaves picked from your own garden has a long tradition, but you should never swallow the concentrated oil straight.
Up Against Foodborne Bacteria
The oil was tested separately against E. coli, Listeria, and Salmonella. All three are known for causing trouble in refrigerated meat and dairy and in washed, prepped produce. E. coli stopped growing at relatively low concentrations, while Listeria and Salmonella took somewhat stronger doses.
These results come from test tubes. It's too early to say the oil would work the same way on food that reaches your table. Still, the findings are worth watching for anyone looking for alternatives to synthetic preservatives. The researchers suggest the oil could be tried in packaging and processing for foods that spoil quickly, such as meat and dairy.
What You Can Try at Home
The study looked at a concentrated essential oil, but there are still ways to put leftover sage branches to use at home.
- Cut up the tough stems, dry them in the shade, then tuck them into a cotton sachet for your closet or shoe cabinet. Keep them away from moisture and the scent will last a long time.
- Steep dried leaves and twigs in hot water, let it cool, and use it as a final rinse for cutting boards and dish towels. It won't replace a disinfectant, but it does help cut down on odors.
- When marinating pork or sausages, add two or three fresh leaves. Sage goes well with richer, fattier cuts.
If you're trimming sage today, don't send the stems straight to the compost pile. Set aside a handful, tie it into a bundle, and hang it somewhere shady. Ten days is plenty of time for it to dry.
