Citation: Galus, S.; Mikus, M.; Ciurzy ´ nska, A.; Janowicz, M. Whey Protein Isolate-Based Edible Coatings Incorporated with Jojoba Oil as a Novel Approach for Improving the Quality of Fresh-Cut Root Parsley during Refrigerated Storage. Appl. Sci. 2022, 12, 9023. https:// doi.org/10.3390/app12189023 Academic Editor: Anna Lante Received: 12 August 2022 Accepted: 6 September 2022 Published: 8 September 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 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/). applied sciences Article Whey Protein Isolate-Based Edible Coatings Incorporated with Jojoba Oil as a Novel Approach for Improving the Quality of Fresh-Cut Root Parsley during Refrigerated Storage Sabina Galus * , Magdalena Mikus, Agnieszka Ciurzy ´ nska and Monika Janowicz Department of Food Engineering and Process Management, Institute of Food Sciences, Warsaw University of Life Sciences—SGGW, Nowoursynowska Str. 159c,02-776 Warsaw, Poland * Correspondence: sabina_galus@sggw.edu.pl; Tel.: +48-22-59-37-579; Fax: +48-22-59-37-576 Abstract: In this paper, the effect of whey-protein-isolate-based edible coatings with the addition of jojoba oil at concentrations of 1 and 2% on the qualitative characteristics of fresh-cut root parsley was evaluated. Changes in hardness, color parameters, and the contents of polyphenols and flavonoids over 28 days of refrigerated storage, as well as changes in structure, were examined. It was observed that fresh-cut parsley, uncoated and coated with a protein solution, was characterized by a decrease in hardness, from 59.32 and 59.88 to 50.98 and 48.33 N, respectively, while parsley coated with whey protein isolate with the addition of jojoba oil showed an increase in hardness during storage, from 56.28 to 66.23 N and from 52.17 to 60.49 for 1% and 2% of jojoba-oil-containing formulations, respectively. The L*, a*, and b* color parameters and hue angle mostly remained at similar levels, which indicate the maintenance of the desired color, but changes in the values were observed during storage. Parameter L* was between 79.56 and 85.33 in the control samples and between 72.54 and 84.19 in the coated samples. It was shown that the use of whey protein coatings and storage time had a positive impact on the contents of polyphenols and flavonoids in the fresh-cut parsley. The highest changes in polyphenols, from 3.13 to 9.82 mg GAE/g d.m., were observed for the samples coated with the formulation containing 1% of jojoba oil. The highest increase in flavonoid content, from 23.65 to 40.60 mg QE/g d.m., was observed for the samples coated with the film-forming solution with 2% of jojoba oil. Scanning electron microscopy showed a smaller number of pores in the vegetable tissue as a result of the coatings, and this was the most noticeable for the samples without the jojoba oil. Storage deteriorated the quality of the fresh-cut parsley surface, and the drying effect was visible. The use of protein coatings incorporated with jojoba oil modifies the quality characteristics of fresh-cut parsley, and this can find application in reducing the waste of minimally processed vegetables during storage. Keywords: edible coatings; root parsley; quality; color; polyphenols; flavonoids 1. Introduction Today, all over the world, there is growing consumer interest in a healthy and nutri- tious diet that includes fresh vegetables, which are perishable products [1]. In addition, fresh vegetables can easily be physically damaged and lose moisture, and as the rate of respiration increases, their shelf life is shortened, causing excessive softening and aging of the raw materials. The shortened shelf life may result from biochemical changes and the development of microorganisms affecting the loss of the desired quality. To extend the shelf life of vegetables and to maintain their quality after harvest, food coating technology is increasingly used [2]. The coating process, consisting of covering the surface of a product with a film-forming material, applied to whole or portioned raw materials, has found its greatest application in the case of vegetables and fruits [3,4]. After drying the product, a protective coating forms on its surface, influencing, e.g., the maintenance of qualitative characteristics by limiting the biochemical, chemical, and physical changes taking place. In addition, edible coatings give products an attractive and glossy appearance, improving Appl. Sci. 2022, 12, 9023. https://doi.org/10.3390/app12189023 https://www.mdpi.com/journal/applsci