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Pachyrhizus ahipa is an unexploited crop known to be rich in proteins compared to other edible roots and tubers. These proteins are not prolamins, thus ahipa represents an interesting new source of ingredients for gluten-free foods. In this work, ahipa proteins (AP) were extracted and partially characterized in pursuit of their use as food ingredients. The effect of ultrasound treatment on protein extraction efficiency was evaluated. AP were characterized by their size, amino acid composition, surface hydrophobicity, intrinsic fluorescence, FTIR spectra, solubility, and thermal and emulsifying properties. AP were efficiently removed from the vegetal tissue using PBS or water, regardless of the use of ultrasound, but not easily recovered by precipitation. This protein fraction was composed of small proteins, with sizes ranging from 9 to 30 kDa, and highly polar. AP resulted particularly rich in aspartic acid (59% of the total amino acid content), for which they can be classified as Asp-rich proteins. Their elevated content of acidic groups was evidenced in the ATR-FTIR spectrum. The amide I band deconvolution as well as the low surface hydrophobicity and denaturation enthalpy indicated that these proteins are mainly unordered structures. The emulsifying properties of AP were enhanced when the concentration was increased from 0.1 to 1% (w/v) but resulted lower than those of soy protein. The high polarity, small size, and low isoelectric point make AP particularly suitable for acidic food matrices.

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Cassava sour starch is a gluten-free product obtained by natural fermentation and sun-drying that outstrips the native starch baking expansion properties. Although maize starch has been subjected to a similar process, this desirable feature could not be achieved. Ahipa, an unexploited tuberous root, renders starch with relatively low gelatinization temperature and amylose content, like that of cassava. The aim of this work was to study the characteristics and technological properties of ahipa starch subjected to different fermentation processes and drying methods (oven- or sun-drying) and compare the bakery quality of its derived products to those from fermented cassava starches. Ahipa starch followed similar fermentation paths to those followed by cassava's, and sun-drying significantly reduced the content of the resultant lactic and butyric acids. Rheological behavior of starch pastes as well as moisture content and hardness of the doughs obtained from fermented and sun-dried ahipa starches differed from those of cassava. Sun-light exposure resulted detrimental for the expansion properties of ahipa sour starches, while the native one showed baking expansion properties like those of fermented sun-dried cassava starch. Thus, ahipa starch represents an interesting ingredient for the elaboration of gluten-free baked products.

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Bradyrhizobium comprises most tropical symbiotic nitrogen-fixing strains, but the correlation between symbiotic and core genes with host specificity is still unclear. In this study, the phylogenies of the nodY/K and nifH genes of 45 Bradyrhizobium strains isolated from legumes of economic and environmental importance in Brazil (Arachis hypogaea, Acacia auriculiformis, Glycine max, Lespedeza striata, Lupinus albus, Stylosanthes sp. and Vigna unguiculata) were compared to 16S rRNA gene phylogeny and genetic diversity by rep-PCR. In the 16S rRNA tree, strains were distributed into two superclades-B. japonicum and B. elkanii-with several strains being very similar within each clade. The rep-PCR analysis also revealed high intra-species diversity. Clustering of strains in the nodY/K and nifH trees was identical: 39 strains isolated from soybean grouped with Bradyrhizobium type species symbionts of soybean, whereas five others occupied isolated positions. Only one strain isolated from Stylosanthes sp. showed similar nodY/K and nifH sequences to soybean strains, and it also nodulated soybean. Twenty-one representative strains of the 16S rRNA phylogram were selected and taxonomically classified using a concatenated glnII-recA phylogeny; nodC sequences were also compared and revealed the same clusters as observed in the nodY/K and nifH phylograms. The analyses of symbiotic genes indicated that a large group of strains from the B. elkanii superclade comprised the novel symbiovar sojae, whereas for another group, including B. pachyrhizi, the symbiovar pachyrhizi could be proposed. Other potential new symbiovars were also detected. The co-evolution hypotheses is discussed and it is suggested that nodY/K analysis would be useful for investigating the symbiotic diversity of the genus Bradyrhizobium.

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The objective of this work was to fit together the starch extraction from Pachyrhizus ahipa roots and the recovery of the proteins present in these storage organs, making an improved use of this novel raw material. The replacement of water by buffer PO4(-3)/NaCl as solvent in the first extraction steps improved protein extraction without lowering the starch yield. The starches obtained from the traditional and the proposed methods exhibited some differences in appearance and technological and thermal properties, which were endorsed to the adjustment in the methodology of extraction rather than to the use of buffer as solvent. Thus, P. ahipa starch obtaining procedure could be coupled to protein extraction with a minimum change in the methodology. This innovation did not significantly shift the characteristics of the starch obtained and allowed to obtain a protein yield of 135.7mg BSA equivalent protein/100g of fresh roots.

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In México, Pachyrhizus erosus (Fabaceae) commonly called "jícama", is widely known for its edible tubers. It is cultivated since the pre-Columbian period, and the powdered seeds have been used for the treatment of mange, lice, and fleas, due to their content of rotenone, a well-known insecticidal compound. On the other hand, P. ferrugineus, a wild species can only be found in the Tropical Forests, and has no commercial value. It is known that plants release volatile organic compounds (VOCs) showing qualitative and quantitative differences if are wild or cultivated. VOCs are also involved as repelling or attracting chemical signals to insect herbivores, and their natural enemies. Until now, the VOCs of the leaves of P. erosus and P. ferrugineus have not been investigated. In the present contribution the VOCs of both species were characterized by headspace solid-phase (HS-SPME) extraction and gas chromatography-mass spectrometry (GC-MS-TOF). In P. erosus 21 VOCs were found, being the most abundant: cyclohexanone (32.8 percent), 3-hexen-1-ol (Z) (32.7 percent), 3-hexenal (Z) (10.5 percent). The majoritarian compounds were C6 or C5 derivatives In P. ferrugineus, the most abundant VOCs were: 5-hexene-1-ol acetate (51.5 percent), undecanal (22.4 percent), 2-hepten-1-al (14.5 percent). The majoritarian compounds were C6, C7 or C11 derivatives.

En México, Pachyrhizus erosus (Fabaceae) es llamada comúnmente "jícama" y es conocida por sus tubérculos comestibles. Se ha cultivado desde el período pre-Colombino y las semillas se han utilizado para el tratamiento tópico de la sarna, piojos, pulgas; las semillas contienen rotenona, un compuesto insecticida. Por otra parte, P. ferrugineus solo está presente en estado silvestre en los bosques tropicales y carece de valor comercial. Se sabe que las plantas liberan compuestos orgánicos volátiles (COV) y muestran diferencias cualitativas y cuantitativas dependiendo, si son silvestres o cultivadas. Los COV también son señales químicas atrayentes o repelentes de los insectos herbívoros y a sus enemigos naturales. Hasta ahora, los COV en las hojas de P. erosus y P. ferrugineus no han sido investigados. En el presente trabajo, los COV se identificaron mediante la microextracción (HS-SPME) en fase sólida, e identificados por cromatografía de gases acoplada a espectrometría de masas (GC-MS-TOF). En P. erosus se encontraron 21 COV, siendo los más abundantes: ciclohexanona (32.8 por ciento), 3-hexen-1-ol (Z) (32.7 por ciento) y 3-hexenal (Z) (10.5 por ciento). Los compuestos mayoritarios son C6 y C5. En P. ferrugineus los más abundantes fueron: 5-hexen-1-ol acetato (51.5 por ciento), undecanal (22.4 por ciento) y 2-hepten-1-al (14.5 por ciento). Los compuestos mayoritarios son C6, C7 o C11.

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Yam bean is a non-conventional horticultural crop adapted to the Amazon region. It presents edible roots, yet, its seeds contain cytotoxic components such as rotenone and pachyrhizin. The Instituto Nacional de Pesquisas da Amazonia has 64 yam bean genotypes in its germplasm bank, however, their diversity is unknown. The aim of this study was to assess the diversity of these genotypes using 10 morphoagronomic traits, plant height, number of secondary branches, shoot biomass, stem diameter, root biomass, number, length, diameter, length/diameter ratio (L/D), and shape. The accessions were planted on non-flooded land, Manaus, Amazonas (02º 59'48.2''S and 60º 01' 22.4''W) in completely randomized design with three replicates and three plants per plot spaced 0.5 x 1 m. The results showed significant diversity for all characters except for stem diameter and visual assessment of root shape. Biplot graphic explained 60% of the total variation, which identified that genotypes P44, P22 and P18 have high values for root yield (80-108 t ha-1), number of secondary branches (15-31) and shoot biomass (0.5-0.8 kg plant-1). Cluster analysis, considering 50% of relative Euclidean distance, revealed 15 major groups. We conclude that the genotypes assessed have wide diversity and some of them high root yield potential. This suggests that a yam bean breeding program can be successful for the yield of roots and seeds in the Amazonian region.(AU)

O feijão-macuco é uma hortaliça não convencional da Amazônia. Suas raízes são comestíveis e suas sementes tóxicas por conter rotenona e paquirizina. O Instituto Nacional de Pesquisas da Amazônia (INPA) tem conservado 64 genótipos de feijão-macuco em seu banco de germoplasma, mas a diversidade genética destes é desconhecida. O objetivo deste trabalho foi avaliar estes acessos utilizando 10 descritores morfoagronômicos tais como: altura de planta, número de ramas secundárias, massa da parte aérea, diâmetro de caule, massa, número, comprimento, diâmetro, relação comprimento/diâmetro e formato de raízes. O experimento foi conduzido em terra firme no município de Manaus (02º 59'48.2''LS e 60º 01' 22.4''LO), em delineamento de blocos ao acaso com três repetições e três plantas por parcela. Os resultados mostraram diversidade significativa para todos os caracteres, exceto para diâmetro do caule e avaliação visual do formato da raiz. O Biplot explicou 60% da variação total o qual mostrou que os genótipos P44, P22 e P18 tem elevada produtividade de raízes (80-108 t ha-1), número de ramificações secundarias (15-31) e massa da parte aérea (0.5-0.8 kg/planta). A análise de agrupamento considerando 50% da distancia euclidiana relativa mostrou 15 grupos principais. Por tanto, concluímos haver ampla diversidade nos genótipos especialmente para produtividade de raízes. Isto indica que o melhoramento de feijão-macuco, na região Amazônica, pode ter sucesso para aumentar a produtividade de raízes e sementes.(AU)

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RESUMO

Yam bean is a non-conventional horticultural crop adapted to the Amazon region. It presents edible roots, yet, its seeds contain cytotoxic components such as rotenone and pachyrhizin. The Instituto Nacional de Pesquisas da Amazonia has 64 yam bean genotypes in its germplasm bank, however, their diversity is unknown. The aim of this study was to assess the diversity of these genotypes using 10 morphoagronomic traits, plant height, number of secondary branches, shoot biomass, stem diameter, root biomass, number, length, diameter, length/diameter ratio (L/D), and shape. The accessions were planted on non-flooded land, Manaus, Amazonas (02º 59'48.2''S and 60º 01' 22.4''W) in completely randomized design with three replicates and three plants per plot spaced 0.5 x 1 m. The results showed significant diversity for all characters except for stem diameter and visual assessment of root shape. Biplot graphic explained 60% of the total variation, which identified that genotypes P44, P22 and P18 have high values for root yield (80-108 t ha-1), number of secondary branches (15-31) and shoot biomass (0.5-0.8 kg plant-1). Cluster analysis, considering 50% of relative Euclidean distance, revealed 15 major groups. We conclude that the genotypes assessed have wide diversity and some of them high root yield potential. This suggests that a yam bean breeding program can be successful for the yield of roots and seeds in the Amazonian region.

O feijão-macuco é uma hortaliça não convencional da Amazônia. Suas raízes são comestíveis e suas sementes tóxicas por conter rotenona e paquirizina. O Instituto Nacional de Pesquisas da Amazônia (INPA) tem conservado 64 genótipos de feijão-macuco em seu banco de germoplasma, mas a diversidade genética destes é desconhecida. O objetivo deste trabalho foi avaliar estes acessos utilizando 10 descritores morfoagronômicos tais como: altura de planta, número de ramas secundárias, massa da parte aérea, diâmetro de caule, massa, número, comprimento, diâmetro, relação comprimento/diâmetro e formato de raízes. O experimento foi conduzido em terra firme no município de Manaus (02º 59'48.2''LS e 60º 01' 22.4''LO), em delineamento de blocos ao acaso com três repetições e três plantas por parcela. Os resultados mostraram diversidade significativa para todos os caracteres, exceto para diâmetro do caule e avaliação visual do formato da raiz. O Biplot explicou 60% da variação total o qual mostrou que os genótipos P44, P22 e P18 tem elevada produtividade de raízes (80-108 t ha-1), número de ramificações secundarias (15-31) e massa da parte aérea (0.5-0.8 kg/planta). A análise de agrupamento considerando 50% da distancia euclidiana relativa mostrou 15 grupos principais. Por tanto, concluímos haver ampla diversidade nos genótipos especialmente para produtividade de raízes. Isto indica que o melhoramento de feijão-macuco, na região Amazônica, pode ter sucesso para aumentar a produtividade de raízes e sementes.

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Biocomposites films based on thermoplastic corn starch (TPS) containing 0.5% w/w fibrous residue from Pachyrhizus ahipa starch extraction (PASR) were obtained by melt-mixing and compression molding. PASR is mainly constituted by remaining cell walls and natural fibers, revealed by Scanning Electron Microscopy (SEM). Chemical composition of the residue indicated that fiber and starch were the principal components. Biocomposites thermo-stability was determined by Thermo-Gravimetric Analysis. A continuous PASR-TPS interface was observed by SEM, as a result of a good adhesion of the fibrous residue to starch matrix. Likewise, films containing PASR presented fewer superficial cracks than TPS ones, whereas their fracture surfaces were more irregular. Besides, the presence of PASR increased starch films roughness, due to fibers agglomerates. Films reinforced with PASR showed significantly lower water vapor permeability (WVP). In addition, PARS filler increased maximum tensile strength and Young's modulus of TPS films, thus leading to more resistant starch matrixes.

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This paper aimed to evaluate the effects of storage periods on the conservation of Pachyrhizus ahipa roots at different temperatures and packaging materials. The roots were harvested, washed, packed in PVC, plastic bags, without wrappings (control) and stored in polystyrene trays in refrigerators, or cold chambers, or at room temperature. Total titratable acidity (TTA), total soluble solids (TSS), pH, as well as their ash, lipid, total carbohydrate and protein (dry basis) contents were analyzed. The lowest loss of root fresh weight was observed in the cold chamber and plastic bags. The TTA remained higher among roots stored in the cold chamber and in PVC packaging. The lowest TSS contents were observed for roots stored in the cold chamber, and these did not vary among the packing materials. The average carbohydrate content percentage for all treatments was 84.9%. The percentage of lipids was highest in roots stored at room temperature while protein and ash contents were highest in roots under refrigeration. The best storage conditions for roots are plastic bags packaging in a cold chamber, with the roots retaining appropriate quality for commercialization for up to 30 days.

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In 2010, yam beans in a field trial in Peru showed viral disease symptoms. Graft-transmission and positive ELISA results using potyvirus-specific antibodies suggested that the symptoms could be the result of a potyviral infection. Small interfering RNA (siRNA) were extracted from one of the samples and sent for high-throughput sequencing. The full genome of a new potyvirus could be assembled from the resulting siRNA sequences, and it was sufficiently different from other sequences to be considered a member of a new species, which we have designated Yam bean mosaic virus (YBMV). Sequence similarity suggests that YBMV has also been detected in yam beans in Indonesia.

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Microbiological processes were used for chitin and chitosan production by Mucor circinelloides (UCP 050) grown in yam bean (Pachyrhizus erosus L. Urban) medium. The polysaccharides were extracted by alkali-acid treatment and structural investigations by X-ray diffraction, Fourier transform IR analysis, viscosity and thermal analysis by TG, DTG, and DTA were done. The highest biomass yield (20.7 g/L) was obtained at 96 hours. The highest levels of chitosan (64 mg/g) and chitin (500 mg/g) were produced at 48 and 72 hours, respectively. It was demonstrated that yam bean shows great potential as an economic medium and it is possible to achieve a good yield of chitosan with chemical properties that enable its use in biotechnological applications.

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The aim of the present work is to study the effect of dietary dietary fiber of similar solubility to that of the cooked common bean in the increase of the small intestine, liver, and pancreas of rats. Recently weaned male Wistar rats were fed ad libitum balanced diets containing cooked common bean (12.9 percent of dietary fiber plus resistant starch) or casein with 5.0 percent (control group), 10.0 percent, 12.5 percent or 15.0 percent of dietary fiber plus resistant starch added, with the same proportions of insoluble and soluble fibers and resistant starch found in bean (8:3:1) for 14 days. Weight gain and diet intake were smaller in the group fed the cooked bean diet. However, this group showed the highest increase in the studied organs. Rats that ingested the diet containing casein with 15.0 percent of dietary fiber added showed a growth of 21.4 percent in the pancreas. Rats fed other casein diets did not show significant differences (p>0.05). The diet containing the cooked common bean led to weight gain of all studied organs (50.0 percent in the pancreas, 25.0 percent in the liver and 33.4 percent in the small intestine) and an increase of 47.1 percent in the small intestine length. Therefore, dietary fiber plus resistant starch had a trophic effect on digestive organs, although they were not the only stimulation factor, because the cooked bean has other chemical components, like phytates and tannins, that probably contribute to that effect.

Ratas Wistar machos recién destetados fueron alimentados ad libitum con dietas balanceadas, conteniendo frijol común cocinado (12,9 por ciento de fibras dietéticas + almidón resistente) o caseína agregado de 5,0 por ciento (grupo control), 10,0 por ciento, 12,5 por ciento o 15,0 por ciento de fibras dietéticas + almidón resistente, con las mismas proporciones de fibras insolubles y solubles y almidón resistente, encontradas en el frijol (8:3:1) por 14 días. El aumento de peso y la ingesta de dieta fueron más pequeños en el grupo alimentado con la dieta del frijol cocinado. Sin embargo, este grupo mostró el aumento más alto en los órganos estudiados. Las ratas que ingirieron la dieta conteniendo caseína con agregado de 15,0 por ciento de fibra dietética mostraron un crecimiento de 21,4 por ciento en el páncreas. Las ratas alimentadas con las otras dietas de caseína no mostraron diferencias significativas (p>0,05). El consumo de dieta conteniendo frijol común cocinado provocó un aumento de peso en todos los órganos estudiados (50,0 por ciento en el páncreas, 25,0 por ciento en el hígado y 33,4 por ciento en el intestino delgado) y un incremento del 47,1 por ciento en el tamaño del intestino delgado. La fibra dietética más almidón resistente ejerce un efecto trófico en los órganos digestivos, aunque no fue ese el único factor estimulante. El frijol cocinado puede tener otros componentes químicos, además de los inhibidores de proteasas, lectinas, fitatos y taninos, que probablemente contribuyen a ese efecto.

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Phosphate rocks have low available P and soluble P fertilizers have been preferably used in plant crop production, although economic and effective P sources are needed. Experiments were carried out on a Brazilian Typic Fragiudult soil with low available P to evaluate the agronomic effectiveness of phosphate rock (PR) compared with soluble phosphate fertilizer. Yam bean (Pachyrhizus erosus) inoculated with rhizobia (strains NFB 747 and NFB 748) or not inoculated was the test crop. Biofertilizers were produced in field furrows by mixing phosphate rock (PR) and sulphur inoculated with Acidithiobacillus (S+Ac) in different rates (50, 100, 150 and 200 g S kg(-1) PR), with 60 days of incubation. Treatments were carried out with PR; biofertilizers B(50), B(100), B(150), B(200); triple super phosphate (TSP); B(200) without Acidithiobacillus and a control treatment without P application (P(0)). TSP and biofertilizers plus S inoculated with Acidithiobacillus increased plant growth. Soil acidity and available P increased when biofertilizers B(150) and B(200) were applied. We conclude that biofertilizers may be used as P source; however, long term use will reduce soil pH and potentially reduce crop growth.

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The study was carried out in order to determine and establish the functional characters of starch extracted from yam bean (Pachyrhizus erosus (L) Urban) compared with cassava starch. Yam bean is a tropical tuber legume easily grown and holds a great potential as a new source of starch. Yam bean starch shows functional properties which are peculiar to those of most starch root crops. Gelatinization temperature (53-63 degrees C) and the pasting temperature (64.5 degrees C) are less than those of cereal starch, however, the swelling power is high (54.4 g gel/g dried starch). Yam bean starch paste presents a high viscosity profile, high retrogradation tendency and low stability on cooking. The functional properties of yam bean starch, similar to those of cassava starch, allows yam bean to be used as a potential new source of starch.

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