Liming and quality of guava fruit cultivated in Brazil

An experiment was conducted on guava trees Psidium guajava L. (cv. Paluma) grown in the Experimental Citrus Culture Station of Bebedouro, SP, on dystrophic, acid Typical Hapludox in order to assess the effects of application of increasing lime doses to the soil on the quality of guava fruits on the basis of the physicochemical changes observed in the fruits after harvesting. The treatments consisted of increasing lime doses applied before planting, considering 0, 1.85, 3.79, 5.56 and 7.41 t ha(-1), applied in August 1999. Leaf calcium content was assessed at flowering time. After fruit harvesting, calcium content in the pulp, total weight, transverse diameter, length, pulp weight, % pulp, Brix degrees (degrees Brix), titratable acidity, and fruit ratio were determined. Loss of fruit fresh mass, firmness and color were determined daily during a period of 8 days of storage. Lime application to an acid Red Latosol before guava tree planting did not affect the physical characteristics of the fruits but provided a lower loss of fresh matter and greater fruit firmness when the fruits presented Ca levels close to 0.99 g kg(-1). It is important to conduct new studies of the effects of liming on guava fruit quality under different edaphic-climatic conditions and on different guava tree genotypes. (c) 2005 Elsevier B.V. All rights reserved.

Balancing guava nutrition with liming and fertilization

A resposta da goiabeira à calagem e à adubação pode ser monitorada por análises de tecido vegetal. O perfil nutricional é definido em relação a padrões de teores de nutrientes. No entanto, os teores de nutrientes-padrão são constantemente criticados por não considerarem as interações que ocorrem entre nutrientes e por gerarem tendências numéricas, decorrentes da redundância dos dados, da dependência de escala e da distribuição não normal. As técnicas de análise composicional de dados podem controlar esses dados tendenciosos, equilibrando os grupos de nutrientes, tais como os envolvidos na calagem e na adubação. A utilização das relações log isométricas (ilr) ortonormais, sequencialmente dispostas, evita tendências numéricas inerentes aos dados de composição. Os objetivos do trabalho foram relacionar o balanço de nutrientes dos tecidos vegetais com a produção de goiabeiras em pomares de 'Paluma' diferentemente corrigidos e adubados, e ajustar os atuais padrões de nutrientes com a faixa de equilíbrio das goiabeiras mais produtivas. Um experimento de calagem de sete anos e três, experimentos de três anos com doses de N, P2O5 e K2O, foram conduzidos em pomares de goiabeiras 'Paluma' em um Latossolo Vermelho-Amarelo. Os teores de N, P, K, Ca e Mg na planta foram monitorados anualmente. Selecionaram-se os balanços [N, P, K | Ca, Mg], [N, P | K], [N | P] e [Ca | Mg] para separar os efeitos da calagem (Ca-Mg) e dos fertilizantes (N-K) nos balanços de macronutrientes. Os balanços foram mais influenciados pela calagem do que pela fertilização. A produtividade das goiabeiras e seu balanço nutricional permitiram a definição de faixas de equilíbrio de nutrientes e sua validação com as faixas de concentrações críticas atualmente utilizadas no Brasil e combinadas em coordenadas ilr.

Effect of liming on the mineral nutrition and yield of growing guava trees in a typic hapludox soil

High soil acidity influences the availability of mineral nutrients and increases that of toxic aluminium (Al), which has a jeopardizing effect on plant growth. The objective of this research was to evaluate the effects of soil liming on the development of guava (Psidium guajava L.) plants, on soil chemical characteristics, and on fruit yield. The experiment was carried out at the Bebedouro Citrus Experimental Station, state of São Paulo, Brazil, in a Typic Hapludox soil, from August 1999 to March 2003. The treatments consisted of limestone dose: D0 = zero; D1 = half dose; D2 = total dose; D3 = 1.5 times the dose, and D4 = 2 times the dose to raise the V value to 70%. The doses corresponded to zero, 1.85, 3.71, 5.56, and 7.41tha(-1) applied to the upper soil layer (0-30cm deep) before planting. The results showed that liming caused an improvement in the evaluated soil chemical characteristics up to a depth of 60cm in soil samples both in the line and between lines. The highest fruit yields were obtained when the base saturation reached a value of 55% in the line and 62% between the lines. Foliar levels of calcium (Ca) and magnesium (Mg) were 8.8 and 2.5gkg-1, respectively. The highest limestone dose maintained the soil base saturation (at the layer of 0-20cm) in the line close to 55% during at least 40 months after the incorporation of limestone.

Minimally processed guava fruits (Psidium guajava L.)

'Paluma' guavas, after internal quality evaluation using magnetic resonance tomography, were used to produce fresh-cut product. Fruits were peeled or not, cut in halves and seed removed, and they were packaged in polystyrene trays covered with PVC film or in a PET container with a lid. These packages were stored for 12 days at 5 degrees C, 10 degrees C and ambient temperature (22.6 degrees C). Tomography evaluation verified that impacts produced internal bruising with loss of cellular integrity and liquefication of the placenta tissues. Compression was more evident on the pericarp and cutting promoted superficial deformation. Storage temperature affected the weight loss, with fruit packaged in the polystyrene tray having a greater weight loss. The peeling did not influence weight loss. Product stored at 5 degrees C and 10 degrees C for 8 days had low microbial growth (< 10(3) UFC.g(-1)) and no coliforms. Rapid spoilage and a short shelf life (3-4 days) occurred when the product was stored at ambient temperature. Peeling reduced ascorbic acid concentration and total soluble solids. Use of calcium to protect fresh-cut products was not efficient. Calcium absorption capacity of 'Pedro Sato' guava was tested using Ca-45. Fruits treated with 2% CaCl2, with or without the radioisotope, were divided in four layers (epicarp, mesocarp, endocarp and seed) and analyzed for the total and Ca-45 calcium. It was observed that the applied calcium remained in superficial layers of fruits, which was confirmed by autoradiography. Internal layers did not contain Ca-45, indicating that calcium was not distributed into different parts of the fruit.

Postharvest Conservation of Mature-Green and Ripe 'Paluma' Guava Stored at Two Temperatures

This work aimed to establish the importance of maturation and ripeness stages and the use of refrigeration for the conservation of 'Paluma' guavas. Fruit picked at the mature-green and ripe stages were stored at ambient conditions (21 degrees C and 85% RH) and also at 10 degrees C (85% RH). The fruit were evaluated every 2 or 3 days for weight loss, appearance, decay, color, firmness, soluble solids, titratable acidity, ascorbic acid, total polyphenols extractable content and total antioxidant activity. The fruit stored at 21 degrees C had higher weight loss than those stored at 10 degrees C. Mature-green guavas at 21 degrees C remained in good quality for 6 days, but at 10 degrees C, the preservation period increased to 15 days. Ripe fruit were preserved for 4 days at 21 degrees C, which was extended with refrigeration to 6 days. Mature-green fruit at 21 degrees C had decay in 6 days; while at 10 degrees C decay happened in 18 days. The peel color of mature-green fruits, at 21 degrees C, showed increasing values of luminosity, indicating that its color became lighter (change from green to yellow) and at 10 degrees C it showed constant values until the end of storage. Pulp firmness of mature-green fruit declined during storage as a result of ripening. In ripe fruits such reduction occurred more slowly, since they were softer. The color of the pulp became intense red for mature fruits. Soluble solids were lower in ripe fruit at 21 degrees C, while in mature fruits at 10 degrees C, it increased. The titratable acidity increased in fruits stored at 10 degrees C. The fruits kept at 21 degrees C and the mature guavas kept at 10 degrees C showed no changes in ascorbic acid content. The ripe fruit at 10 degrees C maintained their ascorbic acid levels. Mature guavas, stored at 10 degrees C, had the longest shelf life and higher contents of soluble solids and titratable acidity, with no changes in total polyphenols extractable content and total antioxidant activity.

Effect of Controlled Atmospheres with Low Oxygen Levels on Extended Storage of Guava Fruit (Psidium guajava L. 'Pedro Sato')

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

DSC studies on protein isolate of guava seeds Psidium guajava

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Thermal study and physico-chemical characterization of some functional properties of guava seeds protein isolate (Psidium guajava)

The guava seed protein isolate ( PI) was obtained from the protein precipitation belonging to the class of the gluteline (Ip 4.5). The conditions for the preparation of the PI were determined by both the solubility curve and simultaneous thermogravimetry-differential thermal analysis (TG-DTA): pH 11.5, absence of NaCl and whiteners and T=( 25 +/- 3) degrees C. Under these conditions a yield of 77.0 +/- 0.4%, protein content of 94.2 +/- 0.3, ashes 0.50 +/- 0.05% and thermal stability, T= 200 degrees C, were obtained. The TG-DTA curves and the PI emulsification capacity study showed the presence of hydrophobic microdomains at pH 11.5 and 3.0 suggesting a random coil protein conformation and, to pH 10.0, an open protein conformation. The capacity of emulsification (CE), in the absence of NaCl, was verified for: 1 - pH 3.0 and 8.5, using the IP extracted at pH 10.0 and 11.5, CE >= 343 +/- 5 g of emulsified oil/g of protein; 2 - pH 6.60 just for the PI obtained at pH 11.5, CE >= 140 +/- 8 g of emulsified oil/g of protein.

Effect of light and temperature on seed germination in guava (Psidium guajava L. Myrtaceae)

The germination of seeds of Psidium guajava L. (Myrtaceae) is controlled by phytochrome. Guava seeds can germinate with at least one hour per day of irradiation of high red:far-red ratio light preceeded or followed by shade light, indicating that phytochrome B controls germination in these conditions. Under alternating temperatures, in a range of at least 5degreesC, seeds will germinate in darkness, suggesting that in gaps of the canopy, when seeds are covered by a thin layer of soil they will germinate once the alternating temperatures are experienced. Under these conditions phytochrome A is responsible for the control of guava seed germination.

Pectin methylesterase activity and ascorbic acid content from guava fruit, cv. Predilecta, in different phases of development

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

Evaluation of guava during different phases of the industrial processing

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

Costs estimates and rentability of the guava culture (Psidium guajava L Paluma cv) in Monte Alto County, São Paulo State

This work intended to calculate the rentability of the guava culture Paluma cv. in Monte Alto region-SP, estimating the costs of the implantation, maintenance, production and the gross income of this culture in the first three years of cultivation. The production system utilized refers to the cultural treatments usually used in this culture in the region. The costs estimates were based on the total operational costs methodology used by the Agricultural Economics Institute (I.E.A.). The results obtained showed that the implantation and maintenance costs of the culture, in the two first years was R$7.402,3 l/alqueire*. Considering the possibility that in guava orchard, on irrigated conditions, reach in the fourthy year a productivity of 80t/alqueire and that the current price is R$0,20/kg, it is possible to estimate the gross income around of R$16.000,00/alqueire, resulting in a net income of R$9.497,06/alqueire.

Mineralogy and forms of potassium in red yellow latosol of a guava (Psidium guajava) tree orchard

A trial was conducted during 1994-95 to study the effect of potassium fertilization on a guava (Psidium guajava L.) culture for 3 years. The control plots (without K) showed fruit production and potassium exportation that did not agree with the levels obtained by chemical analysis of the soil. Physical, chemical, mineralogic and morphologic analyses were performed on the red yellow latosol to identify minerals able to supply potassium, with emphasis on the fact that guava trees have a considerably widespread root system. The results obtained confirmed the presence of minerals in this soil that can supply potassium to the trees through weathering. Feldspars were identified in the silt fraction and micas in the clay fraction by X-ray diffractometry. The determination of total potassium revealed that the silt fraction of the soil had the largest absolute amounts of potassium, followed by clay. However, in view of its greater content, clay was the fraction that contributed most to the total amounts of potassium detected.

Partial purification, heat stability and kinetic characterization of the pectinmethylesterase from Brazilian guava, Paluma cultivars

Pectinmethylesterase (PME) was extracted from guava fruit (Psidium guajava L.), cultivar Paluma, by 70% ammonium sulphate saturation and partially purified by gel filtration on Sephadex G100. Gel filtration showed PME isoenzymes with different values of molecular mass. Two samples were examined: concPME (70% saturation by ammonium sulphate) and Iso4 PME (one of the isoforms from gel filtration with the greatest specific activity). Optimum pH of the enzyme (for both samples) was 8.5 and optimum temperature ranged from 75 and 85 degrees C. The optimum sodium chloride concentration was 0.15 M. The K-M and V-max ranged from 0.32 to 0.23 mg m1(-1) and 244 to 53.2 mu mol/min, respectively, for concPME and Iso4PME. The activation energies (E-a) were 64.5 and 103 kJ/mol, respectively, for concPME and Iso4PME. Guava PME, cv Paluma, is a very thermostable enzyme, showing great heat stability at all temperatures studied. (c) 2005 Elsevier Ltd. All rights reserved.

Effect of apparent viscosity on fluidized bed drying process parameters of guava pulp

Pressure drop and minimum fluidization velocity were experimentally studied in a vibro-fluidized bed of inert particles subjected to different vibration intensities during drying of guava pulp. Maltodextrin was added to the pulp in order to prevent stickiness between particles and the consequent bed collapse. Pulps were initially concentrated, resulting in pastes with different soluble solids content, and a constant fraction of maltodextrin was guaranteed in the final pulp samples. The pulp rheological behavior as affected by temperature and total soluble solids content, including maltodextrin, was evaluated and the effect of pulp apparent viscosity on pressure drop and minimum vibro-fluidization velocity were investigated. Two types of inert particles -3.6 mm glass beads and 3 mm Teflon cylinders were tested and, due to lower pressure drop presented by Teflon cylinders during operation of the dry vibro-fluidized bed, these particles were adopted for pulp drying process. Increasing pulp apparent viscosity caused a considerable increase in the vibro-fluidized bed pressure drop during pulp drying and, as a consequence resulted in a larger value of minimum vibro-fluidization velocity. on the other hand, the negative effect of increasing apparent viscosity could be attenuated by increasing the fluidized bed vibration intensity, which could prevent stickiness between particles. (c) 2006 Elsevier Ltd. All rights reserved.