Alternative Green and Novel Postharvest Treatments for Minimally Processed Fruits and Vegetables

*Mildred Osei-Kwarteng, Gustav K. Mahunu, Moomin Abu and Maurice Apaliya*

## **Abstract**

Minimally processed fresh produce is ready to eat and subjected to minimal technology before consumption. Fresh fruits and vegetables (FFVs) are minimally processed commodities that are metabolically active and undergo physiological processes such as ripening and senescence, reducing their quality and shelf life. Postharvest technologies maintain the quality and prolong the shelf life of harvested produce, without which the quality deteriorates such that significant economic loss ensues due to water and nutrients loss, physiological deterioration, biochemical changes, and microbial degeneration. Conventional postharvest treatments such as temperature management, and chemical and gaseous treatments are widely known for controlling postharvest issues in FFVs. However, there are novel and green alternative safe methods that are employed to maintain the postharvest quality and prolong the shelf life of FFVs. This chapter focuses on seven common alternative novel and green postharvest treatments: nitric oxide, ozone, methyl jasmonate, salicylic acid, oxalic acid, calcium, and heat treatments. These treatments are explained and some of their current application on FFVs are discussed and tabularized indicating the optimum treatment conditions reported in the latest scientific publications.

**Keywords:** calcium, heat, methyl jasmonate, nitric oxide, oxalic acid, salicylic acid, ozone

#### **1. Introduction**

Fresh fruits and vegetables (FFVs) are considered minimally processed because they are ready to eat and subjected to minimal technology before consumption. FFVs are a source of micro- and macronutrients, and secondary metabolites that possess antioxidant and reactive oxygen species (ROS) scavenging abilities for good health [1–4]. FFVs are living tissues and are metabolically active experiencing senescence, and ripening processes that necessitate quality preservation and the reduction of storage losses [4–8]. Postharvest technologies control and prolong the shelf life of

harvested produce, without which the quality (i.e., nutritional, appearance, and pathogenic safety) deteriorates such that significant economic losses ensue [5, 6] due to water and nutrient loss, physiological deterioration, biochemical changes, and microbial degeneration [6, 9]. Hence, optimum postharvest treatments must be employed to impede physiological processes (e.g., senescence and maturation) and minimize the occurrence of microbial contamination to preserve quality loss [5, 6, 10]. Temperature management, physical (e.g., heat, irradiation, and edible coatings) chemical (antimicrobials, antioxidants, and antibrowning), and gaseous treatments (e.g., chlorine dioxide) are some conventional postharvest treatments for FFVs [5, 9]. Nevertheless, there are currently novel and green postharvest treatments that are used to maintain and enhance the quality, and prolong the postharvest shelf life of fresh produce.

Novel postharvest treatments are new postharvest treatments that, among other functions enhance bioactive molecule contents or compounds, retard senescence and ripening, prevent postharvest diseases, prolong shelf life, and ensure the overall safety of fresh produce for consumption [6]. On the other hand, green postharvest treatments are those that are environmentally friendly, such that their application is important and socially acceptable to the industry and consumers at large in maintaining and enhancing the postharvest quality, and prolonging the storage life of fresh produce. Green postharvest treatments include non-chemical applications like biological control agents, natural compounds, biomaterials, irradiation (ultraviolet), and heat treatments [6, 11–13]. Therefore, some novel postharvest treatments are green, but not all novel treatments are green. The quality attributes (i.e., nutritional value, appearance, texture, flavour, and chemical, toxicological, and microbial safety) and shelf life of FFVs are maintained via various novel and green postharvest treatments [5]. This chapter presents seven postharvest treatments (i.e., nitric oxide, ozone, methyl jasmonate, salicylic acid, oxalic acid, calcium, and heat treatment) for FFVs. All seven are novel, but four are green (i.e., salicylic acid, oxalic acid, ozone, and heat treatments) [6, 8, 13].
