"Carrageenan matrix represents a very powerful material for its structural properties to a system and is a good candidate for application such as encapsulation of active substances incorporated in biopolymer coatings or films for food," wrote lead author Thomas Karbowiak from the University of Bourgogne (ENSBANA-IMSAPS).
Carrageenan, a popular hydrocolloid used for texture and viscosity in food products, is a gum extracted from seaweed, largely sourced from the Philippines and Indonesia.
A strong pull in global carrageenan stocks, impacted by an increase in demand from China's booming processed food industry, has led to price spikes for a polysaccharide that is traditionally sold at low cost.
While encapsulation with carrageenans is limited by the polysaccharides being water-soluble, research has shown that adding fat to form an emulsified film can reduce the transfer of water.
The new research, published in the journal Food Hydrocolloids (doi: doi:10.1016/j.foodhyd.2006.07.017), looked at the formation of edible film from iota-carrageenan (Degussa), mixed with glycerol (Fluka), and in the presence of the fat, Grindsted Barrier System 2000 (GBS), supplied by Danisco. Glycerol monostearate (GMS), purchased from Prolabo, and widely used in ice creams, milk products, chewing gum, and chocolates, was used as emulsifying agent.
Dr. Karbowiak and his co-workers applied a high thermal process (100, 150, 200 degrees Celsius for 1, 2, 4, 8 min) in order to promote formation of a two-layer structure, which they hypothesised could produce a better water barrier.
The temperatures and times were chosen to correspond to those typically found in baking processes.
The researchers report that the emulsion formed consisted of a dense and continuous carrageenan matrix with embedded lipid droplets of about 48 micrometres in diameter for 60 per cent GBS. Without GMS, the fat particles increased in size to about 73 micrometres.
No difference in the size of the lipid particles was recorded between the heating temperatures and times. The stability of the films was also high with no phase separation, and did not change significantly when tested for water vapour permeability, said the researchers.
"These results open interesting developments for the use of very resistant carrageenan coatings in a dry state for application such as encapsulation of active substances incorporated in biopolymer films for food," said Karbowiak.
"This tight carrageenan network could indeed be turned to good account for active and edible packaging systems as a carrier for a wide range of molecules including antimicrobial agents, flavour compounds, colorants, antioxidants, vitamins," he concluded.
Historically, the use of carrageenan for food has grown in industrialised countries by at least 5 to 7 per cent per year, particularly on the back of growing demand for convenience foods.
In the EU the food market has grown to use both refined known as E407 on food labels- and semi-refined (E407a) carrageenan. In the US, there is no distinction for the food labels the hydrocolloid is simply known as carrageenan.