Defined shear and heat treatment of apple pomace: impact on dietary fiber structures and functional properties

Abstract Food by-products can be modified by extrusion processing. However, the impact of thermal and mechanical stress, respectively, on structure thus functional properties dietary fiber-rich food is still unknown. In process, stress are coupled, not constant, difficult to measure or calculate. Thus, their influence structural changes cannot evaluated separately. this work, a specific shear cell, denoted closed cavity rheometer, was used treat apple pomace with defined and/or stress. Dietary fiber composition polysaccharide structures appeared more susceptible high temperatures than With increasing temperature (and stress) soluble low-molecular-weight contents increased, whereas insoluble decreased. Arabinans as rhamnogalacturonan type I polysaccharides galacturonic acid containing pectic were identified being most degradation under these conditions. Furthermore, treatment affected properties. Although in water solubility index (WSI) absorption (WAI) detected up 90 °C, WSI WAI decreased significantly at 120 °C. very (160 °C), increased. The application longer times resulted higher values complex viscosities compared low Graphic abstract