Fruit softening and pectin disassembly: an overview of nanostructural pectin modifications assessed by atomic force microscopy

Abstract

In this review, the main features of the pectin disassembly process during fruit ripening are first discussed, and then the nanostructural characterization of fruit pectins by AFM and its relationship with texture and postharvest fruit shelf life is reviewed. In general, fruit pectins are visualized under AFM as linear chains, a few of which show long branches, and aggregates. Number- and weight-average values obtained from these images are in good agreement with chromatographic analyses. Most AFM studies indicate reductions in the length of individual pectin chains and the frequency of aggregates as the fruits ripen. Pectins extracted with sodium carbonate, supposedly located within the primary cell wall, are the most affected.

A comparative study of the physico‐chemical properties affecting the organoleptic quality of fresh and thermally treated yellow tomato ecotype fruit

“…Because the main components of soluble solids are sugars and acids and the levels of reducing sugar are not significantly different among fresh fruit of our four genotypes, we hypothesised that the acidic component is more relevant in determining the higher soluble solids observed in the analysed genotypes. This compound greatly affects fruit softening (Paniagua et al, 2014) and its viscosity before and after the thermal treatment. Interestingly, the Gi aGi u (E40) ecotype showed the highest levels of all the organic acids analysed, except for oxalic acid.…”

EFFECT OF STORAGE PERIOD ON VARIOUS PHYSIOLOGICAL, BIOCHEMICAL AND ENZYMATIC PARAMETERS OF GUAVA (Psidium guajava L.) FRUIT

“…Fruit firmness is one of the most important attributes in determining the post-harvest quality (Maude & Bouageois, 2013). The decline in firmness during storage is mainly caused due to the dissolution of the middle lamella, the reduction of cell-to-cell adhesion and the weakening of parenchyma cell walls as a result of the action of cell wall modifying enzymes leading to shriveling and softening (Paniagua et al, 2014).…”

The nanostructural characterization of strawberry pectins in pectate lyase or polygalacturonase silenced fruits elucidates their role in softening

“…This involves pectin solubilization, i.e. an increase in the content of polyuronides loosely bound to the wall, and depolymerization and the loss of neutral sugars from pectin side-chains (Brummell, 2006;Goulao & Oliveira, 2008;Paniagua et al, 2014). These changes are due to the coordinated action of cell wall modifying enzymes, such as polygalacturonase (PG), pectate lyase (PL), pectin methyl esterase, ␤-galactosidase or ␣-arabinofuranosidase, which are generally encoded by ripeningrelated genes (Brummell & Harpster, 2001;Goulao & Oliveira, 2008;Mercado et al, 2011).…”

“…This type of structural modification can be characterized by atomic force microscopy (AFM) at the nano-structural level (Morris, Kirby, & Gunning, 2010). This technique has only recently been used to investigate pectin disassembly processes during fruit ripening (Paniagua et al, 2014). The main goal of this research was to analyze at the nano-structural level pectins from APG and APEL transgenic fruits to reveal the different effect of each enzyme in the pectin matrix and its implications on the mechanical properties of cell walls.…”