Browsing by Author "Alba, K."

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    Pectin isolation and characterization from six okra genotypes
    (Food Hydrocolloids, 2017) Kpodo, Fidelis M.; Agbenorhevi, Jacob K.; Alba, K.; Bingham, , R. J.; Oduro, Ibok N.; Morris, G. A.; Kontogiorgos, V.; 0000-0002-7949-0502; 0000-0002-8516-7656
    Pectin was isolated by aqueous extraction at pH 6.0 from the pods of six different okra genotypes (Abelmoschus esculentus L.). Genetic diversity was determined using fragment length analysis (FLA) of ten simple sequence repeat (SSR) markers. Physical and chemical evaluation of pectin was performed by means of FT-IR and NMR spectroscopy, sugar composition analysis (GC-MS), size exclusion chromatography coupled to multi-angle laser light scattering (SEC-MALLS), dilute solution viscometry and steady shear rheology assisted by principal component analysis (PCA). Each of the SSR markers detected on average 4.1 alleles and revealed unique genotypes for each sample. Extraction yield was between 11 and 14% resulting in pectin with galacturonic acid content between 43 and 63%, low degree of methyl-esterification (17–25%) and high degree of acetylation (20–40%). All samples were of high weight-average molar mass (Mw) (700–1700 × 103 g mol−1) and sugar composition analysis revealed the structural diversity of samples with HG/RG-I ratios ranging between 1.3 and 3.1. The present work shows that individual okra genotypes provide pectin with different structural properties that could potentially provide a new source of functional pectin for the food or pharmaceutical industries.
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    Pectin isolation and characterization from six okra genotypes
    (Food Hydrocolloids, 2017) Kpodo, Fidelis M.; Agbenorhevi, Jacob K.; Alba, K.; Bingham, R. J.; Oduro, Ibok N.; Morris, G. A.; Kontogiorgos, V.; 0000-0002-7949-0502; 0000-0002-8516-7656; 0000-0003-3731-2684
    Pectin was isolated by aqueous extraction at pH 6.0 from the pods of six different okra genotypes (Abelmoschus esculentus L.). Genetic diversity was determined using fragment length analysis (FLA) of ten simple sequence repeat (SSR) markers. Physical and chemical evaluation of pectin was performed by means of FT-IR and NMR spectroscopy, sugar composition analysis (GC-MS), size exclusion chromatography coupled to multi-angle laser light scattering (SEC-MALLS), dilute solution viscometry and steady shear rheology assisted by principal component analysis (PCA). Each of the SSR markers detected on average 4.1 alleles and revealed unique genotypes for each sample. Extraction yield was between 11 and 14% resulting in pectin with galacturonic acid content between 43 and 63%, low degree of methylesterification (17e25%) and high degree of acetylation (20e40%). All samples were of high weightaverage molar mass (Mw) (700e1700 103 g mol1 ) and sugar composition analysis revealed the structural diversity of samples with HG/RG-I ratios ranging between 1.3 and 3.1. The present work shows that individual okra genotypes provide pectin with different structural properties that could potentially provide a new source of functional pectin for the food or pharmaceutical industries.
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    Structure and physicochemical properties of Ghanaian grewia gum
    (International Journal of Biological Macromolecules, 2019) Kpodo, Fidelis M.; Agbenorhevi, Jacob K.; Alba, K.; Smith, A. M.; Morris, G. A.; ko; Kontogiorgos, V.; 0000-0002-7949-0502; 0000-0002-8516-7656
    Grewia polysaccharides were isolated using sodium metabisulphite and phosphate buffers and the influence of the different extraction techniques on the chemical composition and structural characteristics of the extracts were determined. Structure and chemical composition of the resulting polysaccharide extracts were determined using FT-IR and NMR spectroscopy, neutral sugar analysis, size exclusion chromatography coupled to multi-angle light scattering (SEC-MALS), dilute solution viscometry and steady shear rheology. Chemical composition was similar irrespectively of the extraction solvent used and ranged between 11.1 and 16.5% for protein, 53.4 and 66.9% for total carbohydrate, 18.5 and 35.1% for total uronic acid and 23.5 and 28.6% for rhamnose. Predominate sugars in the extracts were rhamnose and uronic acids with spectroscopy showing the presence of esterified groups. Intrinsic viscosity varied between 6.5 and 9.1 dL g−1 and related with molar mass (754–2778 × 103 g mol−1 ). Grewia polysaccharide dispersions at 1 g dL−1 exhibited a shear thinning flow behaviour with crude and sodium metabisulphite extracts having higher viscosities. Overall, differences in extraction techniques produced grewia samples with tailored bulk properties for use in the food and pharmaceutical industries.
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    Structure and physicochemical properties of Ghanaian grewia gum
    (International Journal of Biological Macromolecules, 2019) Kpodo, Fidelis M.; Agbenorhevi, Jacob K.; Alba, K.; Smith, A. M.; Morris, G. A.; Kontogiorgos, V.; 0000-0002-7949-0502; 0000-0002-8516-7656
    Grewia polysaccharides were isolated using sodium metabisulphite and phosphate buffers and the influence of the different extraction techniques on the chemical composition and structural characteristics of the extracts were determined. Structure and chemical composition of the resulting polysaccharide extracts were determined using FT-IR and NMR spectroscopy, neutral sugar analysis, size exclusion chromatography coupled to multi-angle light scattering (SEC-MALS), dilute solution viscometry and steady shear rheology. Chemical composition was similar irrespectively of the extraction solvent used and ranged between 11.1 and 16.5% for protein, 53.4 and 66.9% for total carbohydrate, 18.5 and 35.1% for total uronic acid and 23.5 and 28.6% for rhamnose. Predominate sugars in the extracts were rhamnose and uronic acids with spectroscopy showing the presence of esterified groups. Intrinsic viscosity varied between 6.5 and 9.1 dL g−1 and related with molar mass (754–2778 × 103 g mol−1 ). Grewia polysaccharide dispersions at 1 g dL−1 exhibited a shear thinning flow behaviour with crude and sodium metabisulphite extracts having higher viscosities. Overall, differences in extraction techniques produced grewia samples with tailored bulk properties for use in the food and pharmaceutical industries.
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    Structure-Function Relationships in Pectin Emulsification
    (Food Biophysics, 2018) Kpodo, Fidelis M.; Agbenorhevi, Jacob K.; Alba, K.; Oduro, Ibok N.; Morris, G. A.; Kontogiorgos, Vassilis; 0000-0002-7949-0502; 0000-0002-8516-7656; 0000-0003-3731-2684
    The emulsifying characteristics of pectins isolated from six different okra genotypes were investigated and their structurefunction relationships have been evaluated. Emulsion formation and stabilization of acidic oil-in-water emulsions (pH 2.0, φ = 0.1) were studied by means of droplet size distribution, ζ-potential measurements, viscometry, interfacial composition analysis and fluorescence microscopy. Fresh and aged emulsions differed in terms of droplet size distribution, interfacial protein and pectin concentrations (Γ) depending on the molecular properties of pectin that was used. Specifically, pectins with intermediate length of RG-I branching with molar ratio of (Ara + Gal)/Rha between 2 and 3 exhibit the optimum emulsification capacity whereas samples with the molar ratio outside this range do not favour emulsification. Additionally, low amounts of RG-I segments (HG/RG-I > 2) improve long term stability of emulsions as opposed to the samples that contain high amounts of RG-I (HG/RG-I < 2) which lead to long term instability. Protein was not found to be the controlling factor for the stability of the dispersions. The present results show that rational design of pectin should be sought before application as functional ingredient in food and/or pharmaceutical systems.
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    Structure-Function Relationships in Pectin Emulsification
    (Food Biophysics, 2018) Kpodo, Fidelis M.; Agbenorhevi, Jacob K.; Alba, K.; Oduro, Ibok N.; Morris, G. A.; Kontogiorgos, Vassilis; 0000-0002-7949-0502; 0000-0002-8516-7656; 0000-0003-3731-2684; 0000-0001-6016-7580
    The emulsifying characteristics of pectins isolated from six different okra genotypes were investigated and their structure function relationships have been evaluated. Emulsion formation and stabilization of acidic oil-in-water emulsions (pH 2.0,φ = 0.1) were studied by means of droplet size distribution, ζ-potential measurements, viscometry, interfacial composition analysis and fluorescence microscopy. Fresh and aged emulsions differed in terms of droplet size distribution, interfacial protein and pectin concentrations (Γ) depending on the molecular properties of pectin that was used. Specifically, pectins with intermediate length of RG-I branching with molar ratio of (Ara + Gal)/Rha between 2 and 3 exhibit the optimum emulsification capacity whereas samples with the molar ratio outside this range do not favour emulsification. Additionally, low amounts of RG-I segments (HG/RG-I > 2) improve long term stability of emulsions as opposed to the samples that contain high amounts of RG-I (HG/RG-I < 2) which lead to long term instability. Protein was not found to be the controlling factor for the stability of the dispersions. The present results show that rational design of pectin should be sought before application as functional ingredient in food and/or pharmaceutical systems.