Salad dressings are a wonderful thing. The simple combination of olive oil, vinegar, lemon juice, and maybe some kind of organic wholegrain mustard if you’re feeling adventurous, can transform a bowl of sad leaves into a respectably zesty and flavourful side dish.
They’re also kind of impossible to mix. Being less dense than H2O, oil will float to the surface of any water-based substance. No matter how hard you shake a French dressing, it will eventually separate into a layer of vinegar and lemon juice with globules of oil up top.
Until now. Scientists at Massachusetts of Technology (MIT) have developed a way to mix oil and water and get them to remain in one stable emulsion for months on end—no shaking required.
Published in the Nature Communications journal, the study saw researchers from the university’s engineering department cool a bath of oil with a soap-like substance, allowing the vapour from the air to condense on the oil’s surface. This formed tiny water droplets that sunk and spread evenly through the oil. The researchers found that by adjusting the oil and soap substance mix, these water droplets could be reduced to a nanoscale size that wasn’t as easily affected by gravity. It formed an oil and water emulsion that stayed mixed for long periods of time.
In an MIT press release published yesterday on the study, graduate student Ingrid Guha explained: “The key to overcoming that separation is to have really small, nanoscale droplets. When the drops are small, gravity can’t overcome them.”
As well as lasting for longer, this new method of mixing oil and water is much cheaper and easier than the current industrial method, which involves shaking or blasting the mixture with soundwaves so that the substances turn into tiny droplets, which take longer to separate. Also commenting in the press release, engineering professor Kripa Varanasi explained that these mixtures “always have an expiration date,” as they eventually separate.
The MIT team also hope that their findings can be used in cosmetics and drugs that require stable emulsions of oil and water—and yes, the food industry too. Guha added: “We envision that you could use multiple liquids and make much more complex emulsions.”
It might be time to crack out the fancy balsamic.