Evidence for a radial strain gradient in apple fruit cuticles

Abstract

The morphological outer side of the apple fruit cuticle is markedly more strained than the inner side. This strain is released upon wax extraction. This paper investigates the effect of ablating outer and inner surfaces of isolated cuticular membranes (CM) of mature apple (Malus × domestica) fruit using cold atmospheric pressure plasma (CAPP) on the release of strain after extraction of waxes. Strain release was quantified as the decrease in area of CM discs following CAPP treatment and subsequent solvent extraction of wax. Increasing duration of CAPP treatment proportionally decreased CM mass per unit area. There was no difference in mass loss rate between CAPP treatments of outer or inner surfaces. Also, there was no difference in surface area of CMs before and after CAPP treatment. However, upon subsequent wax extraction, surface area of CMs decreased indicating the release of strain. Increasing the duration of CAPP treatment resulted in increasing strain release up to 47.7 ± 8.0 % at 20 min when CAPP was applied to the inner surface. In contrast, strain release was independent of CAPP duration averaging about 12.1 ± 0.6 % when applied to the outer surface of the CM. Our results provide evidence for a marked gradient of strain between the outer side (strained) and the inner side of the CM (not strained) of mature apple fruit.

Russeting in Apple Is Initiated After Exposure to Moisture Ends—I. Histological Evidence

“…Earlier studies established that depositions of wax in the expanding cutin network on a growing fruit surface substantially reduce build-up of elastic strain by converting the elastic strain into a plastic strain [ 36 ]. Further, deposition of new layers of cutin underneath the existing old layers fixes the elastic strain of the CM [ 37 ]. Continuing cutin and wax deposition will therefore fix the elastic strain in the dry control skins but to a lesser extent in the skins exposed to moisture.…”

Regulation of cuticle formation during fruit development and ripening in ‘Newhall’ navel orange ( Citrus sinensis Osbeck) revealed by transcriptomic and metabolomic profiling

“…Fruit cuticle is formed during fruit development and influences fruit quality during development and postharvest storage [6][7][8][9]. Development of fruit cuticle is different among species.…”

Low cuticle deposition rate in ‘Apple’ mango increases elastic strain, weakens the cuticle and increases russet

“…Mechanically, the increase in ε resid resulted principally from a deposition of cutin. In Malus apple, the addition of cutin to the inner side (cell-wall side) of the cuticle on the expanding fruit surface resulted in the fixation of elastic strain and, thus, the development of a radial strain gradient within the cuticle [ 11 ]. The incorporation of wax into the cutin network also causes a small degree of ‘fixation’ of elastic strain (reversible) and, hence, also contributes to the plastic strain (irreversible) [ 12 ].…”