Low-fat foods are often disappointing to consumers since removing the fat changes the desirable taste, texture and aroma of the original product.
Now, a team of researchers at the University of Massachusetts Amherst are developing a new technology that could lead to low-calorie foods that taste like the real thing.
"Our goal is to keep the fat in the food, but stop it from being digested by surrounding it with layers of dietary fibre," says Julian McClements, UMass Amherst professor of food science. "Foods produced with these encapsulated fats should have the same qualities as conventional high-fat foods." The research team includes McClements and UMass Amherst food science professors Eric Decker and Yeonhwa Park.
To make the encapsulated fats, small oil droplets are formed by mixing oil, water and a surfactant in a process similar to making salad dressing. The surfactant coats the droplets and keeps them separate from the water until fibre is added to the mix in the final step. Controlling the electrical charges of the surfactant and the fibre molecules allows the oil to attract the fibre like a magnet. Droplets are usually coated with two to three layers of fibre, and other substances such as proteins can be incorporated to hold the fibre layers together or to provide additional benefits.
The process is suitable for encapsulating a wide range of fats and oils, everything from orange oil to olive oil, and uses fibre obtained from apples, oranges, seaweed or shellfish. All the ingredients are food-grade, so this technology requires no FDA approval to use. Encapsulated fats can be used in emulsion-based foods such as beverages, sauces, desserts, yoghurt and salad dressings. They remain stable in acidic foods and during freezing, thawing and cooking, and can also handle large amounts of salt.
How much of the fat can be digested is controlled by the number of layers and the types of fibre used. The team is currently experimenting with ways to chemically link the fibre layers to enhance their ability to stay intact around the fat droplets.
Layers of fibre could also be used to encapsulate vitamins and antioxidants, enabling them to survive a trip through the stomach and be released in the small intestine for absorption by the body, and this process could allow ingredients with proven health benefits but unpleasant taste, like Omega-3 fatty acids, to be included in a wide variety of foods.
Future research by the team will focus on customizing the layers of fibre to respond to different environments, and testing to determine whether this method can be used as a delivery system for therapeutic drugs that can dissolve in fats. "It should be possible to develop coatings that release drugs at specific sites within the human body," says McClements.
McClements and Decker are currently seeking a patent, and the technology is available for licensing and research collaboration.
(Source: University of Massachusetts: February 2008)