Novel emulsifiers from olive mill compost

Emulsifiers fit for use in oil-in-water emulsions were extracted from the composted solid waste of olive oil mills. The extracts were characterized in terms of their molecular populations using size exclusion chromatography (SEC-UV/RI/MALLS); of their charge with the use of zeta potential measurements; of their chemical composition using Fourier-transform infra-red (FTIR) spectroscopy. The capacity of the extracts toward emulsification and emulsion stabilization of oil-in-water emulsions has been studied with the use of static light scattering for droplet distribution measurement and confocal laser scanning microscopy. The long-term stability against coalescence is higher than the ones recorded for extracts from non-composted olive waste, while the end-point interfacial tension values are lower; all the individual populations of the extract partake in forming the interfacial layer. This suggests that the break-down of the olive waste during composting leads to materials of better interfacial coverage, hence better emulsion stabilization. This can lead to novel approaches for handling olives and other fruit processing by-products.