High hydrostatic pressure processing enhances pectin solubilisation on apple by-product improving techno-functional properties

Apple by-product is an extensive and inexpensive residue rich in dietary fibre, mainly insoluble fraction. Regarding soluble fibre, pectins are the predominant component responsible for specific physicochemical characteristics which are intimately related to its functional properties. To valorise apple by-product enhancing the solubility of pectins, high hydrostatic pressure (HHP) processing at 200–600 MPa during 15 and 30 min under controlled temperature was performed. Release of soluble carbohydrates was monitored using ion-exchange HPLC method with refractive index detection and dietary fibre composition was studied. A value of 200 MPa during 15 min was enough to enhance the solubilisation of cell wall components, mainly pectins, increasing significantly (p < 0.05) about threefold high/medium molecular weight soluble carbohydrates and maintaining total phenolic content. HHP preserved brightness, yellowish hue and slightly decreased pH. Furthermore, this valorisation procedure upgraded emulsion activity and stability improving the technological aptitude and enhanced swelling, oil-holding and cation-exchange capacities suggesting a potential lipid-lowering effect.