Ascorbic acid degradation of papaya during drying: Effect of process conditions and glass transition phenomenon

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The aim of the present work was to study the degradation of ascorbic acid during hot air drying of papaya cubes and to verify its relationship with glass transition. A convective tray dryer was used in the drying experiments, which were carried out at air temperatures (T-air) of 40, 50, 60 and 70 degrees C and air velocities of 1.0 and 1.32 m/s. The lowest T-air induced higher retention of this nutrient at end of drying. At 70 degrees C, papaya sample remained in the rubbery state until the end of drying, since product temperature (T-p) was above the glass transition temperature (T-g) along the process. This state is characterized by great molecular mobility inside the food, which facilitates the degradation. At 40 degrees C, the rate of nutrient degradation was very slow as T-g was close to T-p and papaya has suffered phase transition from rubbery to glassy state. (C) 2013 Elsevier Ltd. All rights reserved.123157164Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES