Browsing by Author "Tosh, Susan M."

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    Rheological and microstructural investigation of oat -glucan isolates varying in molecular weight
    (International Journal of Biological Macromolecules, 2011) Agbenorhevi, Jacob K.; Kontogiorgos, Vassilis; Kirby, Andrew R.; Morris, Victor, J.; Tosh, Susan M.; 0000-0002-8516-7656; 0000-0001-6016-7580
    The rheological properties and microstructure of aqueous oat -glucan solutions varying in molecular weight were investigated. The structural features and molecular weights (MW) were characterized by 13C NMR spectroscopy and high performance size-exclusion chromatography (HPSEC), respectively. The microstructure of the -glucans dispersions was also examined by atomic force microscopy (AFM). The samples with -glucan content between 78 and 86% on a dry weight basis had MW, intrinsic viscosity ([ ]) and critical concentration (c*) in the range of 142–2800 × 103 g/mol, 1.7–7.2 dl/g and 0.25–1.10 g/dl, respectively. The flow and viscoelastic behaviour was highly dependent on MW and on the concentration of the -glucans dispersions. Pseudoplastic behaviour was exhibited at high concentrations and Newtonian behaviour was evident atlow concentrations. At the same concentration,the viscosity was higher for higher MW samples. The Cox–Merz rule was applicable for the lower molecular weight samples at higher concentrations whereas the high molecular weight sample deviated at concentrations greater than 1.0%,w/v. The mechanical spectra with variation of both MW and concentration were typical of entangled biopolymer solutions. AFM images revealed the formation of clusters or aggregates linked via individual polymer chains scattered heterogeneously throughout the system. The aggregate size increased with the molecular weight of the samples investigated and has been linked to the rheological behaviour of the samples.
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    Rheological and microstructural investigation of oat -glucan isolates varying in molecular weight
    (International Journal of Biological Macromolecules, 2011) Agbenorhevi, Jacob K.; Kontogiorgos, Vassilis; Kirby, Andrew R.; Morris, Victor J.; Tosh, Susan M.; 0000-0002-8516-7656
    The rheological properties and microstructure of aqueous oat -glucan solutions varying in molecular weight were investigated. The structural features and molecular weights (MW) were characterized by 13C NMR spectroscopy and high performance size-exclusion chromatography (HPSEC), respectively. The microstructure of the -glucans dispersions was also examined by atomic force microscopy (AFM). The samples with -glucan content between 78 and 86% on a dry weight basis had MW, intrinsic viscosity ([ ]) and critical concentration (c*) in the range of 142–2800 × 103 g/mol, 1.7–7.2 dl/g and 0.25–1.10 g/dl, respectively. The flow and viscoelastic behaviour was highly dependent on MW and on the concentration of the -glucans dispersions. Pseudoplastic behaviour was exhibited at high concentrations and Newtonian behaviour was evident at low concentrations. At the same concentration,the viscosity was higher for higher MW samples. The Cox–Merz rule was applicable for the lower molecular weight samples at higher concentrations whereas the high molecular weight sample deviated at concentrations greater than 1.0%, w/v. The mechanical spectra with variation of both MW and concentration were typical of entangled biopolymer solutions. AFM images revealed the formation of clusters or aggregates linked via individual polymer chains scattered heterogeneously throughout the system. The aggregate size increased with the molecular weight of the samples investigated and has been linked to the rheological behaviour of the samples
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    The Effect of Processing on Bioactive Compounds and Nutritional Qualities of Pulses in Meeting the Sustainable Development Goal 2
    (Frontiers in Sustainable Food Systems, 2021-05-21) Acquah, Caleb; Ohemeng-Boahen, Godfred; Power, Krista A.; Tosh, Susan M.
    Diversification of plant-based food sources is necessary to improve global food and nutritional security. Pulses have enormous nutritional and health benefits in preventing malnutrition and chronic diseases while contributing positively to reducing environmental footprint. Pulses are rich in diverse nutritional and non-nutritional constituents which can be classified as bioactive compounds due to their biological effect. These bioactive compounds include but are not limited to proteins, dietary fibres, resistant starch, polyphenols, saponins, lectins, phytic acids, and enzyme inhibitors. While these compounds are of importance in ensuring food and nutritional security, some of the bioactive constituents have ambivalent properties. These properties include having antioxidant, anti-hypertensive and prebiotic effects. Others have a deleterious effect of decreasing the digestibility and/or bioavailability of essential nutrients and are therefore termed antinutritional factors/compounds. Various processing techniques exist to reduce the content of antinutritional factors found in pulses. Traditional processing of pulses comprises soaking, dehulling, milling, germination, fermentation, and boiling, while examples of emerging processing techniques include microwaving, extrusion, and micronization. These processing techniques can be tailored to purpose and pulse type to achieve desired results. Herein, the nutritional qualities and properties of bioactive compounds found in pulses in meeting the sustainable development goals are presented. It also discusses the effect of processing techniques on the nutritional and non-nutritional constituents in pulses as well as the health and environmental benefits of pulse-diet consumption. Major challenges linked to pulses that could limit their potential of being ideal crops in meeting the sustainable development goal 2 agenda are highlighted.