**1. Introduction**

Pulsed electric fields (PEF) involved the application of intermittent electric fields of varying intensity (0.1–50 kV/cm) and short duration (μs–ms) [1]. Currently, this technology has been used as a pretreatment to oil extraction from rapeseeds, sunflower seeds, sesame seeds and olives enhancing oil extraction yield (OEY) and increasing oil acidity [2–5]. The improvement of OEY has been attributed to the electroporation phenomenon, while the increase of oil acidity was associated with triacylglycerols hydrolysis by lipase activity. In a previous study, PEF were applied to fresh pecan nut kernels as a pretreatment employing different specific energy inputs [5]. Results indicated that PEF-treated kernels yielded 21.4% more oil than untreated kernels. Nonetheless, pecan nuts are usually submitted to a drying process for commercialization and the effect of this technology on the OEY of dry kernels has not been reported yet. Furthermore, studies concerning the PEF effect on seeds microstructure and oil acidity are scarce.

Pecan nut kernels (*Carya illinoinensis* (Wangenh. K. Koch)) are well-known for their high concentration of phenolic compounds, mono- and polyunsaturated fatty acids, phytosterols, and tocopherols [6,7]. Besides, pecan nut oil differentiates from other tree nut oils due to its content of polyunsaturated fatty acids (PUFA), β-sitosterol and γ-tocopherol [8,9]. Thus, to extend kernels- shelf-life and avoid oil oxidation, a drying process is carried out reducing the moisture content ( ≤5.5%) and modifying kernels microstructure [10,11]. In pecan nuts, fatty acids are stored as triacylglycerols within oleosomes. These organelles are formed by a monolayer of phospholipids, proteins, and enzymes like lipoxygenase that is the key enzyme in lipids oxidation [12–15].

During oxidative deterioration, lipids are oxidized to hydroperoxides and then to secondary oxidation products that increment free radicals- concentration. Hence, these compounds are considered important biomarkers to measure oil oxidative deterioration [16]. Acidity is the measurement of free fatty acids concentration produced by ester bonds hydrolysis of lipids by either enzyme action, heat or moisture [17]. Thus, its increment is related with a loss of oil stability. Another method to evaluate oil stability is the oil stability index (OSI). In the OSI method, oil is oxidized by air and high temperatures, producing volatile acids that are dissolved in water to follow the change in electrical conductivity [15]. The OSI value expresses the time necessary to complete oil oxidation at given experimental conditions being indicated by a drop of conductivity. Hence, a high OSI value implies a high resistance to oxidation of the analyzed oil [17].

This study was carried out to investigate the effect of PEF on OEY, OEYTOTAL and microstructure of dry pecan nuts. In addition, the stability of the extracted oil was evaluated by determination of acidity, antioxidant capacity, OSI, phytosterols concentration and LOX activity as well as phenolic compounds and antioxidant capacity of the generated byproducts hereinafter referred to as cakes.
