A protein expression system for tandem affinity purification in Xanthomonas citri subsp. citri

Abstract Citrus canker, caused by the Gram-negative bacterium Xanthomonas citri subsp. citri (Xac), is one of the most devastating diseases to affect citrus crops. There is no treatment for citrus canker; effective control against the spread of Xac is usually achieved by the elimination of affected plants along with that of asymptomatic neighbors. An in depth understanding of the pathogen is the keystone for understanding of the disease; to this effect we are committed to the development of strategies to ease the study of Xac. Genome sequencing and annotation of Xac revealed that ∼37% of the genome is composed of hypothetical ORFs. To start a systematic characterization of novel factors encoded by Xac, we constructed integrative-vectors for protein expression specific to this bacterium. The vectors allow for the production of TAP-tagged proteins in Xac under the regulation of the xylose promoter. In this study, we show that a TAP-expression vector, integrated into the amy locus of Xac, does not compromise its virulence. Furthermore, our results also demonstrate that the polypeptide TAP can be overproduced in Xac and purified from the soluble phase of cell extracts. Our results substantiate the use of our vectors for protein expression in Xac thus contributing a novel tool for the characterization of proteins and protein complexes generated by this bacterium in vivo.

Xylella fastidiosa: an in vivo system to study possible survival strategies within citrus xylem vessels based on global gene expression analysis

Xylella fastidiosa inhabits the plant xylem, a nutrient-poor environment, so that mechanisms to sense and respond to adverse environmental conditions are extremely important for bacterial survival in the plant host. Although the complete genome sequences of different Xylella strains have been determined, little is known about stress responses and gene regulation in these organisms. In this work, a DNA microarray was constructed containing 2,600 ORFs identified in the genome sequencing project of Xylella fastidiosa 9a5c strain, and used to check global gene expression differences in the bacteria when it is infecting a symptomatic and a tolerant citrus tree. Different patterns of expression were found in each variety, suggesting that bacteria are responding differentially according to each plant xylem environment. The global gene expression profile was determined and several genes related to bacterial survival in stressed conditions were found to be differentially expressed between varieties, suggesting the involvement of different strategies for adaptation to the environment. The expression pattern of some genes related to the heat shock response, toxin and detoxification processes, adaptation to atypical conditions, repair systems as well as some regulatory genes are discussed in this paper. DNA microarray proved to be a powerful technique for global transcriptome analyses. This is one of the first studies of Xylella fastidiosa gene expression in vivo which helped to increase insight into stress responses and possible bacterial survival mechanisms in the nutrient-poor environment of xylem vessels.

Microscopia eletrônica de varredura de fungos nematófagos associados a Tylenchulus semipenetrans e Pratylenchus jaehni / Scanning electron microscopy of nematophagous fungi associated Tylenchulus semipenetrans and Pratylenchus jaehni

Microscopia Eletrônica de Varredura de Fungos Nematófagos Associados a Tylenchulus semipenetrans e Pratylenchus jaehni. Fungos nematófagos têm sido estudados como uma alternativa promissora para o manejo de nematóides dos citros. Isolados detectados em pomares de citros, principalmente do Estado de São Paulo, foram estudados no Laboratório de Microscopia Eletrônica de Varredura da FCAV/UNESP ­ Câmpus de Jaboticabal-SP. Este estudo teve por objetivo documentar ao microscópio eletrônico de varredura as estruturas morfológicas marcantes para a identificação das principais espécies de fungos nematófagos envolvidas no estudo e comprovar a patogenicidade dos isolados associados a T. semipenetrans e P. jaehni, a saber: Arthrobotrys oligospora, A. conoides, A. robusta, A. musiformis, Dactylella leptospora, Monacrosporium eudermatum e M. elegans. Os dados obtidos no nesse estudo confirmaram que a microscopia eletrônica de varredura é uma ferramenta eficaz para auxiliar no entendimento do modo de ação dos fungos nematófagos e revelar detalhes de suas estruturas reprodutivas e de captura, confirmando a patogenicidade dos isolados a T. semipenetrans e P. jaehni assim como confirmar a identificação de alguns isolados.

Nematophagous fungi have been studied as a promising alternative for the management of nematodes of citrus. This study had the objective of documenting by scanning electron microscopy the outslading morphological structures for the identification of the main species of nematophagous fungi involved in the study and proving the pathogenicity of the isolated ones associated with T. semipenetrans and P. jaehni, Isolated came from in citrus orchards, mainly in São Paulo State, were studied in the Laboratory of Scanning Electron Microscopy of FCAV/UNESP - Campus de Jaboticabal-SP. The data obtained in this study have confirmed that the scanning electron microscopy is an effective tool to assist in the understanding of way of action of the nematophagous fungi: Arthrobotrys oligospora, A. conoides, A. robusta, A. musiformis, Dactylella leptospora, Monacrosporium eudermatum and M. elegans and to reveal details of their reproductive structures and the capture, to confirm the pathogenicity of the isolated to T. semipenetrans and P. jaehni, as well as to confirm the identification of some isolated

Levantamento populacional de cigarrinhas (Hemiptera: Cicadellidae) associadas à transmissão de Xylella fastidiosa em pomares cítricos do Litoral Norte da Bahia / Survey of sharpshooters (Hemiptera: Cicadellidae) associated with Xylella fastidiosa transmission in citrus groves of the North Coast of Bahia State

The causal agent of citrus variegated clorosis, Xylella fastidiosa, is transmitted by leafhoppers of the subfamily Cicadellinae, whose species vary regionally. The goal of this study was to identify potential vectors of this pathogen in citrus groves of Bahia North Coast, Brazil. The survey was done from March/2002 to February/2003 in three seven- to nine-year-old sweet orange (Citrus sinensis, Pêra variety) groves located in Rio Real, BA. Fifteen yellow sticky cards (8.5x11.5 cm) were installed 40 m apart in each grove, hanged at 1.5 m high on the upper north side of citrus canopies, and replaced fortnightly. A sweep net was periodically used to sample leafhoppers on herbaceous weeds inside the groves, by selecting five points at random and performing 30 sweeps in each point. A total of 1,360 specimens of 49 Auchenorrhyncha species were collected in this study, mostly in the family Cicadellidae (90.2 percent). The subfamily Cicadellinae, which includes the sharpshooter vectors of X. fastidiosa, showed the largest number of species (14) and specimens (84.8 percent). Acrogonia flagellata Young, A. citrina Marucci & Cavichioli, Homalodisca spottii Takiya, Cavichioli & McKamey and an unidentified Cicadellini (species 1) were the dominant species trapped on citrus canopies, while Hortensia similis (Walker) and Erythrogonia dubia (Medler) were dominant in the weedy vegetation. Among the Cicadellinae species already known as vectors of X. fastidiosa in citrus, only A. citrina, Bucephalogonia xanthophis (Berg) e Ferrariana trivittata (Signoret) were found. The two latter species were accidentally trapped by sweep net in the weedy vegetation.

O agente causal da clorose variegada dos citros, Xylella fastidiosa, é transmitido por cigarrinhas da subfamília Cicadellinae, cujas espécies variam regionalmente. O objetivo deste trabalho foi identificar potenciais vetores do patógeno em pomares cítricos do Litoral Norte da Bahia. Os levantamentos foram conduzidos de mar/2002 a fev/2003, em três propriedades no município de Rio Real, em pomares de laranjeira doce (Citrus sinensis) variedade Pêra, com sete a nove anos. Em cada pomar, 15 cartões adesivos amarelos foram dispostos a 40 m entre si, instalados a 1,5 m de altura em ramos da face norte, na periferia da copa, sendo substituídos quinzenalmente. Também foram realizadas amostragens com rede de varredura na vegetação rasteira dos pomares, em cinco pontos escolhidos aleatoriamente, efetuando-se 30 redadas por ponto. No total, foram coletados 1360 espécimes pertencentes a 49 espécies de Auchenorrhyncha, a maioria da família Cicadellidae (90,2 por cento). A subfamília Cicadellinae, que inclui os vetores de X. fastidiosa, apresentou maior número de espécies (14) e de indivíduos coletados (84,8 por cento). Entre as espécies de Cicadellinae, Acrogonia flagellata Young, A citrina Marucci & Cavichioli, Homalodisca spottii Takiya, Cavichioli & McKamey e uma espécie não-identificada de Cicadellini (espécie 1) foram dominantes na copa das plantas cítricas, enquanto que Hortensia similis (Walker) e Erythrogonia dubia (Medler) foram dominantes na vegetação rasteira. Entre os cicadelíneos já conhecidos como vetores de X. fastidiosa em citros, apenas A. citrina, Bucephalogonia xanthophis (Berg) e Ferrariana trivittata (Signoret) foram observados, sendo que as duas últimas espécies tiveram ocorrência acidental na vegetação rasteira.

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease / Deficiência nutricional em citros com sintomas da doença da clorose variegada dos citros

It is well known that citrus plants that have been infected by Xylella fastidiosa display nutritional deficiencies, probably caused by production of extracellular polymers by the bacteria that block normal nutrient flow through the xylem. The aim of this work was to study the mineral composition of specific foliar areas in different stages of infection in citrus. Thus, the concentrations of macro and micronutrients in leaves of citrus infected by X. fastidiosa were measured. Samples from four infected citrus orchards in the State of São Paulo, Brazil, were respectively collected from Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto and Paraíso counties. The presence of X. fastidiosa in leaves was confirmed by polymerase chain reaction (PCR) using specific PCR primers. To understand the variation in leaf-nutrient content in citrus plants, we used foliar nutrient values from control (non-symptomatic) plants as a reference. Chemometric analysis showed that the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn were observed in chlorotic areas, although other studies revealed deficiency of zinc in leaves. This is the first report showing that a correlation between chlorotic citrus leaf and higher concentrations of Fe, Mn and Zn are observed when infected and healthy plants were compared.

Já é bem conhecido que cultivares cítricas que foram infectadas pela bactéria Xylella fastidiosa apresentam deficiências nutricionais devido à produção de polímero extracelular por esta bactéria, o qual bloqueia o fluxo normal de nutriente pelo xilema. O objetivo deste trabalho foi o de estudar a composição mineral em áreas foliares específicas em diferentes fases de infecção na planta. Assim, as concentrações de macro e micronutrientes em folhas de citros infectados por X. fastidiosa foram quantificadas. Foram coletadas amostras de quatro pomares cítricos infectados localizados em: Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto e Paraíso, no Estado de São Paulo. A presença de X. fastidiosa em folhas foi confirmada através de reação da polimerase em cadeia (PCR) usando iniciadores específicos. Para entender a variação no conteúdo de nutriente foliar em plantas cítricas, utilizou-se de valores de nutrientes foliares de plantas não sintomáticas (controle) como referência. A análise quimiométrica mostrou que a deficiência de P e K em plantas sintomáticas e concentrações altas de Fe, Mn e Zn foram presentes em áreas foliares cloróticas, embora outros estudos mostrem a deficiência de zinco em folhas. Este é o primeiro relato indicando que uma correlação entre folhas cítricas cloróticas e elevadas concentrações de Fe, Mn e Zn foi observada quando plantas infectadas e saudáveis foram comparadas.

Detección del virus de la tristeza de los cítricos por serología, microscopía e hibridación in situ / In situ serological, microscopy and hybridization detection of CTV

El virus de la tristeza de los cítricos (CTV) es perjudicial para la citricultura y causa la enfermedad llamada tristeza de los cítricos. Infecta las especies del género Citrus ocasionando la muerte de millones de árboles. Los síntomas son decaimiento rápido (QD) y acanalamiento de tallo (SP). En el trabajo se diagnosticó molecular y serológicamente al CTV en aislados provenientes de Citrus aurantifolia o Lima Tahití (LT) y Citrus madurensis (Lour) o Calamondino (Ca), y se realizaron estudios preliminares de detección viral por medio de microscopía óptica e hibridación in situ. Se utilizó IC-RT-PCR e inmunoimpresión de tejido (IMI) expuesto a los anticuerpos monoclonales 3DF1+3CA5, y con el anticuerpo discriminante MCA 13 con técnica de Enzyme Linked Inmunossorbent Assay Doble Sándwich (Elisa-DAS). La detección por microscopía se realizó sobre secciones de pecíolo de LT y C que se tiñeron con Azure A, y con acetato de uranilo y citrato de plomo. Para la hibridación in situ se empleó una sonda marcada con digoxigenina dirigida hacia el gen de la proteína mayor de la cápside. Los resultados de IC-RT-PCR, IMI y Elisa fueron positivos para LT y C, indicando la presencia de variantes virales de tipo severo. Con microscopía de luz se detectaron inclusiones citoplasmáticas en las células acompañantes y del floema, confirmado con IMI y por hibridación in situ. Se visualizaron inclusiones de partículas virales en el tejido vegetal con microscopía electrónica con cambios en la ultraestructura celular como presencia de grandes vacuolas propias de la infección viral. Este trabajo integra distintas técnicas diagnósticas sobre dos especies cítricas exóticas.

Citrus tristeza virus (CTV) is deleterious for citriculture and causes citrus tristeza disease. CTV infects all citrus species thereby causing the death of millions of trees. Its main symptoms are quick decline (QD) and stem pitting (SP). Serological, molecular and microscopy techniques were used in this work for diagnosing CTV in Citrus aurantifolia or Tahiti Lime (Citrus latifolia Tanaka) (TL) and Citrus madurensis (Lour) or Calamondin (Ca) isolates. Petioles were tissue printed (IMI) and exposed to 3DF1+3CA5 monoclonal antibodies; they were then ELISA buffer extracted and exposed to a discriminant MCA 13 monoclonal antibody in a double-antibody sandwich indirect enzyme-linked immunosorbent assay (DASI-ELISA). Immunocapture reverse transcriptase-polymerase chain reaction (IC-RT-PCR) amplification, using specific major coat protein gene (CPG) primers, was used on the ELISA buffer extracts as template. Optical and electron microscopy were used for detection on transversal sections of petiole and stained with azure A, uranyl acetate or lead citrate. Digoxygenin-labelled major CPG CTV probes were used for in situ hybridisation of petioles printing. All IC-RT-PCR, IMI and ELISA results were positive for both LT and C, indicating the presence of severe viral variants. Light microscopy cytoplasm inclusions were detected in the phloem and accompanying cells, confirmed by IMI and in situ hybridisation. Electron microscopy analysis revealed cellular abnormalities with changes in ultrastructure and the presence of big vacuoles which are characteristic of cytoplasmic viral infection. This is the first work integrating all available diagnostic techniques on these two exotic citric species.

[Prevalence of bacterial contamination in orange and apple juices and correlation with some other factors in Shahrekord, 1385]

Fruit juices are becoming an important part of the modern diet among many communities. These juices can be contaminated with bacterial pathogens, leading to different gastrointestinal infections. This study was aimed to assess the prevalence of bacterial contamination in orange and apple juices and its correlation with some other factors. In this descriptive-analytical study, 360 apple and orange juice samples produced of three internal factories with less than six and more than six months of production were examined microbiologically, from August to December 2006 in Shahrekord. Data were analyzed by SPSS software, using Chi-square test. We found a rate of 4.4% contaminated fruit juices with a mean total isolated bacterial count [TBC] of 1.45 x10[3] cfu/ml. Isolated Bacteria included Staphylococcus epidermidis in 10 [62.5%], Staphylococcus aureus in 3 [19%], Bacillus subtilis in 2 [12.5%] and Bacillus cereus in 1 [6%] samples. Data analyses revealed no significant difference between contaminated samples and kind of fruit juices or factories [P>0.05]. However, a statistically significant difference was detected between contaminated samples and production time [P<0.01]. Based on our findings, we recommend consuming these products within six months of manufacturing as well as improving the maintenance and transporting conditions

Brevipalpus mites Donnadieu (Prostigmata: Tenuipalpidae) associated with ornamental plants in Distrito Federal, Brazil

Brevipalpus mites colonize a great number of fruit and ornamental plants. Mite species belonging to this genus have been associated with many plant viruses. Citrus leprosis (CiLV) is the most economically important virus transmitted by B. phoenicis mites. It has recently been shown that ornamental plant species can be alternative hosts of this virus. The high volume of trade and frequent movement of live ornamental plants make them efficient pest disseminators. Because of this, it is desirable to expand knowledge of potential pests aiming to guide the adoption of quarantine measures. This work reports ornamental plant hosts of Brevipalpus mites in the Distrito Federal (DF), as well the occurrence of symptoms consistent with Brevipalpus-borne plant viruses in these same hosts. Between July and September of 2005, five surveys were carried out in 14 localities within DF. Leaves and branches of fifty-five ornamental plant species were sampled. The species Pithecellobium avaremotemo Mart. is for the first time reported as a host for B. phoenicis (Geijskes), B. californicus Banks and B. obovatus Donnadieu species. Additionally, seven new species are reported as hosts for Brevipalpus within South America. New hosts are also listed for individual mite species. Typical symptoms of Brevipalpus-borne viruses were observed in Ligustrum sinense Lour., Pelargonium hortorum L.H. Bailey, Hibiscus rosa-sinensis L. and orchids (Dendrobium and Oncidium). The results of this work emphasize the potential role of the ornamental plants as vehicles for dissemination of Brevipalpus mites.

Os ácaros do gênero Brevipalpus colonizam um grande número de espécies frutíferas e ornamentais e têm sido associados a viroses de muitas plantas. A leprose dos citros é a virose de maior importância econômica transmitida por esses ácaros. Recentemente foi comprovado que algumas plantas ornamentais podem ser hospedeiras alternativas desse vírus. Os grandes volumes e a alta movimentação das plantas ornamentais fazem com que estas ajam como eficientes disseminadoras de pragas. Por essa razão, é necessário ampliar o conhecimento sobre pragas potenciais, de modo a subsidiar a implementação de medidas quarentenárias. Neste trabalho são relatadas as plantas ornamentais hospedeiras de ácaros Brevipalpus no Distrito Federal, assim como a ocorrência de sintomas típicos de viroses a elas transmitidas por Brevipalpus. Entre julho e setembro de 2005, foram realizadas cinco coletas em 14 localidades do DF. Foram amostradas folhas e ramos de 55 espécies de ornamentais. Pithecellobium avaremotemo Mart. é relatada, pela primeira vez, como hospedeira das espécies B. phoenicis (Geijskes), B. californicus Banks e B. obovatus Donnadieu. Adicionalmente, são relatadas sete novas espécies como hospedeiras de Brevipalpus na América do Sul. Novos hospedeiros são também listados para cada uma das espécies. Sintomas típicos de viroses transmitidas por Brevipalpus foram observados em Ligustrum sinense Lour., Pelargonium hortorum L.H. Bailey, Hibiscus rosa-sinensis L. e orquídeas (Dendrobium e Oncidium). Os resultados deste trabalho enfatizam o papel potencial de plantas ornamentais como veículo para disseminação de ácaros Brevipalpus.

Evaluation of the Antimicrobial Properties of Different Parts of Citrus Aurantifolia (Lime fruit) as Used Locally

We investigated the potency of Citrus aurantifolia (Lime fruit); against pathogens; in the different forms in which this fruit plant is used locally (juice of the fruit; burnt rind of the fruit commonly known as ""epa-ijebu"" in the Yoruba dialect) and the oil obtained from steam distillation of the fruit. The antimicrobial activity of ""epa-ijebu"" in different solvents was also compared. The solvents include palm-wine (a local alcoholic drink tapped from palm trees); Seaman's Schnapps 40alcoholic drink; water; ethanol and fermented water from 3 days soaked milled maize known as ""ekan-ogi"" or ""omidun"" in the Yoruba dialect. Antimicrobial activity was carried out by the agar well diffusion. The clinical isolates used included Anaerobic facultative bacteria; namely: Staphylococcus aureus ATCC 25213; Staphylococcus aureus; Salmonella paratyphi;Shigella flexnerii; Streptococcus faecalis; Citrobacter spp; Serratia spp; Klebsiella pneumoniae; Pseudomonas aeruginosa; Escherichia coli ATCC 25922; and Escherichia coli; Fungi such as Aspergilus niger and Candida albicans; and Anaerobes which includes Bacteroides spp; Porphyromonas spp; and Clostridium spp. Crude extracts of all solvents used varied in zones of inhibition. The anaerobes and the Gram-positive bacteria were susceptible to all the extracts with minimum inhibitory concentration (MIC) ranging from 32mg/ml-128g/ml. The activity against the fungi showed only the oil extract potent for A. niger; while Candida albicans was susceptible to all the extracts with MIC ranging from 256mg/ml-512mg/ml. The Gram-negatives have MIC ranging from 64mg/ml-512mg/ml. Minimum bactericidal concentration (MBC) ranged between 32mg/ml to 512mg/ml depending on isolates and extracting solvent. The oil and palm-wine extract of ""epa-ijebu"" showed greater activity than the other extracts. The killing rate of the schnapps extract on S. aureus and E. coli was 1 and 3.5 hours respectively

Comparison of shape analysis methods for Guinardia citricarpa ascospore characterization

Among the diseases affecting the commercial citrus production, the citrus black spot (CBS) is considered to cause substantial losses. The analyses of particles in suspension in the orchards and collected into a disc have been applied as a preventive action trying to identify the presence of fungus spores before symptom appearance. In this paper, we show the results of several shape analysis methods applied to the fungus, the first step to the aimed computer aided vision system, capable to assist the identification process. Experiments and comparative results among the methods are presented in this paper, showing that better results were obtained applying the curvature method.

IP3 production in the hypersensitive response of lemon seedlings against Alternaria alternata involves active protein tyrosine kinases but not a G-protein

IP3 increase and de novo synthesis of scoparone are produced in the hypersensitive response (HR) of lemon seedlings against the fungus Alternaria alternata. To elucidate whether a G-protein and/or a protein tyrosine kinase (PTK) are involved in signal transduction leading to the production of such a defensive response, we studied the HR in this plant system after treatment with G-protein activators alone and PTK inhibitors in the presence of fungal conidia. No changes in the level of IP3 were detected in response to the treatment with the G-protein activators cholera toxin or mastoparan, although the HR was observed in response to these compounds as determined by the scoparone synthesis. On the contrary, the PTK inhibitors lavendustin A and 2,5-dihidroxy methyl cinnamate (DHMC) not only prevented the IP3 changes observed in response to the fungal inoculation of lemon seedlings but also blocked the development of the HR. These results suggest that the IP3 changes observed in response to A. alternata require a PTK activity and are the result of a G-protein independent Phospholipase C activity, even though the activation of a G-protein can also lead to the development of a HR. Therefore, it appears that more than one signaling pathway may be activated for the development of HR in lemon seedlings: one involving a G-protein and the other involving a PTK-dependent PLC.

Levaduras inhibidoras de Penicillium / Inhibitory Penicillium yeasts

El objetivo de este trabajo fue determinar la acción inhibitoria in vitro e in vivo de algunas cepas de levaduras de la zona citrícola jujeña sobre el crecimiento de los mohos patógenos post-cosecha y seleccionarlas para elaborar un producto de biocontrol. Se aislaron de frutos cítricos cepas de los mohos patógenos post-cosecha Penicillium digitatum, P. italicum,P. ulaiense, Phyllosticta sp. y Galactomyces geotrichum, así como de levaduras saprófítas de los géneros Brettanomyces, Candida, Cryptococcus, Kloeckera, Pichia y Rhodotorula. También se obtuvieron algunas levaduras de otras fuentes. Se identificaron las levaduras por las características macro y micromorfológicas y las pruebas fisiológicas. La actividad in vitro e in vivo de las diferentes cepas fue diferente según se enfrentaran a P. digitatum o P. ulaiense. Candida cantarellii y una cepa de Pichia subpelliculosa produjeron una reducción significativa del área de las lesiones provocadas por estas especies de Penicillium, y podrían ser empleadas en la formulación de un producto para biocontrol.

The objective of this work was to establish the in vitro and in vivo inhibition of post-harvest pathogenic moulds by yeasts in order to make a biocontrol product. Post-harvest pathogenic moulds Penicillium digitatumP. italicum, P. ulaiense, Phyllosticta sp., Galactomyces geotrichum and yeasts belonging to genera Brettanomyces, Candida, Cryptococcus, Kloeckera,Pichia, Rhodotorula were isolated from citrus fruits. Some yeasts strains were also isolated from other sources. The yeasts were identified by their macro and micro-morphology and physiological tests. The in vitro and in vivo activities against P. digitatum or P. ulaiense were different. Candida cantarellii and one strain of Pichia subpelliculosa produced a significant reduction of the lesion area caused by the pathogenic moulds P. digitatum and P. ulaiense, and could be used in a biocontrol product formulation.

Embalagem para sucos de frutas / Packaging for fruit juices

Sucos de frutas säo sistemas complexos que, devido às suas características intrínsecas, apresentam vida útil influenciada por fatores como: desenvolvimento de microrganismos deteriorantes, açäo de enzimas e ocorrência de reaçöes químicas que comprometem a qualidade organoléptica e também acarretam perdas nutricionais. Para evitar ou retardar a deterioraçäo microbiana, os sucos säo submetidos a tratamentos térmicos e/ou preservados por conservantes químicos ou pela açäo do frio e desta forma podem ser divididos em 3 categorias básicas: sucos integrais ou prontos para beber, estáveis à temperatura ambiente; sucos concentrados congelados e sucos prontos para beber refrigerados. As características das embalagens utilizadas para essas categorias säo específicas, pois dependem, principalmente, do desempenho frente ao tratamento térmico e/ou temperatura de estocagem e da vida útil pretendida ao produto. Desta forma, as alternativas de embalagem para sucos de frutas säo discutidas separadamente para cada categoria, enfatizando os requisitos a serem preenchidos, vantagens e limitaçöes das embalagens hoje em uso no Brasil e as principais tendências

Estabilidade de suco de laranja näo-pasteurizado, armazenado a 4oC / Stability of unpasteurized orang juice, stored at 4oC

Foi analisada a estabilidade do suco de laranja, sem pasteurizaçäo, extraído em extrator de pequeno porte FMC, modelo Fresh in Squeeze quanto aos aspectos de alteraçöes químicas, microbiológicas e organolépticas. O produto armazenado a 4oC foi acondicionado em dois tipos de embalagens: frascos de polietileno de alta densidade (PEAD) e sacos de polietileno de baixa densidade (PEBD). No presente trabalho, os resultados da avaliaçäo organoléptica foram determinantes na definiçäo da vida-de-prateleira do produto. Os dois tipos de embalagens se adequaram ao produto