Beta-cyclodextrin tested for encapsulation

The study, published online in the Journal of Food Science , supports and emphasises the potential of these polysaccharides to protect value-added ingredients, including nutrients, flavours and colours.

"The terpene complexes with beta-cyclodextrin and modified starch can be used as additives to the foods, to which they are normally added as flavours, with the advantage of higher stability," wrote the researchers from Harokopio University and the Technological Educational Institute of Athens.

Beta-cyclodextrin (B-CD) is a chemically and physically stable polysaccharide produced by the enzymatic modification of starch.

Some cyclodextins are already used as carriers for natural colours, flavours and vitamins, solubilisers of lipids, stabilisers of oil in water emulsions, or flavour or aroma modifiers in a variety of processed foods.

The Greek researchers investigated the potential of B-CD (Aldrich Chemie, Germany) and modified starch (MS, obtained from Cargill) to encapsulate thymol (obtained from Riedel-de Haen, Germany) and geraniol (MP Biomedicals, France).

Thymol has previously been reported to possess antibacterial and antimicrobial activity, as well as helping maintain polyunsaturated fatty acids (PUFA) levels in cell membranes.

On the other hand, geraniol has been reported to exhibit anti-tumour activity against various cancer cell lines, both in vitro and in vivo .

The researchers used both spray- and freeze-drying to test the potential of the encapsulation technique, with MS found to encapsulate both compounds very effectively - encapsulation efficiencies of thymol and geraniol of above 90 per cent for both.

B-CD encapsulated more thymol (more than 95 per cent) than geraniol (about 60 per cent), they report. "

This difference may be assigned to B -CD, which offers the optimum cavity environment for encapsulating phenyl-ringed molecules like thymol ," wrote the researchers.

In order to test the stability of the encapsulate nutraceuticals against oxidative decay, the researchers tested the microcapsules under conditions at which free terpenes are oxidised.

Importantly, thymol and geranoil enclosed in B-CD were protected against oxidation, they said.

Moreover, retention of the compounds in the microcapsules dispersed in water was superior for thymol, with both B-CD and MS retaining about 70 per cent after ten hours.

However, the majority of the geraniol was released when the capsules were dispersed in water.

Microcapsules are tiny particles that contain an active agent or core material surrounded by a shell or coating, and are now increasingly being used in food ingredients preparation.

The research is in-line with the current trend of food manufacturers to turn to encapsulation technologies as a way of achieving much-needed differentiation and enhancing product value.

Tapping into key and emerging consumer trends with innovative techniques is becoming increasingly important for food manufacturers.

Source: Journal of Food Science Published online ahead of print, doi:10.1111/j.1750-3841.2007.00609.x "Encapsulation of Nutraceutical Monoterpenes in ß-Cyclodextrin and Modified Starch" Authors: I. Mourtzinos, N. Kalogeropoulos, S.E. Papadakis, K. Konstantinou, V.T. Karathanos