Arracacha Research Articles

Brotação e produção de mandioquinha-salsa 'Amarela de Carandaí', proveniente de mudas desinfectadas com óleo de eucalipto e enraizadas em bandejas

Objetivou-se avaliar a brotação das mudas e a produção de mandioquinha-salsa 'Amarela de Carandaí', provenientes de mudas desinfectadas com óleo de eucalipto e enraizadas em bandejas de isopor. No pré-enraizamento em bandejas, utilizou-se a matriz experimental Plan Puebla III para combinar concentrações de óleo de eucalipto e tempos de imersão, respectivamente: 0,6%/36 s; 1,4%/36 s; 0,6%/84 s; 1,4%/84 s; 1,0%/60 s; 0,1%/36 s; 1,9%/84 s; 0,6%/6 s e 1,4%/114 s, mais uma testemunha (0,0%/0 s). No campo, utilizaram-se 10 mudas por parcela e seis tratamentos: 0,6% s; 36 s; 0,6%/84 s; 1,0%/60 s; 0,1%/36 s; 0,6%/6 s e 0,0%/0 s. Maiores porcentagens de mudas brotadas e altura de plantas foram obtidas nos tratamentos onde se utilizaram concentrações de óleo de eucalipto menores que 1,0% e na testemunha. As maiores massas frescas de raízes comerciais, nas colheitas aos 264 dias após o plantio, foram obtidas nos tratamentos 0,6%/36 s, 0,6%/84 s e 1,0%/60 s. Houve queima das folhas provocadas por Alternaria sp e Septoria sp., com maior intensidade aos 111 dias após o plantio, associadas e sem possibilidade de quantificação isoladamente. Concluiu-se que, para se obter maior produção de raízes comerciais, as mudas devem ser desinfectadas em solução aquosa com doses de 0,6% ou 1,0% de óleo de eucalipto e imersão em tempos de 36 s a 84 s, sendo a colheita aos 264 dias após o plantio.

Local technologies of arracacha (Arracacia xanthorrhiza Bancroft) production at Boyacá, department of Boyacá

La base de la economia del municipio de Boyaca es la produccion agricola y pecuaria. La arracacha es un producto de gran importancia agro-alimentaria y socio-economica que, alternada con la papa, se cultiva en parcelas de pequenos agricultores, quienes han adquirido tradicionalmente sus conocimientos sobre el sistema de produccion. Debido a la demanda del mercado por ciertas variedades, el caso de paliverde y yema de huevo, como se denominan alli, se han dejado de cultivar otras, como la blanca de tarro y la amarilla de tarro, favoreciendo la perdida de agro-biodiversidad. El objetivo del presente estudio fue describir los aspectos relevantes de este sistema de produccion, a partir de la informacion recopilada sobre materiales cultivados, manejo agronomico y tecnologias locales de cultivo, partiendo del conocimiento acostumbrado de sus agricultores. Se siguio una metodologia participativa, mediante la aplicacion de encuestas. Los resultados indicaron que en Boyaca se encuentran mas de siete materiales geneticos: paliverde, palirrusia, palinegra, yema de huevo, yucatana, blanca de tarro y amarilla de tarro (denominaciones locales). Se siembra en asociacion con leguminosas y/o gramineas o intercalada con frutales, como el tomate de arbol. La incidencia de plagas y de enfermedades es baja; una pudricion de raiz es la mas relevante (Sclerotinia sclerotiorum). El rendimiento vario entre 2 y 4kg/planta (peso total de la raiz). La arracacha es una especie con gran potencial por sus caracteristicas nutricionales y usos agro-industriales, por tanto, se deben plantear estrategias, con el objeto de mejorar la rentabilidad del cultivo y conservar y mejorar los materiales geneticos existentes

Effect of enzymatic hydrolysis on some physicochemical properties of root and tuber granular starches

Enzymatic hydrolysis of granular starch is an important tool to provide information about granule structure. Cassava, sweet potato, Peruvian carrot, and potato starches were hydrolyzed by bacterial α-amylase at 37 °C for 48 hours, and the physicochemical properties of the residues from hydrolysis were determined. Cassava starch was the most susceptible to enzyme displaying 20.9% of hydrolysis, whereas potato starch was the most resistant with 5.9%. The granule average size varied from 10.8 to 23.4 μm for Peruvian carrot and potato starches, respectively. With the use of SEM, a smooth granule surface was observed for all native starches. Cassava and sweet potato starches displayed an A-type X-ray diffraction pattern, while Peruvian carrot and potato starches showed a B-type pattern. After hydrolysis, cassava, sweet potato, and Peruvian carrot starches showed some well degraded granules, whereas potato starch presented a slight sign of degradation. The amylose content of the starches decreased with hydrolysis for cassava, sweet potato, and Peruvian carrot starches and was kept unchanged for the potato starch. As expected, intrinsic viscosity and pasting properties decreased for all hydrolyzed starches. There is no difference between thermal properties of native and hydrolyzed starches. These results suggested that hydrolysis occurred in amorphous and crystalline areas of the granules. The B type diffraction pattern in conjunction with the big granule size of the potato starch may have contributed to the greatest resistance of this starch to hydrolysis.

Qualidade de mandioquinha-salsa minimamente processada e armazenada sob atmosfera modificada

O objetivo deste trabalho foi verificar o efeito da atmosfera modificada, passiva e ativa, sobre a conservação de mandioquinha-salsa minimamente processada da cultivar 'Amarela de Senador Amaral', adquirida de lavoura comercial do Município de Lavras, Minas Gerais (MG). As raízes foram selecionadas, lavadas com detergente neutro e enxaguadas em água corrente. Em seguida, foram imersas em solução de hipoclorito de sódio 300mg L-1, por 15 minutos, e secas em temperatura ambiente. As raízes foram descascadas e cortadas em fatias de aproximadamente 1cm de espessura, imersas em solução de hipoclorito de sódio 50mg L-1, por 10 minutos, drenadas em peneiras plásticas e embaladas. As bandejas contendo as fatias de mandioquinha-salsa foram armazenadas em câmara fria (5±1°C e 98% UR) por 15 dias. As seguintes análises foram realizadas a cada três dias: pH, acidez titulável, sólidos solúveis totais, firmeza, valores L* e b*, amido e avaliação sensorial (aparência e cor). O delineamento experimental foi inteiramente ao acaso (DIC), em esquema fatorial 3 x 6, sendo três tipos de atmosferas (passiva; ativa com injeção inicial das misturas: 2% O2 + 10% CO2 e 5% O2 + 5% CO2) e seis tempos de armazenamento (0, 3, 6, 9, 12 e 15 dias), com três repetições. Os valores médios de pH, acidez titulável, sólidos solúveis e firmeza encontrados neste trabalho foram 6,79, 0,13% de ácido málico, 4,04°Brix e 5,17N, respectivamente. A atmosfera modificada ativa (5% de O2 + 5% CO2) determinou maior valor L* às mandioquinhas-salsa minimamente processadas no sexto e no décimo segundo dia de armazenamento, quando comparada com a atmosfera (2% de O2 e 10% CO2). A atmosfera modificada ativa com 5% O2 + 5% CO2 determinou maiores valor b* e teores de amido às fatias de mandioquinha-salsa em comparação com as outras atmosferas. Conclui-se que a atmosfera modificada passiva, aliada à refrigeração e a boas práticas de fabricação, é suficiente para prolongar a vida útil de mandioquinhas-salsa minimamente processadas, preservando seus atributos de qualidade. Diante da avaliação sensorial realizada, a aparência e a cor das fatias de mandioquinha-salsa mantiveram-se aceitáveis para o consumo até o final do período de armazenamento.

Agrosilício na produção de clones de mandioquinha-salsa

The production of Peruvian carrot clones was evaluated in response to calcium-magnesium silicate, through an experiment carried out in Viçosa, Minas Gerais State, from May 2004 to March 2005. The experiments were arranged in a complete randomized design, in a 9 x 2 factorial scheme, with the nine clones (Araponga, BGH-4550, BGH-5742, BGH-5744, BGH-5747, BGH-6417, BGH-6425, BGH-6525 and Senador Amaral) cultivated with and without calcium-magnesium silicate (2,500 kg ha-1), with three repetitions. Plants were harvested 304 days post-planting, and the assessed parameters included plant height and diameter, fresh mass of aerial part, commercial roots per plant and yield of commercial and noncommercial roots (rejects), rotten roots and crown, measured in kg ha-1. There was no significant effect of calcium-magnesium silicate application on the yield of commercial roots. Senador Amaral, Araponga, BGH-5747, BGH-5742 and BGH-4550 were the most productive clones, with all having commercial yields above 18,000 kg ha-1. Clone BGH-5744 gave the lowest yield of commercial roots, although it stood out for plant height, diameter and production of fresh mass of aerial part. Further research is recommended to evaluate the effect of calcium-magnesium silicate on the production of Peruvian carrot commercial roots and resistance to diseases.

Characterization of native and oxidized starches of two varieties of Peruvian carrot (Arracacia xanthorrhiza, B.) from two production areas of Paraná state, Brazil

Two commercial varieties of Peruvian carrot ('Amarela de Carandaí' and 'Senador Amaral') were processed into flour, starch and bagasse and chemically evaluated. The starch was extracted, modified with H2O2 and characterized by the physicochemical methods. By using the methylene blue dyeing, the granules of the modified starches showed intense blue color. The carboxyl content, the reducing power and the amount of the water liberated from the pastes after the freeze-thawing were higher for the oxidized starches and their pastes were clearer than those of the native starches of the two varieties from the two production areas. The RVA viscoamylography showed that the modified starches had lower viscosities with differences between the varieties. In the thermal analysis, the temperatures of the pyrolysis were higher for the native (310.37, 299.08, 311.18 ºC) than for the modified starches (294.16, 296.65 e 293.29 ºC) for both the varieties. This difference could be related with the larger surface of the granules due to the partial degradation promoted by the chemical modification. In almost all results, the differences were evident between the varieties but not for the cultivation places.

Produtividade de mandioquinha-salsa sob diferentes densidades de plantio e tamanho das mudas

Objetivou-se, no presente trabalho, estudar a resposta produtiva da mandioquinha-salsa 'Amarela de Carandaí', propagada por mudas grandes-MG (22,1 g); médias-MM (14,1 g); pequenas-MP (9,7 g) e muito pequenas-MMP (5,7 g) e cultivada em canteiros com duas-2F e três fileiras-3F de plantas. Foram feitas colheitas aos 211 e 239 dias após o plantio-DAP. Todas as características avaliadas nas plantas, nas duas colheitas, foram influenciadas de forma variável pela interação tamanho das mudas e número de fileiras no canteiro. As maiores alturas das plantas foram daquelas do tratamento MP3F, nas duas épocas de colheita, mas, as colhidas aos 211 DAP (35,64 cm) apresentaram 4,50 cm a mais em relação às colhidas aos 239 DAP (31,14 cm). As massas frescas de folhas foram maiores nas plantas do tratamento MG2F (23,86 t ha-1), aos 211 DAP, e as do MM3F (22,09 t ha-1), aos 239 DAP. As maiores médias de massas frescas de rebentos (8,66 t ha-1) e de coroas (5,66 t ha-1) foram obtidas aos 239 DAP, em relação às dos 211 DAP (7,19 e 4,20 t ha-1). As maiores produções de raízes comerciais (11,61 t ha-1) e de não comerciais (5,80 t ha-1) foram do tratamento MG3P, aos 211 DAP e dos tratamentos MMP2F (14,48 t ha-1) e MP3F (5,92 t ha-1), respectivamente, aos 239 DAP. As massas frescas de raízes comerciais representaram apenas 18,31% e 23,08%, aos 211 DAP e 239 DAP, respectivamente, em relação à produção total das plantas.

Characterization of a member of a new Potyvirus species infecting arracacha in Brazil

An arracacha (Arracacia xanthorrhiza) plant collected in Brazil was found to be infected by a new virus. This viral isolate (named C17) systemically infected Nicotiana benthamiana and Apium graveolens. A polyclonal antibody was raised, and analysis of our arracacha germplasm collection showed a high infection rate of C17-like viruses (93% infection). Sequencing of the ca. 1.7 kb 3'-terminal genomic region revealed a typical potyvirus genome organization. It shared less than 70% nucleotide identity with any other potyvirus sequence, which thus indicated that it is possibly a member of a new Potyvirus species tentatively named Arracacha mottle virus (AMoV).

Avaliação de herbicidas no controle de plantas daninhas em mandioquinha-salsa

Avaliou-se a eficiência de herbicidas aplicados em pré e pós-emergência no controle de plantas daninhas e na produção de mandioquinha-salsa na Fazenda Experimental da EPAMIG, em Oratórios (MG), de maio a dezembro de 2002. Utilizou-se o delineamento de blocos casualizados com quatro repetições e 15 tratamentos incluindo duas testemunhas, com e sem capina. Em cada tratamento, foi usado um herbicida em pré e outro em pós-emergência das plantas, aplicados aos três e aos 45 dias após o plantio (DAP) respectivamente. A eficiência de controle e a toxidez dos herbicidas foram avaliadas aos 60 DAP e a produção de matéria seca de plantas daninhas aos 60 e 130 DAP. Na colheita, avaliou-se produção de raízes, coroa e parte aérea. A emergência de plantas foi máxima aos 45 DAP e, posteriormente, houve redução no estande, quando se utilizaram os herbicidas atrazine + óleo mineral e oxadiazon, em pós-emergência. Esses herbicidas, apesar de eficientes no controle de plantas daninhas, causaram toxidez à cultura. Na produção de raízes, destacaram-se os tratamentos: atrazine +fluazifop-p-butil; diuron + fluazifop-p-butil; diuron + Oxadiazon; linuron + fluazifop-p-butil; metolachlor + metribuzin + linuron e oxadiazon + diuron, com bom controle de plantas daninhas e rendimentos de raízes comerciais semelhantes ao da testemunha mantida no limpo (8,62 t ha-1).

Características estruturais e físico-químicas de amidos de mandioquinha-salsa (Arracacia xanthorrhiza)

Starch has very important physicochemical properties that depend on its botanical source and structural characteristics. Peruvian carrot starch displays special characteristics, which make it appropriate for industrial application in many processed foods. In this work, starch from two Peruvian carrot varieties, Amarela de Carandai (AC) and Amarela de Senador Amaral (ASA), were isolated and their physicochemical and structural properties were determined. Starch from the ASA variety exhibited granules with a greater average diameter than those from the AC variety and more than double the number of granules with size >20 µm, when compared to the other variety. Starches from both varieties, observed in a Scanning Electron Microscope, showed smooth granule surface with circular and polyhedral shapes for large and small granules, respectively. Molecular size distribution, intrinsic viscosity and degree of cristallinity of starches from both varieties were similar; however, amylose content was higher for the starch from the AC variety. Higher values of viscosity, swelling power and gelatinization temperatures were observed for the starch from the ASA variety, which could be related to the lower amylose content and the higher proportion of large granules exhibited by this starch.

Yield and gross income of arracacha in monocrop and intercropping with the Japanese bunching onion and parsley

The objective of this work was to study the yield performance and to determine the gross income of arracacha (Arracacia xanthorrhiza Bancroft), cultivar Amarela de Carandaí, grown in monoculture as well as in intercropping with the Japanese bunching onion (Allium fistulosum L.), cultivar Todo Ano (A-JBO) and parsley (Petroselinum crispum (Mill.), cultivar Lisa Preferida (A-P). Arracacha and the Japanese bunching onion were vegetatively propagated, while parsley was propagated by seeds. The Japanese bunching onion was first harvested 87 days after the planting (DAP), with resprouts harvested 154 and 212 DAP. Parsley was first harvested 105 days after the sowing (DAS), and, resprouts, 171, 212, and 268 DAS. Arracacha was harvested 268 DAP. At the harvest carried out 212 DAP, the Japanese bunching onion plants in monocrop significantly exceeded those in intercropping in 1.73 cm height and 0.99 t ha-1 commercial fresh mass (CFM). In parsley, the CFM yield in monocrop significantly exceeded the intercropping figures in 0.63, 0.66, and 0.72 t ha-1 at harvests carried out respectively 171, 212, and 268 DAS. Plant height and CFM of the Japanese bunching onion and parsley increased after every new harvest, except in parsley, for plant height 171 DAS and CFM 268 DAS. No significant differences were found in any of the evaluated characteristics when arracacha as single crop was compared to the A-JBO intercropping arrangement. Nevertheless, the A-P intercropping arrangement significantly reduced all characteristics in relation to the other systems, except for yield of non-commercial arracacha roots. A-JBO intercropping arrangement was viable (LER = 1.49) and therefore may be employed by farmers. A-P intercropping, on its turn, was unfeasible (LER = 0.97).

PProdução da mandioquinha-salsa consorciada com alface e beterraba

Estudaram-se os monocultivos da mandioquinha-salsa cv. Amarela de Carandaí, Arracacia xanthorrhiza (Umbelliferae), da beterraba cv. Tall Top Early Wonder, Beta vulgaris L. (Chenopodiaceae) e da alface cv. Grand Rapids, Lactuca sativa L. (Asteraceae), além dos consórcios mandioquinha-beterraba e mandioquinha-alface. Os cinco tratamentos foram arranjados no delineamento experimental em blocos casualizados, com três blocos e duas repetições internas em cada bloco. Foram avaliadas as massas frescas e secas das cabeças da alface, da parte aérea e das raízes da beterraba e das partes aéreas, rebentos, coroas e raízes da mandioquinha-salsa. Também foram avaliados os diâmetros das cabeças da alface e das raízes da beterraba. Os consórcios foram avaliados em função da razão de área equivalente (RAE) e da renda bruta. As três espécies apresentaram produção superior em monocultivo, em todas as características avaliadas. Considerando-se as produtividades de raízes totais e de raízes comercializáveis, respectivamente, a RAE para o consórcio mandioquinha-beterraba foi de 1,07 e 0,87 e para mandioquinha-alface foi 1,3 e 1,1. O consórcio mandioquinha-alface propiciou renda bruta de R$ 40.970,00. Concluiu-se que o consórcio da mandioquinha-salsa com a alface é viável.

Combinações de cálcio, atmosfera modificada e refrigeração na conservação pós-colheita da mandioquinha-salsa

Os objetivos desse trabalho foram avaliar o efeito do cálcio e o tipo de embalagem na conservação pós-colheita de mandioquinha-salsa, Arracacia xanthorhiza (Umbelliferae), sob refrigeração. Os tratamentos constaram do uso ou não de cálcio (pulverização com 0,18 mol/L de CaCl2; 1 t/ha de calcário calcítico no solo e ausência de cálcio); embalagem de PVC, CF filme e ausência de embalagem, em três avaliações (42, 84 e 126 dias de armazenamento). As raízes foram pesadas e armazenadas sob refrigeração a 4oC. O experimento foi conduzido em esquema fatorial 3 x 3 x 3, em DIC, com três repetições. Foram analisados a perda de massa e os teores de proteína, nitrogênio, cálcio, fósforo, magnésio, ferro e carotenóides totais. Os tratamentos de cálcio não reduziram a perda de massa e nem contribuíram para preservar a qualidade nutricional das mandioquinhas. Embora as raízes armazenadas na embalagem com PVC tenham apresentado perda de massa maior que em CF filme, elas apresentavam-se com aparência apropriada para comercialização. As raízes sem embalagem encontravam-se impróprias para comercialização aos 21 dias

Heat‐Moisture Treatment and Enzymatic Digestibility of Peruvian Carrot, Sweet Potato and Ginger Starches

AbstractThe aim of this work was to study the effects of heat‐moisture treatment (27% moisture, 100°C, 16 h) and of enzymatic digestion (alpha‐amylase and glucoamylase) on the properties of sweet potato (SP), Peruvian carrot (PC) and ginger (G) starches. The structural modification with heat‐moisture treatment (HMT) affected crystallinity, enzyme susceptibility and viscosity profile. The changes in PC starch were the most pronounced, with a strong decrease of relative crystallinity (from 0.31 to 0.21) and a shift of X‐ray pattern from B‐ to A‐type. HMT of SP and G starch did not change the X‐ray pattern (A‐type). The relative crystallinity of these starches changed only slightly, from 0.32 to 0.29 (SP) and from 0.33 to 0.32 (G). The extent of these structural changes (PC > SP > G) altered the susceptibility of the starches to enzymatic attack, but not in same order (PC > G > SP). HMT increased the starches digestion, probably due to rearrangement of disrupted crystallites, increasing accessible areas to attack of enzymes. The viscosity profiles and values changed significantly with HMT, resulting in higher pasting temperatures, decrease of viscosity values and no breakdown, i.e., stability at high temperatures and shear rates. Changes in pasting properties appeared to be more significant for PC and SP starch, whereas the changes for G starch were small. Setback was minimized following HMT in SP and G starches.

Atuação das enzimas oxidativas no escurecimento causado pela injúria por frio em raízes de batata-baroa

In this experiment roots of arracacha (Arracacia xanthorrhiza Bancroft) were stored at temperature of 5 and 10ºC for 28 days. At every seven days, the roots were removed from the cold storage and visually analyzed for the presence of chilling symptoms. Afterwards, the roots were grinded for polyphenoloxidase, peroxidase activities and soluble phenolic compounds. Both temperature of 5 and 10ºC induced external and internal darkening of the roots, with higher intensity at 5ºC. Activities of polyphenoloxidase, peroxidase and content of phenolic compounds were enhanced at cold storage. Activity of polyphenoloxidase and content of phenolic substances increased up to the 14th day of storage in both temperatures. The activity of peroxidase was elevated up to the seventh day of storage in both temperatures, which was kept constant at 5 and at 10ºC. The highest activity was detected at the 14th day of storage. These results show that peroxidase is involved in the initial stress response to the harvest and chilling, followed by the involvement of polyphenoloxidase in the enzymatic darkening and accumulation of phenolic compounds in the tissues

Características físico-químicas de amidos modificados com permanganato de potássio/ácido lático e hipoclorito de sódio/ácido lático

Amidos oxidados em elevadas concentrações produzem pastas fluidas, são estáveis à retrogradação e aplicados em indústrias de papel, têxtil e de alimentos. Esta propriedade é atribuída à presença de carboxilas, com cargas negativas e mais volumosas que as hidroxilas. Neste trabalho, amidos de batata, batata doce, mandioca, mandioquinha salsa, milho e milho ceroso foram modificados com KMnO4/ácido lático e NaOCl/ácido lático e caracterizados quanto ao teor de carboxilas, poder redutor, coloração diferencial, propriedade de expansão e propriedades viscoamilográficas, em água e tampões acetato (pH 4,0) e fosfato (pH 7,0). Amidos de milho ceroso e de mandioca modificados com KMnO4/ácido lático apresentaram elevadas expansões (25,8 e 24,1 mL.g-1, respectivamente). As pastas de amido de milho ceroso resistiram a ciclos de congelamento/descongelamento. A coloração diferencial e o teor de carboxilas não permitiram diferenciar as amostras; apenas o amido de batata reagiu com azul de metileno devido aos grupos fosfato. Quanto ao pH e acidez, as amostras apresentaram valores próximos da neutralidade, exceto o amido de milho e milho ceroso modificados com NaOCl. Amidos oxidados com KMnO4/ácido lático apresentaram picos de viscosidade inferiores aos tratados com NaOCl. Os picos de viscosidade em tampão fosfato foram inferiores aos em água e em tampão acetato.

Produção e renda bruta de mandioquinha-salsa, solteira e consorciada com cenoura e coentro

‘Amarela de Carandai’ Peruvian carrot (M), ‘Brasilia’ carrot (Ce) and ‘Tipo Portugues’ coriander (Co) were studied in monocrop system and intercropped with carrot and coriander. Five treatments were arranged at field in a completely randomized block design with five replications. Harvest of carrot occurred 95 days after sowing; coriander harvest occurred 112 days after sowing; and the Peruvian carrot harvest, 247 days after planting. Plant height (42.3 cm) and fresh masses of total (9.07 t ha -1 ) and commercial (6.55 t ha -1 ) roots of carrot in the MCe intercrop had significant increases of 4.4 cm, 2.34 and 1.73 t ha -1 , respectively, in relation to those plants in monocrop system. Coriander height (24.0 cm) and fresh mass of leaves (2.98 t ha -1 ) of plants from monocrop system were significantly higher than those intercropped. As for Peruvian carrot, there was significant influence on cultivation and the highest values of fresh mass, in t ha -1 , of leaves (17.84), shoots (4.07), crows (3.99) and total (14.04), commercial (10.46) and noncommercial (3.58) roots were obtained with the monocrop system. The MCe intercrop was considered effective (LER= 1.47) and the MCo was ineffective (LER = 0.76). Gross income showed that both intercroppings are not recommended for the Peruvian carrot producer since they induced losses of R$ 8,650.00 and R$ 7,011.25, respectively.

First Report of Phytophthora palmivora, Causal Agent of Black Pod, on Cacao in Puerto Rico.

Black pod or Phytophthora pod rot is the most economically important and widespread disease of cacao, Theobroma cacao L. Total losses due to Phytophthora exceed $400 million worldwide (1), and several species are known to attack cacao with P. palmivora (E.J. Butler) E. J. Butler as the most common. All plant parts are infected, but pod infections are particularly damaging. Symptoms resembling those of black pod disease were observed at the National Plant Germplasm Collection System of cacao at the USDA-ARS Tropical Agriculture Research Station (TARS) in Mayaguez, Puerto Rico for a number of years. During May of 2005, to determine the etiology of the disease, small, surface disinfested sections of pod lesions were placed on water agar and incubated for 4 days. The formation of papillate, deciduous, ellipsoidal to ovoid sporangia produced on sympodial sporangiophores on fruits, fit the description of P. palmivora and the identification was confirmed on cultures on water agar (2). Chlamydospores were readily observed in diseased pods and observed in pure cultures on V8 agar (2). Eight, single hyphal tips were transferred to potato dextrose agar (PDA) (Sigma-Aldrich, St. Louis, MO) and maintained as stock cultures. For pathogenicity tests, healthy mature pods were surface disinfested and placed in a humidity chamber lined with moist paper towels. Eight isolates were tested on four fruits per isolate and the pathogenicity test was repeated once. Inoculum was prepared by growing each isolate on PDA for 5 days with irradiation at 24°C, adding approximately 3.0 ml of water to each plate, dislodging the sporangia with a glass rod, mixing the suspension, estimating spore numbers with a hemacytometer, and adjusting to 104 sporangia per ml. A small, sterile scalpel was used to make an approximately 20.0 mm cut on the fruit epidermis, and approximately 0.2 ml of inoculum was placed on the wound. Pods were evaluated daily for 2 weeks. For molecular analysis, each of the eight cultures were grown in 50% potato dextrose broth to produce mycelia for DNA extraction using the FastDNA kit (Q-Biogen1, Irvine, CA). The internal transcribed spacer (ITS) region of the ribosomal RNA gene cluster was amplified, purified, and sequenced for all eight isolates. The ITS sequences of GenBank Accession Nos. DQ987915 to DQ987922 were identical and exhibited strong similarity (>99% identity) to that of three previously described isolates of P. palmivora from cacao (GenBank Accession Nos. AF 228097, AF467093, and AF467089). P. palmivora has been reported on citrus, coconut, black pepper, and Arracacia xanthorrhiza in Puerto Rico (2,3) and inoculum may have originated from these host or imported on cacao planted into the cacao collection before 2000. USDA-ARS-TARS is the official site for the cacao germplasm collection, thus, a detailed integrated pest management plan that includes the evaluation for resistance, sanitation measures, and use of fungicides to reduce disease levels has been implemented. Decreasing incidence and severity of this disease is a top priority. To our knowledge, this is the first report of P. palmivora on cacao in Puerto Rico.

Características físico-químicas e utilização em alimentos de amidos modificados por tratamento oxidativo

The use of modified starches in foods is made to improve characteristics that the native cannot confer. The objective of this work was to evaluate physicochemical characteristics of starches from several botanical sources after chemical modification with H2O2 considering technological properties of interest to the food industry. The modified starches were used in dulce de leche and starch gum and the sensorial acceptance of these products was verified. The chemical treatment included the suspension of the native starches in a 0.01% Fe2SO4, followed by addition of 1.25% H2O2 at pH 3.0 and reaction time of 15 min at 45 °C. After this period the starch was recovered by filtration, washed and oven-dried at 45 °C for 24 hours. The modified starches had higher expansion, carboxyl content, reducing power and susceptibility to syneresis. There was a decrease in the viscosity peak of the modified starches especially when the samples were analyzed in pH 7.0. The sensorial evaluation indicated that dulce de leche produced with addition of Peruvian carrot modified starch and regular corn acid-modified starch were the preferred samples. The starch gum made with modified starch of Peruvian carrot reached the second position on global preference between the panelists.

Vida útil e metabolismo de carboidratos em raízes de mandioquinha-salsa sob refrigeração e filme de PVC

O objetivo deste trabalho foi avaliar a influência da temperatura de armazenamento e do uso do filme de cloreto de polivinila (PVC) sobre a perda de matéria fresca e água, incidência de danos causados por frio e metabolismo pós-colheita dos carboidratos, em raízes tuberosas de mandioquinha-salsa (Arracacia xanthorrhiza). O filme de PVC reduziu a perda de matéria fresca e manteve o teor de água das raízes, durante o armazenamento por 60 dias a 5 e 10ºC. Os danos causados por frio foram inibidos nas raízes embaladas em filme de PCV, em ambas as temperaturas de armazenamento. As baixas temperaturas induziram o acúmulo de açúcares solúveis e a degradação de amido e, para as raízes armazenadas sem PVC, o aumento do conteúdo dos açúcares solúveis foi transiente e a taxa de degradação de amido foi superior à das raízes armazenadas com PVC.