Effect of pre-freezing and solutes on mass transfer during osmotic dehydration and colour of oven-dried African star apple during storage

The effects of freezing, solutes (glucose and sucrose) and concentrations (44, 52 and 60 degrees Bx) on water loss and solid gain during osmotic dehydration and on CIE colour parameters, colour intensity (Delta E) and chroma (Delta C), of osmo-oven-dried African star apple pulp during storage were investigated. Water loss and solid gain were higher in fruits immersed in glucose solutions than in sucrose solutions. Freeze-thawed fruits recorded a rapid increase in water loss and solid gain within 30 min of immersion when compared with the fresh African star apple that showed higher water loss after 2-3 h of immersion. Generally, L* value increased in the osmo-air-dried African star apple preosmosed in glucose and sucrose solution while a* and b* values decreased during storage. Higher colour intensity and chroma values were recorded in air-dried African Star apple preosmosed in glucose solution than in sucrose solution.