Características físicas, químicas e biológicas do café (Coffea arabica L.) natural e descascado

• Autor(a) principal: Nogueira, Bruna Lourenço
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3549
• topic: Armazenamento; Taxa respiratória; Perda de matéria seca; Storage; Respiration rate; Dry matter loss; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE PROCESSAMENTO DE PRODUTOS AGRICOLAS

The aim of this work was to evaluate the influence of moisture content, maturity stage and storage period over the respiration rate and dry matter loss of coffee (Coffea arabica L.). In the first stage of the experiment, coffee fruits were utilized, variety “Catuaí Vermelho”, harvested in different maturity stages (green, “verdoengo” and cherry), dried in a forced air circulation chamber at 40 ºC until the desired moisture contents, which varied between 55 to 12 % (w.b.). A portion of the fruits, in the cherry stage, were manually dehulled and dried until moisture content range from 30 to 12 % (w.b.). The samples were weighed and conditioned in glass jars and the respiration rate was measured, through the determination of the carbon dioxide quantity produced in an hour, at 25 ºC, in a respirometer brand Sable Systems International. The values of CO2 production were used to determine the consumption of dry matter through stoichiometry of the respiration equation (C6H12O6 + 6O2 → 6CO2 + 6H2O + 2835 kJ). On the second part of this work, coffee samples in cherry stage, fruit and dehulled, were dried in an oven at 40 ºC and in cement yard until moisture content of 11 % (w.b.). The samples were homogenized, packed in jute sacks and kept under environmental conditions. At the beginning of storage and regular intervals of 45 days, during six months, analysis of the respiration rate, dry matter loss (through stoichiometry and weight of a thousand grains methodology), moisture content, bulk density, fungi detection, electrical conductivity, color and pH were made. Through the xiii obtained results, all samples had an increment in the respiration rate and dry matter loss in function of the moisturecontent. To moisture contents above 15 % (w.b.), this increase was more pronounced. The green coffee presented the highest values of CO2 production, followed by “verdoengo” and cherry coffee, respectively. By means of the model identity technique, it was concluded that the models to describe the respiration rate evolution of coffee fruit and dehulled did not differ among each other, being able to use a single equation to represent this trend. Regarding the storage, moisture contents of grain was maintained among the acceptable range of a secure storage (between 11 to 13 % (w.b.)). The fungi infection was considered low during the evaluated period. An increase of the respiration rate and dry matter loss of coffee occurred with the increase of the storage time, being more accentuated in the natural coffee. Values of dry matter loss calculated through the respiration rate were inferior than the observed values during storage. In general, dehulled coffee presented the best quality characteristics (lower values of electrical conductivity, green color loss and dry matter loss, higher values of pH and bulk density), related to the lower respiration rate. It wasn’t observed differences in the respiration rate and dry matter loss regarding to the drying method employed. There were variations at the behavior of the remaining evaluated characteristics relating to the drying method, not allowing the choice of one of them to proportionate a product with superior quality.