Secagem de abacaxi em secador de leito fixo

• Autor(a) principal: Rodrigues, Ester
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/759
• topic: Abacaxi; Secagem; Qualidade; Modelagem; Pineapple; Drying; Quality; Modeling; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE PROCESSAMENTO DE PRODUTOS AGRICOLAS::PRE-PROCESSAMENTO DE PRODUTOS AGRICOLAS

The current worries of Brazil as one of the world s greatest fruit producers are the field losses during their processing and commercializing. The adoption of methods to reduce these losses has been studied by many researchers, outstanding, the ones directed towards fruit drying. This study aimed at the pineapple in natura some physical properties evaluation, and after drying, the water activity (Aw), the hydrogenised potential (pH), the acidity (ATT), the total soluble solids (SST) and color; the pineapple kinetics drying in a fixed bed drier under the influence of temperatures of 60, 65 and 70 oC, and the drying air speed of 0,5, 0,75 and 1,00 m s-1, as well as the validation of the Thompson model adapted to the pineapple cut in slices drying and dried in a fixed bed. The study was carried out in the Vegetal Products Pre-processing Laboratory in the Agricultural Engineering Department, and the laboratorial analysis in the Natural Pigmentation and Drying Laboratory of the Food Engineering Department, both at the Federal University of Viçosa (UFV). An electrical resistance drier, a 0.5 HP fan and a 0.335 m platter were used. The pineapple was peeled, cut in slices of a 0,01 m thickness and set on a tray in two layers. The room temperature dried and humid bulb and the exhausting air temperature were obtained through thermopairs, where the reading data were monitored in regular intervals of one minute on a data acquisition system. The air speed exit the drier was measured by a thermo anemometer, with a heating system of turned off air. The product mass was measured on a digital scale, in thirty-minute intervals. On the qualitative parameters evaluation, the water activity indicated that the product didn t present conditions to make possible microorganism s infestation after drying, the acidity decrease and the total soluble solids increase and SST/ATT provided a more sweetened flavor to the pineapple after drying. In relation to the color, a product darkening was evidenced in all the treatments used in the experiment. It was observed that the temperature and the drying speed air exercised influence in the drying time. The equation proposed by Lewis is valid to represent the humidity mean in relation to time. The mathematical model proposed by Thompson for the corn drying adapted to the pieced pineapple drying using a fixed bed drier, considering the experimental conditions, presented a satisfactory precision, and is valid to simulate the pineapple drying. The computational program developed, Desidrat 1.0, can be used to preview the results related to the conditions in which the drying was carried out.