Effect of chitosan-gelatin coating containing nano-encapsulated tarragon essential oil on the preservation of pork slices

Highlights

• Tarragon essential oil (TEO) loaded nanoparticles were prepared.

• Pork slice was coated with chitosan-gelatin coating containing free or encapsulated TEO.

• Coating inhibited lipid oxidation, microbial growth, and improved sensory attributes.

• Chitosan-gelatin coating containing encapsulated TEO showed the best performance on meat preservation.

Abstract

There is an increasing demand for bio-based packaging materials incorporated with active nanoparticles as one of the new technologies to obtain food products with improved quality and extended shelf-life. The objectives of this study were to develop a chitosan-gelatin based edible coating incorporated with nano-encapsulated tarragon essential oils (TEO) and to investigate the effects of chitosan-gelatin coatings containing TEO or TEO-loaded nanoparticles (TEO-NPs) on the preservation of pork slices during refrigerated storage for 16 days. Nanoparticles with the average diameters of 246.27–504.60 nm were produced using different mass ratios of chitosan to TEO (1:0, 1:0.2, 1:0.4, 1:0.6, 1:0.8 and 1:1) by ionic gelation method. Zeta potential and encapsulation efficiency (EE) of the prepared TEO-NPs were 27.07–37.12 mV and 9.83–35.57%, respectively. TEO-NPs with the maximum EE were applied for preparing the edible coatings. The results suggested that the coating treatments could significantly inhibit quality deterioration of pork slices. Nano-encapsulation contributed to the sustained release of TEO and caused an improved antioxidant, antibacterial and sensory properties. The study suggests that chitosan-gelatin coating incorporated with TEO-NPs could be developed as a prospective active packaging to preserve pork slices.

Introduction

The demand of antimicrobial and antioxidant compounds from natural and renewable resources has been growing due to the negative health impacts of synthetic chemical additives. In recent years, plant extracts and essential oils have been widely valued for their unique fragrance and antibacterial effects. Plant essential oils have a variety of biological activities and are widely used in the field of food preservation (Kumar, Mendiratta, Agrawal, Sharma, & Singh, 2018). Tarragon (Artemisia dracunculus L.) is a perennial herb belonging to the Asteraceae family. Tarragon essential oil and extract have high medicinal values and biological activities (Alizadeh Behbahani, Tabatabaei Yazdi, Shahidi, Mortazavi, & Mohebbi, 2017; Behbahani, Shahidi, Yazdi, Mortazavi, & Mohebbi, 2017). This can be attributed to the total phenolic content and high level of methyl chavicols in tarragon (Chaleshtori, Rokni, Razavilar, & Kopaei, 2013). Therefore, TEO could be considered as a potential antioxidant and antimicrobial agent to be added to food products. Sharafati-Chaleshtori et al. (2014) stated that incorporation of tarragon essential oil to beef burgers inhibited microbial growth and improved overall acceptability during storage. It was also reported that tarragon essential oil played an effective role in prolonging the shelf life of beef slices (Alizadeh Behbahani et al., 2017). Nevertheless, there are some problems regarding the direct application of essential oils in complicated food systems such as adverse impacts on the chemical and physical stability of the food, reducing the activity of the biologically active compounds (Hosseini, Amraie, Salehi, Mohseni, & Aloui, 2019).

Encapsulation can supply an effective method to conquer these problems by enhancing the oxidation stability of bioactive compounds, avoiding undesirable interaction with food constituents, maintaining their stability in the process of food production and preservation, and supplying regulated or targeted transport (Rakmai, Cheirsilp, Mejuto, Torrado-Agrasar, & Simal-Gándara, 2017). Recently, the development of nano-encapsulation technology has grown considerably. Compared with conventional encapsulation, subcellular nano-encapsulation can provide a higher surface area and stabilization, also can enhance the efficacy and stability of sensitive bioactive ingredients (Hasheminejad, Khodaiyan, & Safari, 2019).

In spite of the potential advantages of nanoparticles containing bioactive ingredients in food utilization, there is a restriction regarding their application in meat products where the direct addition of them is impracticable (Donsì, Annunziata, Vincensi, & Ferrari, 2012). Incorporation of nanoparticles in edible coating can be an effective way to evade the abovementioned restriction and enhance the mobilization of nanoparticles on the surface of solid foods (Xing et al., 2019). This approach is effectual not only in putting bioactive ingredients on the solid foods surface, but also in regulating the delivery of functional components, alleviating the negative sensorial effect of essential oils, and reducing their dispersing speed, that can ultimately decrease the needed concentration to obtain the expected impacts, extend the acting time of active coatings, and give full play to the usefulness of edible coatings (Castelo Branco Melo et al., 2018). In addition, edible coatings can as well retard the reduction of food quality by functioning as barrier materials to prevent moisture losses, oxygen and solute migration during short storage time (Castelo Branco Melo et al., 2018). Several researches have confirmed the positive effects of embedding plant extracts or essential oil nanoemulsions into edible coatings on retarding the quality deterioration of meat-based products (Mehdizadeh & Mojaddar Langroodi, 2019; Vieira et al., 2019).

Chitosan has been widely investigated and used in the food production due to the distinctive film-formation abilities, high gas barrier properties, and antimicrobial and antioxidant activity (Karagöz & Demirdöven, 2019). However, chitosan edible coating or film presents a relatively poor moisture barrier (Xiong, Chen, Warner, & Fang, 2020). Gelatin made from the partial hydrolysis of collagen has been extensively used to prepare biopolymers (Gómez-Guillén et al., 2009). Chitosan mixed with gelatin can form a compact construction through hydrogen bonding and electrostatic interaction, which can effectively improve the flexibility and the permeability of water molecules of the edible coating/film (Pereda, Ponce, Marcovich, Ruseckaite, & Martucci, 2011). Packaging meat products with chitosan-gelatin film/coating has been demonstrated in some researches to be effectual for improving the quality of meat products and retarding their spoilage (Cardoso et al., 2016; Farajzadeh, Motamedzadegan, Shahidi, & Hamzeh, 2016).

Meat because of its particular constitution is liable to microorganism invasion as well as lipid oxidative degradation and color deterioration (Ahmad Mir, Ahmad Masoodi, & Raja, 2017). Retarding bacterial reproduction on the surface of meat through employing bioactive coating appears to be a promising strategy to maintain its quality and safety and acquire a longer shelf-life. Application of nano-encapsulated essential oils or extracts as conveyance and regulated-liberation systems in plastic packaging and biodegradable edible coating is scarce but is increasing in late researches (Pabast, Shariatifar, Beikzadeh, & Jahed, 2018). As far as we know, there are no studies on the formulation of chitosan-gelatin based composite edible coating employing TEO and TEO-loaded nanoparticles (TEO-NPs). In addition, no data is available on the using of chitosan-gelatin coating containing nanoparticles loaded with EOs in meat products. This work was designed to facilitate the exploitation of active biodegradable packaging systems by incorporating of TEO-NPs into chitosan-gelatin based coating and investigation of its antimicrobial and antioxidant impacts on the preservation of fresh pork slices.