Estudo de diferentes processos de torração de café por metodo convencional e microondas

Orientadores: Antonio Marsaioli Jr., Hilary Castle de MenezesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de AlimentosResumo: Este trabalho teve como escopo contribuir com um maior conhecimento sobre a aplicação da tecnologia de microondas, na torração de café, em comparação ao método convencional, nas diferentes qualidades de cafés arabicas (duro para melhor, mole e estritamente mole). Para este fim, foram desenvolvidas condições experimentais para a torração dos grãos de café por microondas a 3500W, 3700We 3850W, na freqüência de 2450 MHz, em um secador rotativo combinado a ar quente, em planta piloto, e para a torração por método convencional [doméstico e rápido (industrial) a 210°C e 220°C], em um torrador de prova de café. o sistema de aquecimento por microondas promoveu um aumento de qualidade no café duro para melhor, menor qualidade de café neste estudo, quando torrado à potências de 3500W e de 3700W, passando de uma resposta sensorial de café duro para melhor com acidez forte para café mole com acidez considerável. Todavia, no café mole, de maior qualidade que café duro para melhor, as microondas apenas proporcionaram a manutenção desta mesma qualidade na potência de 3500W, e uma diminuição desta a 3700W. Nas condições estudadas, não foi possível torrar o café estritamente mole, por este sistema de aquecimento não convencional. Assim, a tecnologia de microondas, desponta como um potencial de desenvolvimento, principalmente para a aplicação em cafés verdes de menor qualidade. Os parâmetros físicos [densidade aparente, diâmetro do grão, grau de inchação, aumento de volume e aumento de tamanho do grão, atividade de água, pH, concentração iônica, cor CIELAB e perda de peso] do café verde e torrado foram avaliados nas diferentes condições de aquecimento convencional e de microondas. As propriedades dielétricas (coeficiente de atenuação, profundidade de penetração, coeficiente dielétrico, fator de perda dielétrica, tangente de perda dielétrica, coeficiente de fase, velocidade de fase, condutividade dielétrica, intensidade de campo elétrico, energia dissipada por volume, fator de perda dielétrica efetiva e tangente de perda dielétrica efetiva) do café também foram determinadas a fim de se avaliar o seu comportamento sob a ação das microondas, e relacioná-Ias com o processo de torração por microondas. A presença de cafeína e dos ácidos 5-cafeoil quínico e caféico foram determinados por CLAE, no café verde e torrado, de maneira a, relacioná-Ios com os diferentes processos de torração e as diferentes qualidades de café arabica. Testes sensoriais foram realizados por classificadores e provadores de café. A utilização das propriedades dielétricas para a avaliação do processo de microondas permitiu uma maior compreensão dos fenômenos que ocorreram durante a torração do café. E desta maneira prever e avaliar o comportamento do café, frente a um determinado campo eletromagnético. No grão verde de café duro para melhor, uma maior densidade aparente média em um maior diâmetro de grão, ou seja, uma estrutura de grão verde mais compactada em relação as outras qualidades de café, reportou em termos de propriedades dielétricas, uma maior constante de atenuação, menor profundidade de penetração, menor impedância intrínseca (maior reflexão e menor transmissão), maior coeficiente dielétrico, maior perda dielétrica, maior condutividade dielétrica, maior coeficiente e velocidade de fase, em uma menor tangente de perda dielétrica. Estas em diferentes potências de microondas, no café torrado, resultaram em uma menor taxa de aumento de temperatura, menor intensidade de campo elétrico (Erms) a 3500 W e 3700 W, menor perda de peso (mas em valores de menor luminosidade para L*) em comparação ao café mole. A resposta sensorial para estes cafés torrados a 3500W e a 3700W foi de, cafés moles com acidez considerável.Abstract: The objective of this study was to contribute a greater knowledge about different coffee roasting processes by both conventional and microwave methods, comparing the effects on different qualities of arabica coffee (hard to better, soft and very soft). Thus experimental coffee roasting conditions were developed [domestic and rapid (industrial) at 210°C and 220°C] using a laboratory scale roaster, and by microwaves at 3500W, 3700Wand 3850W at a frequency of 2450 MHz, in a pilot rotary dryer combined with hot air. The heating system using microwaves resulted in an increase in quality in the lowest quality coffee sample studied (hard to better), when roasted at 3500W and at 3700W, improving from a classification of hard to better with strong acidity to soft with considerable acidity. However, with the soft coffee sample, the use of microwaves at 3500W only maintained this classification, and at 3700W, resulted in a decrease in quality. Under the conditions studied, it was not possible to roast the very soft coffee sample using microwaves. Thus a technology with potential for development, especially for application in lower quality coffees, was demonstrated. The physical parameters [apparent density, bean diameter, bean swelling, increase in volume and size, water activity, pH, ionic concentration, CIELAB colour and loss of weight] of the rawand roasted coffees, were evaluated for the different heating conditions by both conventional and microwave systems. The dielectric properties (attenuation coefficient, depth of penetration, dielectric coefficient, dielectric loss factor, dielectric loss tangent, phase coefficient and velocity, dielectric conductivity, electric field intensity, energy dissipated per volume, factor and tangent of the effective dielectric loss) of the coffees were also determined, in order to evaluate the behaviour under the action of microwaves, and relate this to the microwave roasting process. Caffeine, 5-caffeoylquinic acid and caffeic acid were determined in both the raw and roasted coffees by HPLC, so as to relate them to the different roasting processes and to the different qualities of arabica coffee. Sensory tests were carried out by qualified coffee tasters and classifiers. The use of the dielectric properties to evaluate the microwave process allowed for a greater understanding of the phenomena occurring during the roasting of coffee, and thus forecast and evaluate the behaviour of the coffee when submitted to a determined electromagnetic field. In the raw coffee bean of the hard to better sample, a greater mean apparent density in a bean with a greater diameter, that is, a more compact green bean structure in relation to the other coffee qualities, resulted in the following effects on the dielectric properties: a greater attenuation constant, greater depth of penetration, lower intrinsic impedance (greater reflection and lower transmission), greater dielectric coefficient, greater dielectric loss, greater dielectric conductivity, greater phase coefficient and velocity, in a smaller tangent of dielectric loss. These effects, at the different microwave powers, resulted in roasted coffees with a lower rate of temperature increase, a lower intensityo f electric field (Erms)at 3500Wand 3700W and a smaller weight loss (but with lower values for luminosity L*), as compared to the soft coffee. The sensory classification of these coffees, roasted at 3500W and at 3700W, was soft coffees with considerable aeidity. The hard to better eoffee roasted at 3500W, exhibited a greater L* and greater "f' factor, a greater degree of thermal destruction on the bean surface as compared to that in the internal part of the grain, a greater degree of thermal lack of uniformity. When roasted at 3700W, it showed a lower positive ~L* and lower positive "f' factor, and, together with this, less thermal destruction on the bean surface and a greater degree of lack of uniformity with the thermal treatment.DoutoradoDoutor em Tecnologia de Alimento

O tempo e o tipo de embalagem sobre a erva-mate tipo chimarrão durante armazenagem em condições ambientais Influence of time and kind of packaging on mate during storage under ambient conditions

O objetivo deste estudo foi avaliar a influência dos fatores embalagem e tempo na alteração da cor e degradação da clorofila, durante armazenamento de erva-mate tipo chimarrão em condições ambientais. Amostras de erva-mate, acondicionadas em embalagem de papel ou laminada, foram colocadas em câmara de armazenagem e analisadas em sete períodos, totalizando 12 semanas. Foram determinadas a concentração de clorofila (a, b e total), cor instrumental (CIELAB), umidade e atividade de água. Verificou-se degradação dos pigmentos clorofílicos nas amostras em embalagem laminada (redução de 59,5% na concentração de clorofila a e de 28,0% na de clorofila b) e resultados controversos para as amostras em embalagem de papel, os quais provavelmente tiveram interferência da reação de Maillard. As alterações de cor durante o período de armazenamento foram: redução no valor de L* para a erva-mate acondicionada em embalagem de papel (de 49,3 para 48,1) e aumento de L* para o produto em embalagem laminada (de 49,3 para 51,5); redução de -a* e redução de b* para o produto de ambas as embalagens, papel (a*=de -13,2 para -5,9; b*=de 29,3 para 28,5) e laminada (a*=de -13,3 para -7,0; b*=de 29,5 para 24,9). Concluiu-se que o tempo de armazenagem e o tipo de embalagem influenciaram significativamente (P<0,05) os itens analisados, e a alteração de cor foi provavelmente influenciada pelas reações de feofitinização e oxidação dos pigmentos clorofílicos da erva-mate.<br>The aim of this research was to evaluate the influence of packaging and time factors in color change and degradation of chlorophyll during storage of mate, mate type, in environmental conditions. Samples of mate, packaged in laminated flexible film or paper, were placed in a storage chamber, and analyzed at seven periods, during 12 weeks. Chlorophyll (a, b and total), instrumental color (CIELAB), moisture and water activity were determined. In the analysis of chlorophyllian pigments, it was verified their degradation in the samples packaged in laminated film (a reduction of 59.5% in chlorophyll a and 28.0% in chlorophyll b), and controversial results were found in the samples on paper package. This result probably suffered the interference of Maillard reaction. The mate color changes during storage were: L* reduction in the samples on paper package (from 49.3 to 48.1) and L* increase in the samples on laminated package (from 49.3 to 51.5); -a* reduction and b* reduction in the product on both packages, paper (a*=from -13.2 to -5.9; b*=from 29.3 to 28.5) and laminated film (a*=from -13.3 to -7.0; b*=from 29.5 to 24.9). It was concluded that the storage time and the kind of package significantly influenced (P<0.05) the items analized and that the color change was probably influenced by pheophytinization as well as by oxidation of chlorophyllian pigments in mate

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora