Pedro Amorim Berbert

Estimating the total leaf area of the green dwarf coconut tree (Cocos nucifera L.)

Leaf area has significant effect on tree transpiration, and its measurement is important to many study areas. This work aimed at developing a non-destructive, practical, and empirical method to estimate the total leaf area of green dwarf coconut palms (Cocos nucifera L.) in plantations located at the northern region of Rio de Janeiro state, Brazil. A mathematical model was developed to estimate total leaf area values (TLA) as function of the average lengths of the last three leaf raquis (LR3), and of the number of leaves in the canopy (NL). The model has satisfactory degree of accuracy for agricultural engineering purposes.

Desidratação por imersão-impregnação e secagem por convecção de goiaba

O objetivo deste trabalho foi avaliar as caracteristicas fisico-quimicas e sensoriais de goiabas in natura e submetidas a desidratacao por imersao-impregnacao e a secagem complementar por conveccao, alem de avaliar a estabilidade da cor das goiabas secadas apos 30, 60 e 90 dias de armazenamento sob refrigeracao. Amostras de goiaba foram imersas em solucoes de sacarose a 0,4 e 0,5 g mL-1, sacarose a 0,3 g mL-1 + sucralose a 0,2 g L-1, acucar invertido a 41% (p/p) e acucar invertido sem diluicao. Foram avaliados solidos soluveis totais, acidez titulavel, pH, cor, aroma, aparencia, sabor e textura. O teor de solidos soluveis totais das amostras aumentou linearmente em funcao do tempo de imersao, sem efeito significativo do tipo de acucar empregado no preparo da solucao. A preservacao do teor de acido citrico foi mais pronunciada em solucoes menos concentradas de sacarose. Amostras secadas nao submetidas a desidratacao osmotica exibiram maior alteracao de cor do que aquelas previamente desidratadas. Solucoes de sacarose sao mais eficazes na estabilidade da cor do que as de acucar invertido. As goiabas submetidas a desidratacao por imersao-impregnacao tiveram boa aceitacao sensorial, e aquelas secadas apenas por conveccao nao foram aceitas pelos provadores.

Secagem de fatias de abacaxi in natura e pré-desidratadas por imersão-impregnação: cinética e avaliação de modelos

The effect of glucose and invert sugar impregnation on the convective drying rate of pineapple and the suitability of nine mathematical models to describe the drying curves were investigated. Tests were conducted using fresh pineapple rings and samples which were pre-treated by osmotic dehydration in sucrose solutions (0.40, 0.44, and 0.47 g mL-1) and in invert sugar syrup. Osmotic pre-treatments were performed at 40 and 50 oC for 2 hours at 60 min-1. The convective drying was performed in a tray cabinet dryer using heated ambient air at 60 oC and 1.25 m.s-1. The adjustment levels of the models were based on the correlation coefficient, the root mean square error, mean absolute percentage error, and residual plot analysis. The highest rates of convective drying were obtained for the fresh samples. In the osmotically pre-treated fruits, with both temperatures, an increase in the solution concentration was followed by a decrease in the convective drying rate. The Wang and Singh model was considered the most adequate in describing the convective drying of pineapple rings.

Cinética del secado de tomillo

Los objetivos del trabajo fueran estudiar la cinetica del secado de tomillo con posterior ajuste de diferentes modelos matematicos a los datos experimentales y determinar los valores de la difusividad efectiva y energia de activacion. Para el desarrollo del experimento de secado fueran utilizadas las temperaturas 30, 40, 50, 60 y 70 oC. El diseno experimental fue de bloques completamente aleatorizados, con tres repeticiones. Para el ajuste de los modelos matematicos a los datos experimentales fue realizado el analisis de regresion no lineal, por el metodo Simplex-Quasi-Newton. Los resultados mostraron que el modelo matematico de Page obtuve un mejor ajuste a los datos experimentales, los valores de los coeficientes de difusividad efectiva variaron entre 3,69 x 10-12 e 1,19 x 10-10 m2 s-1 y el valor de la energia de activacion fue de 77,16 kJ mol-1.

Qualidade fisiológica de semente de mamão em função da secagem e do armazenamento

A literatura apresenta resultados conflitantes sobre a manutencao do potencial fisiologico de semente de mamao armazenada por longos periodos com baixo teor de agua e em ambientes a baixas temperaturas. Neste trabalho, sementes de mamao do cultivar UENF-CALIMAN 01 foram secadas a sombra ate teor de agua de 12,6% b.u. e submetidas a secagem complementar a 37o C, em secador de bandejas, ate atingir teor de agua de 7,7% b.u. A germinacao e o vigor da semente, estimado pela contagem de plântulas normais fortes aos 14 dias, foram avaliados depois de submetidos aos dois processos de secagem e aos quatro e oito meses de armazenamento, em embalagem hermetica a 15o C. O vigor da semente, inicialmente de cerca de 46%, aumentou para 77%, depois de quatro meses de armazenamento. O percentual de germinacao, depois dos processos de secagem, foi de 75%, aumentando para 87% e declinando para 66%, aos quatro e oito meses de armazenamento, respectivamente. Os resultados obtidos no presente trabalho indicam que o comportamento da semente de mamao se aproxima mais daquele observado em sementes ortodoxas, que tem sua viabilidade extendida pela reducao simultânea do teor de agua e da temperatura, durante o armazenamento.

Avaliação nutricional e sensorial de caqui cv Fuyu submetido à desidratação osmótica e secagem por convecção

A crescente preocupacao com a saude humana tem promovido o aumento da demanda pelo consumo de frutas, tanto in natura como processadas. Neste trabalho, foram realizadas as avaliacoes nutricional e sensorial de caqui Fuyu submetido a desidratacao osmotica e secagem por conveccao. Cilindros de caqui com diâmetro de 15 mm e altura de 40 mm foram imersos por 2 horas em solucao com concentracao de sacarose de 0,47 g.mL-1, a 40 oC, utilizando-se relacao fruta/xarope de 1:10 e grau de agitacao de 60 min-1. A reducao do teor de agua ate 17% b.u. foi realizada a 60 oC, empregando-se velocidade do ar de 1,25 m/s. Apos a secagem, foram realizadas as seguintes analises fisico-quimicas: acidez, pH, oBrix, carboidratos, proteinas, lipidios, vitamina C, cinzas, fibras insoluveis e analise sensorial. Os resultados mostraram incremento em todas as caracteristicas fisico-quimicas avaliadas para o caqui desidratado em comparacao ao caqui in natura. A analise sensorial evidenciou que o produto obteve elevado indice de aceitacao, correspondendo ao segundo e terceiro niveis da escala hedonica (gostei muito e gostei regularmente). A caracteristica que influenciou predominantemente a aceitacao do produto foi a textura (88%), seguida do sabor (84%). A aparencia foi o atributo que menos influenciou a aceitacao (80%).

Thin-layer drying of passion fruit seeds

The original mathematical drying model proposed by Page (1949) was used to derive a thin-layer drying equation to describe the drying of seeds of yellow passion fruit (Passiflora edulis L.). With this purpose, experimental drying data were collected using a fixed-bed prototype drier, using three levels of drying-air temperature (30, 37 e 40oC); three levels of specific airflow rate (24, 48 e 71 m3 min-1 m2), and one level of initial moisture content (30.4±2.0% w.b.). All tests were conducted in an Agricultural Engineering Laboratory where the average temperature and humidity ratio were 28.4±1.0oC, and 0.0138±0.0016 kg kg-1, respectively. The values of errors produced by the equation derived by non-linear regression analyses were considered unacceptable for engineering purposes; this may suggest the need to evaluate other theoretical or empirical models to describe the thin-layer drying of yellow passion fruit seeds. Experimental data revealed, as expected, that as the drying air increased, the total time of drying decreased. Nonetheless, specific airflow rate appears to have no influence on drying time to reduce the initial moisture content of seeds of yellow passion fruit to a final value of 9.9±0.4% w.b.

Efeito da temperatura do ar de secagem sobre o teor e a composição química do óleo essencial de Pectis brevipedunculata

Leaves and flower heads of P. brevipedunculata were submitted to four drying-air temperatures (room temperature, 40, 50 and 60 oC). Room temperature (approximately 30 oC) and higher temperature drying (50 and 60 oC) had a deleterious effect on the essential oil content. The recommended drying-air temperature for the species is 40 oC for it results in the same amount of essential oil observed in fresh cut plants. Overall, 13 components accounting for more than 92% of the total composition were identified. Citral was the major component, followed by α-pinene and limonene. The essential oil showed high toxicity against Artemia salina larvae.

Qualidade nutricional de goiabas submetidas aos processos de desidratação por imersão-impregnação e secagem complementar por convecção

During dewatering and impregnation soaking (DIS), transfer of water and of natural compounds from the product to the hypertonic solution occurs, however, few studies have been carried out to identify and quantify the losses of these compounds. Thus, this work reports on the losses of vitamin C and of the following minerals: Na, K, Ca, Mg, Zn and Mn, in red guavas submitted to the combined process of DIS (at 50 oC for 2 hours) and convective drying (at 60 oC and air velocity of 1.25 m/s, to a final moisture content of 20% w.b.). Studies were carried out employing two types of solutes: sucrose (in 0.4 and 0.5 g.mL-1 solutions) and liquid invert sugar (in a 41% w/w solution and as an undiluted syrup). Also, a test was performed using a solution comprised of 0.3 g.mL-1 sucrose and 0.2 g.L-1 sucralose. The control treatment consisted of drying guava solely in the convective drier. The effect of storage conditions on the stability of ascorbic acid was assessed after 60 days at 7 and 25 oC. Results indicated reductions in the range of 20 to 64% in the amounts of the minerals studied at the end of the DIS process, as compared to the amount found in fresh fruits, and negligible losses of vitamin C, except in the treatment with undiluted liquid invert sugar. Convective drying promoted losses of vitamin C in the range of 32 to 68%. The ranges of vitamin C loss in storage at 7 and 25 oC were 58 to 82% and 70 to 86%, respectively.

Desidratação por imersão-impregnação de abacaxi em soluções de sacarose e em xarope de açúcar invertido

This work consisted of evaluating the effect of the type of osmotic agent, degree of stirring, and temperature and concentration of the hypertonic solution on the kinetics of osmotic dehydration of sliced pineapple. The osmotic agents used here were sucrose in solutions with concentrations of 0.40, 0.44 and 0.47 g.mL-1, and undiluted inverted sugar syrup. Osmotic dehydration was carried out using a fruit to syrup weight ratio of 1:10, and employing two levels of temperature of the solutions, 40 and 50 °C, two shaking rates, 0 and 60 min-1, and a total immersion time of 2 hours. The results showed that immersion in undiluted inverted sugar caused a greater increase in the total soluble solids content in sliced fruit. The parameters characterizing the kinetics of osmotic dehydration showed higher values in the sliced fruit dehydrated in syrup at 40 to 50 °C under shaking.