Akademska digitalna zbirka SLovenije - logo
E-resources
Full text
Peer reviewed
  • Pectins from food waste: Ex...
    Petkowicz, C.L.O.; Vriesmann, L.C.; Williams, P.A.

    Food hydrocolloids, April 2017, 2017-04-00, Volume: 65
    Journal Article

    Fresh and lyophilized watermelon rinds were treated with boiling ethanol for pigment removal and then used to extract pectins giving rise to fractions FW and LW, respectively. The pectins were characterized by chromatographic and spectroscopic methods. Both pectins had a galacturonic acid content higher than 65%, meeting the commercial requirement. However, FW had a higher yield (19.3%) than LW (14.2%). The protein contents were 3.9 and 3.6% for FW and LW, respectively. FW and LW had a high degree of methyl-esterification (∼60%) and low molar mass, 34,510 g/mol for FW and 40,390 g/mol for LW. The viscosity of 5% (w/w) aqueous solutions of watermelon rind pectins at 25 °C showed shear thinning behavior with a low shear Newtonian plateau of ∼30 Pa s for FW and ∼10 Pa s for LW. Mechanical spectra of FW and LW at 5% (w/w) at 25 °C showed a weak gel like behavior for both pectins. The dynamic surface tension, foaming ability and emulsifying properties of FW and LW were evaluated and compared with gum Arabic. FW and LW showed lower dynamic surface tension and higher foaming ability than gum Arabic at the same concentration. Emulsions were prepared with polysaccharides at concentrations ranging from 0.5% to 4% (w/w). The droplet size decreased for both pectins as the concentration increased. Values of surface weighted mean diameter D3,2 and volume weighted mean diameter D4,3 obtained for emulsions prepared with FW and LW were found to be similar to gum Arabic, which is well known for its emulsifying properties. Display omitted •Pectin was extracted from waste watermelon rind.•Its chemical and physicochemical characteristics have been determined.•5% w/w solutions were shown to form weak gels.•The pectin was able to form stable oil-in-water emulsions.