*Article* **Effect of Pulsed Electric Fields (PEF) on Extraction Yield and Stability of Oil Obtained from Dry Pecan Nuts (***Carya illinoinensis* **(Wangenh. K. Koch))**

**Lourdes Melisa Rábago-Panduro 1,2, Mariana Morales-de la Peña 3, María Paz Romero-Fabregat 2, Olga Martín-Belloso 1,2 and Jorge Welti-Chanes 1,\***


**Citation:** Rábago-Panduro, L.M.; Morales-de la Peña, M.; Romero-Fabregat, M.P.; Martín-Belloso, O.; Welti-Chanes, J. Effect of Pulsed Electric Fields (PEF) on Extraction Yield and Stability of Oil Obtained from Dry Pecan Nuts (*Carya illinoinensis* (Wangenh. K. Koch)). *Foods* **2021**, *10*, 1541. https://doi.org/ 10.3390/foods10071541

Academic Editors: Adrián Rabadán and Rodolfo Bernabéu

Received: 30 May 2021 Accepted: 30 June 2021 Published: 3 July 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Abstract:** Pulsed electric fields (PEF) have been reported to increase the total oil extraction yield (OEYTOTAL) of fresh pecan nuts maintaining oil characteristics and increasing phenolic compounds in the remaining by-product. However, there is no information regarding the PEF effect on dry pecan nuts. Dry kernels were pretreated at three specific energy inputs (0.8, 7.8 and 15.0 kJ/kg) and compared against untreated kernels and kernels soaked at 3, 20 and 35 min. OEYTOTAL, kernels microstructure, oil stability (acidity, antioxidant capacity (AC), oil stability index, phytosterols and lipoxygenase activity), along with by-products phenolic compounds (total phenolics (TP), condensed tannins (CT)) and AC were evaluated. Untreated kernels yielded 88.7 ± 3.0%, whereas OEYTOTAL of soaked and PEF-treated kernels were 76.5–83.0 and 79.8–85.0%, respectively. Kernels microstructural analysis evidenced that the 0.8 kJ/kg pretreatment induced oleosomes fusion, while no differences were observed in the stability of extracted oils. PEF applied at 0.8 kJ/kg also increased by-products CT by 27.0–43.5% and AC by 21.8–24.3% compared to soaked and untreated kernels. These results showed that PEF does not improve OEYTOTAL when it is applied to dry pecan nuts, demonstrating that kernels- moisture, oil content and microstructure play an important role in the effectiveness of PEF.

**Keywords:** pulsed electric fields; pecan nut oil; oil extraction yield; microstructural analysis; oil stability; enzyme activity
