Cyclodextrin tested for flavonol protection to add value

"The complexation of polyphenols has proven to be useful in both enhancing the solubility and their bioavailability and also protecting them from enzymatic oxidation," wrote lead author Carmen Lucas-Abellan from Universidad Catolica San Antonio de Murcia.

"Beta-CDs and their derivates may be useful in improving the dissolution and the bioavailability of quercetin and myricetin in functional beverages," she added in the Journal of Agricultural and Food Chemistry .

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 new study investigated the potential of the polysaccharide to encapsulate the flavonols quercetin and myricetin, both of which have been linked to the inhibition of lipid oxidation, which has knock-on benefits for heart health.

"Given the many health-promoting activities of quercetin and myricetin, a method for increasing their bioavailability and stability was thought to be necessary," wrote Lucas-Abellan.

The researchers incorporated the individual flavonols in cyclodextrin and tested their stability when exposed to horseradish peroxidase, known to oxidise the flavonols in the presence of hydrogen peroxide.

Lucas-Abellan and co-workers report that the presence of cyclodextrins (CDs) led to an inhibition of the oxidation, due to the complexation of the flavonol in the hydrophobic cavity of the polysaccharide.

The type of CD affected the strength of the complexes formed, with hydroxypropyl-beta-CDs performing better than maltosyl-beta-CDs, which performed better than the beta-CDs.

"The complexation efficiency (CE) values for hydroxypropyl-beta-CDs and quercetin or myricetin were calculated (267.4 and 5.3, respectively), indicating that hydroxypropyl-beta-CDs are more efficient for the complexation of quercetin than myricetin in the studied conditions," wrote the researchers.

"It is important to note that cyclodextrins can be used not only to decrease the free flavonol concentration while the total flavonol concentration remains constant (in which case the free flavonol concentration depends only on the complexation constant) but also to increase total flavonol concentration while the free flavonol concentration remains constant.

In the latter case, the level of total flavonol depends on the complexation efficacy," they added.

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 Agricultural and Food Chemistry Volume 56, Number 1, Pages 255-259, doi: 10.1021/jf0720640 "Encapsulation of Quercetin and Myricetin in Cyclodextrins at Acidic pH" Authors: Carmen Lucas-Abellan, I. Fortea, J.A. Gabaldon, and E. Nunez-Delicado