Modelling osmotic dehydration of lemon slices using new sweeteners

Abstract

Lemon slices were osmotically dehydrated using the following healthy sweeteners as osmotic agents: tagatose, isomaltulose, oligofructose and aqueous extract of stevia. A kinetic study using a Fickian approach was performed, which also analysed the changes in water activity, total mass, mass of water and mass of soluble solids in lemon slices. The results showed that the greatest value of effective diffusivity (De) in osmodehydrated lemon slices was obtained from a combination of oligofructose and stevia [De = (10.2 ± 0.3) × 10-9 m2·s-1]. However, the level of water activity (aw) reached with this syrup was the highest (aw = 0.978 ± 0.004 after 1440 min) meaning that the product might be less stable. Additionally, isomaltulose favoured the total mass loss, whereas tagatose did the opposite. Finally, the syrup recommended for dehydrating lemon slices would be a combination of tagatose, oligofructose and aqueous extract of stevia as its De was similar to the value obtained when only oligofructose and stevia were used, but aw values were lower.