ORIGINAL ARTICLE Assessing impacts of pulsed electric fields on quality attributes and furfural and hydroxymethylfurfural formations in apple juice Gulsun Akdemir Evrendilek 1 | Perihan Celik 1 | Erdal Agcam 2 | Asiye Akyildiz 2 1 Department of Food Engineering, Faculty of Engineering and Architecture, Abant Izzet Baysal University, Bolu, Turkey 2 Department of Food Engineering, Faculty of Agriculture, Cukurova University, Adana, Turkey Correspondence Gulsun Akdemir Evrendilek, Department of Food Engineering, Faculty of Engineering and Architecture, Abant Izzet Baysal University, Bolu, Turkey. Email: gevrendilek@yahoo.com Abstract Effects of pulsed electric fields (PEF) processing on physical properties, bioactive compounds, and formations of furfural and hydroxylmethylfurfural (HMF) were determined for apple juice. A central composite design to determine the optimal number and order of experimental runs and the best-fit multiple nonlinear regression (BF-MNLR) models to quantify and predict rates of change in the response variables as a function of the PEF processing were used. No signifi- cant difference was detected between the control and PEF-treated apple juice in terms of physical properties, organic acids, and polyphenols of (2)-epicatechin, caffeic acid, p-coumaric acid, ferrulic acid, quercetin, and gallic acid. The highest predictive power (R 2 pred ) belonged to a* (88%), (1)-catechin (90.7%), and HMF (93.8%). Except for chlorogenic acid, no significant decrease was detected in the initial concentrations of the bioactive compounds. PEF process- ing provided retention of quality attributes and bioactive compounds without significant formation of furfural and HMF. Practical applications Heat processing causes degradation of bioactive compounds, changes in physical properties, and formation of undesirable compounds in apple juice; however, PEF processing provided the preser- vation of most bioactive compounds without significant changes in physical properties. Thus, findings in this study revealed that PEF processing is a viable option for fruit juice industry, espe- cially, for apple juice pasteurization. 1 | INTRODUCTION The consumption of apple juice, one of the most popular fruit crops, reached 76 million tons globally and 15 million tons in Europe in 2012 (FAOSTAT, 2013). Apple juice plays an important role in human nutrition owing to its high level of antioxidants, phenols or phenolic compounds that may defend humans against free radical damage, thus reducing the incidences of coronary heart disease and cancer (Lee, Hwang, & Ha, 2003). Heat processing is the most com- mon processing method commercially applied to fruit juices (Aadil et al., 2015). However, the deterioration of juice quality, flavoring agents, and compounds with antioxidant properties during the heat processing have oriented consumer preferences towards minimally processed fresh-like juices with enhanced nutritional and sensory properties. Thus, many studies have focused on novel nonthermal pasteurization technologies of fruit juices including pulsed electric fields (PEF) with different magnitudes of electric field strength (Evrendilek & Varzakas, 2015). There are numerous studies about effects of PEF on bioactive compounds, enzyme and microbial inactivation, physical and sensory properties, and shelf life extension (Agcam, Akyildiz, & Evrendilek, 2014; Aguilar-Rosas, Ballinas-Casarrubias, Elias-Ogaz, Martin-Belloso, & Ortega-Rivas, 2013; Bi et al., 2013; Evrendilek, 2015; Geveke et al., 2015; Leong, Burritt, & Oey, 2016). However, there exist a few studies about PEF-induced changes in bioactive compounds of apple or other juices such as phenolic compounds, organic acids, and formation of such undesirable compounds as furfural and hydroxylmethylfurfural (HMF) (Katiyo, Yang, Zhao, Hua, & Gasmalla, 2014; Soliva-Fortuny, Balasa, Knorr, & Martin-Belloso, 2009). There- fore, the objectives of this study were to quantify and compare effects of changing the processing variables of electric field strength, treatment time, temperature, and energy on physical properties, J Food Process Eng 2016; 1–10 wileyonlinelibrary.com/journal/jfpe V C 2016 Wiley Periodicals, Inc. | 1 Received: 9 September 2016 | Revised: 27 September 2016 | Accepted: 8 November 2016 DOI 10.1111/jfpe.12524