Aspectos sensoriais e físico-químicos de “iogurtes” de soja com espessantes/estabilizantes a base de fécula de inhame (Dioscorea alata), amido modificado e gelatina

This study had as objective to evaluate the effect of yam starch, modified starch from Cargill-Brasil (Amidomax 4800 (R)) and gelatin from Gelita-Brasil (GEL-LAC) as stabilizers/thickeners in different ratios and combinations in the soy yoghurt fermented with Enterococcus faecium and Lactobacillus helveticus ssp jugurti. Ten soy yoghurt formulations containing these different stabilizers/thickeners, always totalizing 0.5% in relation to the final formulation, were analyzed in sensorial and physical-chemical terms. Based on the observed results, it was concluded in relation to the sensorial point of view that the more appropriate product was processed only with gelatin at 0.5% concentration. This product also presented the best physical-chemical results related to consistency, syneresis and water holding capacity. However, the isolated use of gelatin increased fermentation time of the soy yoghurt.

Effects of extraction methods on yam (Dioscorea alata) starch characteristics

Starch extraction from roots and tubers uses grating with water and sieves to separate the starch slurry from residual mass. The starch is recovered by decantation or centrifugation. The yam starch extraction is difficult due to high viscosity of the slurry caused by non-starch polysaccharides (NSP). The establishment of an efficient extraction process may turn yam into a competitive raw material. In this paper Dioscorea alata starch extracted by four methods was characterized in order to establish the impact of treatments. When the tubers were digested with an aqueous oxalic acid/ammonium oxalate (OA/AO) 1/1 solution, it was easier to separate the starch slurry from residual mass, because viscosity was reduced. For all the others methods tested, the viscosity remained almost the same. The nitrogen present in yam tubers was removed during the different extractions to a different extent. The largest nitrogen reduction was observed with ONAO followed by the control (water). The spectrum of starch granules sizes obtained also varied according to the treatment. Results proved that NSP carries small starch granules over to the waste water. The smaller starch granules diameter varied from 1.9 mu m (OA/AO extraction) to 13.5 mu m (water and pectinase extractions). The larger diameter varied from 41.0 mu m (NaOH treatment) to 67.7 mu m (ONAO). All starches extracted showed a RVA behavior in agreement with literature for yam starch, but with small differences due to the influence of methods. ONAO extraction showed the best recovery (18 g of starch/100 g tuber yam) and granular variation but it interfered with the rheological behavior of starch.

Aspectos sensoriais e físico-químicos de iogurtes de soja com espessantes/estabilizantes à base de fécula de inhame (Dioscorea alata), amido modificado e gelatina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Distribution, management and diversity of yam local varieties in Brazil: a study on Dioscorea alata L.

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Home gardens and Dioscorea species – A case study from the climatic zones of Sri Lanka

Home gardens are considered as vital units for enhancing food security particularly in developing nations of South Asia, such as Sri Lanka. Although the yam crop Dioscorea spp. constitute a popular but still minor component in Sri Lankan home gardens, they have the potential of producing large quantities of edible material with minimal inputs. However, their real value in South Asian home gardens is not yet reported. Hence, this study was carried out to get insights into home garden characteristics, gardener demography as well as current management practices within 300 Sri Lankan home garden systems that are located along a climatic gradient. By using interviews and field observations, gardeners, who cultivated in particular Dioscorea species, were studied within 10 of the 25 administrative districts distributed in the wet, intermediate and dry climatic zone of Sri Lanka. Furthermore, current management practices of yams cultivation were analyzed on local scale and compared afterwards with management recommendations published in the year 2006 by the Department of Agriculture. Dioscorea species were found in a majority of home gardens, especially in wet and intermediate zones of Sri Lanka. D. alata was the most prominent species and was managed at a subsistence level and not as per recommendations developed by the Department of Agriculture. Our results revealed that Dioscorea alata is an essential component of Sri Lankan home gardens in rural areas and can yield substantial quantities of edible tubers with low input, especially during times of food scarcities, and has therefore the potential to enhance food security and rural development.

Sistemas de cultivo do cará dioscorea spp. por pequenos agricultores da baixada Cuiabana – MT

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cucumber mosaic virus infection of kava (Piper methysticum) and implications for cultural control of kava dieback disease

Cucumber mosaic virus (CMV) was found by reverse transcription polymerase chain reaction (RT-PCR) to be not fully systemic in naturally infected kava (Piper methysticum) plants in Fiji. Twenty-six of 48 samples (54%) from various tissues of three recently infected plants were CMV-positive compared with 7/51 samples (14%) from three long-term infections (plants affected by dieback for more than 1 year). The virus was also found to have a limited ability to move into newly formed stems. CMV was detected in only 2/23 samples taken from re-growth stems arising from known CMV infected/dieback affected plants. Mechanical inoculation experiments conducted in Fiji indicate that the known kava intercrop plants banana (Musa spp.), pineapple (Ananas comosus), peanut (Arachis hypogaea) and the common weed Mikania micrantha are potential hosts for a dieback-causing strain of CMV It was not possible to transmit the virus mechanically to the common kava intercrop plants taro (Colocasia esculenta), Xanthosoma sp., sweet potato (Ipomoea batatas), yam (Dioscorea alata), papaya (Carica papaya) or the weed Momordica charantia. Implications of the results of this research on a possible integrated disease management strategy are discussed.

Efeitos de parâmetros de extrusão nas propriedades físicas de produtos expandidos de inhame

Effect of extrusion parameters was studied on the expansion index, specific volume, water absorption index (WAI) and water solubility index (WSI) of expanded yam snacks. The central composite design was used to study the parameters effect. It was verified three levels of temperature in the barrel (100, 115 and 130°C), three levels of screw speed (163, 204 and 245 rpm) and three levels of flour moisture (12, 15 and 18%). The results showed that expansion properties (expansion index and specific volume) depend on flour moisture and extrusion temperature. The WSI was dependant of three parameters. Higher levels of temperature and screw speed increase the water solubility index (WSI). The studied parameters did not influence the water absorption index (WAI).

Nutrient deficiencies in greater yam and their effects on leaf nutrient concentrations

This paper describes the first systematic study of nutritional deficiencies of greater yam (Dioscorea alata). Yam plants (cv. 'Mahoa'a') were propagated from tuber discs and grown in nutrient solution, with nutrients supplied following a modified programmed nutrient-addition method. After an establishment period of four weeks, deficiencies of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), boron (B), manganese (Mn), copper (Cu), zinc (Zn), and molybdenum (Mo) were induced by omitting the relevant nutrient from the solution. Foliar symptoms were recorded photographically. Notably, deficiencies of the mobile macronutrients failed to induce senescence of oldest leaves, while vine growth and younger leaves were affected. Leaf blades of the main stem were sampled in sequence and analyzed chemically, providing the distribution of each nutrient from youngest to oldest leaves in both adequately supplied and deficient plants. The nutrient-concentration profiles, together with the visible symptoms, indicated that little remobilization of mobile macronutrients had occurred. For both macro- and micronutrients, young leaves gave the best separation of nutrient concentrations between well-nourished and deficient plants.

Caracterización y evaluación preliminar de quince clones de Ñame dioscorea sp.

Se caracterizaron y evaluaron quince accesiones de Ñame (Dioscorea sp) provenientes de ocho países de la cuenca del Caribe. El ensayo se estableció en el programa de Recursos Genéticos Nicaragüenses (REGEN). Del Instituto Superior de Ciencias Agropecuarias (ISCA), Managua. Utilizando un arreglo fr bloques al azar con dos repeticiones. Se observaron 89 descriptores, entre los cuales se seleccionaron para análisis 42 cualitativos y 23 cuantitativos. Los datos se sometieron a análisis de agrupamiento por encadenamiento simple: El fonograma de descriptores cualitativos determino la experiencia de dos especies: D alata y D. Trífida mientras que dos clones que se sospecha eran duplicados por cercanía geográfica, presentan alta diferenciación: Del análisis muy similar al patrón presentado por el total de diez descriptores de color: sugiriendo la importancia de los primeros en la diferenciación de accesiones. El fonograma de descriptores cualitativos resulto diferente en conformación e integrantes de los grupos, que los obtenidos del análisis de descriptores cualitativos: los datos de rendimiento se procesaron de la misma manera, sometidos a un análisis de varianza que arrojo diferentes pruebas de medidas de Duncan se obtuvieron dos niveles de diferenciación a y b. concordante con rendimiento presento estrecha concordancia con el de los descriptores cuantitativos. De 23 descriptores cuantitativos se seleccionaron trece, que sometidos a prueba de t. determinó nueve capaces de encontrar diferencias significativas entre pares de grupos de accesiones. De la relación entre el color y rendimiento, se desprende que los clones con subcuticula morada. Blanco amarillenta y amarillo pálido, con pulpa morada o blanca amarillento. Tienen tendencia a generar altos rendimientos. Se elaboró un catálogo de características morfológicas de las accesiones estudiadas.

Biotransformation of cholesterol to diosgenin by freely suspended and immobilised cells of Dioscorea bulbifera L.

The cell suspension cultures, established from the friable callus which was risen from the nodal segments of Dioscorea bulbifera L. in Murashige-Skoog (MS) medium supplemented with indole-3-butryic acid (20 mg L- 1), was examined for cell growth in MS medium fed with cholesterol (50 mg L- 1 and 100 mg L- 1) after 8, 10, 12, 14, 16, and 18 days of culture. The growth index of the cell suspension culture on the 8th day was 1.2 and gradually inclined to 1.9 on the 16th day and remained the same at the 18th day. There is no marked difference in the cell growth of cholesterol-treated and control cell suspension culture. The maximum accumulation of diosgenin was noticed on the 14th day in control and cholesterol-treated cell suspension culture and immobilised cell cultures. The highest concentration of diosgenin, 2.94% and 2.14% dry weight, was obtained in immobilised cell culture and cell suspension culture treated with 100 mg L- 1 cholesterol, respectively.

Efecto terapeutico del Jicaro Sabanero (Crescentia alata H.B.K.), Madero negro (Gliricidia sepium (Jacq) y Neem (Azadirachta indica A. Jus) en dermatopatias de los conejos y diagnostico de las mismas en el Rancho Agropecologico en especies menores ebenezer, Niquinohomo, Nicaragua

Con el objetivo de determinar los principales agentes etiológicos de las dermatopatías en conejos y determinar el efecto terapéutico de tres tratamientos fitoterapéuticos 1) Jícaro Sabanero, 2) madero negro y 3) Neem, sobre las mismas, se realizó un estudio en el Rancho Agropecológico en especies menores, Ebenezer (RAEME), Niquinohomo, Nicaragua. El trabajo se realizó en 59 conejos divididos en cuatro grupos y sometidos a los diferentes tratamientos. Para evaluar la efectividad de los tratamientos se realizaron 3 aplicaciones de cada uno de ellos a sus respectivos grupos, con intervalos de siete días cada uno, durante 21 días; a excepción del jícaro que se aplicó tres días continuos, cada siete días, durante 21 días. Se determinó que los principales agentes etiológicos presentes en el estudio, fueron el ácaro Listrophorus sp, los hongos Mucor sp, Aspergillus sp, zygomices sp, Penicillium sp. De los tres tratamientos aplicados, el tratamiento a base de Neem (Azadirachta indica) fue el que presentó un efecto altamente significativo (P< 0.0001)sobre el control de las dermopatías y permitió un mejor grado de recuperación de los conejos tratados. El tratamiento a base de jícaro (Crescentia alata) presenta algún grado de efectividad para el control de las dermopatías encontradas. El tratamiento a base de madero negro (Gliricidia sepium ), presentó muy poca efectividad en el control de las dermopatías en estudio.

Análisis de la producción de semilla y componentes del rendimiento del jícaro (Crescentia alata HBK) en ocho localidades de Nicaragua

La semilla de jícaro (Cresentia alata HBK, Bignoniácea) es altamente nutritiva, lo que proviene a esta especie en un recurso a manejarse actualmente, por su potencial cultivo y agroindustria. En septiembre –Octubre 1983, cosecha de primera, se muestreo 10 árboles en parcelas mínimas de 5,625m2 en 8 diferentes sabanas de jícaro en el pacifico de Nicaragua. Se caracterizaron 16 descriptores morfológico del árbol. El procedimiento estadístico STEP –WISE mostro 19 correlaciones de 128 combinaciones, de las cuales las más altas se presentaron entre las características del fruto. Siendo las ecuaciones: 1rº y (peso de semilla por fruto).= 3.93 +0.04x (peso x fruto), r=0.72, P-0.05. 2dº y (peso de semilla por fruto)= -17.26 +4.43 X (diámetro del fruto),r=0.6.68, p-0.05; importantes para estimar la producción : el análisis de varianza mostró que la variación en producción de semilla por fruto no es significativa (P-0.05) entre arboles de una localidad, pero entre poblaciones de diferentes localidades la variación es altamente significativa, siendo mayor la producción en la zona más húmedas. Para estimar la producción es necesario usar los siguientes paramentos;: peso de semillas por fruto, números por frutos por árbol y número de árboles productivos por área; pudiéndose estimar el peso de semilla por fruto a través del peso del fruto o diámetro del fruto El estudio demostró que la producción de semilla es de 5.37 (X=192.86 +160.24) 548.74 kg /ha: siendo Somotillo, Chinandega; La Reynaga e IZAPA. León; las localidades de más alto s rendimientos.