CARACTERIZAÇÃO FÍSICA, QUÍMICA E NUTRICIONAL DA PITAIA-ROSA DE POLPA VERMELHA

RESUMOA pitaia-rosa de polpa vermelha é uma cactácea com potencial para exploração econômica, devido aos seus componentes nutricionais e ao alto valor comercial; no entanto, poucas são as pesquisas quanto a suas características pós-colheita. O objetivo do trabalho foi caracterizar física, química e nutricionalmente pitaias-rosas de polpa vermelha. Frutos colhidos totalmente maduros foram sanitizados, selecionados e divididos em grupos de quatro frutos por repetição, constituindo um total de 30 amostras. Em seguida, as amostras foram submetidas às seguintes avaliações: comprimento, diâmetro, espessura de casca, massa fresca, massa de casca e polpa, teor de umidade, firmeza da casca, sólidos solúveis, pH, acidez titulável, açúcares e fibra bruta, cromaticidade, ângulo hue e luminosidade da casca e da polpa, e o teor de nutrientes. Para os dados obtidos, foram determinados a média, o valor mínimo e máximo, desvio-padrão e o coeficiente de variação. A fruta apresentou valores elevados de conteúdo de água, teor de fibras e dos nutrientes nitrogênio, potássio, cálcio, ferro, manganês e zinco. Quanto ao teor de sólidos solúveis, a média observada foi de 13,14° Brix, e para acidez titulável,0,29 mg de ác. málico 100-1 mL de suco. Verificaram-se para os açúcares valores de 5,56; 8,79 e 3,07 %, respectivamente, para os açúcares redutores, totais e não redutores. Quanto à coloração, os frutos apresentaram valores maiores para luminosidade e cromaticidade da casca e ângulo Hue da polpa. A pitaia-rosa de polpa vermelha (Hylocereus polyrhizus) apresenta características físicas, químicas e nutricionais interessantes para o consumo in natura.

CARACTERIZAÇÃO FÍSICA E QUÍMICA DE FRUTOS DE MARACUJAZEIRO-AMARELO ENXERTADO EM ESPÉCIES SILVESTRES DO GÊNERO PASSIFLORA CULTIVADO EM AMBIENTE PROTEGIDO

RESUMO O mercado de frutas frescas do maracujá-amarelo valoriza as qualidades interna e externa dos frutos. O uso de espécies silvestres como porta-enxertos tem sido preconizado como possível medida de controle de doenças. São escassas as informações sobre o efeito de espécies silvestres do gênero Passiflora como porta-enxertos sobre as características físicas e químicas em frutos de maracujazeiro. O objetivo deste trabalho foi determinar a influência de duas espécies de passifloráceas silvestres P. mucronata Lam e P. gibertii N.E. Brow como porta-enxertos sobre as características físicas e químicas dos frutos do maracujazeiro-amarelo em ambiente protegido. Adotou-se o delineamento inteiramente casualizado, com quatro tratamentos e 25 repetições, consistindo em 100 parcelas. Cada parcela foi representada por uma planta conduzida em vaso de 30 L. Os porta-enxertos avaliados foram: Passiflora edulis Sims, Passiflora gibertii N.E. Brow e Passiflora mucronata Lam. Comotratamento-testemunha, foram utilizadas plantas de P. edulis Sims provenientes de sementes. Avaliaram-se a massa fresca do fruto (MF), a massa fresca da casca (MC), a massa fresca da polpa (MP), o diâmetro do fruto (DF), o comprimento longitudinal do fruto (CF), a espessura da casca dos frutos (EC), a coloração do suco e da casca dos frutos, o teor de sólidos solúveis (SS), a acidez titulável (AT), a relação SS/AT, a relação MP/MF e o teor de vitamina C (ácido ascórbico). As plantas enxertadas sobre espécies silvestres produziram frutos mais alongados que as plantas provenientes de sementes, porém dentro dos padrões de comercialização.

Hidrólise enzimática de casca de arroz utilizando-se celulases: efeito de tratamentos químicos e fotoquímicos

In the present work we reported the study of rice hull enzymatic hydrolysis using a commercial cellulase preparation. The results showed that previous treatment with light and sodium chlorite inhibits the enzymatic process (31.4 and 11.8%, respectively) while hydrogen peroxide and ozone favoured the enzymatic production of reducing sugars (5.9 and 54.9%, respectively). Studies performed by quimiluminescence showed that the chlorite treatment produced the most significant change in the structure of rice hull. Nevertheless, this treatment did not favour the subsequent enzymatic process. Photomicrographs obtained from rice hull hydrolysates showed that pre-treatment changed mainly the inner epidermis and parenchyma cell and that they did not change cellular organization of the hull.

Aplicação de extratos brutos de flores de quaresmeira e azaléia e da casca de feijão preto em volumetria ácido-base. Um experimento para cursos de análise quantitativa

Crude extract of Tibouchina granulosa, Rhododendron simsii and Phaseolus vulgaris L. were prepared and used as alternative indicators in quantitative analysis teaching in standardization of NaOH solutions and in the determination of acetic acid contents in vinegar. Effect of using such natural extracts as indicators was very attractive to the students and the quantitative results were compared with conventional indicators with good agreement. Concepts of data statistics can successfully be discussed using the interest revived by the use of natural indicators.

Caracterização de cinza de casca de arroz para uso como matéria-prima na fabricação de refratários de sílica

The characterization of rice husk ash, a deriving by-product of the burning of the rice husk during the rice processing is the object of this study. This by-product, for being rich in silica, can be an important raw material for the production of siliceous ceramics, such as thermal insulators and refractory. A combination of surface analysis, thermal analysis and microscopy analysis techniques was used for the characterization. The characterized by-product presented as main component the silica, under amorphous form, with a maximum content of alkalis around 1%, features that become it potentially interesting for the production of ceramic materials.

Aplicabilidade das cinzas da casca de arroz

Currently, the accumulation of rice husk is a serious environmental problem. The burning of rice husk generates a considerable volume of ash, that falls to the ground and gets into the air and the rivers, causing a disequilibrium in the ecosystem. This motived research into solutions that aim to exploit the husks for energy generation and the ashes for developing diverse technological products. This work presents the possibilities of using rice husks and their ashes after burning.

Estudo comparativo entre sílica obtida por lixívia ácida da casca de arroz e sílica obtida por tratamento térmico da cinza de casca de arroz

A comparison between silica by acid leaching of rice husk (RH) and silica obtained from thermal treatment of rice husk ash (RHA) is presented. The best leaching results were obtained using 10% hydrochloric acid followed by washing with water. The alternative method, calcination of RHA at 700 ºC for 6 h followed by grinding for 80 min, was more effective. Silica obtained from RH was about 97% amorphous, had a 17.37 µm mean particle size, and a specific surface area of 296 m²/g. On the other hand, for silica obtained from RHA the values were about 95% amorphous material 0.68 µm, and 81 m²/g.

Constituintes químicos da casca do caule de Amburana cearensis A.C. Smith

The phytochemical analysis of the ethanol extract trunk bark of Amburana cearensis allowed the isolation and identification of twelve constituents: coumarin, sucrose, two phenol acids (vanillic acid and protocatechuic acid), five flavonoids (afrormosin, isokaempferide, kaempferol, quercetin and 4'-methoxy-fisetin), a phenol glucoside (amburoside A) and a mixture of glucosilated b-sitosterol and stigmasterol. Their structures were elucidated by spectroscopic methods such as IR, MS, ¹H and 13C NMR, including uni and bidimensional techniques, in addition to comparison with literature data.

Planejamento estatístico de experimentos como uma ferramenta para otimização das condições de biossorção de Cu(II) em batelada utilizando-se casca de nozes pecã como biossorvente

In order to reduce the total number of experiments for achieving the highest amount of adsorbed Cu2+ (qmax) using pecan nutshells (Carya illinoensis) as biosorbent, a full 2(4) factorial design with two central points was carried out (mass of biosorbent- m, pH, initial metallic ion concentration- C0, time of contact- t). In order to continue the optimization of the system, a central composite surface analysis design with two factors and five central points was carried out. The maximum amount of Cu2+ taken up by the pecan nutshells was 20 mg g-1. These results were confirmed by determining a Cu2+ isotherm using the best conditions attained by the statistical design of experiments.

Uso da casca de coco verde como adsorbente na remoção de metais tóxicos

Green coconut shells were treated with acid, base and hydrogen peroxide solutions for 3, 6, 12 and 24 h for removing toxic metals from synthetic wastewater. The removal of ions by the adsorbent treated with 0.1 mol L-1 NaOH/ 3h was 99.5% for Pb2+ and 97.9% for Cu2+. The removal of Cd2+, Ni2+, Zn2+, using adsorbent treated with 1.0 mol L-1 NaOH/3 h, was 98.5, 90.3 and 95.4%, respectively. Particle size, adsorbent concentration and adsorption kinetics were also studied. An adsorbent size of 60-99 mesh and a concentration of 30-40 g/L for 5 min exposure were satisfactory for maximum uptake of Pb2+, Ni2+, Cd2+, Zn2+ and Cu2+ and can be considered as promising parameters for treatment the aqueous effluents contaminated with toxic metals.

Preparação e caracterização de carvão ativado quimicamente a partir da casca de arroz

This work consists in a study about the chemical activation of charred rice hulls using NaOH as the activation agent. The influence of the naturally-occurring silica was particularly evidenced. X-ray diffraction patterns showed the formation of sodium carbonate and silicates in the activated samples, whereas thermogravimetric curves revealed a strong reduction in the ash content of these samples after washing with water. Nitrogen adsorption data indicated a microporosity development only in the washed samples, with BET surface area values of 450 and 1380 m²/g achieved for the samples activated at 800 °C starting from the precursor with or without silica, respectively.

Caracterização de cinza obtida por combustão de casca de arroz em reator de leito fluidizado

The rice husk combustion in a bubbling and atmospheric fluidized bed reactor was investigated. This paper presents the rice husk ash characterization employing the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) among others. After combustion, a rice husk ash containing 93% amorphous silica and <3% unburned char was produced. Methods usually applied to fixed bed considering external sources of energy and high reaction times were employed. Thus, the potential of this type of reactors with respect to speed, continuity and self-sufficiency energy of the process was shown.

Uso da cinza da casca do arroz (CCA) obtida da geração de energia térmica como adsorvente de Zn(II) em soluções aquosas

The removal study was conducted using 1.00 g of the rice husk ash (RHA) and 20.0 mL solution with concentrations in the range of 10-1000 mg/L of Zn(II). The influence of contact time, initial metal concentration, agitation and pH of the removal process was investigated. Superior removals to 95% were obtained at the end of 24 h of contact. The agitation increased in 20% the removal of Zn(II), being needed only 5 min to reach the equilibrium. The adsorption process was studied by the models of isotherms of Langmuir, Freundlich and BET, obtaining results of R L and 1/n for a process favorable of adsorption. BET isotherm best represents the equilibrium adsorption. The results showed that the RHA has the largest capacity and affinity for the removal of Zn(II).

Aplicação da casca de arroz na adsorção dos íons Cu2+, Al3+, Ni2+ e Zn2+

The potential use of rice husk as biosorbent to remove Cu2+, Al3+, Ni2+ and Zn2+ ions from aqueous solutions was investigated under both noncompetitive and competitive conditions. The biosorbent was used in the form of particles with size smaller than 0.5 μm and in the concentration of 500 mg L-1 (dry weight). The experiments were performed using batch adsorption technique for concentrations of 10, 30 and 70 mg L-1 of metal ions at pH 4.0 and 5.0. The chemical speciation of metals in the experimental conditions used in this work was predicted by the software Visual MINTEQ 2.6.

Emprego de catalisadores heterogêneos de CaO e SnO2 suportados em cinza de casca de arroz na obtenção de biodiesel

Silica obtained from rice husk after acid leaching and calcination was compared to commercial silica as a catalyst support. CaO and SnO2 catalysts were prepared by impregnation and tested in the transesterification of soybean oil and the esterification of oleic acid. CaO catalysts showed basic character and were the most active for transesterification, whereas SnO2 catalysts were acid and the most effective for esterification. In both cases the performances of the catalysts prepared with rice husk ash and commercial silica were similar. These results demonstrate that rice husk is a cost-effective and environmentally-friendly source of silica that can be used as a catalyst support.