Articles
Fruit surface microstructure modifications induced by edible coating and cold plasma treatment
Article number
1466_4
Pages
27 – 34
Language
English
Abstract
Maintaining the integrity of the fruit cuticle is important for extending postharvest shelf life.
This study investigated the effects of sodium alginate coating (CO) and the combined effects of coating and cold plasma (CO+CP) treatment on the surface microstructure and composition of pear, nectarine and apple fruits using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy.
The obtained results were compared against the untreated (control) fruit.
A consistent trend across all fruit types showed that coating provided a physical barrier that partially masked the microcracks and turgor loss observed on untreated fruits.
The combined treatment results in a highly homogenised, dense and pore free protective layer.
SEM analysis confirmed that CP treatment improved coating dispersion and adhesion on pome fruit and prevented cuticle cracking in nectarines.
The FTIR analysis identified key functional groups including O-H (3300 cm‑1), C-H (2920 cm‑1) and carboxylate (1610 cm‑1) stretching.
The FTIR analysis further revealed a divergent spectral response between nectarine and pome fruit surfaces.
In nectarines, the CO+CP treatment induced a significant increase in transmittance intensity across the 3300 and 1610 cm‑1 regions.
In contrast, ‘Granny Smith’ apples and ‘Forelle’ pears exhibited closely clustered spectral curves with minimal intensity variation between treatments.
Most importantly, the characteristic aliphatic C-H peaks associated with cuticular waxes remained present across all treatments across the fruit.
This demonstrated neither the alginate coating nor the CP treatment degraded the fruit’s natural protective wax layer.
These results further highlighted that while the physical improvements of plasma activation are universal, the measurable chemical impact is highly dependent on the fruit-specific wax composition and surface energy.
This study investigated the effects of sodium alginate coating (CO) and the combined effects of coating and cold plasma (CO+CP) treatment on the surface microstructure and composition of pear, nectarine and apple fruits using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy.
The obtained results were compared against the untreated (control) fruit.
A consistent trend across all fruit types showed that coating provided a physical barrier that partially masked the microcracks and turgor loss observed on untreated fruits.
The combined treatment results in a highly homogenised, dense and pore free protective layer.
SEM analysis confirmed that CP treatment improved coating dispersion and adhesion on pome fruit and prevented cuticle cracking in nectarines.
The FTIR analysis identified key functional groups including O-H (3300 cm‑1), C-H (2920 cm‑1) and carboxylate (1610 cm‑1) stretching.
The FTIR analysis further revealed a divergent spectral response between nectarine and pome fruit surfaces.
In nectarines, the CO+CP treatment induced a significant increase in transmittance intensity across the 3300 and 1610 cm‑1 regions.
In contrast, ‘Granny Smith’ apples and ‘Forelle’ pears exhibited closely clustered spectral curves with minimal intensity variation between treatments.
Most importantly, the characteristic aliphatic C-H peaks associated with cuticular waxes remained present across all treatments across the fruit.
This demonstrated neither the alginate coating nor the CP treatment degraded the fruit’s natural protective wax layer.
These results further highlighted that while the physical improvements of plasma activation are universal, the measurable chemical impact is highly dependent on the fruit-specific wax composition and surface energy.
Publication
Authors
Z.A. Belay, N.F. Monyela, L.P. Aphane, S. Khumalo
Keywords
‘Forelle’, ’Granny Smith’, microcracks visual quality, scanning electron microscopy
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