**1. Introduction**

"Newhall" navel orange (*Citrus sinensis* L., Osbeck) fruits enjoy great popularity in China and around the world, for their good taste, abundant vitamin, C and widespread availability [1]. However, there are serious problems restricting the sound development of citrus production. Postharvest losses, frequent decay caused by a variety of plant pathogenic fungi, and a lack of scientific management, are issues of concern that need to be solved; of these, postharvest decay is the biggest hurdle that needs urgent resolution.

Pathogen infection is an important factor that affects citrus fruit postharvest physiology, disease resistance, and metabolism. Blue and green mold of citrus, caused by *Penicillium italicum* and *Penicillium digitatum*, respectively, are the most economically important postharvest diseases of citrus, and cause heavy losses during storage, transportation, and marketing, thus debasing the commodity value of harvested fruits [2]. The two *Penicillium* molds may cause 60%–80% decay losses under ambient conditions [3], which leads to severe economic losses for exporting countries. At present, the primary means for controlling of the two *Penicillium* molds still relies mainly on the use of chemical fungicides, especially imazalil (IMZ), prochloraz, thiabendazole (TBZ), calcium polysulfide pyrimethanil, or different mixtures of these compounds [4–7]. Increasing public concern of chemical residues on human health and environmental pollution, due to excessive use of chemical fungicides, have prompted investigation of alternative strategies for reducing postharvest decay and maintaining citrus fruit postharvest quality, without any human, environmental, or plant toxicity [8–10]. A variety of plant-derived compounds have been recognized and generally regarded as safe (GRAS) substances for their antifungal activities, and are being used for controlling postharvest fungal rotting of fresh horticultural products [11–13]. In recent years, numerous researchers have documented the antifungal effects of plant extracts or essential oils for reducing postharvest disease development caused by pathogenic fungus, leading to heavy losses and serious deterioration of citrus fruits [14–17].

The hairy fig is a deciduous plant widely distributed in southern China as a traditional plant resource used as medicinal and edible food by Hakka people. It is a clearly recognizable plant for its five-fingered leaf shape and mature fruit that resembles wild peach (Figure 1). Moreover, the fruits of hairy fig are a famous herb used by Hakka people in Chinese folk medicine for inhibiting tumor growth, promoting lactation, as anticoagulant, and for improving fatigue resistance [18,19]. Currently, our previous research demonstrated that HFE has strong antifungal activity against *P. italicum* and *P. digitatum* in vitro conditions [20,21]. Not surprisingly, chitosan coating enriched with HFE provided an enhanced antifungal activity, and it is likely that research will broaden the practicability of the botanical fungicide. Development of antimicrobial/antioxidant coatings from polysaccharides, such as chitosan, have been studied extensively, whereas few works have been conducted on developing films using the combination of chitosan and natural plant extract-based antifungal components. The purpose of this research was to evaluate the effect of chitosan coating enriched with or without HFE for cold-stored navel orange preservation.

**Figure 1.** The (**A**) leaves and (**B**) fruits of hairy fig (*Ficus hirta* Vahl.).

#### **2. Materials and Methods**

### *2.1. Materials*

Fruits of navel oranges (*Citrus Sinensis* L. Osbeck cv. Newhall), used throughout this study, were harvested at the peak of the harvesting season from an orchard situated in the southeast of Ganzhou city (Jiangxi, China). The fruits were picked on the basis of consistent size (240–280 g) and uniform color (citrus color index, 3.5–4.8). Fruits with any mechanical injury, blemish, or diseases were discarded.
