Scientists fill in encapsulation knowledge gaps

Scientists from Kaunas University of Technology in Lithuania and the Technical University of Denmark investigated the effect of different commercial modified food starch carrier materials on peppermint essential oil encapsulation, with the aim of clarifying the effects of water activity and volatile release data.

"Such information could expand the existing knowledge and fill some gaps still present in the quality control and applications of various spray-dried encapsulated natural flavour products," wrote the authors in the Journal of Agricultural and Food Chemistry .

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 technology can be used to deliver a host of ingredients - flavours, oils, peptides, amino acids, enzymes, acidulants, colours and sweeteners - in a range of food formulations, from functional foods to ice cream.

As such, encapsulation of sensitive ingredients has become one of the most important and innovative applications in the food industry.

The researchers, led by Renata Baranauskiene, tested encapsulation properties of six chemicall n-octenyl succinic anhydride (OSAN)-modified starches (three supplied by National Starch Group and three from Cerestar) and two acid- and/or enzyme-hydrolysed starches (dextrins).

The encapsulated flavours were prepared using the spray-dry technique, the most commonly used technology in the food industry because of the low costs and availability of equipment.

They report that higher emulsification and encapsulation efficiencies were obtaiend for all OSAN-modified starches, compared to the dextrins.

"It could be concluded that OSAN-modified starches CIEmCap 12633 and Capsul resulted in the highest retention of peppermint volatiles and that these matrices could be recommended when low release of volatiles is required," said the researchers.

"On the contrary, both hydrolysed starches Encapsul 855 and Crystal Tex 627 showed the poorest retention of peppermint essential oil; the leakage of volatiles into the headspace from these matrices was faster, and consequently, they could be applied when a rapid release of aroma compounds into the environment is needed," they added.

Knowledge gaps still exist, said the researchers and further research should focus on determining the glass transition temperature - properties of the material to change from a crystalline (glass) to a liquid, which would affect flavour release.

Source: Journal of Agricultural and Food Chemistry ASAP Article, published on-line ahead of print, doi: 10.1021/jf062508c S0021-8561(06)02508-8 "Flavor Retention of Peppermint (Mentha piperita L.)

Essential Oil Spray-Dried in Modified Starches during Encapsulation and Storage " Authors: R. Baranauskiene, E. Bylaite, J. Zukauskaite, and R.P. Venskutonis