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Air quality is often assessed using particulate matter (PM) mass concentration without considering its toxicity, thus possibly leading to improper control policies or inadequate health protection. Here, we studied differences in oxidative potentials (OPs) of PM samples collected using automobile air conditioning (AC) filters from 19 global cities, as well as influences from microbial contents. Dithiothreitol (DTT) assay showed remarkable differences in the PM OPs among cities (p-values ≤ 0.001, Kruskal-Wallis test). For example, the normalized index of oxidant generation (NIOG) of PM samples in San Francisco (2.20 × 10−2, annual average PM10 = 16 μg/m3) was found to be twice that in Beijing (1.14 × 10−2, annual average PM10 = 135 μg/m3). Limulus amebocyte lysate (LAL) assay found that PM-borne endotoxin ranged from 12.16 EU/mg (Florianopolis, Brazil) to 2518.23 EU/mg (Chennai, India) among cities. Besides, culturing method and real-time qPCR revealed significant differences of up to ∼100-fold in both bacterial and fungal levels among 19 cities. Spearman's correlation analysis implied that PM-borne microbes such as bacteria and fungi as well as metals could strongly influence the PM OP. As an example, our results in Xi'an, China further suggest that the PM2.5 OP evolves for a particular city over the time, which is attributable to both the urbanization and air pollution control measures. This work highlights the importance in optimizing the current air quality control measures by considering the toxicity factor and its microbial constituents.

Despite its emerging significant public health concern, the presence of antibiotic resistance genes (ARGs) in urban air has not received significant attention. Here, we profiled relative abundances (as a fraction, normalized by 16S rRNA gene) of 30 ARG subtypes resistant to seven common classes of antibiotics, which are quinolones, β-lactams, macrolides, tetracyclines, sulfonamides, aminoglycosides, and vancomycins, in ambient total particulate matter (PM) using a novel protocol across 19 world cities. In addition, their longitudinal changes in PM2.5 samples in Xi’an, China as an example were also studied. Geographically, the ARGs were detected to vary by nearly 100-fold in their abundances, for example, from 0.07 (Bandung, Indonesia) to 5.6 (San Francisco, USA). The β-lactam resistance gene blaTEM was found to be most abundant, seconded by quinolone resistance gene qepA; and their corresponding relative abundances have increased by 178% and 26%, respectively, from 2004 to 2014 in Xi’an. Independent of cities, gene network analysis indicates that airborne ARGs were differentially contributed by bacterial taxa. Results here reveal that urban air is being polluted by ARGs, and different cities are challenged with varying health risks associated with airborne ARG exposure. This work highlights the threat of urban airborne transmission of ARGs and the need of redefining our current air quality standards in terms with public health.

The environmental impacts of the transformation of cassava roots into starch were assessed for three contrasting technologies at small and large scale (1-2 and 100-200t starch per day), using the Life Cycle Assessment (LCA) methodology. The objective was to assess impacts for each unit operation, so as to identify impacts hotspots as well as sustainable practices, with a view to uncover opportunities for improving the environmental performance of cassava starch production. The system boundaries were defined as the unit operations used to transform fresh cassava roots delivered at factory gate into loose, dry cassava starch. Inventory data indicated wide variations in energy and water consumption. The large scale technology required 702kWh/t starch, mainly (75%) from fuel oil used for the drying operation, but was most efficient in terms of water use (10m3/t starch) due to water recycling between unit operations. The two small scale technologies were similar in terms of electricity use (59kWh/t starch), and relied on solar energy for drying. In contrast, their water consumption varied from 20 to 60m3/t starch due to differences in the design of the rasping and starch recovery (extraction) operations. The LCA characterizations, using the ReCiPe method, indicated that the main impact contributions were at the drying operation for the large scale technology, and at the extraction operation for the small scale technologies, mainly because of energy use, as well as water use in the case of the most water-intensive technology. Hence strategies to reduce the impacts of cassava starch production could focus on: Increasing the energy efficiency of the drying operation or replacing fossil energy with a renewable source (biogas), which can be produced from the factory wastewater; Improving the design of some unit operations with regards to water and energy efficiency; and Promoting the transfer and adoption of water recycling practices.

The environmental impacts of the transformation of cassava roots into starch were assessed for three contrasting technologies at small and large scale (1-2 and 100-200t starch per day), using the Life Cycle Assessment (LCA) methodology. The objective was to assess impacts for each unit operation, so as to identify impacts hotspots as well as sustainable practices, with a view to uncover opportunities for improving the environmental performance of cassava starch production. The system boundaries were defined as the unit operations used to transform fresh cassava roots delivered at factory gate into loose, dry cassava starch. Inventory data indicated wide variations in energy and water consumption. The large scale technology required 702kWh/t starch, mainly (75%) from fuel oil used for the drying operation, but was most efficient in terms of water use (10m3/t starch) due to water recycling between unit operations. The two small scale technologies were similar in terms of electricity use (59kWh/t starch), and relied on solar energy for drying. In contrast, their water consumption varied from 20 to 60m3/t starch due to differences in the design of the rasping and starch recovery (extraction) operations. The LCA characterizations, using the ReCiPe method, indicated that the main impact contributions were at the drying operation for the large scale technology, and at the extraction operation for the small scale technologies, mainly because of energy use, as well as water use in the case of the most water-intensive technology. Hence strategies to reduce the impacts of cassava starch production could focus on: Increasing the energy efficiency of the drying operation or replacing fossil energy with a renewable source (biogas), which can be produced from the factory wastewater; Improving the design of some unit operations with regards to water and energy efficiency; and Promoting the transfer and adoption of water recycling practices.

The environmental impacts of the transformation of cassava roots into starch were assessed for three contrasting technologies at small and large scale (1-2 and 100-200t starch per day), using the Life Cycle Assessment (LCA) methodology. The objective was to assess impacts for each unit operation, so as to identify impacts hotspots as well as sustainable practices, with a view to uncover opportunities for improving the environmental performance of cassava starch production. The system boundaries were defined as the unit operations used to transform fresh cassava roots delivered at factory gate into loose, dry cassava starch. Inventory data indicated wide variations in energy and water consumption. The large scale technology required 702kWh/t starch, mainly (75%) from fuel oil used for the drying operation, but was most efficient in terms of water use (10m3/t starch) due to water recycling between unit operations. The two small scale technologies were similar in terms of electricity use (59kWh/t starch), and relied on solar energy for drying. In contrast, their water consumption varied from 20 to 60m3/t starch due to differences in the design of the rasping and starch recovery (extraction) operations. The LCA characterizations, using the ReCiPe method, indicated that the main impact contributions were at the drying operation for the large scale technology, and at the extraction operation for the small scale technologies, mainly because of energy use, as well as water use in the case of the most water-intensive technology. Hence strategies to reduce the impacts of cassava starch production could focus on: Increasing the energy efficiency of the drying operation or replacing fossil energy with a renewable source (biogas), which can be produced from the factory wastewater; Improving the design of some unit operations with regards to water and energy efficiency; and Promoting the transfer and adoption of water recycling practices. (Texte intégral)

The environmental impacts of the transformation of cassava roots into starch were assessed for three contrasting technologies at small and large scale (1-2 and 100-200t starch per day), using the Life Cycle Assessment (LCA) methodology. The objective was to assess impacts for each unit operation, so as to identify impacts hotspots as well as sustainable practices, with a view to uncover opportunities for improving the environmental performance of cassava starch production. The system boundaries were defined as the unit operations used to transform fresh cassava roots delivered at factory gate into loose, dry cassava starch. Inventory data indicated wide variations in energy and water consumption. The large scale technology required 702kWh/t starch, mainly (75%) from fuel oil used for the drying operation, but was most efficient in terms of water use (10m3/t starch) due to water recycling between unit operations. The two small scale technologies were similar in terms of electricity use (59kWh/t starch), and relied on solar energy for drying. In contrast, their water consumption varied from 20 to 60m3/t starch due to differences in the design of the rasping and starch recovery (extraction) operations. The LCA characterizations, using the ReCiPe method, indicated that the main impact contributions were at the drying operation for the large scale technology, and at the extraction operation for the small scale technologies, mainly because of energy use, as well as water use in the case of the most water-intensive technology. Hence strategies to reduce the impacts of cassava starch production could focus on: Increasing the energy efficiency of the drying operation or replacing fossil energy with a renewable source (biogas), which can be produced from the factory wastewater; Improving the design of some unit operations with regards to water and energy efficiency; and Promoting the transfer and adoption of water recycling practices. (Texte intégral)

Several starch-producing plants are grown in South-East Asia, from which starch is extracted at small scale for local use. This study undertakes to identify properties specific to some of these starches in model food systems, in order to demonstrate their potential as food ingredients and thereby encourage the development of economic activities related to their production and use. Selected starches were canna, mungbean, sago, kudzu, taro and yam bean, and were sourced from Vietnam or Thailand. Cassava, rice and maize starches were also included as references. The different starches showed distinct behaviors in terms of gel texture, noodle texture, expansion ability and syneresis under refrigerated and frozen conditions. Mungbean and canna gave hard gels with high compressive strengths (13000-30000kg/m2), whereas taro, yam bean, kudzu, rice and maize gave much softer gels with compressive strengths below 6000 kg/m2. Compressive strains at peak force evidenced further differences between starches, with sago and taro able to undergo large (0.47-0.50), mungbean, canna and yam bean intermediate (0.35-0.44), and kudzu only small (0.20) deformations. Hence different types of starches can create a range of gel textures, from soft to hard and from fairly brittle to more cohesive. In particular, canna and mungbean formed unusually hard gels, compared to commonly used starches such as rice and maize. Noodles prepared from canna and mungbean were fairly rigid with high tensile strengths (4000-10000kg/m2) and low strains at break (0.2-0.4), while noodles from kudzu, sago and cassava were soft and extensible with low tensile strengths (1340, 1590, 430 kg/m2, respectively) and either intermediate (kudzu, sago) or high (cassava) strains at break (0.63, 0.94, 1.21, respectively). Noodles made of cassava blended with other starches showed mechanical properties intermediate between those of the pure starches, which raised the question of starch compatibility and blend morphology in sy

Several starch-producing plants are grown in South-East Asia, from which starch is extracted at small scale for local use. This study undertakes to identify properties specific to some of these starches in model food systems, in order to demonstrate their potential as food ingredients and thereby encourage the development of economic activities related to their production and use. Selected starches were canna, mungbean, sago, kudzu, taro and yam bean, and were sourced from Vietnam or Thailand. Cassava, rice and maize starches were also included as references. The different starches showed distinct behaviors in terms of gel texture, noodle texture, expansion ability and syneresis under refrigerated and frozen conditions. Mungbean and canna gave hard gels with high compressive strengths (13000-30000kg/m2), whereas taro, yam bean, kudzu, rice and maize gave much softer gels with compressive strengths below 6000 kg/m2. Compressive strains at peak force evidenced further differences between starches, with sago and taro able to undergo large (0.47-0.50), mungbean, canna and yam bean intermediate (0.35-0.44), and kudzu only small (0.20) deformations. Hence different types of starches can create a range of gel textures, from soft to hard and from fairly brittle to more cohesive. In particular, canna and mungbean formed unusually hard gels, compared to commonly used starches such as rice and maize. Noodles prepared from canna and mungbean were fairly rigid with high tensile strengths (4000-10000kg/m2) and low strains at break (0.2-0.4), while noodles from kudzu, sago and cassava were soft and extensible with low tensile strengths (1340, 1590, 430 kg/m2, respectively) and either intermediate (kudzu, sago) or high (cassava) strains at break (0.63, 0.94, 1.21, respectively). Noodles made of cassava blended with other starches showed mechanical properties intermediate between those of the pure starches, which raised the question of starch compatibility and blend morphology in sy

This study attempts at exploring the physicochemical and functional characteristics of several types of tropical starches separated from starch-producing plants from South-East Asia. In Vietnam and Thailand, despite the fact that starch is the major component of tubers, these crops remain underutilized and represent a potential field for post-harvest applications. In this work, selected root and tuber crops were potato, sweet potato, cassava, taro, yam bean and canna. Sago was the tree crop sample; kudzu and mung bean as legumes samples. Common cereals like rice and maize were also selected as references. Granule size was measured by laser diffraction. Thermal properties were obtained by DSC analysis. Viscosity properties were determined by RVA. The results obtained with cereals, legumes and other types of starches, were contrasted, suggesting a separate analysis of starches from root and tubers. The selected root and tuber starches had lipid, protein and ash contents in the range of 0.16-0.52%, 0.08-0.21% and 0.01-0.44% respectively. Significant differences in the granule size distribution between starches were observed with the largest type of granules for canna (55^m). DSC gelatinization temperatures were lower for cassava than for aroids. Further investigations are needed to better understand the relationships between proximate analysis, granule distribution and thermal properties of starches, thus the quality of the foodstuffs manufactured from root and tuber crops. (Texte intégral)

This study attempts at exploring the physicochemical and functional characteristics of several types of tropical starches separated from starch-producing plants from South-East Asia. In Vietnam and Thailand, despite the fact that starch is the major component of tubers, these crops remain underutilized and represent a potential field for post-harvest applications. In this work, selected root and tuber crops were potato, sweet potato, cassava, taro, yam bean and canna. Sago was the tree crop sample; kudzu and mung bean as legumes samples. Common cereals like rice and maize were also selected as references. Granule size was measured by laser diffraction. Thermal properties were obtained by DSC analysis. Viscosity properties were determined by RVA. The results obtained with cereals, legumes and other types of starches, were contrasted, suggesting a separate analysis of starches from root and tubers. The selected root and tuber starches had lipid, protein and ash contents in the range of 0.16-0.52%, 0.08-0.21% and 0.01-0.44% respectively. Significant differences in the granule size distribution between starches were observed with the largest type of granules for canna (55ìm). DSC gelatinization temperatures were lower for cassava than for aroids. Further investigations are needed to better understand the relationships between proximate analysis, granule distribution and thermal properties of starches, thus the quality of the foodstuffs manufactured from root and tuber crops. (Texte intégral)

Several starch-producing plants are grown in South-East Asia, from which starch is extracted at small scale for local use. This study undertakes to identify properties specific to some of these starches in model food systems, in order to demonstrate their potential as food ingredients and thereby encourage the development of economic activities related to their production and use. Selected starches were canna, mungbean, sago, kudzu, taro and yam bean, and were sourced from Vietnam or Thailand. Cassava, rice and maize starches were also included as references. The different starches showed distinct behaviors in terms of gel texture, noodle texture, expansion ability and syneresis under refrigerated and frozen conditions. Mungbean and canna gave hard gels with high compressive strengths (13000-30000kg/m2), whereas taro, yam bean, kudzu, rice and maize gave much softer gels with compressive strengths below 6000 kg/m2. Compressive strains at peak force evidenced further differences between starches, with sago and taro able to undergo large (0.47-0.50), mungbean, canna and yam bean intermediate (0.35-0.44), and kudzu only small (0.20) deformations. Hence different types of starches can create a range of gel textures, from soft to hard and from fairly brittle to more cohesive. In particular, canna and mungbean formed unusually hard gels, compared to commonly used starches such as rice and maize. Noodles prepared from canna and mungbean were fairly rigid with high tensile strengths (4000-10000kg/m2) and low strains at break (0.2-0.4), while noodles from kudzu, sago and cassava were soft and extensible with low tensile strengths (1340, 1590, 430 kg/m2, respectively) and either intermediate (kudzu, sago) or high (cassava) strains at break (0.63, 0.94, 1.21, respectively). Noodles made of cassava blended with other starches showed mechanical properties intermediate between those of the pure starches, which raised the question of starch compatibility and blend morphology in sy

Several starch-producing plants are grown in South-East Asia, from which starch is extracted at small scale for local use. This study undertakes to identify properties specific to some of these starches in model food systems, in order to demonstrate their potential as food ingredients and thereby encourage the development of economic activities related to their production and use. Selected starches were canna, mungbean, sago, kudzu, taro and yam bean, and were sourced from Vietnam or Thailand. Cassava, rice and maize starches were also included as references. The different starches showed distinct behaviors in terms of gel texture, noodle texture, expansion ability and syneresis under refrigerated and frozen conditions. Mungbean and canna gave hard gels with high compressive strengths (13000-30000kg/m2), whereas taro, yam bean, kudzu, rice and maize gave much softer gels with compressive strengths below 6000 kg/m2. Compressive strains at peak force evidenced further differences between starches, with sago and taro able to undergo large (0.47-0.50), mungbean, canna and yam bean intermediate (0.35-0.44), and kudzu only small (0.20) deformations. Hence different types of starches can create a range of gel textures, from soft to hard and from fairly brittle to more cohesive. In particular, canna and mungbean formed unusually hard gels, compared to commonly used starches such as rice and maize. Noodles prepared from canna and mungbean were fairly rigid with high tensile strengths (4000-10000kg/m2) and low strains at break (0.2-0.4), while noodles from kudzu, sago and cassava were soft and extensible with low tensile strengths (1340, 1590, 430 kg/m2, respectively) and either intermediate (kudzu, sago) or high (cassava) strains at break (0.63, 0.94, 1.21, respectively). Noodles made of cassava blended with other starches showed mechanical properties intermediate between those of the pure starches, which raised the question of starch compatibility and blend morphology in sy

This study attempts at exploring the physicochemical and functional characteristics of several types of tropical starches separated from starch-producing plants from South-East Asia. In Vietnam and Thailand, despite the fact that starch is the major component of tubers, these crops remain underutilized and represent a potential field for post-harvest applications. In this work, selected root and tuber crops were potato, sweet potato, cassava, taro, yam bean and canna. Sago was the tree crop sample; kudzu and mung bean as legumes samples. Common cereals like rice and maize were also selected as references. Granule size was measured by laser diffraction. Thermal properties were obtained by DSC analysis. Viscosity properties were determined by RVA. The results obtained with cereals, legumes and other types of starches, were contrasted, suggesting a separate analysis of starches from root and tubers. The selected root and tuber starches had lipid, protein and ash contents in the range of 0.16-0.52%, 0.08-0.21% and 0.01-0.44% respectively. Significant differences in the granule size distribution between starches were observed with the largest type of granules for canna (55^m). DSC gelatinization temperatures were lower for cassava than for aroids. Further investigations are needed to better understand the relationships between proximate analysis, granule distribution and thermal properties of starches, thus the quality of the foodstuffs manufactured from root and tuber crops. (Texte intégral)

This study attempts at exploring the physicochemical and functional characteristics of several types of tropical starches separated from starch-producing plants from South-East Asia. In Vietnam and Thailand, despite the fact that starch is the major component of tubers, these crops remain underutilized and represent a potential field for post-harvest applications. In this work, selected root and tuber crops were potato, sweet potato, cassava, taro, yam bean and canna. Sago was the tree crop sample; kudzu and mung bean as legumes samples. Common cereals like rice and maize were also selected as references. Granule size was measured by laser diffraction. Thermal properties were obtained by DSC analysis. Viscosity properties were determined by RVA. The results obtained with cereals, legumes and other types of starches, were contrasted, suggesting a separate analysis of starches from root and tubers. The selected root and tuber starches had lipid, protein and ash contents in the range of 0.16-0.52%, 0.08-0.21% and 0.01-0.44% respectively. Significant differences in the granule size distribution between starches were observed with the largest type of granules for canna (55ìm). DSC gelatinization temperatures were lower for cassava than for aroids. Further investigations are needed to better understand the relationships between proximate analysis, granule distribution and thermal properties of starches, thus the quality of the foodstuffs manufactured from root and tuber crops. (Texte intégral)

In Colombia and in Vietnam, small-scale cassava starch processing is conducted at similar scales but with contrasted extraction technologies. Based on the methodology of diagnosis previously applied in Vietnam, two set of trials with two different cassava cultivars (var. mper183 and var. algodona) were carried out in a typical processing plant from Northern Cauca in Colombia. Moisture, starch, crude fibres and ash content analysis were carried out on samples collected from the manufacturing process to establish the mass balance of starch. Production capacity, water consumption, electrical requirements and capital-labor costs per tonne of starch (12% moisture) were also reported. The manufacturing process enabled 65% recovery of the starch present in fresh roots, with no significant change observed in the composition of starch for the two varieties. The bottleneck of the manufacturing process occurred at extraction stage were low capacity were observed (0.3 t of peeled roots per hour). Water consumption per ton of starch was 67 m3, in which washing, rasping, and extraction stages accounted for 9, 3, and 42 m3, respectively. Electrical power per tone of starch was 59 kWh, in which, washing, rasping, and extraction stages accounted for 8, 14 and 38 kWh. The comparison proposed in this study allowed to recommend technological options for small-scale cassava processing industries.

In Colombia and in Vietnam, small-scale cassava starch processing is conducted at similar scales but with contrasted extraction technologies. Based on the methodology of diagnosis previously applied in Vietnam, two set of trials with two different cassava cultivars (var. mper183 and var. algodona) were carried out in a typical processing plant from Northern Cauca in Colombia. Moisture, starch, crude fibres and ash content analysis were carried out on samples collected from the manufacturing process to establish the mass balance of starch. Production capacity, water consumption, electrical requirements and capital-labor costs per tonne of starch (12% moisture) were also reported. The manufacturing process enabled 65% recovery of the starch present in fresh roots, with no significant change observed in the composition of starch for the two varieties. The bottleneck of the manufacturing process occurred at extraction stage were low capacity were observed (0.3 t of peeled roots per hour). Water consumption per ton of starch was 67 m3, in which washing, rasping, and extraction stages accounted for 9, 3, and 42 m3, respectively. Electrical power per tone of starch was 59 kWh, in which, washing, rasping, and extraction stages accounted for 8, 14 and 38 kWh. The comparison proposed in this study allowed to recommend technological options for small-scale cassava processing industries.

Une démarche d'expérimentation rationnelle et exhaustive a été développée pour apprécier réellement l'efficacité de chaque équipement d'une ligne de production d'amidon de manioc par voie humide. Elle est indispensable pour améliorer, mettre au point chaque élément d'une ligne de transformation. Notre démarche vise à effectuer un nombre minimal de mesures pour avoir les données caractérisant tous les équipements de la chaîne tout en ayant la possibilité de recouper un certain nombre, de ces données pour vérifier les mesures. Elle s'appuie sur une feuille Excel indiquant le diagramme de transformation avec les flux entrant et sortant pour chaque équipement. Chaque flux est caractérisé en débit ou quantité par batch et en qualité (humidité, % amidon, % de fibre dans le cas de la production d'amidon). Les points de mesures à effectuer sont choisis en fonction des possibilités de mesures (facilité d'accès au flux), de leur précision et des relations de bilan permettant le calcul de voleurs non mesurées. Les mesures sont plus nombreuses lors des essais préalables et selon les résultats et leurs précisions, le nombre de mesures est ensuite réduit. L'utilisation de cette méthode au Vietnam, a permis le diagnostic de trois technologies utilisées dans les villages métiers pour la production d'amidon humide.

La production à petite échelle d'amidon de manioc à partir des racines nécessite plusieurs opérations unitaires. Si le procédé reste sensiblement toujours le même (lavage, fragmentation, séparation de l'amidon, réduction de la teneur en eau) de nombreuses variantes ont été apportées de part le monde aux équipements à petite, échelle et à leur mode d'utilisation. Un développement d'une production économique et de qualité d'amidon de manioc en Afrique, nécessite une parfaite connaissance de ces différents équipements, de leurs variantes techniques et surtout de leur principe de fonctionnement. La connaissance de leurs avantages et de leur limites permet de les choisir, les utiliser au mieux, voire, de les modifier pour les adapter aux conditions locales d'utilisation. A partir des réalisations développées dans les différents pays du Sud, l'article propose une présentation détaillée de chaque équipement utilisé pour la production d'amidon de manioc par voie humide. Il s'agit de faire le point sur les acquis en matière de recherche et de développement d'équipements de production d'amidon et de proposer un support pour un échange d'expérience entre les participants de l'atelier.

Au Vietnam, différentes échelles de valorisation de l'amidon de manioc coexistent, à savoir : l'extraction d'amidon des racines et ses utilisations ultérieures dans les filières alimentaires et pharmaceutiques. Une étude diagnostique réalisée dans les villages métiers du delta du fleuve rouge, a montré qu'il existait à cette échelle, de nombreuses utilisations de l'amidon de manioc et de ses produits dérivés. Toutefois, une évaluation de la qualité des amidons pourra être réalisée pour mieux comprendre les modes d'utilisation de ces produits tout au long de l'année.

L'objet de la mission est d'apporter un appui scientifique et technique au travail de thèse de Guillaume Da sur la caractérisation des unités de transformation du manioc en amidon dans les villages métiers à la périphérie de Hanoi au Vietnam. La thèse est intitulée: "Innovations cies procédés de transformations post-récolte du manioc au Vietnam". Suite à l'important travail réalisé en 2005 par Guillaume Da pour établir les bilans matière de trois procédés de transformation à petite et moyenne capacité, la mission a permis de compléter ce travail en prenant en compte la dimension énergie dans l'évaluation des équipements de transformation du manioc par la mesure des puissances électriques consommées pour tous les équipements.

Au Vietnam, différentes échelles de valorisation de l'amidon de manioc coexistent, à savoir : l'extraction d'amidon des racines et ses utilisations ultérieures dans les filières alimentaires et pharmaceutiques. Une étude diagnostique réalisée dans les villages métiers du delta du fleuve rouge, a montré qu'il existait à cette échelle, de nombreuses utilisations de l'amidon de manioc et de ses produits dérivés. Toutefois, une évaluation de la qualité des amidons pourra être réalisée pour mieux comprendre les modes d'utilisation de ces produits tout au long de l'année.

La production à petite échelle d'amidon de manioc à partir des racines nécessite plusieurs opérations unitaires. Si le procédé reste sensiblement toujours le même (lavage, fragmentation, séparation de l'amidon, réduction de la teneur en eau) de nombreuses variantes ont été apportées de part le monde aux équipements à petite, échelle et à leur mode d'utilisation. Un développement d'une production économique et de qualité d'amidon de manioc en Afrique, nécessite une parfaite connaissance de ces différents équipements, de leurs variantes techniques et surtout de leur principe de fonctionnement. La connaissance de leurs avantages et de leur limites permet de les choisir, les utiliser au mieux, voire, de les modifier pour les adapter aux conditions locales d'utilisation. A partir des réalisations développées dans les différents pays du Sud, l'article propose une présentation détaillée de chaque équipement utilisé pour la production d'amidon de manioc par voie humide. Il s'agit de faire le point sur les acquis en matière de recherche et de développement d'équipements de production d'amidon et de proposer un support pour un échange d'expérience entre les participants de l'atelier.

Une démarche d'expérimentation rationnelle et exhaustive a été développée pour apprécier réellement l'efficacité de chaque équipement d'une ligne de production d'amidon de manioc par voie humide. Elle est indispensable pour améliorer, mettre au point chaque élément d'une ligne de transformation. Notre démarche vise à effectuer un nombre minimal de mesures pour avoir les données caractérisant tous les équipements de la chaîne tout en ayant la possibilité de recouper un certain nombre, de ces données pour vérifier les mesures. Elle s'appuie sur une feuille Excel indiquant le diagramme de transformation avec les flux entrant et sortant pour chaque équipement. Chaque flux est caractérisé en débit ou quantité par batch et en qualité (humidité, % amidon, % de fibre dans le cas de la production d'amidon). Les points de mesures à effectuer sont choisis en fonction des possibilités de mesures (facilité d'accès au flux), de leur précision et des relations de bilan permettant le calcul de voleurs non mesurées. Les mesures sont plus nombreuses lors des essais préalables et selon les résultats et leurs précisions, le nombre de mesures est ensuite réduit. L'utilisation de cette méthode au Vietnam, a permis le diagnostic de trois technologies utilisées dans les villages métiers pour la production d'amidon humide.

The cassava starch value chain has been highly changed over the past ten years in Vietnam. Both small and large firm's developments have been leading to a complex situation where small farming and processing scales are prevailing in the North. Participatory rural appraisal (PRA) and semi-structured interviews in Duong Lieu, Cat Que and Minh Khai (Hoai Duc district, Ha Tay province, Vietnam) have been lead to distinguish between 3 categories of small-sized wet starch processors. Thus, the appraisal has shown the urgent need to reduce the negative impact of cassava processing on the environment. All the stakeholders approve the remaining nuisance caused by liquid waste from cassava processing.

The cassava starch value chain has been highly changed over the past ten years in Vietnam. Both small and large firm's developments have been leading to a complex situation where small farming and processing scales are prevailing in the North. Participatory rural appraisal (PRA) and semi-structured interviews in Duong Lieu, Cat Que and Minh Khai (Hoai Duc district, Ha Tay province, Vietnam) have been lead to distinguish between 3 categories of small-sized wet starch processors. Thus, the appraisal has shown the urgent need to reduce the negative impact of cassava processing on the environment. All the stakeholders approve the remaining nuisance caused by liquid waste from cassava processing.

Les objectifs de ce rapport sont de présenter le projet "Systèmes de Culture de Montagne" et plus particulièrement la contribution du volet Systèmes de Culture au sein de ce projet pour la période octobre 2002 - Septembre 2004. Le document s'appuie entre autre sur ceux obtenus au cours de la mission de volontariat international MAE-CIRAD, dont le descriptif du poste se résumait ainsi: Volontaire du Ministère des Affaires Etrangères - Détaché au CIRAD, et intégré au projet SAM en tant qu'assistant technique. La mission consistait à: - Mettre en place des expérimentations agronomiques en zone de montagnes (dans une problématique de fixation de l'agriculture, d'intensification et de diversification agricoles) en concertation avec les coordinateurs franco-vietnamiens et les équipes d'ingénieurs associées au projet. Ces essais consistent en l'étude de systèmes de culture innovants alternatifs aux systèmes traditionnels, et reposant sur le semis direct avec couverture végétale (déclinés pour les principales cultures vivrières: riz, maïs, manioc), et intégrant les composantes agriculture et élevage; Ils sont réalisés principalement dans deux provinces montagneuses du nord Vietnam: Bac Kan (200 kms au nord d'Hanoi) et Yen Bai (200 kms au nord-ouest d'Hanoi). - Animer les équipes locales d'ingénieurs (3 à Bac Kan, 4 à Yen Bai) pour assurer une bonne marche des essais tout au long de la campagne agricole (de mars à novembre environ): maintenance des sites, suivi des mesures et des opérations agricoles (semis,..., récolte). - Organiser la logistique des terrains: stocks d'intrants, achats et conservation de semences, maintenance informatique, etc. Assurer l'accueil des visiteurs sur les matrices de démonstration des systèmes de culture innovants. - Partager l'information de terrain entre les membres du projet. - Analyser et valoriser les activités de terrain et les résultats de recherche associées, après collecte des données et rédaction de rapport de campagne et/ou d'activité

Les objectifs de ce rapport sont de présenter le projet "Systèmes de Culture de Montagne" et plus particulièrement la contribution du volet Systèmes de Culture au sein de ce projet pour la période octobre 2002 - Septembre 2004. Le document s'appuie entre autre sur ceux obtenus au cours de la mission de volontariat international MAE-CIRAD, dont le descriptif du poste se résumait ainsi: Volontaire du Ministère des Affaires Etrangères - Détaché au CIRAD, et intégré au projet SAM en tant qu'assistant technique. La mission consistait à: - Mettre en place des expérimentations agronomiques en zone de montagnes (dans une problématique de fixation de l'agriculture, d'intensification et de diversification agricoles) en concertation avec les coordinateurs franco-vietnamiens et les équipes d'ingénieurs associées au projet. Ces essais consistent en l'étude de systèmes de culture innovants alternatifs aux systèmes traditionnels, et reposant sur le semis direct avec couverture végétale (déclinés pour les principales cultures vivrières: riz, maïs, manioc), et intégrant les composantes agriculture et élevage; Ils sont réalisés principalement dans deux provinces montagneuses du nord Vietnam: Bac Kan (200 kms au nord d'Hanoi) et Yen Bai (200 kms au nord-ouest d'Hanoi). - Animer les équipes locales d'ingénieurs (3 à Bac Kan, 4 à Yen Bai) pour assurer une bonne marche des essais tout au long de la campagne agricole (de mars à novembre environ): maintenance des sites, suivi des mesures et des opérations agricoles (semis,..., récolte). - Organiser la logistique des terrains: stocks d'intrants, achats et conservation de semences, maintenance informatique, etc. Assurer l'accueil des visiteurs sur les matrices de démonstration des systèmes de culture innovants. - Partager l'information de terrain entre les membres du projet. - Analyser et valoriser les activités de terrain et les résultats de recherche associées, après collecte des données et rédaction de rapport de campagne et/ou d'activité