Novel dry state co-milling encapsulation of olive leaf extract

Micro-encapsulation or nano-encapsulation is nowadays representing an interesting strategy to enhance the functionality of bioactives and other biomolecules, serving several purposes such as solubility enhancement, increased gastrointestinal absorption or targeted delivery of bioactive compounds (Li et al., 2015). High energy ball milling is used in the pharmaceutical industry to produce fine dispersions or “molecular alloys” of the active ingredient in a carrier/matrix to enhance solubility and bioavailability (Bandarkar and Vavia, 2011), to produce similar solid dispersion obtained with freeze-dying or spray drying (Willart et al., 2006). Modified starch by ball milling has been applied to encapsulate β-carotene (Roa et al., 2016), but no co-milling in the dry state to encapsulate food bioactives has been implemented yet. Olive leaves phenolic compounds have been widely studied for their health promoting properties (Martín-Peláez et al., 2013) In this work, olive leaf extract (OLE) was co-milled with maltodextrin/maltodextrin-trehalose as carrier, at different ratios and milling treatment time, using a planetary ball-mill. A milling time of 60 min resulted in maximized encapsulation efficiency (95-97%). When a higher ratio of OLE to matrix was applied, encapsulation efficiency was slightly lower compared to lower ratio up to 60 min treatment, but was maximized upon longer treatment. Microstructural analysis of the highly encapsulated OLE dispersions (60-180min) using CLSM microscopy showed fine and homogeneously distributed dispersion of OLE in the internal surface of the maltodextrin/maltodextrin-trehalose matrix. Also in these samples, OLE seemed to be protected from environmental moisture/solvent compared to low encapsulated samples (0-30min) as observed during microscopy analysis. Colour analysis of powder dispersions highlights that co-milling resulted in lighter yellowish homogeneous powders as compared to non-milled, thereby masking the brownish-yellowish colour of OLE. Further experiments are needed to confirm the encapsulation and stabilization of OLE by co-milling with a carrier in order to produce stable ingredients with nutritional and health promoting potential. References BANDARKAR, F. S. & VAVIA, P. R. 2011. An optimized commercially feasible milling technique for molecular encapsulation of meloxicam in beta-cyclodextrin. Drug Dev Ind Pharm, 37, 1318-28. MARTÍN-PELÁEZ, S., COVAS, M. I., FITÓ, M., KUŠAR, A. & PRAVST, I. 2013. Health effects of olive oil polyphenols: Recent advances and possibilities for the use of health claims. Molecular Nutrition & Food Research, 57, 760-771. ROA, D. F., BUERA, M. P., TOLABA, M. P. & SANTAGAPITA, P. R. 2016. Encapsulation and Stabilization of β-Carotene in Amaranth Matrices Obtained by Dry and Wet Assisted Ball Milling. Food and Bioprocess Technology, 10, 512-521. WILLART, J. F., DESCAMPS, N., CARON, V., CAPET, F., DANÈDE, F. & DESCAMPS, M. 2006. Formation of lactose-mannitol molecular alloys by solid state vitrification. Solid State Communications, 138, 194-199.