Effect of Combined Air-Drying-Osmotic Dehydration on Kinetics of Techno-functional Properties, Color and Total Phenol Contents of Lemon (Citrus limon. v. lunari) Peels

Combined osmotic dehydration (sucrose solution: 50-70% w/w, 30-50 degrees C for 2 h followed by air drying at 40 and 60 degrees C) is an appropriate process for preservation of oil retention capacity, lightness and yellowness of lemon peels (Citrus limon. v. lunari). Incorporation of sugars to lemon cuboids pieces increased drying rate during the first falling rate phase of the air dehydration step and improved their color stability. Osmotic dehydration process allows protective effect against further total phenol loss during air drying: significant loss of total phenol content (70-80%) was recorded during osmotic dehydration and then it remains constant during air drying at 40 and 60 degrees C. For the investigated temperature of osmotic pretreatment (30-50 degrees C), water retention capacities were reduced by up to 70% and were maintained constant during air drying.