Professor Aarhus University Aarhus, Midtjylland, Denmark
Abstract: Oleosomes are naturally occurring emulsions in oilseeds. They are composed of a triglyceride core protected by a continuous phospholipid monolayer and hydrophobic proteins, oleosins. Extraction of whole oleosomes has been suggested as a sustainable way of producing biobased emulsions, where there is no need for adding emulsifiers or applying homogenization to create stabilized oil droplets. Intact oleosomes can efficiently be extracted from whole rapeseed with a simple aqueous procedure. By controlling extraction conditions, it is possible to obtain colloidal fractions with different compositions, and thereby creating an array of functional ingredients. This talk will discuss the effect that extraction pH and pectinase addition have on the colloidal interactions between proteins and oleosomes, and the resulting extracts.
The colloidal assemblies were visualized by CLSM, and investigated by light scattering and gel electrophoresis. Different pH values were evaluated (pH 5.7 and 8.5) and showed changes in the concentration of proteins co-extracted with the oleosomes, because of the interactions forming the supramolecular structure between oleosomes. Treatments with SDS and urea buffers on the colloidal structures showed that weak hydrophobic interactions were involved in the formation of these supramolecular structures at alkaline pH. Bridging between proteins and oleosomes through electrostatic interactions occurs at acidic pH; and treatment with pectinase has the potential not only to affect extraction yields, but also to modify the technological functionality of the oleosome fraction. These results are of relevance to the industry as they demonstrate how process conditions can be used to tailor the properties of functional protein and oleosome rich ingredients.
