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Emulsifiers from Partially Composted Olive Waste

Authors
  • Koliastasi, Aikaterini1
  • Kompothekra, Vasiliki2
  • Giotis, Charilaos2
  • Moustakas, Antonis K.2
  • Skotti, Efstathia P.2
  • Gerakis, Argyrios2
  • Kalogianni, Eleni1
  • Ritzoulis, Christos1
  • 1 Department of Food Science and Technology, International Hellenic University, Sindos Campus, 57400 Thessaloniki, Greece
  • 2 Department of Food Science and Technology, Ionian University, Vergoti Avenue, 28100 Argostoli, Greece
Type
Published Article
Journal
Foods
Publisher
MDPI AG
Publication Date
Jul 20, 2019
Volume
8
Issue
7
Identifiers
DOI: 10.3390/foods8070271
PMID: 31330775
PMCID: PMC6678798
Source
PubMed Central
Keywords
License
Green

Abstract

Partial (one month) composting of solid olive processing waste is shown to produce extractable emulsifiers. Size exclusion chromatography (SEC) and Fourier-transform infra-red spectroscopy (FTIR) show that these consist of polysaccharides and proteins from the composted waste. Aqueous extraction at pH 5, pH 7, and pH 9 all yield extracts rich in oligosacchrides and oligopeptides which derive from the break-down of the macromolecules under composting, with the extract obtained at pH 5 being the richer in such components. Fourier-transform infra-red (FTIR) spectroscopy also confirms that these materials consist of proteinic and poly/oligosaccharidic populations. These materials can emulsify stable oil–in–water emulsions at pH 3 for a few days, while the same emulsions collapse in less than 24 h at pH 7. Confocal microscopy and droplet size distribution data suggest that Ostwald ripening, rather than coalescence, is the major course of emulsion instability. The above point to a short-process alternative to full composting in producing a high added value product from solid olive processing waste.

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