title: Infrared Spectroscopy of Bilberry Extract Water-in-Oil Emulsions: Sensing the Water-Oil Interface.
abstract: Water-in-oil (w/o) emulsions are of great interest in many areas of the life sciences, including food technology, bioprocess engineering, and pharmaceuticals. Such emulsions are complex multi-component systems and the molecular mechanisms which lead to a stable emulsion are yet to be fully understood. In this work, attenuated total reflection (ATR) infrared (IR) spectroscopy is applied to a series of w/o emulsions of an aqueous anthocyanin-rich bilberry extract dispersed in a medium chain triglyceride (MCT) oil phase. The content of the emulsifier polyglycerin-polyricinoleat (PGPR) has been varied systematically in order to investigate whether or not its concentration has an impact on the molecular stabilization mechanisms. The molecular stabilization is accessed by a careful analysis of the IR spectrum, where changes in the vibrational frequencies and signal strengths indicate alterations of the molecular environment at the water/oil interface. The results suggest that adding emulsifier in excess of 1% by weight does not lead to an enhanced stabilization of the emulsion.
authors.affiliation: Technische Thermodynamik, Universität Bremen, Badgasteiner Str. 1, Bremen 28359, Germany. jkiefer@uni-bremen.de.|Erlangen Graduate School in Advanced Optical Technologies, University of Erlangen-Nuremberg, Erlangen 91052, Germany. jkiefer@uni-bremen.de.|School of Engineering, University of Aberdeen, Aberdeen AB24 3UE, UK. jkiefer@uni-bremen.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Kiefer
authors.affiliation: Section I: Food Process Engineering, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany. heike.schuchmann@kit.edu.|Present affiliation: BASF SE, Ludwigshafen 67056, Germany. heike.schuchmann@kit.edu.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Frank
authors.affiliation: Technische Thermodynamik, Universität Bremen, Badgasteiner Str. 1, Bremen 28359, Germany. f.zehentbauer@uni-bremen.de.
authors.forename: Florian M
authors.initials: FM
authors.lastname: Zehentbauer
authors.affiliation: Section I: Food Process Engineering, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany.
authors.forename: Heike P
authors.initials: HP
authors.lastname: Schuchmann
mesh_terms: D045703:Emulsifying Agents / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry*; D009821:Oils / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D029800:Vaccinium myrtillus / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D045703:Emulsifying Agents; D004655:Emulsions; D009821:Oils; D010936:Plant Extracts; D014867:Water
keywords: MCT oil; anthocyanin; functional food; hydrogen bonding; interfacial layer; vibrational spectroscopy