The aim of this work was to assess the geographic distribution of coffee quality in Minas Gerais state, Brazil, and to study its interactions with chemical and environmental factors. Correlations between environmental factors, chemical compounds and sensory quality of participants of the Minas Coffee Quality Contest were made through Principal Component Analysis and Biplot Graphics. The results showed discriminations of high and low scores as a result of environmental variables, demonstrating a strong influence of temperature, rainfall, altitude and latitude on the quality of the coffees studied. In addition to the environmental characteristics, the chemical compounds trigonelline, caffeine, and especially the acid-5-cafeiolquinic were also relevant in discriminating the scores obtained through sensory analysis. This work is an initial indication of the factors that determine the quality of coffees produced in Minas Gerais.
This work presents a new technique as a potential methodology to analyse seeds. The technology is known as dynamic speckle, or biospeckle, an optical phenomenon produced when active materials, such as biological tissue, are illuminated by laser light. In the present work, the biological activity of seed tissues has been inferred from quantitative and qualitative measurements of their speckle activity. The aim is to show that the biospeckle technique has a potential as a methodology to assess seed viability. One aspect that needs to be investigated is how the water content in the seeds affects bio speckle activity. An experiment has been performed to determine the effect of humidity in the results. Seed activity for different levels of humidity was determined using quantitative and qualitative methods. Also, in others experiments, viable and non viable seeds with different specific humidity levels could be classified using the same technique. £)
RESUMOObjetivou-se no presente trabalho verificar a qualidade do café natural e despolpado durante a secagem em terreiro e secagem com ar aquecido a 40º e 60ºC. O trabalho foi realizado no Departamento de Engenharia e no Pólo de Tecnologia em Pós-Colheita do Café da Universidade Federal de Lavras. A colheita do café, cultivar Topázio, foi seletiva. Parte do café foi despolpado e outra parte processado de forma natural. Uma parcela de cada tipo de café foi conduzida para a secagem em terreiro e outra parcela para secagem com temperaturas de 40ºC e 60ºC. Para avaliação da qualidade, foram feitos teste de condutividade elétrica e lixiviação de potássio; determinação de acidez titulável total; teste de acidez graxa; açúcares totais e redutores. Os resultados obtidos permitem concluir que: o tempo para secagem é afetado pelos diferentes tipos de secagem e processamentos; a condutividade elétrica, a lixiviação de potássio, a acidez titulável total e a acidez graxa aumentam com a elevação da temperatura de secagem, independente do tipo de processamento; os açúcares redutores e os açúcares totais diminuem com o aumento da tem peratura de secagem independente do tipo de processamento; a secagem com temperatura de 60ºC afetou negativamente a qualidade do café.Termos para indexação: Café, processamento, secagem e qualidade. ABSTRACTThe present work has the aim of verifying the quality of natural and washed coffee during its drying with air heated at 40º and 60ºC. The work was accomplished in the Engineering Department and in the Coffee Post-harvest Technology Pole at the Federal University of Lavras. The harvest of Topázio cultivar cultivar was selective. A part of the coffee was pulped and the other part processed in the dry method. A portion of each kind of coffee was led to drying on ground and the other portion for drying at temperatures of 40ºC and 60ºC. For quality evaluation, electric tests and potassium leaching, total titrable acidity; fatty acidity test, total sugars and reducing sugars were conducted. The results obtained in the present work allow to conclude that: drying time is affected by the different sorts of drying and processings; electric conductivity, potassium leaching, total titrable acidity and fatty acidity increase with increasing drying temperature independently of the kind of processing; reducing sugars and total sugars decrease with rise of drying temperature independently of the sort of processing; the drying at the temperature of 60ºC affected negatively coffee quality.
RESUMOConduziu-se este trabalho, com o objetivo de avaliar o efeito de diferentes temperaturas e períodos de pré-secagem em terreiro na composição química e qualidade da bebida do café ½cereja descascada½. Foram usadas temperaturas na massa de 40°C, 50°C e 60°C com fluxo de ar de 20m 3 m -1 m 2 . Após a secagem, foram retirados os defeitos visíveis das amostras de café. Para avaliação da qualidade, foram realizadas as seguintes análises: análise sensorial, açúcares totais, açúcares redutores e não redutores, condutividade elétrica, lixiviação de potássio e acidez graxa. Verificou-se que menores temperaturas de secagem e um maior período de pré-secagem contribuíram para obtenção de uma bebida de melhor qualidade. Os açúcares não redutores diminuíram com o aumento da temperatura e com o aumento da pré-secagem, enquanto que elevaram-se os valores de açúcares redutores. A condutividade elétrica, lixiviação de potássio e acidez graxa aumentaram significativamente com a elevação da temperatura e a lixiviação de potássio reduziu com o aumento do período de pré-secagem. O teste de acidez graxa mostrou-se sensível a temperatura de secagem.Termos para indexação: Secagem, composição química, bebida, Coffea arabica L. ABSTRACTThis work had the aim of evaluating the effect of different temperatures and pre-drying periods on yard on the chemical composition and quality of the beverage of peeled cherry coffee. Temperatures of 40°C, 50°C and 60°C were used in the mass with air flow of 20m 3 m -1 m 2 . After drying, the visible defects of the coffee samples were removed. For evaluation of quality, the following analyses were performed: sensorial analyses, total sugars, reducing sugars and non-reducing sugars, electrical conductivity, potassium leaching and fatty acidity. One verified that lower drying temperature and greater pre-drying period had contributed for the attainment of a better quality drink. The increase of temperature and pre-drying periods decreased the non-reducing sugars content while the values of reducing sugars increased. The electrical conductivity, potassium leaching and fatty acidity increased significantly with the rise of temperature and potassium leaching reduced with increasing of the pre-drying period. The fatty acidity test showed to be sensible to the drying temperature. INTRODUÇÃOPara que o café seja considerado de qualidade, as propriedades químicas, físicas e sensoriais devem estar de acordo com os padrões estabelecidos. A qualidade do café como bebida é determinada pelo sabor e aroma, que estão associados às substâncias químicas existentes no grão e que são influenciados pela temperatura e taxa de secagem. Os estudos desenvolvidos nesse sentido abrangem componentes como açúcares, proteínas, compostos fenólicos, enzimas, lipídeos, bem como umidade, condutividade elétrica dos grãos e lixiviação de potássio, entre outros (BÁRTHOLO et al., 1989;PEREIRA, 1997).Na literatura, existem relatos sobre os danos causados pela secagem em grãos de café, os quais comprometem a obtenção de uma bebida de boa qua...
The Bourbon coffee cultivar has a high potential for producing a quality beverage, which is highly valued in specialty coffee markets. The objective of this study was to verify the occurrence of more promising genotypes for the production of specialty coffees in three different environments. In addition, the chemical composition of the grains was studied with a view toward relating these compounds to the genotypes and environments and to the interaction of these factors.The experimental design included three Brazilian locations in combination with different Arabica coffees, including eleven bourbon and three commercial genotypes. Trigonelline, caffeine and 5-caffeoylquinic acid (5-CQA) from coffee bean samples were analyzed by HPLC, and sensory analyses were performed by professional cuppers accredited by the Coffee Quality Institute. A group of Bourbon genotypes with potential for the production of specialty coffees was identified for each environment assessed. The trigonelline content allowed for discrimination among the three environments studied.
ABSTRACT. The objective of this study was to evaluate the correlation between a group of physiological variables (electrical conductivity, potassium leaching, and germination percentage) and a group of drying kinetics variables (drying time and drying rate) in addition to verifying the relation between drying kinetics variables and coffee quality as a function of processing type, temperature, and drying airflow. Coffee drying was conducted in a fixed-layer dryer at two temperatures and two airflows. After drying, an evaluation of the physiological and sensorial quality was conducted. Based on the results obtained, the following conclusions were drawn: coffee that is processed via a dry method is more sensitive to mechanical drying with heated air than coffee processed via a wet method, resulting in poor physiological performance; airflow does not interfere with the physiological quality of pulped and natural coffees; a temperature increase from 40 to 45°C resulted in a decrease in the physiological quality only for pulped coffee; and an increase in the drying rate as a result of an increase in the drying temperature to 40°C had a negative effect on the sensorial quality of pulped coffee.Keywords: drying kinetics, processing, drying rate.Qualidade fisiológica e sensorial do café arábica submetido a diferentes temperaturas e fluxos de ar de secagem RESUMO. Este trabalho foi realizado com o objetivo de avaliar a correlação entre um grupo de variáveis fisiológicas (condutividade elétrica, lixiviação de potássio e porcentagem de germinação) e um grupo de variáveis de cinética de secagem (tempo e taxa de secagem), bem como verificar a relação entre as variáveis de cinética de secagem e a qualidade sensorial do café, em função do tipo de processamento, da temperatura e do fluxo de ar de secagem. A secagem do café foi realizada em secador de leito fixo com duas temperaturas e dois fluxos de ar. Após a secagem, foi avaliada a qualidade fisiológica e sensorial. A partir dos resultados obtidos, conclui-se que: o café processado via seca é mais sensível à secagem mecânica com ar aquecido do que o processado via úmida, apresentando pior desempenho fisiológico; o fluxo de ar não interfere na qualidade fisiológica do café despolpado e natural; a elevação da temperatura de 40 para 45°C resultou em queda da qualidade fisiológica apenas para o café despolpado e a elevação da taxa de secagem, por meio da elevação do fluxo de ar de secagem, para a temperatura de 40°C teve efeito negativo na qualidade sensorial do café despolpado.Palavras-chave: cinética de secagem, processamento, taxa de secagem.
RESUMOA manutenção da integridade das membranas celulares, entre outros eventos, é um forte indicativo de que a qualidade do café foi preservada na pós-colheita. Objetivou-se neste trabalho, analisar o efeito de diferentes métodos de secagem na manutenção da integridade da parede celular e da membrana plasmática de café natural e café despolpado, buscando determinar as condições e o momento em que ocorrem as rupturas microscópicas. Os cafés foram submetidos a um período de pré-secagem em terreiro. Após este, uma parcela de cada tipo de café foi desidratada no terreiro e, outra, à temperatura de 40ºC e 60ºC em secadores de camada fixa, monitorando-se a temperatura e o teor de água até 11% (bu). Nesse período, grãos foram aleatoriamente amostrados e fragmentos do endosperma preparados para a microscopia eletrônica de varredura, registrandose diversas eletromicrografias, avaliando-se as alterações na membrana plasmática da célula do endosperma dos grãos de cafés em função do teor de água e tempo de secagem. O citoplasma das células a 11% (bu) de teor de água não foi comprometido na secagem em terreiro e a 40°C; na secagem a 60°C, observou-se comprometimento nas estruturas celulares nos cafés com teor de água de 20% (bu).Termos para indexação: Café, processamento, secagem, microestrutura. ABSTRACTThe maintenance of the integrity of cellular membranes, among other events, is a strong indicator that the quality of the coffee was preserved in the post-harvesting process. Therefore, this work aimed to analyze the effect of different drying methods on the maintenance of the integrity of cell walls and plasma membrane of natural and de-pulped coffee in order to determine the conditions and the moment that microscopic ruptures take place. The coffee was submitted to a pre-drying period on a concrete patio. After this, a sample of each type of coffee was dehydrated outdoors and another, with heated air at 40ºC and 60ºC in fixed-layer dryers, controlling the grain temperature and the moisture content to 11% (bu). During the drying process the coffee grains were randomly sampled and fragments of the endosperm were prepared for scanning electron microscopy and eletromicrographs were taken. Measurements of the cells were taken for evaluating changes in the plasma membrane of the endosperm cells in relation to the moisture content and drying period. The cell cytoplasm of the coffee grains with 11% moisture content was not affected when dried under sun light and at the temperature of 40°C. When dried at 60°C, changes in the cellular structures of the cytoplasm were observed for coffees with moisture content of 20%.
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