Next-generation coatings give protection to unstable bioactives

"Traditionally, we've used hydrogenated vegetable oils for encapsulation, which are great for taste masking but can't withstand high temperatures," he said. "By contrast, cellulose derivatives are heat stable, but can swell in water unless you add other coatings as well. The third option is vegetable wax."

The next generation of coatings would tackle these problems, he claimed. "We've been conducting extensive trials with vitamin C, which is sensitive to heat and humidity. If we can get good results with this, it will work with anything."

Microencapsulation was being driven by growing demand for the inclusion of unstable functional ingredients in new foods and drinks, Karlinski said. However, new European legislation introducing maximum levels for vitamin and minerals added to foods would also boost the market. "Historically, people have just thrown in large amounts of things like vitamin A into products to ensure that some will be left at the end of the shelf-life because it degrades. In future, they won't be able to, so microencapsulation will become a necessity to ensure that active ingredients remain intact throughout shelf-life."

Most manufacturers wanted microencapsulated ingredients to mask taste or smell; protect them from heat, light, moisture or gastric juices; or prevent them from interacting with other ingredients, said Karlinski. However, the desire to control release was also important.

"We are now seeing demand to microencapsulate aspartame and sucralose in chewing gum so that the sweet flavour lasts longer. We're also receiving requests from manufacturers keen to control the release of caffeine so that people get controlled kicks, rather than one big hit."

The market for micro-encapsulated ingredients is growing at more than 10% a year, according to Leatherhead Food International.

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