Browsing by Author "Ofosu, Isaac Williams"

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    3-Monochloropropandiol and glycidyl esters in heat-processed oil-based food products: Exposure and risk
    (Applied Food Research, 2024-06) Yabani, Daniel Sitsofe; Ofosu, Isaac Williams; Ankar-Brewoo, Gloria Mathanda; Lutterodt, Herman Erick; 0000-0001-5442-6654; 0000-0002-9553-0834; 0000-0001-8574-3409; 0000-0001-7015-7597
    Fatty acid esters of 3-monochloro-1,2-propanediol (3-MCPDE) and glycidol (GE) are potentially harmful heatinduced contaminants produced during food processing. In this study, 100 heat-treated oil-based food samples covering fried, smoked, grilled, and baked food groups were collected in Koforidua, Ghana and analysed for the two esters using gas chromatography-mass spectrometry. The dietary exposures were estimated by a probabilistic approach using Monte Carlo Simulation. Levels of 3-MCPDE and GE in the foods ranged from
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    Consumption Patterns, Protein Quality and Hazards of “NULs” Utilization
    (NOVEMBER, 2017) Ofosu, Isaac Williams
    Many people consume large quantities of plant-based products, including neglected and underutilized legumes (NULs), because of their availability or affordability. This makes NULs a critical food security resource. However, NULs are known to contain toxins such as lectins (glycoproteins) which persistently resist heat inactivation, making them a potentially serious health hazard. In order to promote their continuous and sustainable utilization, consumption profile, safety and nutritional quality by way of essential amino acids need to be investigated. Furthermore, suitable ways of attenuating the possible risks of lectins in NULs need to be investigated. A survey was carried out aimed at finding the processing and consumption patterns of five selected NULs; Vigna subterranea, Cajanus cajan, Mucuna pruriens, Phaseolus lunatus and Canavalia ensiformis focusing on consumer characteristics such as: age, house hold numbers, educational levels, marital status and occupation. Also considered were, the familiarity of NULs, perception of hazards and the risks, in terms of exposure assessment and exposure frequency of dishes consumed per body weight of consumers. Time-heat inactivation of the lectins in NULs flours, as well as their NULs’ model dishes were studied, from which risk was evaluated, using the hazard-based approach. Five different NULs protein extracts were profiled to ascertain the essential amino acids, and the quality evaluated by matching them against the standard FAO/WHO dietary indispensable amino acids for three age groups; infants, children and adults. −Radiated starches prepared using radiation doses from 3 to 42 kGy were composited at 10% composition with defatted NULs flours, with respect to quantities of native starches present in NULs. The composites were agitated in an extruder which operated within intrinsic temperature ranging from 2 to 12 oC. Residual lectins from the extrudates were quantified by ELISA analysis. The statistical analysis of the collected survey data involved the use of Palisade @Risk software to fit each measured parameter to the most adequate probabilistic distribution, based on its Akaike information criterion. Subsequently, the central tendency characteristics of the measured parameters, together with their variations, uncertainties and distribution functions were recorded. In the survey of the consumption of NULs, it was observed that, majority of the respondents who were over 40 years (67.6%) were familiar (59.4%) with NULs and consumed NULs dishes. The most popular dishes were prepared from Vigna subterranea (15.9%) and Phaseolus lunatus (14.95%). The majority of consumers (66%), perceived the presence of hazards in NULs, citing pesticide residues (58.7%), but no intrinsic hazards as threat. However, a few (16.6%) considered the interaction between pesticide residues and food additives as dangerous. Majority (66.1%) regarded NULs dishes as safe, while at the same time complained of stomach discomfort (97.2%) after consumption. In spite of these observations, they would still recommend their use to others. Through the ELISA analysis, significantly high quantities of lectins still remained in Vigna subterranea flours even after cooking for 1 h. Risk analysis of the modelled foods revealed that the hazard quotient (HQ) of all the NULs dishes were above 1, meaning consumers are at risk of systemic toxicity. Assessment of essential amino acids revealed that, out of the five NULs studied, Vigna subterranea had adequate quantities of histidine (26.2 mg/g) that met the dietary requirements of all the three age groups. However, the levels of isoleucine (35.9 mg/g) and the aromatic amino acids phenylalanine and tyrosine (94 mg/g) were adequate for only children and adults. In the case of Phaseolus lunatus, lysine (53.6 mg/g) and threonine (44 mg/g) were relatively high. However, this could only meet the adults’ requirement. In spite of these contributions of amino acids, protein quality of Vigna subterranea and Phaseolus lunatus proteins, based on digested indispensable amino acid scores (DIAAS) presented a different outlook. Thus, the DIAAS of Vigna subterranea (3.6) and Phaseolus lunatus (2.5), show low quality, relative to international standards. In the studies involving the attenuation of lectins in NULs, Mamdani type fuzzy logic inference system was used to model the two input variables of the NULs flour treatment to predict the optimal lectin inactivation at 100% accuracy. While lectins from Canavalia ensiformis recorded 83% inactivation, lectins from Vigna subterranea rather potentiated up to 44%. Thus, -radiated starches incorporation into NULs flours during low temperature extrusion treatment, inactivated NULs lectins at varying degrees and these were adequately predicted by the model.
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    ‘Preparation of acetylated and carboxylated starches and their applications in salad cream preparation’
    (2000-02-01) Ofosu, Isaac Williams
    Cassava cultivar, Abasafltaa and Afisiafi and sweet potato cultivar, Sauti and Faara starch acetates and carboxylates were produced. The Crop Research Institute, Ghana released these cultivars. Starch acetates and carboxylates of varying solubilities, swelling powers, retrogradation, % acetyl, % carboxyl groups and viscosities were obtained. Modified starches obtained from 20% v/w acetic acid anhydride which gave % acetyl group of 1.71, solubility of 83.1%, swelling power of 4.70g/g and least retrogradation was used to prepare salad creams. The products were analysed on their sensory properties; aroma, colour and taste. The results indicated that the cream with 2.4% modified starch and 0.002% bixin per 100-mi coloured vegetable oil compared favourably (P>0.05) with the control salad cream obtained from the market. However, long storage period and freeze — thaw tests revealed that the control salad cream was more stable (P>0.05) than the cream prepared from the selected cassava starch acetate in terms of colour and emulsion respectively. The sweet potato starches modified below 50°C, as well as all the carboxylated starches and the native starches retrograded over a 24hour period so they were not used to prepare the creams.