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Effect of granulometry and packaging on water sorption by roasted and ground coffee
Get PDFObjetivou-se com este trabalho avaliar o efeito da granulometria e da embalagem na sorção de água pelo café torrado e moído. Foram utilizados grãos de café arábica com teor de água inicial de 0,1234 kga kgms -1, torrados no ponto de torra médio, com perda de massa de 17%, tendo sido estabelecido quatro níveis granulométricos: grão inteiro, grossa, média e fina. Para a obtenção das isotermas de sorção da água e das propriedades termodinâmicas, foram analisadas diferentes condições de temperatura e umidade relativa, variando entre 25 e 30 °C e de 0,3 a 0,8 (decimal), respectivamente. Para a etapa de armazenamento, o café torrado e moído, nos diferentes níveis granulométricos especificados a cima, foram acondicionados em embalagens de dois diferentes tipos de filmes: PEBD/PP (embalagem 1) e PET/BOPP metalizado (embalagem 2) e armazenados em câmara tipo BOD a 25 °C. A cada 30 dias eram feitas as seguintes análises: teor de água, atividade de água, massa específica unitária, avaliação da cor e análise sensorial. O modelo de Copace foi o que melhor representou o equilíbrio higroscópico para a sorção do café torrado, nos diferentes níveis granulométricos; o teor de água de equilíbrio do café torrado é diretamente proporcional à umidade relativa do ar ambiente e decresce com o aumento de temperatura para um valor de umidade relativa; com a redução do teor de água, ocorre aumento da energia liberada pela sorção da água no produto, representada pelos valores do calor isostérico integral de sorção; com a redução do teor de água, ocorre aumento dos valores da entropia diferencial de sorção, sendo que, para um mesmo teor de água, a entropia diferencial do café torrado no nível granulométrico fina foi maior que
do no nível média e grossa, respectivamente, devido à maior superfície específica; a teoria da compensação entalpia-entropia pode ser satisfatoriamente aplicada ao fenômeno de sorção, sendo controlado pela entalpia; os tipos de filmes utilizado na composição do material das embalagens não afetaram a qualidade final do café torrado nos diferentes níveis granulométricos; o teor de água do café torrado nos diferentes níveis granulométricos e dois tipos de embalagens não ultrapassou os limites estabelecidos pela legislação brasileira; a atividade de água do café torrado
nos diferentes níveis granulométricos aumentou ao longo do armazenamento na embalagem 1, e na embalagem 2, ela diminuiu pela presença de válvula; a
massa específica unitária não foi sensível ao aumento do teor de água do café
torrado; o café torrado escureceu ao longo do armazenamento; o café torrado e
moído nos diferentes níveis granulométricos e armazenado em dois tipos de
embalagens enquadra-se na categoria gourmet, mantendo as características
positivas de acidez, doçura e corpo.The objective of this study was to evaluate the effect of granulometry and types of packaging on the water sorption by roasted and ground coffee. Arabica coffee grains were utilized with an initial water content of 0.1234 kgw kgdm
-1, roasted until the medium roast point, with a weight loss of 17%, in wich four granulometric levels were established: whole grains and thick, medium and thin granulometries. To obtain the water sorption isotherms and the thermodynamic properties, different conditions of temperature and relative humidity were analyzed, ranging between 25 to 30 °C and 0,3 to 0,8 (decimal), respectively. In the storage stage, roasted and ground coffee in the above specified granulometries were packaged with two different types of films: LDPE/PP (Package 1) and PET/metalized BOPP (Package 2), and stored in a BOD chamber at 25 °C. Every 30 days, were performed the following analysis: moisture content, water activity, unitary density, color evaluation and sensorial analysis. Copace model was the one that better represented the hygroscopic equilibrium for sorption in roasted coffee, for all granulometric levels; the equilibrium moisture content of roasted coffee is
directly proportional to the relative humidity of ambient air and decreases when increasing the temperature for a relative humidity value; with the reduction in moisture content, the energy released by product water adsorption increases, represented by integral isosteric heat of sorption values; by reducing the moisture content, values of differential entropy of adsorption increase, and for the same moisture content, the differential entropy for roasted coffee in thin granulometry was higher than for the coffee in medium and thick granulometry, due to a higher specific surface; the theory of enthalpy-entropy compensation can be satisfactorily applied to the sorption phenomenon, being controlled by enthalpy. The types of films used in the composition of packaging material did not affect the final quality of roasted coffee for all granulometric levels; the moisture content of roasted coffee did not exceed the limits established by Brazilian legislation for all granulometric levels and both types of packaging; the water activity for roasted coffee in all granulometric levels increased during storage in package 1, and in the package 2 it decreased due to the presence of a valve; the unitary density was not sensitive to the increase in roasted coffee moisture content; the roasted coffee became darker during storage; the roasted and ground coffee stored in two types of packaging with different granulometries fits into gourmet category, keeping the positive characteristics of acidity, sweetness and body.Conselho Nacional de Desenvolvimento Científico e Tecnológic
Physico chemical parameters in getting the soursop powder by drying in foam bed
No full textObjetivou-se estudar e caracterizar o processo de produção de graviola em pó pelo método de secagem em leito de espuma através da escolha do melhor emulsificante e concentração, bem como determinar as propriedades físico-químicas do produto in natura, da espuma e do pó formado além disso, obter as isotermas de sorção e as propriedades termodinâmicas. Foram utilizados frutos de graviola (Annona muricata L.) das quais a polpa foi obtida e acondicionada em garrafas tipo PET higienizadas com água clorada, e armazenada em freezer a -18 °C para posterior utilização. Foram adicionados à polpa os emulsificantes albumina, emustab®, maltodextrina e superliga neutra® nas proporções de 0,0, 2,5, 5,0, 7,5 e 10,0% em massa. Essa mistura foi submetida à agitação, em uma batedeira doméstica por 15 min para a obtenção da espuma. Em seguida foram feitas as seguintes análises: teor de água, atividade de água, acidez total titulável, pH, teor sólidos solúveis totais, açúcares solúveis totais e redutores, cor e massa específica aparente, estabilidade e expansão. Para a secagem, a melhor espuma obtida considerando-se os diferentes emulsificantes e concentrações foi espalhada sobre bandejas formando uma camada fina de cerca de 5,0 mm de espessura. Em seguida, a espuma foi levada para a secagem em estufa de circulação forçada de ar na qual as temperaturas e a velocidade do ar de secagem foram de 40, 50, 60, 70 e 80 °C, e 5,6 m s-1, respectivamente. Utilizando-se dados da perda de água durante a secagem foi proposto e ajustados modelos matemáticos, determinado o coeficiente de difusão efetiva e a energia de ativação. Após a secagem o pó formado foi utilizado para obtenção do teor de água no equilíbrio, pelo método estático em câmaras tipo BOD mantidas nas temperaturas de 10, 20, 30, 40 e 50 °C e dessecador com soluções saturadas. Aos dados observados do equilíbrio higroscópico foram ajustados modelos matemáticos e calculadas as propriedades termodinâmicas como, calor isostérico integral de sorção, entropia e energia livre de Gibbs. Também foram determinadas as seguintes propriedades físico-químicas do pó: teor de água, atividade de água, acidez total titulável, pH, teor de sólidos solúveis totais, açúcares solúveis totais e redutores, cor e massa específica aparente e unitária, porosidade e ângulo de repouso. As propriedades físico-químicas das espumas indicam que as alterações apresentadas não comprometem a possível secagem em leito de espuma do produto; A albumina na concentração de 7,43% foi o melhor emulsificante para a produção de espuma de graviola uma vez que atendeu aos critérios de massa específica, expansão e estabilidade; O modelo de Midili se ajustou bem aos dados experimentais da secagem de espuma de graviola sendo, portanto apto a descrever o fenômeno em estudo; O modelo proposto para determinar o ponto de transição entre o período de taxa de secagem constante e o de taxa de secagem decrescente ajustou-se bem aos dados experimentais podendo servir como uma ferramenta para determinar o teor de água crítico e o tempo crítico; Obteve- se acréscimo no coeficiente de difusão efetiva com a elevação da temperatura de secagem e energia de ativação de 33,10 kJ mol-1; Os modelos de GAB, Halsey modificado e Sigma- Copace são aptos para descrever o fenômeno de sorção de água do pó de graviola; As propriedades termodinâmicas apresentaram comportamento ímpar devido aos elevados teores de açúcares encontrado no pó; As propriedades físico-químicas do pó de graviola indicam boa estabilidade do produto obtido pelo método de secagem em leito de espuma.The objective was to study and characterize the soursop production process powder by drying in foam bed by choosing the best emulsifier and concentration as well as determine the physical and chemical properties of the product in natura, foam and powder formed. Furthermore, to obtain the sorption isotherms and thermodynamic properties. Soursop fruits were used (Annona muricata L.) of which the pulp was obtained and packaged in PET type bottles sanitized with chlorinated water, and stored at -18 ° C for later use. Albumin, emustab®, maltodextrin and superaliga neutra® were added to the pulp in proportions of 0.0, 2.5, 5.0, 7.5 and 10.0%. This mixture was subjected to agitation in a household mixer for 15 min to obtain the foam. Then the following analyzes were performed: water content, water activity, titratable acidity, pH, soluble solids content, total soluble and reducing sugars, color, bulk density, stability and expansion. For drying, the best foam obtained considering different emulsifiers and concentrations, was spread on trays forming a thin layer about 5.0 mm thick. Then, the foam was taken for drying in a forced air circulation oven in which the drying temperature and air velocity were 40, 50, 60, 70 and 80° C, and 5.6 m s-1 respectively. Using data water loss during drying has been proposed and adjusted mathematical models to determine effective diffusion coefficients and activation energy. After drying, the formed powder was used to obtain the water content at equilibrium with the static method in BOD chambers maintained at temperatures of 10, 20, 30, 40 and 50 °C and desiccator with saturated solutions. To observed data of the equilibrium moisture content were adjusted mathematical models and calculated the thermodynamic properties as integral isosteric heat of sorption, entropy and Gibbs free energy. It was also determined the following physical and chemical properties of powder: water content, water activity, titratable acidity, pH, total soluble solids, total and reducing sugars, color, apparent and true density, porosity and angle of repose. The physicochemical properties of foams indicate that the proposed amendments do not affect the drying of the product in foam bed; Albumin at a concentration of 7.43% was the best emulsifier for soursop foam production since it met the criteria density, expansion and stability; The model Midili fitted well to the experimental data of the foam drying soursop is therefore able to describe the phenomenon under study; The proposed model for determining the point of transition between the period of constant rate drying and the decreasing rate of drying set and the experimental data can serve as a tool to determine the critical water content and the critical time; Obtained increase in the effective diffusion coefficient with drying temperature rise and activation energy of 33.10 kJ mol-1; The models of GAB, modified Halsey and Sigma- COPACE are able to describe the water sorption phenomenon of soursop powder; The thermodynamic properties showed odd behavior due to the high sugar content found in the powder; The physico-chemical properties of the powder soursop indicate good stability of the product obtained by the drying in foam bed method.Conselho Nacional de Desenvolvimento Científico e Tecnológic
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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