The effect of ultrasound and osmotic dehydration pretreatments on papaya drying kinetics was investigated. The ultrasound pretreatment was carried out in an ultrasonic bath at 30 A degrees C. The osmotic pretreatment in sucrose solution was carried out in an incubator at 34 A degrees C and agitation of 80 rpm for 210 min. The drying process was conducted in a fixed bed dryer at 70 A degrees C. Experimental data were fitted successfully using the Page model for dried fresh and pretreated fruits, with coefficient of determination greater than 0.9992 and average relative error lower that 14.4 %. The diffusional model was used to describe the moisture transfer, and the effective water diffusivity was identified in the order of 10(-9) m(2) s(-1). It was found that drying rates of osmosed fruits were the lowest due to the presence of infused solutes, while the ultrasound pretreatment contributed to faster drying rates. Evaluation of the dried fruit was performed by means of total carotenoids retention. Ultrasound treatments in distilled water prior to air-drying gave rise to dried papayas with retention of carotenoids in the range 30.4-39.8 % and the ultrasonic-assisted osmotic dehydration of papayas showed carotenoids retention values up to 64.9 %, whereas the dried fruit without pretreatment showed carotenoids retention lower than 24 %.FACEPE (State of Pernambuco Science and Technology Foundation)Departamento de Engenharia Química, Universidade Federal de Pernambuco, Av. Prof. Arthur de Sá, s/n, Cidade Universitária, Recife, PE, 50740-521, BrazilUniversidade Estadual da Bahia, Av. Edgard Chastinet Guimarães, s/n, São Geraldo, Juazeiro, BA, 48905-680, BrazilUniversidade de Pernambuco, FFPP, Av. Cardoso de Sá, 01, Vila Eduardo, Petrolina, PE, 56300-000, BrazilUniversidade de Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, 52171-900, BrazilDepartamento de Botânica, Universidade Estadual Paulista Júlio de Mesquita Filho, Caixa Postal 510, AC Rubião Júnior, Botucatu, SP, 18618-970, Brazil