This study is aimed at evaluating the quality of strawberry nectar following high-pressure processing (HPP) at different pressure levels (400, 500, and 600 MPa for 3 minutes) and thermal pasteurization (TT) at 75°C for 15 s. Key parameters include total colour difference (), aparent viscosity, colour analysis via CIELAB coordinates, and pH. Additionally, residual enzymatic activity (RA%) of polyphenol oxidase (PPO) and peroxidase (POD) was measured. Strawberry nectar (12°Brix) was prepared and subjected to processing, with thermal treatment in 50 mL tubes and HPP in 40 mL polyethylene bags. Samples were stored under refrigeration during 21 days, with microbial analysis conducted to assess microbiological stability during storage. TT exhibited a more pronounced reduction in total aerobic microbial count (TAMC) compared to HPP, which showed no detectable yeast and mould. Apparent viscosity varied among samples, with HPP at 600 MPa displaying a significant increase of 52.1% compared to the control. The pseudoplastic behavior, characterized by values lower than 1, was consistent across all treatments. TT led to a reduction in brightness value during storage, whereas HPP-treated samples underwent colour changes over time with of 3.1 for 400 MPa, 3 minutes, at 21 days. For PPO and POD, the 600 MPa treatment exhibited the highest inhibition (44% and 4% RA, respectively). This comprehensive study provides insights into how different HPP processing conditions affect the quality attributes, enzymatic activity, and microbiological stability of strawberry nectar during production and refrigerated storage. The research’s significance lies in its holistic comparison of HPP with traditional thermal pasteurization, offering valuable information for both industry and consumers.

This study validates the performance of a pilot‐scale ohmic heating plant for vitamin C retention and Escherichia coli surrogate inactivation in strawberry nectar, based on thermal kinetics determined using a thermoresistometer. Initial experiments with the thermoresistometer established the thermal kinetics of vitamin C degradation and E. coli ATCC 8739 inactivation in surrogate media and strawberry nectar. The use of the thermoresistometer was selected due to its rapid heating mechanism, which closely matches the heating rates of ohmic heating. The D values for the microorganism ranged from 19.8 to 123.6 s, and the activation energy for vitamin C was 25.83 ± 0.48 kJ/mol for the surrogate media and 31.00 ± 2.62 kJ/mol for the nectar. Based on these results, treatments in the pilot‐scale ohmic heating system were designed to achieve a 5‐log microbial reduction and minimal vitamin C loss. The pilot trial on strawberry nectar demonstrated effective microbial inactivation and a reduction in vitamin C of 17%, which was higher than the calculated 2.7% from thermoresistometer data, likely due to differences in processing conditions. This research confirms that ohmic heating can achieve comparable microbial safety and nutrient preservation to conventional pasteurization, while offering potential advantages in energy efficiency.

Pulsed electric field (PEF) and high-pressure processing (HPP) are non-thermal treatments, developed to ensure preservation of food products whilst maintaining taste and valuable nutrients. In this study, we investigated their potential for the inactivation of 3 commercial exogenous pectinases (polygalacturonase, pectin transeliminase, pectin esterase) commonly used in juice processing for clarification of juices. The inactivation of these enzymes after processing is mandatory by European law. Clear apple juice was treated with both non-thermal processing methods, as well as with thermal pasteurization as the standard method. For HPP, 3 pressures (250, 450, and 600 MPa) and different holding times (from 2 to 12 min) were tested. For PEF, 3 electric field intensities (10, 13, and 15 kV/cm) and different specific energy values (from 121 to 417 kJ/kg). Standard thermal pasteurization resulted in a complete inactivation of all tested pectinases. HPP treatment only showed marginal effects on polygalacturonase and pectin transeliminase at the highest pressure and holding times, which are beyond levels used in industrial settings. For PEF, dependence upon high electric field strength and specific energy values was evident; however, here too, the effect was only moderate at the levels attainable within the scope of this study. Assuming a continued linear relationship, usable results could be achieved in an industrial setting, albeit under more extreme conditions.