Shelf Life Potential and the Fruit Cuticle: The Unexpected Player

Abstract

The plant cuticle is an extracellular barrier that protects the aerial, non-lignified parts of plants from the surrounding environment, and furthermore plays important functions in organ growth and development. The role of the cuticle in post-harvest quality of fruits is a topic currently driving a lot of interest since an increasing bulk of research data show its modulating influence on a number of important traits determining shelf life and storage potential, including water transpiration and fruit dehydration, susceptibility to rots, pests and disorders, and even firmness. Moreover, the properties of fruit cuticles keep evolving after harvest, and have also been shown to be highly responsive to the external conditions surrounding the fruit. Indeed, common post-harvest treatments will have an impact on cuticle integrity and performance that needs to be evaluated for a deeper understanding of changes in post-harvest quality. In this review, chemical and biophysical properties of fruit cuticles are summarized. An overview is also provided of post-harvest changes in cuticles and the effects thereupon of some post-harvest procedures, with the purpose of offering a comprehensive summary of currently available information. Identification of natural sources of variability in relevant quality traits would allow breeding for the improvement of post-harvest life of fruit commodities.

Keywords: cell wall; cuticle; fruit; mechanical properties; post-harvest; shelf life; treatments; water loss.

FIGURE 1

Cross-sections of tomato fruit epicarp. (A) Transmission electron micrograph of the outer epidermal cell wall of an immature fruit. Bar: 0.5 μm. (B) Mature tomato epicarp stained with Sudan IV and Calcofluor to visualize the cuticle and cell walls, respectively. Bar: 25 μm.

FIGURE 2

Main compounds present in the analyzed cuticles of fruit crops. Data taken from literature (Kosma et al., 2010; Fernández et al., 2011; Parsons et al., 2013; Belge et al., 2014a,b; España et al., 2014b; Wang et al., 2015; Huang et al., 2017; Leide et al., 2018).

FIGURE 3

Simplified schematics of the interactions observed in the cuticle among temperature, relative humidity, and mechanical resistance.