Studies on the Osmotic Dehydration and Rehydration Characteristics of Pineapple Slices

Abstract

The study investigated the influence of two osmotic conditions (50°Brix sugar and 47:3% w/w sugar/salt solutions) on osmotic dehydration (water loss, solid gain, electrical conductivity and pH of the medium) and rehydration characteristics (Dry-matter loss, rehydration capacity, electrical conductivity and pH of the medium) of dried pineapple slices. Pineapple slices were osmotically dehydrated (4 hr), and oven dried (60°C for 27 hr). Slices were rehydrated at 90°C for 15 min and at room temperature (RT) for 6 hr. Osmotic dehydration enhanced solid gain, water loss, dry-matter loss and rehydration capacity. Mass transfer (water loss and solid gain) was higher in sugar/ salt solution than in the sugar solution. Sugar/salt mix reduced the amount of electrolytes released into the medium. Regression models gave a good fit of high R2 value when water loss, solid gain, and electrical conductivity variables were related, but dry-matter loss, rehydration capacity, pH and electrical conductivity gave low R2 values.