La consommation alimentaire des ignames. Synthèse des connaissances et enjeux par la recherche

Cette synthèse des connaissances sur la consommation alimentaire de l'igname s'appuie sur des statistiques nationales et sur des données d'enquêtes auprès de consommateurs des principaux pays producteurs. L'analyse des données statistiques sur la période 1961-1994 permet de dresser une typologie des pays en fonction de la disponibilité alimentaire de l'igname et de son évolution. Quinze pays, qui totalisent près de 170 millions d'habitants — parmi les 31 où la consommation d'igname est significative —, en consomment en moyenne plus de 20 kg/personne/an. Malgré le peu d'études sur la consommation et son évolution, les informations disponibles mettent en évidence le rôle important joué par l'igname dans l'activation des identités géo-culturelles spécifiques. Dans les zones traditionnellement productrices, la consommation d'igname est fortement ritualisée. Mais les consommateurs d'igname s'élargissent à des populations traditionnellement non utilisatrices, en particulier dans les villes. Sur les marchés urbains, la compétitivité de l'igname est handicapée par sa faible durée de conservation qui entraîne de fortes variations saisonnières en disponibilité, des pertes post-récolte et un coût de transport élevés. Au sud-ouest du Nigeria et au Bénin, le développement d'une filière marchande de cossettes d'igname séchées a permis de lever ces contraintes. La diffusion de ce s a v o i r-faire endogène mériterait d'être étudiée et encouragée. Si la diversité des savoir-faire culinaires existe sur le plan domestique, elle reste peu connue de la recherche et n'a, semble-t-il, été que peu valorisée. Dans un contexte de diversification alimentaire il y aurait, sans doute là, un enjeu important pour la recherche en technologie alimentaire

Etat des connaissances et de la recherche sur la transformation et les utilisations alimentaires de l'igname.

Cet article présente une synthèse bibliographique des travaux concernant les utilisations alimentaires de l'igname à travers le monde. Les systèmes traditionnels de transformation de ce tubercule, ainsi que les initiatives semi-industrielles ou industrielles sont recensés. Cette synthèse montre que la transformation de l'igname a fait l'objet de recherches relativement limitées par rapport à la racine de manioc. De plus, ces travaux se sont souvent déroulés en laboratoire, sans véritable connexion ni application directe en entreprise, ni connaissance suffisante des réelles attentes des consommateurs. L'igname et ses dérivés sont toujours considérés comme chers et sont concurrencés par des produits importés. Par ailleurs, les études menées jusqu'ici se sont essentiellement focalisées sur quelques produits classiquement connus, tels que les pâtes élastiques (foufou et foutou), la farine et les flocons. Dans le but de relancer cette filière et de valoriser le potentiel nutritionnel, socio-économique et technique de ce tubercule, la diversification des produits à base d'igname paraît incontournable. Des recherches appliquées sont alors nécessaires pour, d'une part, améliorer les systèmes techniques de transformation à différentes échelles (artisanale, semi-industrielle et industrielle) et, d'autre part, mieux connaître et appréhender la demande des marchés et des consommateurs. Des pistes de recherche intéressantes et prometteuses se profilent actuellement. Celles-ci s'orientent vers une meilleure connaissance des caractéristiques variétales et de leur aptitude à la transformation afin de mieux cibler leurs utilisations technologiques potentielles, ainsi que vers la mécanisation de certaines étapes technologiques (épluchage, séchage...) qui interviennent dans la plupart des procédés de transformation. Enfin, l'élaboration de produits fermentés à base d'igname serait une voie de valorisation de ce tubercule, à l'instar de ceux fermentés à partir de manioc et reconnus pour leur valeur nutritionnelle

Low Molecular Weight Branched-Chain and n-Chain Fatty Acids in Caprine and Bovine Colostrum

Colostrum from French-Alpine and Anglo-Nubian goats and Holstein cows was collected and analyzed for both total and FFA of 12 and fewer carbon atoms. Short-chain VFA were separated from long-chain fatty acids using simultaneous distillation extraction. The n-butyl esters of fatty acids were quantified by gas chromatography, and their identity was confirmed by gas chromatography-mass spectrometry. The concentration of decanoic acid was 33 and 83% less in Holstein colostrum than in colostrum from Alpine and Nubian goats, respectively. Colostrum from Nubian goats had twice as much decanoic acid as colostrum from Alpine goats. The FFA in colostrum that differed between species but not between goat breeds were octanoic and decanoic acids. These respective fatty acids were approximately two and three times greater in colostrum from goats than in colostrum from Holsteins. The quantity of decanoic acid was different between goat breeds and between animal species. The ratio of total fatty acid concentration to free-state concentration for hexanoic acid appeared to be useful for differentiating between Nubian and Alpine goat colostrum as well as between Nubian and Holstein colostrums. © 1993, American Dairy Science Association. All rights reserved

Low Molecular Weight Branched-Chain and n-Chain Fatty Acids in Caprine and Bovine Colostrum

Colostrum from French-Alpine and Anglo-Nubian goats and Holstein cows was collected and analyzed for both total and FFA of 12 and fewer carbon atoms. Short-chain VFA were separated from long-chain fatty acids using simultaneous distillation extraction. The n-butyl esters of fatty acids were quantified by gas chromatography, and their identity was confirmed by gas chromatography-mass spectrometry. The concentration of decanoic acid was 33 and 83% less in Holstein colostrum than in colostrum from Alpine and Nubian goats, respectively. Colostrum from Nubian goats had twice as much decanoic acid as colostrum from Alpine goats. The FFA in colostrum that differed between species but not between goat breeds were octanoic and decanoic acids. These respective fatty acids were approximately two and three times greater in colostrum from goats than in colostrum from Holsteins. The quantity of decanoic acid was different between goat breeds and between animal species. The ratio of total fatty acid concentration to free-state concentration for hexanoic acid appeared to be useful for differentiating between Nubian and Alpine goat colostrum as well as between Nubian and Holstein colostrums. © 1993, American Dairy Science Association. All rights reserved

Effects of bovine and caprine Monterey Jack cheeses fortified with milk calcium on bone mineralization in rats

Bovine and caprine Monterey Jack cheeses were produced unfortified (cheese) or fortified with milk calcium (Ca-cheese). Five groups of male rats were fed a control diet or one of four experimental diets: bovine cheese diet, bovine Ca-cheese diet, caprine cheese diet, and caprine Ca-cheese diet to test their effects on calcium absorption as well as bone mineralization. Significant differences (P \u3c 0.05) were found for calcium absorption and digestibility with the data yielding the pattern: caprine Ca-cheese\u3ecaprine cheese=bovine Ca-cheese\u3ebovine cheese\u3econtrol. Significant increases (P \u3c 0.05) occurred in bone mineral content (BMC), bone mineral density (BMD) and breaking force in the femoral bone with the pattern: caprine Ca-cheese\u3ecaprine cheese\u3ebovine Ca-cheese\u3ebovine cheese\u3econtrol. Our findings suggest that caprine cheese unfortified or fortified with milk calcium had the most positive effects on calcium absorption and bone mineralization in rats, with bovine cheeses still having significantly greater effects than the non-casein control. © 2006 Elsevier Ltd. All rights reserved

Effects of bovine and caprine Monterey Jack cheeses fortified with milk calcium on bone mineralization in rats

Bovine and caprine Monterey Jack cheeses were produced unfortified (cheese) or fortified with milk calcium (Ca-cheese). Five groups of male rats were fed a control diet or one of four experimental diets: bovine cheese diet, bovine Ca-cheese diet, caprine cheese diet, and caprine Ca-cheese diet to test their effects on calcium absorption as well as bone mineralization. Significant differences (P \u3c 0.05) were found for calcium absorption and digestibility with the data yielding the pattern: caprine Ca-cheese\u3ecaprine cheese=bovine Ca-cheese\u3ebovine cheese\u3econtrol. Significant increases (P \u3c 0.05) occurred in bone mineral content (BMC), bone mineral density (BMD) and breaking force in the femoral bone with the pattern: caprine Ca-cheese\u3ecaprine cheese\u3ebovine Ca-cheese\u3ebovine cheese\u3econtrol. Our findings suggest that caprine cheese unfortified or fortified with milk calcium had the most positive effects on calcium absorption and bone mineralization in rats, with bovine cheeses still having significantly greater effects than the non-casein control. © 2006 Elsevier Ltd. All rights reserved

Effects of bovine and caprine Monterey Jack cheeses fortified with milk calcium on bone mineralization in rats

Bovine and caprine Monterey Jack cheeses were produced unfortified (cheese) or fortified with milk calcium (Ca-cheese). Five groups of male rats were fed a control diet or one of four experimental diets: bovine cheese diet, bovine Ca-cheese diet, caprine cheese diet, and caprine Ca-cheese diet to test their effects on calcium absorption as well as bone mineralization. Significant differences (P \u3c 0.05) were found for calcium absorption and digestibility with the data yielding the pattern: caprine Ca-cheese\u3ecaprine cheese=bovine Ca-cheese\u3ebovine cheese\u3econtrol. Significant increases (P \u3c 0.05) occurred in bone mineral content (BMC), bone mineral density (BMD) and breaking force in the femoral bone with the pattern: caprine Ca-cheese\u3ecaprine cheese\u3ebovine Ca-cheese\u3ebovine cheese\u3econtrol. Our findings suggest that caprine cheese unfortified or fortified with milk calcium had the most positive effects on calcium absorption and bone mineralization in rats, with bovine cheeses still having significantly greater effects than the non-casein control. © 2006 Elsevier Ltd. All rights reserved