Characterisation of fresh-like orange juice prepared by ultrasound treatment followed by high-pressure processing under industrial setting

The rising demand for minimally processed nutritious food has led to advancements in non-thermal food processing technologies. This study evaluated the effects of combined ultrasound (US) and high-pressure processing (HPP) on the quality of Navel orange juice. Fresh juice was treated with US at 40 W/mL (K1), HPP at 450 MPa for 3 min (CP), or both US and HPP (UH). This study found that none of the treatments significantly altered the pH, total soluble solids, colour attributes, or total phenolic content compared to the untreated control (K0). HPP effectively eliminated microorganisms, reducing microbial counts below detection limits. US showed greater effectiveness than HPP in deactivating pectin methylesterase (PME) and maintaining cloud stability for up to 7 days at 4 degrees C. PME activity decreased from 6.5 x 10-4 unit/mL in K0 to 4.6 x 10-4 unit/mL with US, 5.3 x 10-4 unit/mL with HPP, and 3.8 x 10-4 unit/mL with the combined treatment, extending cloud stability to 14 days. Sensory evaluations indicated that US-HPP-treated juice was rated significantly better than CP and K0 samples. However, both treatments increased polyphenol oxidase and peroxidase activities by 22 % and 17 %, respectively. Further research is needed to optimize conditions to reduce these browning enzymes while preserving freshness.