Eletrodo modificado com filme de poli aminoácido para determinação de hidrazina em água de caldeira

Eletrodos de carbono vítreo foram modificados com filmes de poli ácido glutâmico (PAG) pela eletropolimerização do ácido glutâmico em tampão fosfato pH 7,0, utilizando-se varreduras sucessivas de potencial entre ­0,8 a +2,0 V. Os eletrodos modificados foram aplicados na determinação de hidrazina, a qual é pré-concentrada na superfície através da interação entre grupos carboxílicos livres no filme e grupo amino da hidrazina. Embora a hidrazina não seja oxidada em intervalo útil de potencial sobre eletrodo convencional, no eletrodo modificado caracteriza-se pelo pico de oxidação em potencial de +0,57 V usado para fins analíticos. Gráfico de calibração linear foi obtido no intervalo de concentração entre 4 x 10-5 a 1 x 10-3 mol L-1, usando voltametria de pulso diferencial. O limite de detecção foi de 1,2 x 10-6 mol L-1. O método foi aplicado para a determinação de hidrazina em amostras coletadas de água de caldeira com recuperação de 94%.

Desenvolvimento de metodologia analítica baseada em eletrodo de carbono vítreo modificado com filme de bismuto: aplicação em águas de chuva de regiões de Santa Catarina

Neste estudo foi desenvolvida uma metodologia analítica para determinação de 2,4-dinitrofenol (2,4-DNP) em amostras de águas de chuva de regiões de Santa Catarina utilizando a voltametria de onda quadrada (VOQ) e de forma ex situ. O estudo envolveu a aplicabilidade de utilizar o eletrodo de carbono vítreo modificado com filme de bismuto. A formação do filme de bismuto foi otimizada por voltametria cíclica e em seguida, estudos de pH e eletrólito de suporte foram investigados para a redução do 2,4-DNP. Os parâmetros analíticos que afetam a sensibilidade da VOQ foram otimizados. Na sequência, as figuras analíticas de mérito foram obtidas: faixa linear de trabalho de 3,2 x 10-7 - 4,6 x 10-6 mol L-1, coeficiente de correlação de 0,996, RSD% = 17,5 (1,3 x 10-6 mol L-1, n = 6), 11,7 (2,5 x 10-6 mol L-1, n = 6) e 6,4 ( 4,5 x 10-6 mol L-1, n = 6), limite de detecção de 1,2 x 10-7 mol L-1. E, finalmente estudos de recuperação foram realizados para avaliar a exatidão da metodologia. Valores obtidos ficaram entre 84-112% (2,5 x 10-6 mol L-1) e 89 - 113% (4,5 x 10-6 mol L-1).

Efeitos da cobertura do solo com filme de polietileno azul no consumo de água da cultura da alface cultivada em estufa

A cobertura do solo é uma prática agrícola que visa, principalmente, a controlar as plantas invasoras, a diminuir as perdas de água por evaporação do solo e a facilitar a colheita e a comercialização, uma vez que o produto se torna mais limpo e sadio. Porém, ao se cobrir o solo, também são alterados parâmetros importantes do microclima e, conseqüentemente, a germinação das sementes, o crescimento das raízes, a absorção de água e nutrientes, a atividade metabólica das plantas e o armazenamento de carboidratos. O objetivo do presente trabalho foi avaliar o efeito da cobertura do solo com filme de polietileno azul no consumo de água da cultura da alface (Lactuca sativa L.). O experimento foi instalado em uma estufa convencional, no município de Araras - SP, e conduzido durante o período de 22-3-2001 a 1º-5-2001. O consumo de água foi medido em dois lisímetros de pesagem instalados no interior da estufa. O espaçamento da cultura foi de 0,25 m x 0,25 m. Também foi avaliado o índice de área foliar (IAF) em seis épocas distintas e determinada a eficiência do uso de água (EU) ao final do ciclo da cultura. O delineamento estatístico foi o de blocos inteiramente casualizados, com dois tratamentos, "solo descoberto" e "solo coberto". O consumo médio de água foi de 4,17 mm dia-1 para o tratamento "solo descoberto" e de 3,11 mm dia-1 para o tratamento "solo coberto". O índice médio de área foliar não diferiu estatisticamente entre os tratamentos.

Technical and economic indicators of the yellow passion fruit tree irrigated with underground water supply

The research aimed to quantify technical and economic indicators of yellow passion fruit tree irrigated with fractions of irrigation with underground source of water, to generate information that helps farmers in decision making on the implementation of investment in irrigated fruit growing (yellow passion fruit). For this purpose, we used the passion fruit crop irrigated with Microjet type irrigation system, with conducting system in simple espaliers. The treatments consisted of five hours of application of the depth of water required by the crop with irrigation frequency of two days. The results showed that the highest yield (16660kg ha-1) was obtained with the fractionation of irrigation twice a day (50% to 7h and 50% to 21h30), which provided an increase in productivity of 54%, demonstrating the financial viability and being highly profitable to the interest rate of 2% per year, with low sensitivity of financial risk to real interest rates above the prevailing market.

Efetividade do uso combinado de filme de ácido lático e tela de polipropileno na formação de aderências intraperitoneal: um modelo experimental em ratos

OBJETIVO: Avaliar a eficácia do uso de um biomaterial de ácido lático (SurgiWrap®) como protetor de tela de polipropileno (Marlex®) em relação à formação de aderências intraperitoneais em ratos. MÉTODO: Quarenta ratas Wistar formaram os grupos a seguir: Grupo 0 (Sham) - apenas laparotomia; Grupo I - tela de polipropileno; Grupo II - tela de polipropileno protegida por filme de ácido lático. Estes animais foram operados com laparotomia e colocação das telas no fechamento. Após 21 dias foram sacrificados para análise aderencial quanto ao tipo (0 a 3), porcentagem de área acometida e força necessária para rompimento. RESULTADOS: O Grupo 0 não apresentou aderências intraperitoneais. Em relação à classificação foi evidenciado a maior prevalência de aderências tipo 3 em ambos os grupos. Quanto à força para ruptura aderencial o Grupo 1 obteve média de 1,58 N e o Grupo 2 de 1,23 N. A tela foi envolvida por aderências em mais de 50% da área de sua superfície em 87% no Grupo 1 e 84% no Grupo 2. Por diferentes métodos estatísticos constatou-se que não houve diferença significativa entre os grupos nas variáveis estudadas. CONCLUSÃO: A utilização do combinado tela de polipropileno e bioprotetor de ácido lático demonstrou índices semelhantes em relação à formação de aderências intraperitoneais quando comparada ao uso individual da mesma tela.

Desenvolvimento e avaliação de filme antimicrobiano na conservação de manteiga

A indústria alimentícia, buscando atender a um mercado consumidor cada vez mais exigente, vem desenvolvendo embalagens ativas para proporcionar qualidade e segurança aos produtos acondicionados. Neste sentido, esta pesquisa objetivou desenvolver filmes ativos incorporados com agente antimicrobiano e avaliá-los na conservação de manteiga. Os filmes de base celulósica foram incorporados com 0% (controle) e 7% (ácido sórbico). Teste de halo de inibição em presença de fungos mostrou um halo de 3,4 cm. Amostras de manteiga foram fatiadas e inoculadas com 1 x 10(8) UFC.mL-1 de fungos filamentosos e leveduras, previamente isolados de manteiga. As amostras foram envolvidas com o filme ativo, embaladas em papel alumínio e armazenadas sob temperatura de refrigeração. As análises microbiológicas da manteiga foram realizadas após 0, 10 e 20 dias de armazenamento à temperatura de 7 ± 2 ºC. A contagem inicial de fungos filamentosos com leveduras na manteiga foi de 3 x 10(6) UFC.g-1 e após 10 e 20 dias de estocagem observou-se redução de 1 ciclo log (9 x 10(5) UFC.g-1) e 2 ciclos log (8 x 10(4) UFC.g-1) para a manteiga embalada com filme incorporado com 7% de ácido sórbico, respectivamente. Os valores de espessuras foram de 22,5 ± 3 µm e 25 ± 5 µm, de carga máxima: 37,4 ± 7 N e 52,4 ± 7 N, e de alongamento 1,7 ± 0,7% e 2,3 ± 0,7%, para os filmes incorporados com 0 e 7% de ácido sórbico, respectivamente. Pode-se concluir que o filme antimicrobiano apresentou maior resistência e alongamento, além de ter sido eficiente na redução de fungos filamentosos e leveduras em manteiga.

Effects of different concentrations of passion fruit peel (Passiflora edulis) on the glicemic control in diabetic rat

Diabetes mellitus, an endocrine disorder, is the major cause of morbidity in developing countries, and it is considered the fourth leading cause of death worldwide. The conventional therapy for diabetes is insulin treatment. The peel of the Passion fruit is rich in fiber and prevents the absorption of carbohydrates, and thus can control and reduce the blood sugar rate. The objective of this study was to analyze the effect of the passion fruit peel flour on the glicemia of diabetic rats, as well as to study the probable action mechanisms. Wistar rats were used in the experiment and were offered the flours of the passion fruit peel in three concentrations: 5, 10, and 15%, and a casein diet as control. The most significant effect on the reduction of the glicemic rate was obtained with the 5% diet. The best values of hepatic glycogen were found in the 5 and 10% diets. The results of this study suggest that the 5% passion fruit flour diet was the one that provided the best reduction of blood glucose levels (59%) and the higher increase of the hepatic glycogen level (71%). The conversion of blood glucose into hepatic glycogen was considered the probable action mechanism involved.

Evaluation of the in vitro glycemic index of a fiber-rich extruded breakfast cereal produced with organic passion fruit fiber and corn flour

The aim of this study was to determine the influence of process parameters and Passion Fruit Fiber (PFF) addition on the Glycemic Index (GI) of an extruded breakfast cereal. A 2³ Central Composite Rotational Design (CCRD) was used, with the following independent variables: raw material moisture content (18-28%), 2nd and 3rd barrel zone temperatures (120-160 ºC), and PFF (0-30%). Raw materials (organic corn flour and organic PFF) were characterized as to their proximate composition, particle size, and in vitro GI. The extrudates were characterized as to their in vitro GI. The Response Surface Methodology (RSM) and Principal Component Analysis (PCA) were used to analyze the results. Corn flour and PFF presented 8.55 and 7.63% protein, 2.61 and 0.60% fat, 0.52 and 6.17% ash, 78.77 and 78.86% carbohydrates (3 and 64% total dietary fiber), respectively. The corn flour particle size distribution was homogeneous, while PFF presented a heterogeneous particle size distribution. Corn flour and PFF presented values of GI of 48 and 45, respectively. When using RSM, no effect of the variables was observed in the GI of the extrudates (average value of 48.41), but PCA showed that the GI tended to be lower when processing at lower temperatures (<128 ºC) and at higher temperatures (>158 ºC). When compared to white bread, the extrudates showed a reduction of the GI of up to 50%, and could be considered an interesting alternative in weight and glycemia control diets.

Effect of drying method on the adsorption isotherms and isosteric heat of passion fruit pulp powder

The sorption behavior of dry products is generally affected by the drying method. The sorption isotherms are useful to determine and compare thermodynamic properties of passion fruit pulp powder processed by different drying methods. The objective of this study is to analyze the effects of different drying methods on the sorption properties of passion fruit pulp powder. Passion fruit pulp powder was dehydrated using different dryers: vacuum, spray dryer, vibro-fluidized, and freeze dryer. The moisture equilibrium data of Passion Fruit Pulp (PFP) powders with 55% of maltodextrin (MD) were determined at 20, 30, 40 and 50 ºC. The behavior of the curves was type III, according to Brunauer's classification, and the GAB model was fitted to the experimental equilibrium data. The equilibrium moisture contents of the samples were little affected by temperature variation. The spray dryer provides a dry product with higher adsorption capacity than that of the other methods. The vibro-fluidized bed drying showed higher adsorption capacity than that of vacuum and freeze drying. The vacuum and freeze drying presented the same adsorption capacity. The isosteric heats of sorption were found to decrease with increasing moisture content. Considering the effect of drying methods, the highest isosteric heat of sorption was observed for powders produced by spray drying, whereas powders obtained by vacuum and freeze drying showed the lowest isosteric heats of sorption.

Stability of volatile profile and sensory properties of passion fruit juice during storage in glass bottles

This study aimed at assessing the stability of passion fruit juice in glass bottles during a 120-day storage period, regarding its volatile compounds profile and sensory properties (aroma and flavor). Samples were obtained from a Brazilian tropical juice industry (Fortaleza, Brazil) and submitted to sensory and chromatographic analyses. The characteristic aroma and flavor of passion fruit were evaluated by a trained panel with a non-structured scale of 9 cm. The headspace volatile compounds were isolated from the product by suction and trapped in Porapak Q, analyzed through high-resolution gas chromatography and identified through gas chromatography-mass spectrometry (GC-MS). Twelve odoriferous compounds were monitored: ethyl butanoate, ethyl propanoate, 3-methyl-1-butanol, 3-methyl-2-butenol, (E)-3-hexenol, (Z)-3-hexenol, 3-methylbutyl acetate, benzaldehyde, ethyl hexanoate, hexyl acetate, limonene and furfural. The slight variations observed in the volatile profile were not enough to provoke significant changes in the characteristic aroma and flavor of the passion fruit juice.

Volatile compounds from organic and conventional passion fruit (Passiflora edulis F. Flavicarpa) pulp

The volatile compositions from organic and conventional passion fruit pulps produced in Brazil were investigated. The pulps were also physicochemically characterized. The volatile compounds from the headspace of the passion fruit pulp were stripped to a Porapak Q trap for 2 hours; they were eluted with 300 µL of dichloromethane, separated by gas chromatography/flame ionisation detection and identified through gas chromatography/mass spectrometry. Both pulps conformed to the requirements of the Brazilian legislation, indicating they were suitable to be industrialized and consumed. A total of 77 compounds were detected in the headspace of the passion fruit pulps - 60 of which were identified, comprising 91% of the total chromatogram area. The major compounds were the following: ethyl butanoate, 52% and 57% of the total relative area of the chromatogram for the organic and conventional passion fruit pulps, respectively; ethyl hexanoate, 22% and 9%, respectively; and hexyl butanoate, 2% and 5%, respectively. The aroma of the organic passion fruit pulp is mainly related to the following volatile compounds: ethyl hexanoate, methyl hexanoate, β-myrcene and D-limonene. The conventional passion fruit pulp presented methyl butanoate, butyl acetate, hexanal, 1-butanol, butyl butanoate, trans-3-hexenyl acetate, cis-3-hexen-1-ol, butyl hexanoate, hexyl butanoate, 3-hexenyl butanoate and 3-hexenyl hexanoate as the main volatile compounds for aroma.

Quality of yellow passion fruit stored under refrigeration and controlled atmosphere

In this study, it was evaluated the quality of yellow passion fruits stored under refrigeration and controlled atmospheres of different composition aiming to extend the postharvest life of the fruits. The characteristics of skin color, appearance, mass loss, as well as the chemical quality of the juice of yellow passion fruits stored at: 21% O2 plus 0.03% CO2; 1% O2 plus 0.03% CO2; 5% O2 plus 0.03% CO2; 12% O2 plus 5% CO2; and 5% O2 plus 15% CO2, with 1 control treatment (refrigeration at 13 ºC and 90% UR) were determined. The analyses were performed before and after 30 days of storage and after removing the controlled atmospheres and storage for 9 days under refrigeration at ambient atmosphere. The data were interpreted by simple statistical analysis using the test by confidence intervals with 95% of probability. It was concluded that the application of atmospheres with low oxygen concentration and high carbon dioxide level minimized quality losses. At atmosphere with 5% O2 and 15% CO2, it was observed the lowest color change indexes and mass loss, and also the smallest decrease in acidity, soluble solids content, vitamin C, reducing sugars, and total soluble sugars.

Chemical and physicochemical characteristics changes during passion fruit juice processing

Passion fruit is widely consumed due to its pleasant flavour and aroma acidity, and it is considered very important a source of minerals and vitamins. It is used in many products such as ice-cream, mousses and, especially, juices. However, the processing of passion fruit juice may modify the composition and biodisponibility of the bioactive compounds. Investigations of the effects of processing on nutritional components in tropical juices are scarce. Frequently, only losses of vitamin C are evaluated. The objective of this paper is to investigate how some operations of passion fruit juice processing (formulation/homogeneization/thermal treatment) affect this product's chemical and physicochemical characteristics. The results showed that the chemical and physicochemical characteristics are little affected by the processing although a reduction in vitamin C contents and anthocyanin, large quantities of carotenoids was verified even after the pasteurization stage.

Sensory acceptability and physical stability evaluation of a prebiotic soy-based dessert developed with passion fruit juice

The aim of this study was to use a factorial design approach for developing a palatable and stable soy-based dessert with the addition of Soy Protein (SP), oligofructose, and Passion Fruit Juice (PFJ). Panelists (n = 50) used a seven-point hedonic scale to assess the overall liking, degree of liking of creaminess, taste, and color of the desserts. In addition, the samples were submitted to a preference ranking test in order to evaluate the products' preference. Water Holding Capacity (WHC) and backscattering (BS) measures were also determined to assess the physical stability of the trials. Sample F3 (35% PFJ and 2% SP) was the only one that presented a WHC index of 94.8%; moreover, none of the developed samples had synerisis after 72 hours of storage indicating adequate physical stability of the emulsion process. Samples F2 (25% PFJ, and 3.0% SP), F4 (35% PFJ, and 3.0% SP), and F5 (30% PFJ, and 2.5% SP) presented mean hedonic scores above 'slightly liked' for all sensory attributes. The acceptance index of samples varied from 62.50 to 88% showing the great sensory potential of such products.

Influence of passion fruit albedo, citric acid, and the pulp/sugar ratio on the quality of banana preserves

The objective of this research was to evaluate the effect of the citric acid concentration, pulp/sugar ratio, and albedo concentration of the passion fruit peel on physical, physiochemical, and sensorial characteristics of the 'Silver' banana preserves. A 2³ factorial design and 3 repetitions in the central point were used. The albedo concentration between 0 and 3% had significant influence on the reduction of the reducing sugars and on the decrease in titratable acidity. The increase in the pulp/sugar ratio exerted a negative effect on the pH and positive on the titratable acidity; the acid addition reduced the non-reducing sugar level. The sensorial evaluation and purchase intention indicated that the incorporation of a maximum of 1.5% albedo in formulations containing 50% pulp and 0.5% citric acid resulted in products with good acceptability in comparison with the formulation in which 60% pulp and an absence of acid or albedo is utilized.