Submitted by Leticia Schettini (leticia@ufrrj.br) on 2016-10-11T14:28:18Z No. of bitstreams: 1 2005 - Jonatas de Aguiar Ferreira.pdf: 582914 bytes, checksum: cf08766dd08ac2ba431524c048eecb30 (MD5) / Made available in DSpace on 2016-10-11T14:28:18Z (GMT). No. of bitstreams: 1 2005 - Jonatas de Aguiar Ferreira.pdf: 582914 bytes, checksum: cf08766dd08ac2ba431524c048eecb30 (MD5) Previous issue date: 2005-08-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior-CAPES / In this research, the drying kinetics and equilibrium conditions during osmotic dehydration of chayote (Sechium edule, Sw.) were studied using 20, 30 and 40 % (w/v) sucrose solutions. A thermostatic bath was built to allow the experimental evaluation of osmotic dehydration kinetics and equilibrium moisture content determination. The experiments were carried out at three different temperatures (30 ?C, 40 ?C and 50 ?C) in order to evaluate the influence of temperature and sucrose concentration. Chayote fruits were washed and submerged in sodium hypochloride solution for ten minutes, for sanitization. Afterwards, the fruits were dried and cut into slices of about 0.5 cm thickness. Then, the slices were put into hypertonic sucrose solutions during preestablished time intervals. After osmotic dehydration, the solution was discarded and the slices were softly dried with absorbent paper to remove surface moisture. The moisture content was determined gravimetrically. Long time experiments up to 96 h were performed to provide information about the equilibrium moisture content. An specific equilibrium isotherm was selected by statistical methods. The correlation that better described equilibrium moisture content behavior was the Smith sorption isotherm, adapted to osmotic environment. The Overhults model was used to describe osmotic dehydration kinetics and estimate the drying constants k and n. Based on the results obtained in this research, it could be demonstrated that the equilibrium moisture content is strongly influenced by sucrose concentration and that k is a parameter dependent on the temperature and sucrose concentration, whereas n may be considered constant for the given experimental setup. / Neste trabalho foi feito um estudo da desidrata??o osm?tica de fatias de chuchu em um sistema que possibilitou a determina??o da umidade de equil?brio e dos coeficientes do modelo de Overhults para descrever a cin?tica de desidrata??o osm?tica das fatias. O procedimento experimental consistiu em lavar e escovar os frutos, para a remo??o de impurezas da casca, fatiar o chuchu, em fatias de 5 mm de espessura, num fatiador dom?stico de alimentos, submeter o material ? desidrata??o osm?tica em solu??o hipert?nica de sacarose a 20,30 e 40%, por at? 96 horas, tomando amostras em per?odos determinados para levantar a curva de desidrata??o do material e tamb?m determinar a umidade de equil?brio das fatias de chuchu como uma fun??o da concentra??o inicial da solu??o hipert?nica e da temperatura. Com base nos resultados obtidos foi poss?vel determinar os par?metros do modelo de Overhults para as fatias de chuchu, bem como a uma correla??o para a umidade de equil?brio do material e constatar que h? forte influ?ncia da temperatura e da concentra??o sobre a cin?tica de desidrata??o osm?tica do chuchu, que cerca de 50 % da umidade das amostras ? removida nas primeiras duas horas de imers?o, que a umidade de equil?brio ? atingida em cerca de 48 horas de imers?o e que o modelo de Overhults descreve satisfatoriamente as curvas de desidrata??o osm?tica.