Influence of Pulsed Electric Field and Ohmic Heating Pretreatments on Enzyme and Antioxidant Activity of Fruit and Vegetable Juices.

Cinzia Mannozzi,Urszula Tylewicz,Marco Dalla Rosa,Thomas Fauster,Kamon Rompoonpol,Henry Jaeger,Santina Romani

doi:10.3390/foods8070247

Cinzia Mannozzi, Urszula Tylewicz + Show 5 more

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https://doi.org/10.3390/foods8070247

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Abstract

The objective of this work was to optimize pulsed electric field (PEF) or ohmic heating (OH) application for carrot and apple mashes treatment at different preheating temperatures (40, 60 or 80 °C). The effect of tissue disintegration on the properties of recovered juices was quantified, taking into account the colour change, the antioxidant activity and the enzyme activity of peroxidase (POD) in both carrot and apple juice and polyphenol oxidase (PPO) in apple juice. Lower ΔE and an increase of the antioxidant activity were obtained for juice samples treated with temperature at 80 °C with or without PEF and OH pretreatment compared with those of untreated samples. The inactivation by 90% for POD and PPO was achieved when a temperature of 80 °C was applied for both carrot and apple mash. A better retention of plant secondary metabolites from carrot and apple mashes could be achieved by additional PEF or OH application. Obtained results are the basis for the development of targeted processing concepts considering the release, inactivation and retention of ingredients.

Highlights

Low-intensity pulsed electric field (PEF) can enhance the mass transfer during extraction by increasing cell membrane permeability, known as electroporation
A better retention of plant secondary metabolites from carrot and apple mashes could be achieved by additional PEF or ohmic heating (OH) application
Colour changes represent an indicator for enzymatic browning, as well as for process-induced browning due to heat-induced of for Colour changes represent formation an indicator enzymatic browning, as wellvariation as for process-induced untreated carrot andformation apple juice analysed andcolour is shown in Figure browning and duetreated to heat-induced ofsamples

Summary

Introduction

Low-intensity pulsed electric field (PEF) can enhance the mass transfer during extraction by increasing cell membrane permeability, known as electroporation. PEF treatments can enhance the release of specific intracellular compounds from plant tissues [1,2,3,4]. Ohmic heating (OH) as an alternative thermal pretreatment could be used prior to extraction. The volumetric energy dissipation and the rapid and uniform heating represent advantages, especially for viscous particulate products such as fruit or vegetable mash [5]. The short processing times during the OH treatment may cause less degradation of colour- and heat-sensitive substances. Antioxidant compounds are mainly located in the vacuoles, whereas the enzymes peroxidase (POD) and polyphenoloxidase (PPO) are found in plastids [6]

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