Kinetics of moisture transfer during air drying of blanched and/or osmotically dehydrated mango

NIETO, A B; CASTRO, M A; ALZAMORA, STELLA MARIS

JOURNAL OF FOOD ENGINEERING

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2001 vol. 50 p. 175 - 185

0260-8774

The effect of previous blanching and/or osmotic dehydration (at atmosphericpressure or in vacuum) with glucose syrups on the kinetics of water transport during the first falling rate period of air drying of mango at 60°C was investigated. Both pre-drying treatments decreased strongly the effective moisture diffusivity (Deff) calculated with Fick´s second law. For osmotically concentrated fruit at atmospheric pressure, the increase in glucose concentration of the immersion solution decreased the drying rate. Deff values were similar for mangoes predehydrated to aw 0.97 by vacuum or atmospheric osmosis, but previous blanching slightly decreased the Deff value for vacuum treated slices compared with those osmotically dehydrated to the same aw at atmospheric pressure. The air drying behaviour of blanched and/or osmotically dehydrated mangoes was ascribed to glucose uptake during the impregnation step, volume shrinking, low modification of cell wall resistance to water flux by the pretreatments and/or gelatinization ofstarch and denaturation of protein carbohydrate mucilage.