Food Microbiology & Safety Fabrication and characterization of a promising oregano-extract/psyllium-seed mucilage edible film for food packaging Pegah Hajivand , Sara Aryanejad, Iman Akbari , and Azadeh Hemmati Abstract: Herein, Psyllium-seed mucilage (PSM) and oregano extract (OE) were incorporated into the design of a promising, biodegradable, and antimicrobial edible film to enhance the shelf life of food. Various OE-PSM films with different concentrations of OE, PSM, and glycerol, as a plasticizer, were fabricated. Further physicochemical, mechanical, and structural studies demonstrated an enhancement in the films’ thickness, extensibility, and water-related properties (excluding water vapor permeability [WVP]) by increasing the glycerol and OE content. Also, the final OE-PSM films presented a bit yellow and opaque appearance. The effectiveness of fabricated films against microbial attacks was confirmed by the in vitro zone of inhibition measurement against Staphylococcus aureus and Escherichia coli, almost 118 and 77 mm, respectively. In addition, the efficiency of films on the extension of the postharvest lifetime of strawberries to 16 days was optically approved by determining the coated strawberries decay. All mentioned above confirmed the potential of the developed OE-PSM as a promising edible film. Keywords: Antimicrobial Edible Film, Oregano Extract, Psyllium-seed Mucilage, Shelf life, Strawberry Practical Application: Recently, new technology and materials have prompted to meet the consumers’ demand for healthier and safer food. To support this claim, we developed a productive edible film (plasticized OE-PSM film) which showed acceptable biodegradability, mechanical stability, water resistance, and antimicrobial efficiency. The unique properties of this edible film have made it a promising film, which is not only potent to extend the shelf life of food products, leading to facilitate the commercialization activities, but also inexpensive and more available over the traditional synthetic ones. These properties turn this film to a productive candidate, deserve to be implemented by the food and agricultural industries. 1. INTRODUCTION The demands of modern life as well as the deficiencies of com- mon food packaging methods, for example, low shelf life, toxic- ity, hard degradability, and eco-destructiveness, particularly with perishable food and minimally processed products, have led to in- troducing novel alternative biorenewable polymer-based materials for packaging (Muriel-Galet, Cran, Bigger, Hern´ andez-Mu ˜ noz, & Gavara, 2015; T´ oth & Hal´ asz, 2019). Biopolymers are highly biodegradable and beneficial in reduc- ing chemical hazards and domestic waste (Jafarzadeh et al., 2017; Vartiainen, V¨ ah¨ a-Nissi, & Harlin, 2014). They also have provided food packaging and agricultural industry with advantages (Chong et al., 2019; Farhan & Hani, 2017; Jafarzadeh, Alias, Ariffin, & Mahmud, 2018; Khalil et al., 2017). Psyllium, also called Plantago Psyllium, is a traditional plant with more than 200 cultivable species (Nep et al., 2020). Recently, it was approved by U.S. Food and Drug Administration (FDA) as a dietary fiber additive (Fratelli, Muniz, Santos, & Capriles, 2018) and it has been employed in various products due to its acceptable sensory, low calory, and healthy functionalities (Bhat, Deva, & Amin, 2018). Psyllium-seed mucilage (PSM) consists of JFDS-2020-0169 Submitted 2/8/2020, Accepted 5/16/2020. Authors are with Faculty of Petroleum and Chemical Engineering, Tehran Science and Research Branch, Islamic Azad Univ., Tehran, 1477893855, Iran. Direct inquiries to author Akbari (E-mail: iman.akbari@srbiau.ac.ir). arabinoxylans, which are made of a xylan backbone (1,4-linked-ß- D-xylopyranose) with xylose and arabinose side chains. This forms a high molecular weight and highly branched structure classified as comb-like polymers (Yu et al., 2017). Oregano is a common spice with special aromatic properties, particularly employed as a flavor and aroma enhancer in the food industry. Moreover, it is popular for its antimicrobial and an- tioxidant effects, mainly due to its unique components such as oleanolic, ursolic, caffeic, rosmarinic, and lithospermic acids as well as flavonoids, hydroquinones, tannins, and phenolic glyco- sides (Koci´ c-Tanackov et al., 2012). However, the most effec- tive antimicrobial and antifungal activators of oregano, which have frequently been mentioned in the literature, are carvacrol and thymol (Lukas, Schmiderer, Franz, & Novak, 2009). Inter- estingly, while it has widely been employed due to its antimi- crobial impact (Hern´ andez-Gonz´ alez et al., 2017; Muriel-Galet et al., 2015; Sabino et al., 2018; Wang, Marcone, Barbut, & Lim, 2012), a few reports have concerned oregano to incorporate it into polysaccharide-based edible films (Wang et al., 2012). In line with the necessity of meeting the urgent need of food and agricultural industries for biodegradable, accessible, and eco- friendly packaging, the purpose of this study is to investigate the possibility of employing PSM, rarely reported forming ed- ible films, combined with oregano extract (OE) to fabricate a unique active packaging film. In addition to its competitive price and biodegradability, this film would provide coated food with antimicrobial protection. To achieve the mentioned objectives, C  2020 Institute of Food Technologists R  doi: 10.1111/1750-3841.15331 Vol. 85, Iss. 8, 2020  Journal of Food Science 2481 Further reproduction without permission is prohibited