Global mass transfer coefficients in osmotic dehydration of guava

Abstract

The global water (K*) and solids (K) transfer coefficients of osmotically dehydrated guava were determined. Fruit segments were immersed in a 65 ºBRIX sucrose solution. Three temperatures: 30, 40 and 50ºC for 30, 60, 90, 120, 150 and 180 min and three pressure regimens: atmosphreric, pulsed vacuum (5 min under vacuum and then atmospheric pressure) and continuous vacuum were tested. K* y K coefficients were calculated by fitting the experimental data to a mathematical model relating the ratios of the standardized water and solids contents to the square root of time. The global mass transfer coefficients were proven to be functions of the pressure regimen and temperature. The highest K* values were reached at 50 ºC and the highest K values were achieved with pulsed vacuum at 40ºC.