**Abstract**

Fresh fruits and vegetables provide essential nutrition to the diet, and it is critical to maintain product quality and nutrition from harvest through to the consumer. Fresh fruit and vegetables are still 'alive' even after detached from the plants and continue to respire. Besides, the climacteric fruits ripen after harvest. Therefore, it is important to manage the ripening process and prevent decay to reduce postharvest losses. In addition, foodborne illnesses are a major public health concern, and postharvest practices to improve food safety are essential. While traditional postharvest technologies such as synthetic chemicals have been effective at controlling postharvest decay and maintaining fruit quality during storage, there is an urgent need to develop alternative 'green technologies' to maintain product quality through to the consumer. Many new innovative green postharvest technologies are being developed to delay ripening, reduce pathogenic microorganisms, maintain freshness, and improve nutrition. This chapter discusses some new innovative green postharvest technologies such as the application of edible coatings and films, light emitting diode (LED), ultrasound, UVC irradiation, and plasma technology, which have been shown to reduce postharvest losses and improve the nutritional quality of fresh produce.

**Keywords:** eco-friendly technology, food waste, food safety, nutritional quality, postharvest losses, sanitizing

### **1. Introduction**

Fresh produce including fruits and vegetables are perishable crops. The major problems are quality degradation, microbial spoilage, and postharvest disease infection, resulting in quality and nutritional losses and short storage life. Postharvest handling is a crucial step to maintain the quality of fresh produces. However, applying chemical treatments to reduce microbial growth and inhibit postharvest diseases may cause chemical residue when it is overused, and chemical methods cannot apply to

organic produce. Therefore, using postharvest green technology such as ultrasound, light emitting diode (LED), edible coatings, UVC irradiation, and plasma technology to reduce postharvest losses and improve the nutritional quality of fresh horticultural produce may be taken into consideration as an alternative treatment for applying after harvest.

## **2. Edible coatings and films**

#### **2.1 Edible coatings**

Edible coatings are a thin layer (˂0.3 mm) of biodegradable materials wrapped or coated around the surface of fruits which act as a barrier for the exchange of moisture and gases between fruits and the surrounding environment which can then delay fruit respiration, ethylene production, and slow down microbial growth [1–3]. Edible coatings are commonly classified into three main groups. Lipid-based materials (such as fatty acids and waxes), protein-based materials (such as zein, casein, whey protein, soy protein, egg albumin, and gelatin), and polysaccharide-based materials (such as starch, cellulose, chitosan, alginate, and gums) or mixtures of them [4]. These edible coatings are considered 'green technologies' which are simple, safe, and eco-friendly and can be applied in liquid form by dipping, spraying, or brushing. The fundamental characteristics of edible coatings are that they must be food-safe, tasteless, odorless, and flexible [5]. Water loss from harvested fruit and vegetables is primarily through transpiration. Edible coatings have been widely reported to reduce weight loss in a range of fruit and vegetables such as sweet cherries, peaches, and plums [6–8]. Edible coatings primarily reduce quality losses by creating a semipermeable gas barrier around the product to restrict transpiration and regulate gaseous (O2 and CO2) exchange between the internal atmosphere of fruits and the external environment [9]. Therefore, edible coatings can enhance shelf life by decreasing weight loss, retarding physicochemical changes, and delaying fruit ripening. Hong et al. [10] reported that the use of 2% chitosan in coating guava fruits reduced weight loss, delayed changes in total soluble solids (TSS) and titratable acidity (TA), and maintained firmness during 12 days of storage at 11°C. Green pepper fruit coated with 2% chitosan exhibited a reduction of weight loss and extend postharvest life for 16 days at 12°C [11]. Similarly, Mandal et al. [12] found that 2% chitosan coatings on mango fruits reduced weight loss, remained green of color peel, and increased the shelf life compared to the untreated fruit at room temperature. Moreover, the application of 1% chitosan also delayed changes in weight loss, TSS, TA, and external color compared to the untreated fruit [13]. In addition, Ruelas-Chacon et al. [14] suggested that guar gum (1.5%) coating had great potential in reducing the respiration rate of tomatoes. Li et al. [15] reported that 1% peach gum polysaccharides coating on the surface of cherry tomatoes decreased weight loss, reduced respiration rate, maintained firmness, and extended the shelf life of cherry tomatoes. Similarly, sweet cherry coated with 5% alginate reduced respiration rate and higher in fruit firmness and TA compared to untreated fruit [16]. Ratra et al. [17] reported that aloe vera gel (50%) reduced weight loss, lower the respiration rate, and increased the shelf life of bananas. Moreover, other research confirmed that sweet cherry, pineapple, and apple benefited from aloe vera coating with significantly lower weight loss and delayed fruit ripening [18–20]. In addition, 'Alberta' peaches coated with methyl cellulose and sodium alginate reduced respiration rate by 62% and 68%, respectively, during storage at 15°C [21].

*Green Technology for Reducing Postharvest Losses and Improving the Nutritional Quality… DOI: http://dx.doi.org/10.5772/intechopen.109938*

The mixture of high concentrations of chitosan and low concentrations of glycerol has been reported to decrease the respiration rate and delay the ripening of coated tomatoes [22]. Duong et al. [23] demonstrated that sodium alginate solution mixed with 40 mL L−1 calcium chloride (CaCl2) significantly reduced the weight loss and respiration rate of the rose apple for 10 days at 13°C, while Mandal et al. [24] reported that 3% carboxymethyl cellulose blended with 2% chitosan and wax extended the shelf life of tomato for 24 days at 20–25°C by delaying the ripening process. These numerous examples clearly demonstrate the application of 'green' edible coatings to improve the shelf life of fresh produce and minimize postharvest losses.

#### **2.2 Edible films**

Edible films are usually prepared by dissolving in water, alcohol, or a mixture of solvents. A plasticizer is often added to the solution in order to improve flexibility and elasticity of film. Other additives, such as antimicrobial agents, colors, and flavor can be added to the solution to create specific film properties and functionality [25]. Polysaccharide-based edible films such as carrageenan and chitosan can be used as a strong barrier to non-polar aroma compounds, reducing aroma loss and oxidation [26]. Hydrocolloid-based edible films such as alginate and carboxymethylcellulose (CMC) have the potential to prevent moisture losses [27]. Another essential factor to contemplate for selecting edible film material is the ability to serve as an effective carrier for antimicrobials. Edible chitosan film combined with bioactive compounds and essential oils allowed for the reduction of *Escherichia coli* and *Listeria monocytogenes* and the enhancement of the overall quality of broccoli [28]. Pullulan-based edible films combined with antibrowning and antimicrobial agents prevented enzymatic browning, delayed tissue softening, decreased weight loss, reduced respiration rates, and inhibited the growth of microorganisms in fresh-cut apples [29]. Although edible coatings and films are not replacing conventional packaging completely, they can be used as alternative packaging. Edible films do not only decrease the postharvest losses but also reduce the environmental pollution in long term.
