Influence of high-pressure homogenization on functional properties of orange pulp

• High-pressure homogenization at 800 bar functionalizes orange pulp.
• Suspension with increased water holding capacity and improved swelling and flow properties
• Functionalization related to abundant presence of largely disintegrated orange pulp material
• High-pressure homogenization also affects pectic polymers in orange pulp cell walls.

The current work evaluated whether high-pressure homogenization (HPH) could functionalize orange pulp in terms of water holding and swelling capacity and rheological properties. The orange pulp particle size was gradually decreased by applying HPH at increasing pressure (200 and 800 bar) whereby the mechanical impact at 800 bar resulted in the appearance of a more homogeneous, smoother suspension with a twofold increase in yield stress. HPH also affected the pectin properties within the orange pulp cell walls. More specifically, HPH at 800 bar increased the relative presence of water-extractable pectin. By investigating subsamples containing particles with different sizes isolated from orange pulp before and after HPH, it became clear that particle size is inversely related to water holding capacity and the ability of the particle network to deform prior to flow. Especially highly disintegrated orange pulp material (<40 μm) contributes to water holding capacity and soft particle network behavior.Industrial relevanceOrange pulp is of particular interest in the context of producing fiber-rich functional ingredients because of its large quantity available within the juice industry. High-pressure homogenization (HPH) at pressures higher than the ones usually applied in food industry seems required to functionalize orange pulp as HPH at 200 bar (a common pressure applied in the food industry) could not increase the relative presence of small particles, contributing to water holding capacity and soft particle network behavior, as substantially compared to HPH at 800 bar.