The best things do come in small packages

Taste is one of the most important facets of the food industry. Much of spending on research and development involves finding ways of intensifying and delivering flavours - and of protecting the often sensitive compounds that impart flavour.

Microencapsulation techniques, although not new, are currently the focus of much attention.

Microencapsulation involves enclosing particles of flavour compounds within a carrier, usually an inert material such as a starch or gum. It was first used in the 1930s, when liquid flavours were spray-dried to form powdered flavourings for baked goods or drinks. But new techniques, often borrowed from the pharmaceutical industry, are making it one of the hottest research subjects in the food industry.

Spray-drying forms a solid matrix, with a random distribution of flavour particles, but provides no protection for sensitive flavours which might be degraded by contact with air or water. It also gives no control over how the flavouring is released. Newer microencapsulation techniques such as extrusion and fluid bed coating are now beginning to solve these problems.

Food scientists can now produce capsules where the flavouring is coated by a shell of a protective substance, often a food-compatible polymer, a hardened fat or oil, or a mixture such as sodium caseinate and lactose, whose composition can be controlled so that it degrades at a known rate. This can also make processing easier by improving the flowability of food components, such as sugars and other sweeteners, which tend to absorb moisture and become sticky in their natural state.Controlled release techniques were developed for drug formulation, but are finding different uses in the food industry.

Its simplest use is to ensure that flavours in confectionery, such as chewing gum, last as long as possible. In the bakery industry, companies such as TasteTech encapsulate herb and spice oils flavours in a protective shell of hardened fats which breaks down at a particular temperature, releasing the flavouring at the ideal point in the baking process. If non-encapsulated products were used, the molecules imparting the flavours would break down and be lost early in the baking process.

It isn't just flavourings which can be encapsulated. Salt, for example, can be encapsulated to control colour degradation, rancidity and yeast growth. Sugar also has a non-flavour application - it is added to baked goods to ensure that they brown.

Encapsulation techniques are also becoming more complex. Fluid Technologies, a high-tech food science firm based in Atlanta and Wigan, produces bio-engineered capsules based on yeast cells which have been encouraged to strengthen their cell walls to form capsules.

The process, called Micap, uses a very pure strain of yeast with a bland taste and a pale colour. This is grown continuously in large fermenters, forming into uniform capsules around 8-12µm across. Because the conditions in the fermenters are rather harsh, the yeast develops a strong outer wall.

Manipulation of the cell wall and lipid membrane causes the cells to engulf the active ingredients, providing a barrier which the company claims is resistant to evaporation, oxidation and UV degradation, and provides such intense flavouring that concentration can be reduced by 60 per cent. Moreover, it claims, the cells can be spray-dried to produce free-flowing particles.

The best things, it seems, can come in small packages.