Rheological effects of high-pressure processing and high-pressure homogenization on not-from-concentrate orange juice.

Abstract

Background: 'Not-from-concentrate' (NFC) orange juice faces stability challenges. Its rheological properties are also important for optimizing processes such as pumping. These issues affect companies in terms of their cost implications, and they affect product quality and consumer acceptance directly. This study investigates the rheological properties of NFC orange juice subjected to high-pressure homogenization (HPH) following high-pressure processing (HPP).

Results: The viscosity coefficient (k) of HPH-treated orange juice reduced significantly, by 92.16%, and was accompanied by a 163.82% increase in the flow coefficient (n) and a 48.12% increase in zeta potential. High-pressure processing treatment reduced viscosity effectively while enhancing the fluidity and stability of the orange juice. However, no significant differences were observed in the major functional groups or particle size distribution in comparison with a thermal pasteurization (TP) group. Alterations in the polysaccharide structure were identified as the primary reason for the observed changes in rheological properties. Specifically, the molecular weight (M_w) of soluble dietary fiber (SDF) increased, whereas the M_w of cellulose decreased in the HPP treated juice. This correlated with the results for viscosity, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) analyses.

Conclusion: In comparison with the TP group, the fluidity, and stability of HPH orange juice after HPP were enhanced significantly, and the viscosity was reduced. This speeds up the juice-pumping process, reducing energy consumption and costs. The combination of HPP and HPH pretreatment effectively improved the physical properties and sensory quality of orange juice. © 2025 Society of Chemical Industry.