Researchers from Kasetsart University (Bangkok) and Pennsylvania State University report that the benefits for the flavours is due to the native lipid content of the high-amylose maize starch.
"Besides the lower raw material cost, the use of native high amylose maize starch for flavour encapsulation by this inclusion technique has the advantage of effectively entrapping low solubility flavour compounds that are not entrapped without the presence of native lipid," wrote lead author Onanong Tapanapunnitikul in the Journal of Agricultural and Food Chemistry .
The combination of starch and flavours is not new, but has mostly focussed on amylose- and lipid-free starch preparations, explained the researchers.
"To accomplish flavour encapsulation using a commercial native starch would be of interest because the material cost would be less than for prepared amylase," explained Tapanapunnitikul.
The researchers prepared inclusion complexes of high-amylose maize starch, with and without native lipid, with flavour compounds.
To investigate the effects of water solubility, they used terpenes with high (thymol and menthone) and low (limonene and cymene) water solubility.
When the lipid-free starch was used, the entrapment of limonene and cymene was very low, of only about one per cent.
On the other hand, thymol and menthone were entrapped at 5.8 and 10.4 per cent, respectively, wrote the researchers.
"Only in the presence of native lipid was any appreciable yield of limonene and cymene observed (73.9 and 17.8 per cent, respectively)," reported Tapanapunnitikul.
This result showed that the inclusion of the flavours was affected by both the degree of water solubility and the lipid content of the starch.
"The lipid in native high-amylose maize starch may enhance complexation with low-solubility compounds by forming co-inclusion complexes of starch-lipid-flavour," stated the researchers.
"We conclude that water solubility of flavour compounds influences the extent of complexation with high-amylose maize starch; the higher-water-solubility flavour compounds led to greater precipitated starch yield and also to more flavour entrapment .
"The impact of native lipid of high amylose maize starch on flavour release and flavour quality remains to be explored," they concluded.
Source: Journal of Agricultural and Food Chemistry January 2008, Volume 56, Pages 220-226 "Water Solubility of Flavor Compounds Influences Formation of Flavor Inclusion Complexes from Dispersed High-Amylose Maize Starch" Authors: O. Tapanapunnitikul, S. Chaiseri, D.G. Peterson, D.B. Thompson