A. DUFFY • S. PENET • Valérie JEANNE-ROSE.

L’Oréal Recherche et Innovation, 1, avenue Eugène Schueller 93601 Aulnay-sous-Bois cedex. FRANCE

In this study we explore a innovative way to encapsulate anthocyanin extracts by using enzyme-catalyzed polyphenol polymerization in inverse emulsion. Our first results demonstrate that by selection isooctane as oil, dioctyl sodium sulfosuccinate as surfactant, and HRP with H2O2 as catalyzer we could obtain well defined microcapsules. The morphology depends strongly on the solvent, and stabilizer and on the activity of the enzyme. We demonstrate that new natural pigments can be developped by bio conversion of natural flavor and valorization of colored extract.

CONCLUSION

[1] Hiroshi Uyamaa, Hideharu Kuriokab, Shiro Kobayashia, Colloids and Surfaces A: Physiochemical and Engineering Aspects 153 (1999). 189-194[2] M. Ayyagari *, J.A. Akkara, D.L. Kaplan Materials Science and Engineering C 4 (1996) 169-173[3] Karayigitoglu, Cigdem F.; Xu, Xiaodong; Webb, Philip R.; John, Vijay T.; Gonzalez, Richard D.; Akkara, Joseph A.; Kaplan, David L; Polymeric Materials Science and Engineering (1993), 68, 171-2[4] unpublished results[5] Wang, J.; Gonsalves, K. E. Journal of polymer Science: Part A: Polymer chemistry, Vol. 37, 169-178 (1999)

REFERENCES

The objective of this study is to elaborate red pigments with high coverage and stability properties according to green chemistry guidelines. We explore the encapsulation of anthocyanin extracts. Many sources of anthocyanin are available and easy to supply. They offer a wide range of colors from red to blue but are well-known to be unstable toward light and oxidation and temperature. On the other hands, polyphenol resins are well-known to have thermal stability and poor solubility. So, we decide to encapsulate the unstable anthocyanin extract in « green » polyphenol. We started from published studies [ref.1,2,3] on enzyme-catalyzed polymerization of p-ethylphenol leading to polyphenol compounds. P-ethyl phenol is a interesting monomer because of its natural origin: it’s a flavor in wine. This processes describe the polyphenol microcapsules formation but without any encapsulated active. The microencapsulation experiments are carried out in water-in-oil microemulsions with horse radish peroxydase (HRP) as enzymatic catalyst. Several conditions are tried to obtain solid colored microcapsules.

INTRODUCTION

Polyphenol resins are well known for their industrial applications due to their high thermal stability and toughness, such as bakelite or novolaks. Enzymatic polymerization has already been studied as an alternative to chemical synthesis to avoid toxic reagents [ref.1,2,3] . P-ethylphenol is known as a natural flavor in wine. In this study, microencapsulation of anthocyanin and beet root extracts using enzyme-catalyzed polymerization of p-ethylphenol in the presence of hydrogen peroxide was investigated. P-ethylphenol as the monomer and horseradish peroxidase as catalyst were used in inversed emulsion to obtained poly(p-ethylphenol) particles. Using polyvinylalcool (Mw= 13000-23000) or polyglyceryl- 4 diisostearate/polyhydroxystearate/sebacate as nonionic stabilizer for the emulsion, microencapsulation failed while with dioctyl sodium sulfosuccinate (AOT) as anionic surfactant 10µm particles containing the natural dye were obtained. We also demonstrated that the morphology of the particle was affected by the nature of the solvent, enzyme activity, and hydrogen peroxide.[4] We showed that we could obtain new colored powders obtained by bioconversion of a natural molecule leading to a solid microcapsule associated to natural dye. Based on this technology we could obtain a range of natural pigments.

ABSTRACT

ENCAPSULATING ANTHOCYANINS THROUGH ENZYME-CATALYZED POLYMERIZATION IN WATER-IN-OIL MICROEMULSIONS

Starting Materials:p-ethylphenol, Isooctane, 1-4-dioxane, PVA Mw = 13000-23000, H2O2, elderberry extract, HRP 5KU, HRP 25KU, Dioctyl sodium sulfosuccinate (AOT)

Synthesis equipment:- Water / Oil Emulsion process: Glass reactor with cooling / heating jacket.Ultraturrax

Analytical- equipment:- Shape and morphology of particles: Scanning electron microscopy Jéol JSM 6390-LV. Optical microscopy- FTIR: perking elmer with ATR equipment

MATERIAL AND METHODS

POLYPHENOL MICROCAPSULES SYNTHESIS:FTIR analysis confirm that the polymerization occurs in 24h as shown by disappearance[5] of bands between 3000 et 1700 cm-1.

Optimization of emulsification conditions: we try two media for the microcapsules.

RESULTS

ANTHOCYANIN ENCAPSULATION :Impact of the anthocyanin: the elderberry extract seems to stabilize the emulsion.

We observe that polymerization occurs even in presence of the anthocyanin.

Impact of enzyme activity on the morphology: broken capsules are obtained with HRP 5KU. Spherical morphology obtained with HRP 25 KU.

As the activity rises as the shell of the capsule become stronger avoiding cracks.