Comparative analysis of aroma and phenolic compounds in strawberry nectar subjected to equivalent thermal, ohmic heating, high pressure, and pulsed electric fields processes at pilot scale

Abstract

This study investigates the effects of four preservation treatments: thermal pasteurization (TP), ohmic heating (OH), high-pressure processing (HPP), and pulsed electric fields (PEF), on the aroma and phenolic compounds of strawberry nectar, under equivalent microbial inactivation conditions (5-log reduction) on pilot-scale systems. Changes during 60 days of storage at 4 °C were also evaluated. HPP was the most effective method for retaining aroma compounds, with initial levels of 5.29 ± 0.03 mg/L, closely to the untreated samples, while TP showed the lowest retention (2.94 ± 0.13 mg/L). During storage, HPP-treated samples had a 41.6 % reduction in aroma compounds but still the highest remaining concentrations after storage compared to the other treatments. Key aroma markers, such as mesifurane, methyl and ethyl butyrate, were significantly better preserved in HPP and PEF treated samples compared to TP and OH. Phenolic content followed a similar trend: immediately after treatment HPP and PEF samples exhibited the highest total phenolic content (TPC), including anthocyanins like pelargonidin-3-glucoside, which constituted up to 81 % of total anthocyanins. Non-thermal methods (HPP and PEF) preserved phenolics better than TP, although differences between treatments were not significant after 60 days of storage. OH demonstrated intermediate performance due to its uniform heating process that minimized thermal degradation. Overall, non-thermal methods emerged as the most effective for preserving both aroma and phenolic profiles, followed by OH, while TP resulted in the greatest losses. These findings highlight the potential of non-thermal and alternative thermal technologies over thermal pasteurization to maintain the sensory and nutritional quality of fruit-based beverages.