Effectiveness of three different storage structures and curing process for the storage of sweet potato (Ipomoea batatas) in Ghana

Three different storage structures and two curing processes for the storage of sweet potato (Ipomoea batatas) were studied at the CSIR-Food Research Institute, Accra. Sweet potato roots initially cured under warm(30-35 °C) and very humid (90-95% relative humidity) conditions for 7 and 14 days were stored in local (traditional), pit, and clamp storage structures for 84 days. After 0-84 days of storage, the roots were sampled and physically assessed into wholesome, sprouted, fungalinfected, and insect and rodent-damaged. The decrease in percentage wholesome roots corresponded to an increase in percentage fungal-infected roots from 0 to 84 days of storage in all the three different storage structures. Clamp storage structure recorded the highest percentage wholesome roots (20.0%) compared to pit (16.3%) and local (0%) after 84 days of storage when roots were cured for 7 days. However, for 14 days cured roots stored for 84 days, local storage structure recorded the highest percentage wholesome roots (20%), pit (0%), and clamp (10%). Higher percentages of fungal-infected sweet potato roots were recorded from roots cured for14 days. Percentage sprouted roots was higher in clamp, followed by pit and local storage structures. Sprouting was delayed for sweet potato roots that were cured for 14 days in all the storage structures. Percentage damage of sweet potato roots by insect and rodent was lower inall the three storage structures compared to the fungalinfected sweet potato roots

Utilization of Nutritional Compounds and Sclerotial Development of Sclerotium Rolfsii Isolated From Elaeis Guineensis and Xanthosoma Mafaffa in Ghana

Sclerotium rolfsii is a facultative soil parasite of economic importance causing disease of several economic crop plants. Bacterial and fungal parasites are themselves an assemblage of strains differing genetically and liable to variation. The possible effect of external nutrients on different S. rolfsii strains in Ghana has not been studied. In this study the utilization of twelve different nutritional compounds and sclerotia formation by five strains of Sclerotium rolfsii, SrXLL, SrXA1, SrXA2, SrEL1 and SrEL2 was investigated. In broth media with different carbon compounds - fructose, glucose, maltose, starch and sucrose - and with different nitrogen compounds - Ammonium chloride, Ammonium nitrate, Asparagine, Peptone and Sodium nitrate - a clearly discernible order of ability to utilize the two groups of compounds was noticed. The order of the strains in descending order of efficiency was SrEL2 > SrEL1 > SrXLL > SrXA1 > SrXA2. Among the carbon compounds the least utilized was starch. The best carbon compound varied with the strains. Peptone was universally a good nitrogen source. Over a concentration range of 0.5 to 2.0%, the greatest amount of pectolytic enzymes was produced in pectin media (20.0 per minute). Filtrates of strains SrXLL, SrXA1 and SrEL2 showed greater pectolytic enzymes activity than those of strains SrXA2 and SrEL1. But strains SrXA1 and SrXA2 showed greater ability to break down cellulose than the other three strains. In all the media studied the pH of the culture filtrate decreased to acidic levels at the end of incubation period. Journal of the Ghana Science Association Vol. 10 (2) 2008: pp. 116-12

Effect of agitation and antagonism between sucrose and sodium chloride on mass transfer during osmo-dehydration in plant materials

Osmotic dehydration studies on two varieties of apple (Golden Delicious and Cox), potato and banana found that the amount and rate of water loss occurred in the following descending order: Golden Delicious > Cox > potato > banana. However, minimal improvement on the mass transfer in the amount of water loss and solids gain and their corresponding rates was observed in the presence of sodium chloride and agitation of the osmotic solution especially for the first 30 minutes of osmotic dehydration for all the plant materials. Concentration of the osmotic solution and immersion time of samples in the osmotic solution had a significant effect on amount and rate of water loss from all commodities. The mass transfer in all the studied commodities depicted two distinct phases for the amount of water loss and rate of water loss. A corresponding uptake of solids from the osmotic solution occurred, the rate been greatest over the first 30 minutes, before declining significantly thereafter. For the mass transfer the rate of water loss was 3 - 8 times higher than solids gain

Application of radial basis function network with a Gaussian function of artificial neural networks in osmo-dehydration of plant materials

The study presents a critical evaluation of Artificial Neural Networks (ANNs) in food processing by successfully predicting the mass transfer in three plant materials. The used of ANNs in osmo-dehydration was evaluated using two varieties of apple (Malus domestica Borkh) of Golden Delicious and Cox, banana cultivar Cavendish and potato (Solanum tuberosum L.) variety Estima. In the ANNs, the radial basis function (RBF) network with a Gaussian function employing the orthogonal least square (OLS) learning method was used. A single hidden layer of few neurones (NHL = 20) resulted in the neural network being limited in its ability to model the process efficiently and the coefficient of determination (R2) was 0.76 for water loss. Increased neurones (NHL = 100) the network was improved significantly (R2 = 0.84) for water loss. Subsequent increase of the neurones to 120 (NHL = 120) showed a significant improvement of the network (R2 = 0.91) for sucrose gain. The mass transfer in the three plant materials were successfully predicted by the ANN models indicating the ability of ANN to model both linear and non-linear models as an advantage over empirical equations for quality predictions in food processing

Examining the physicochemical, functional and rheological properties in flours of farmers’ 7 key yam (Dioscorea spp.) varieties in Ghana to enhance yam production

Yam (Dioscorea spp.) is an important tuber crop in Ghana with high industrial potential. However the suitability of some yam varieties for diverse culinary and industrial purposes have not been widely studied to inform in their production. This study determined the physicochemical, functional and pasting characteristics in flours of farmers’ 7 key varieties of Dioscorea rotundata (white yam) and Dioscorea alata (water yam). Colour, pH, proximate composition, solubility index, swelling power and pasting properties were determined. Flours from the yam varieties were light in colour and fairly neutral in pH (6.3–6.6). Crude protein levels were between 3.7% for matches and 5.9% Serwah varieties, whereas crude fat was less than 0.5% and the mean ash content was 2.1%. Although significant differences existed between the flours, no clear trend was established to differentiate between D. rotundata and D. alata varieties based on their proximate composition. Swelling power (SP), solubility index (SI) and water absorption capacity (WAC) of the flours differed clearly. D. rotundata varieties had a relatively higher SP (12.5%) and WAC (7.1%), whereas D. alata (20.1%) had the highest SI. Significant differences (p < 0.05) in pasting behaviour were observed. Apart from Serwah and Mutwumudoo varieties, higher peak viscosity and positive retrogradation tendency were observed in the D. rotundata varieties. Among the 7 varieties, pastes from Akaba and Pona varieties were the most stable. The study has revealed that the properties of these varieties of Ghanaian yams make them suitable in diverse culinary and industrial applications

Evaluation of the physical and sensory characteristics of bread produced from three varieties of cassava and wheat composite flours. Food and Public Health

Abstract This study determines the most suitable cassava variety and an acceptable maximum substitution level of wheat flour with cassava flour for bread production in terms of baking and organoleptic characteristics using three varieties of cassava. High Quality Cassava Flour produced from three cassava varieties (Afisiafi, Bankye hemmaa and Doku duade) was used together with wheat in composite at 10%, 20% and 30% substitution levels. Bread samples were baked from the resulting composites and examined for its specific volume, density and hardness. The products were also subjected to sensory analysis for appearance, taste, texture and overall acceptability by a semi-trained panel of consumers. Increasing proportion of cassava flour in the composite bread reduced bread specific volume and increased density and hardness. Increasing the content of cassava in the composite resulted in bread that was less springy and difficult to chew. Springiness of bread substituted with 10% and 20% cassava flour compared well with the control, while those with 30% cassava were significantly less springy than the control. A substitution level of 10% Afisiafi and 20 % Bankye hemmaa cassava flour in composite bread on overall acceptable was similar to 100% wheat bread and therefore has the most suitable potential to replace part of wheat flour in bakery products

Identifying Biomass-Based Value Webs for Food Security in Sub-Saharan Africa: A Systems Modeling Approach

Food security in Sub-Saharan Africa (SSA) is dependent on complex networks of interconnected actors and the flows of resources (biomass, capital) and information among them. However, the degree to which actors and value chains of different crops are in fact interconnected and their current systemic influence on food security are unclear. Therefore, the concept of &#8220;value webs&#8221; to better capture the complexity within the networks emerges. Biomass-based value webs of selected crops in Ghana, Nigeria, and Ethiopia are modeled using the systems analysis software iMODELER and by eliciting factors as well as their interconnections through participatory stakeholder workshops. Furthermore, a generic model was created compiling the country models to identify overarching system dynamics with supporting and hindering factors impacting food security in SSA. Findings from the country models show highly complex value webs, suggesting that the predominant value chain approach may oversimplify actual structures and resource flows in real life settings. However, few interconnections within the value webs link the actors and flows of different crops, contradicting predictions emerging from other research. Results from the generic model allow for a critical reflection on the relation between value web dynamics and food security policy in SSA. Current national and regional policy trends targeting market integration, mechanization, and reduction of post-harvest losses are supported by model results