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Coupling lipophilization and amylose complexation to encapsulate organic molecules of interest

A group of researchers coordinated by Patricia Le Bail has developed a method for preparing complexes comprising amylose assembled with a lipophilic derivative of an antioxidant organic molecule of interest. Encapsulation of polyphenols will so find numerous applications in the food industry and animal nutrition.

Schematic model of the amylose-4-O-palmitoyl chlorogenic acid complex. Note the helical cavity of amylose (red) trapping the aliphatic chain grafted onto the chlorogenic acid.. © INRA
Updated on 10/29/2013
Published on 10/29/2013

Amylose is a carbohydrate fraction of starch known for its ability to form stable complexes with hydrophobic (or lipophilic) molecules due to its essentially linear character and almost exclusive presence of α(1-4) linkages. This phenomenon of complexation with amylose is used in techniques of molecular encapsulation allowing the protection of a molecule of interest. However, many molecules are not able to form such complexes with amylose. It’s the case of most antioxidants - phenolic compounds - due to their steric hindrance, structure and/or polarity.

The research group coordinated by Dr. Le Bail has recently developed a method for the preparation of inclusion complexes comprising the following steps:

  • 1) lipophilization reaction consisting of grafting a long aliphatic chain onto an organic molecule of interest for the preparation of a lipophilic derivative,
  • 2) contacting the aqueous solutions containing the lipophilic compound and amylose,
  • 3) formation of said amylose-lipophilic derivative complexes according to a hydrothermal stirring protocol.

The aim of the lipophilization reaction is to functionalize an organic molecule of interest by significantly decreasing its polarity so as to impart properties of a complexing agent with amylose, preferably by trapping this grafted aliphatic chain in the helical cavity of the single helix of amylose (Figure).
Complexes obtained by this hydrothermal method can be either in a powder form or in a gel form, and be incorporated into food bases or directly used as a stable aqueous phase of an emulsion, respectively.
The organic compound of interest is advantageously chosen among polyphenols, preferably from phenolic acids, particularly hydroxycinnamic acids or esters of hydroxycinnamic acids.
Using differential scanning calorimetry, X-ray diffraction and 13C solid state NMR, the researchers have thus analyzed the various assemblies prepared with chlorogenic acid and its acylated or alkylated derivatives.

  • 1) use of a biopolymer - amylose - alone or as starch,
  • 2) functionalization by lipophilization of a molecule of interest in order to impart a complexing action with amylose,
  • 3) the complexes obtained are in the form of a powder or a gel,
  • 4) encapsulation of numerous natural polyphenols with antioxidant properties,
  • 5) formation of complexes for ensuring encapsulation of organic molecules interest in order to protect them against oxidation, to consider their release by enzymatic digestion thanks to pancreatic amylase, intestinal lipase, or acid attack during digestion or predigestion, to ensure their stability, to increase their bioavailability, to mask their taste, etc.

Industrial applications of these new amylose-active compound complexes concern the food industry and animal nutrition.
INRA Transfert is seeking industrial partners to develop this patented technology (WO2013/054063) filed by INRA and the Maine University, through licence or licence option with a R&D program.

Scientific contact(s):

  • Patricia LE BAIL UR Biopolymères Interactions Assemblages
INRA Transfert’s licensing-out officer:
Nathalie TURC (+33 1 42 75 92 93)