Effect of moisture content and water mobility on microwave expansion of imitation cheese

The effects of moisture content (60-45%), and refrigerated storage (1-9 days) on the functional properties, water mobility and microwave expansion of imitation cheese are investigated. Cheese hardness, elastic (G') and viscous moduli (G '') increased with decreasing moisture content and decreased during storage. Flowability, loss tangent (tan delta) and water mobility decreased with decreasing moisture content and increased during storage. Microwave expansion of imitation cheese decreased with decreasing moisture content and increased with prolonging storage time prior to microwaving. The changes in texture, rheology and flowability of cheese with decreasing moisture content, changes in water mobility and storage time reflected the level of cheese plasticisation by water and had strong linear correlations with microwave expansion. This work provides evidence that moisture content influences microwave expansion of imitation cheese by providing the driving force for expansion and plasticising the cheese matrix. (C) 2010 Elsevier Ltd. All rights reserved.