Hydrocolloids from quince seed: Extraction, characterization, and study of their emulsifying/stabilizing capacity

Hydrocolloids were extracted from the alcohol-insoluble solids of defatted, freeze-dried and ground quince seeds using temperature-controlled aqueous solutions buffered at pH 4, pH 6, pH 8 and pH 10 (processed in parallel, named QE4, QE6, QE8, QE10 respectively). The extracts and their principal macromolecular components were characterized in terms of polysaccharide and protein content; of their macromolecular polyelectrolyte distribution using gel electrophoresis (SDS-PAGE); of their generic chemical composition using Fourier-transform infra-red (FTIR) spectroscopy; and of their macromolecular populations distribution using size exclusion chromatography (SEC), and zeta potential measurement. Their capacity toward emulsification was studied at pH 3 and at pH 7 using light scattering for droplet distribution measurement and light microscopy for coalescence/flocculation control. QE4 and QE6 are good emulsifiers under conditions, while QE8 is a good emulsifier. Their emulsifying activity is correlated to their composition and the topology of their protein content. The emulsion stabilization capacity of QE4 and QE6 has been studied, the findings being correlated to the physico-chemical data.