**1. Introduction**

The potato (*Solanum tuberosum* L.) is a type of grain and vegetable crop with high starch, high protein, high vitamin, and low calorie contents that plays an important role in our daily life [1,2]. Potato has been the vital economic crop in many countries. China, India, the Russian Federation, Ukraine, and the United States of America were the top five highest average potato production countries during 2000 to 2019 [3]. Potato processing has shown a tremendous growth in the recent past. Post-harvest processing of sweet potato involves grading and sorting, cleaning, peeling, drying or secondary processing, and storage [4]. Fresh-cut fruits and vegetables, having been cleaned, peeled, and cut, with the maintenance of the characteristics of freshness and nutrition, are therefore healthy and ready to eat and use [5]. Hence, they are increasingly becoming the focus of consumer attention. In this context, an increase in fresh-cut potatoes as a type of fresh-cut fruit and vegetable appears an inevitable future trend in the potato industry. The potato is the largest vegetable crop, grown in 79% of the countries of the world [6]. In 2016, approximately 21 kg

**Citation:** Sarengaowa; Wang, L.; Liu, Y.; Yang, C.; Feng, K.; Hu, W. Screening of Essential Oils and Effect of a Chitosan-Based Edible Coating Containing Cinnamon Oil on the Quality and Microbial Safety of Fresh-Cut Potatoes. *Coatings* **2022**, *12*, 1492. https://doi.org/10.3390/ coatings12101492

Academic Editor: Maria Jose Fabra

Received: 13 September 2022 Accepted: 5 October 2022 Published: 7 October 2022

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(46 lbs) of potatoes was consumed per capita in the United States, with almost half of that consumption represented by fresh potatoes [7]. However, cutting potatoes causes the cells and tissues to rupture due to mechanical damage [8]. In terms of appearance, they show a softening of texture; there is a loss of flavour, there is microbial infection, and there are other problems, resulting in a shortened shelf life and reduced quality [9]. Therefore, it is urgent to develop effective and environmentally friendly methods to maintain the quality of fresh-cut potatoes during their shelf life.

An edible coating (EC) is an oxygen and moisture barrier that can improve the shelf life and quality of fresh-cut fruits and vegetables [10]. The gas exchange, migration of moisture and solutes, respiration, and oxidative reactions of the surface of fruits and vegetables can be reduced through coating [11]. Different types of ECs, such as chitosan, pectin, starch, alginates, gums, and carrageenan, have been widely studied for the preservation of fresh-cut fruits and vegetables [12–15]. Among these, chitosan EC has received a great deal of attention from the food industries. This derivative of chitin is a copolymer of N-acetylglucosamine and glucosamine residues linked by β-1,4-glycosidic bonds that is insoluble in dilute acids. The main properties of chitosan include film forming, antimicrobial activity, its nontoxic nature, biodegradability, and biocompatibility [16]. As a preservative coating for fruits and vegetables, chitosan has been proven to be edible and biologically safe [17]. In the form of a semipermeable film, chitosan EC can alter the internal atmosphere, reduce transpiration loss, and delay the ripening of fruits and vegetables. These properties make chitosan a superior edible coating [18]. Several recent studies have also indicated that chitosan has beneficial effects in food preservation [19].

According to the Food and Drug Administration, essential oils (EOs) are safe for human consumption [20]. It is widely recognised that EOs contain a broad range of antiparasitic, antibacterial, antifungal, and antiviral constituents [21]. Cinnamon oil is mainly extracted from the bark, leaves, and twigs of cassia that is predominantly grown in China, Indonesia, Vietnam, and Sri Lanka [22,23]. The main components of cinnamon oil are cinnamaldehyde, cinnamyl ester, salicylaldehyde, eugenol, vanillin, and other components [24]. It exhibits antimicrobial activity against several bacteria, yeasts, and fungi. Some studies have indicated that cinnamon oil can damage the cell wall and cell membrane of bacteria, leading to the increased permeability of cell membranes, leakage of cell contents, and reduced rates of bacterial survival [25]. In addition, the volatilisation properties of cinnamon oils can easily enhance the antibacterial activity against pathogenic and spoilage organisms on fresh-cut fruits and vegetables for preservation. However, the strong smell of cinnamon oil can affect the flavour of fresh-cut fruits and vegetables and their acceptability in terms of sensory evaluation. It is, therefore, necessary to combine cinnamon oil with other technologies to reduce its adverse effects on fresh-cut fruits and vegetables. The preservation effects of lemongrass, rosemary, cinnamon, tea tree, mint, palmarosa, oregano, and vanilla oils incorporated into EC have been evaluated on some fresh-cut fruits such as Fuji apples, pineapple, melon, and citrus [26–30].

In this study, the antibacterial activity of eighteen essential oils was screened against *Salmonella typhimurium*, *Staphylococcus aureus*, *Listeria monocytogenes*, and *Escherichia coli* O157:H7, and cinnamon oil showed the strongest antibacterial activity. In the preservation of fruits and vegetables, the chitosan edible coating has great prospects in maintaining the quality of fruits and vegetables among various types of edible coatings. However, no published studies have reported on the effects of the incorporation of cinnamon oil into chitosan edible coating for fresh-cut potatoes. Therefore, the current study aimed at evaluating the effects of different concentrations of cinnamon oil incorporated into chitosan edible coating on the quality, naturally occurring microorganisms, and artificially inoculated *Listeria monocytogenes* (Figure 1). The quality change of fresh-cut potatoes was assessed by measuring the colour, weight loss, and firmness. The safety of fresh-cut potatoes was evaluated through analysing the number of total plate counts, yeast and mould counts, total coliform counts, and lactic acid bacteria counts; and *Listeria monocytogenes*. The antibacterial

and preservation agents of chitosan EC containing cinnamon oil were developed to provide a safe, convenient, and low-cost preservative for fresh-cut potatoes.

**Figure 1.** Diagram of experimental method.
