Fruit as well as their juices are essential in human diet by virtue of their vitamins, minerals, and other bioactive compounds. Quality of the juices are degraded by several factors such as the quality of the fruits, method of processing, and activity of the enzymes such as polyphenol oxidase (PPO), lipoxygenase (LOX), polygalacturonase (PG), and pectin methylesterase (PME) (Roobab et al., 2022; Salehi, 2020) in addition to growth of microorganisms and/or oxidative reactions. Enzymatic activities cause detrimental changes in the quality characteristics including color, texture, and nutrient content as well as the oxidation of polyphenols resulting in browning of the juices (Iqbal et al., 2019; Marszałek, Kruszewski, Woźniak, & Skąpska, 2017). Therefore, inactivation of enzymes with preservation of physical, bioactive, and sensory properties are in demand.

Heat treatment as one of the main and most widely used processing technology is commonly utilized method for enzyme inactivation. Moreover, enzyme inactivation is further carried out by combined application of heat treatment, utilization of chemical inhibitors, and differences in pH (Iqbal et al., 2019); but inactivation of some heat-stable isoenzymes requires intense heat treatment that may cause undesirable changes in quality, bioactive, and nutritional properties of the foods. Thus, implementation of thermal and nonthermal technologies such as ohmic heating, radio frequency heating, microwave, high hydrostatic pressure (HPP), high-pressure carbon dioxide (HPCD), ultrasound (US), and pulsed electric fields (PEF) are in high demand (Atencio et al., 2022; Kantala, Supasin, Intra, & Rattanadecho, 2021; Li, Yang, & Zhao, 2021; Ranjha et al., 2021; Roobab et al., 2022). PEF technology being a continuous process, having very short processing time with low energy consumption and low processing temperature has provided opportunities to process fruit juices (Lindgren, Aronsson, Galt, & Ohlsson, 2002; Ranjha et al., 2021). Studies revealed substantial loss of enzyme activities such as pectin methyl esterase (PME), poly galacturonase (PG), peroxidase (POD), and lipoxygenase (LOX) in watermelon juice (Aguiló-Aguayo, Soliva-Fortuny, & Martín-Belloso, 2010), PME and PG in strawberry juice (Aguiló-Aguayo, Oms-Oliu, Soliva-Fortuny, & Martín-Belloso, 2009), polyphenol oxidase (PPO) in fruit and vegetable products (Tinello & Lante, 2018), PME in orange juice (Agcam, Akyıldız, & Evrendilek, 2014), but no inactivation or even enhancement of β-glucosidase (β-GLUC) (Aguiló-Aguayo, Oms-Oliu, et al., 2009) and LOX (Aguiló-Aguayo, Soliva-Fortuny, & Martín-Belloso, 2009) in strawberry juice were also reported. PEF processing parameters of electric field strength, frequency, treatment time, and applied energy are the most important processing parameters for preservation of quality properties and enzyme inactivation. Even though studies conducted with PEF reported the inactivation/deactivation of different enzymes, behaviors of PME, PPO, and LOX in orange, grape, and tomato juice with respect to changes in quality parameters were not reported yet. Thus, the objectives of the present study were to determine effectiveness of PEF treatment on the inactivation of PME, PPO, and LOX with respect to inactivation kinetic model generated for PEF treatment parameters, and investigate quality changes in orange, grape, and tomato juices, respectively.