טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentCohen Benshitrit Revital
SubjectMolecular Complexes of Amylose for Controlled Release of
Polyphenolic Bioactives
DepartmentDepartment of Biotechnology and Food Engineering
Supervisor Dr. Eyal Shimoni
Full Thesis textFull thesis text - English Version


Abstract

Amylose complexes with small hydrophobic molecules are based on non-covalent interactions. These helical forms have the advantages of being readily available, cheap, safe, and biodegradable. However, scares data exist on the ability of amylose to form complexes with polyphenolic molecules.

In this research genistein was used as a polyphenolic molecule model. Like other phytochemicals, genistein has beneficial health effects, but its introduction into food is limited due to its bitter taste and low water solubility. These research goals were to develop amylose complexes with genistein, to study their structure properties and to correlate them to the complexation capacity, genistein retention in the complex and to genistein bioavailability.

Complexes of amylose or high amylose corn starch (HACS) with genistein were prepared by the acidification of an alkali solution and the structural properties of the complexes were studied. X-ray diffraction results showed that the complexes yield a V6III structure, particles size analysis and atomic force microscopy revealed that amylose-?genistein complexes formed well defined large crystals made of small uniform particles. The effect of genistein on the amylose complexes was also examined in different genistein-amylose ratios, and a model for genistein organization in the amylose complexes was suggested.

Genistein retention in the complex was tested under different pHs, temperature and simulated gastrointestinal (GI) conditions. The complexes were stable at different pHs, with less than 10% of the complexed genistein released, and were stable up to 50ºC. All complexes showed high retention of genistein in simulated stomach conditions, and genistein release upon digestion in pancreatin solution.

Finally, this research studied the effect of complexation of genistein with HACS on genistein bioavailability. Genistein release from these complexes was tested in-vivo in rats fed HACS-genistein complexes compared to those fed a physical mixture of HACS and genistein. Genistein concentration in the plasma was twice as high in the experimental group vs. controls; genistein concentration in the urine was also higher in the experimental group, but lower in the feces.

It is therefore suggested, that the complexes can be used as carriers for slow release of genistein. These results indicate that starch-genistein complexes increase genistein bioavailability, and suggest that starch can affect the bioavailability of additional food components. In this research a novel delivery system for polyphenolic bioactives was developed for the first time. The important properties of this delivery system can find applications in pharmacology and in food industry.