Browsing by Subject "Maniok"

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Foam mat drying of cassava and associated properties : comparison between white-flesh and yellow-flesh varieties
(2021) Ayetigbo, Oluwatoyin Elijah; Müller, Joachim
Cassava is an important staple food crop in Africa, Asia and Americas, serving as food, raw material, feed, and source of livelihoods. However, cassava has poor post-harvest physiological stability, deteriorates rapidly, has high toxic cyanogenic contents and poor physicochemical properties. Foam mat drying was considered as a technique to combat these challenges. First, a comparison of the different properties of variants of cassava based on colour was made from the perspective of sustainability. Afterwards, an optimization of the foaming process was conducted for two varieties (white-fleshed and yellow-fleshed) of cassava using various foaming variables. Optimal variables were not different between both varieties. Foaming reduced cyanogenic toxicity and retained carotenoids in cassava significantly, but also had significant influence on colour. The foams developed had asymmetrical distribution in air bubble diameter, while foam powder microstructure showed close association between the hydrocolloids and starch. Furthermore, an optimization of the drying conditions of optimal cassava foams was conducted based on temperature and foam thickness. Drying kinetics (moisture removal ratio, diffusivity, dying rate) of the cassava foams and the effect of various drying conditions on selected physicochemical properties of cassava foam powder was researched. Two falling rates were found during drying, Diffusivity was significantly affected by temperature but not foam thickness. The cassava foam powders had acceptably low cyanogenic contents, and had high retention of carotenoids. Foam powder microstructure did not change significantly with temperature, but yellow cassava foam powder had higher coalescence.
Public attitudes towards genetically modified provitamin A Cassava in Brazil
(2010) Gonzalez Rojas, María Carolina; Qaim, Matin
Cassava is a basic staple food crop with worldwide distribution, mainly in developing countries. A fundamental source of energy for the poor, cassava grows well on marginal soils and resists pests and drought. In Latin America, Brazil is the largest cassava producer and consumer. The crop is especially important in the northeastern (NE) part of the country, where poverty and malnutrition rates are higher than in the rest of the country. However, despite the crop?s dietary importance, relatively little is known about consumer preferences, which holds true not only for Brazil but also for other developing countries. Understanding consumer preferences is crucial for technology and market development, especially in the context of provitamin A biofortification, as this entails a yellow-colored cassava root. The first article, titled ?Consumer Preferences for Cassava Characteristics in Pernambuco, Brazil?, addresses this research gap. Consumer preference for different cassava attributes are analyzed using household survey data and econometric techniques. A hedonic price model is specifically developed to estimate the values that consumers place on specific product attributes. Results show the most important characteristics for local consumers are ease of peeling, time of cooking, and texture; however, root color and size as well as market location are other relevant attributes in determining price. The second article, titled ?Consumer Acceptance of Second-Generation GM Foods: The Case of Biofortified Cassava in the Northeast of Brazil?, examines whether consumers would appreciate provitamin A biofortification and accept GM cassava. For this purpose, stated preference data, collected as part of the household survey, are used. Findings suggest that attitudes towards GM biofortified cassava are generally quite positive among local consumers. Three-quarters of all respondents in the survey said they would support the introduction of this new technology. Using contingent valuation techniques, consumers were shown to be willing to pay an average price premium of 64% for GM biofortified cassava. This is high but not unrealistic, given that vitamin A deficiency and related health problems are widespread in NE Brazil. In addition, a contingent ranking choice experiment was used to better understand the trade-offs between different cassava characteristics and estimate the partial willingness to pay (WTP) for each relevant attribute. For the provitamin A attribute alone, the average consumer is willing to pay a large premium of 160%. However, a discount is required for the color change of cassava from white to yellow (-29%), and an additional discount results from the fact that the cassava is genetically modified (-61%). These are important findings for biofortification research programs that have to make choices between conventional and GM breeding techniques. It is noted that a significantly positive WTP does not imply that GM provitamin A cassava will indeed be sold at a premium. The technology is being developed by the public sector with the aim to reduce malnutrition among the poor, so a low price should be sought to enable easy access. Hence, the WTP survey is a tool to better understand consumer attitudes rather than an approach to develop a pricing strategy for a new commercial product. The third article, titled ?Stakeholder Positions toward GM Food: The Case of Vitamin A Biofortified Cassava in Brazil?, gathers experiences from around the world and shows that stakeholder positions can crucially influence the efficiency of GM regulatory approaches and the success of new technologies. This research builds on a survey of a large range of local stakeholders. Overall, stakeholder perceptions about GM foods are relatively positive in Brazil. Statistical analysis shows that three groups of stakeholders can be distinguished: those in favor of GM crops, those against, and those that have a more or less neutral position. Representatives of local and multinational industries and those of several governmental entities belong mostly to the first group; international and national NGOs form the second group, while scientists are mostly found in the third group. Information sources and institutional/personal relationships influence individual stakeholder positions, as do socio-demographic characteristics, such as the level of education and age. An important result is also the high level of trust that stakeholders in Brazil have, in general, in the country?s research and academic sectors. Therefore, taking into account the relevance of information and the role played by the research sector, an effective system of distributing GM crop information via government agencies and/or public media is necessary to complement the knowledge of consumers so that they can make their own informed decisions.