Articles
Microscopic differences observed in Opuntia ficus-indica ‘Algerian’ and ‘Turpin’ during postharvest refrigerated storage – Part 1
Article number
1452_42
Pages
319 – 324
Language
English
Abstract
Polysaccharide extracts from Opuntia cacti have been applied to regulate viscosity in foods.
Many factors, from preharvest conditions and method of extraction to the growing environment of the plants, are known to play a role in the chemical and physical properties of these extracts.
This study examined the effect of post-storage time in pre-extraction refrigerated conditions of harvested cladodes from two cultivars of Opuntia ficus-indica (L.) Mill. (OFI), ‘Algerian’ and ‘Turpin’, selected for weekly mucilage extraction during a 4-week storage period for comparison.
To determine the effect of refrigerated storage on the functional properties of extracts, viscosity of the extracts was measured for each week.
The extracts were also prepared for scanning electron microscopy (SEM). Distinctions in the morphologies of the material were classified into eight distinct groupings.
Great morphological diversity between OFI ‘Algerian’ and ‘Turpin’ was found, despite similar viscosities (34 mPa s average for OFI ‘Algerian’ and 39 mPa s average for OFI ‘Turpin’). OFI ‘Algerian’ and ‘Turpin’ each had five unique morphologies, while four morphologies could be observed in both over the same period.
There were also differences over storage time.
In OFI ‘Algerian’, only three of the morphologies, visible in week 0 (initial extract), were visible in week 4 (final extract). Four morphologies, not present in the initial extract, occurred by the end of the study period.
OFI ‘Turpin’, having lower initial diversity, increased in morphological diversity over time.
This indicated that despite similar viscometric results, the underlying material which resulted in these viscosities were different at a microscopic scale.
These results suggest differences in the material structure and composition, as well as how the materials interact with the environment.
This may impact the potential use and effectiveness as a food additive.
Many factors, from preharvest conditions and method of extraction to the growing environment of the plants, are known to play a role in the chemical and physical properties of these extracts.
This study examined the effect of post-storage time in pre-extraction refrigerated conditions of harvested cladodes from two cultivars of Opuntia ficus-indica (L.) Mill. (OFI), ‘Algerian’ and ‘Turpin’, selected for weekly mucilage extraction during a 4-week storage period for comparison.
To determine the effect of refrigerated storage on the functional properties of extracts, viscosity of the extracts was measured for each week.
The extracts were also prepared for scanning electron microscopy (SEM). Distinctions in the morphologies of the material were classified into eight distinct groupings.
Great morphological diversity between OFI ‘Algerian’ and ‘Turpin’ was found, despite similar viscosities (34 mPa s average for OFI ‘Algerian’ and 39 mPa s average for OFI ‘Turpin’). OFI ‘Algerian’ and ‘Turpin’ each had five unique morphologies, while four morphologies could be observed in both over the same period.
There were also differences over storage time.
In OFI ‘Algerian’, only three of the morphologies, visible in week 0 (initial extract), were visible in week 4 (final extract). Four morphologies, not present in the initial extract, occurred by the end of the study period.
OFI ‘Turpin’, having lower initial diversity, increased in morphological diversity over time.
This indicated that despite similar viscometric results, the underlying material which resulted in these viscosities were different at a microscopic scale.
These results suggest differences in the material structure and composition, as well as how the materials interact with the environment.
This may impact the potential use and effectiveness as a food additive.
Authors
J.A. Viktor, M. de Wit, A. du Toit, G. Osthoff
Keywords
scanning electron microscopy, viscometry, polymers, morphology
Groups involved
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