Thermomechanical Changes during Reheating Pizza Shells as Related to Heating Method

Two transitions were studied in pizzas, T1 (4 ± 40°C at 33.5% m.c.) which decreased amplitude upon vacuum drying and T2 (60 ± 40°C) which was moisture independent. Moisture loss in the microwave (more rapid) heated samples below ‘freezable’ water range resulted in T1 and T2 gradually changing in their proportion. T2 increasingly became predominant eventually merging with T1. Resulting differences in thermo-mechanical and rheological properties were related to temperature-moisture profiles, shrinkage, the observed loss of ‘freezable’ water and networking. T2 (60 ± 40°C) was found responsible for the leathery texture in microwaved pizza while T1 (0 ± 30°C) was the dominating transition in the soft conventional product. Retrogradation of starch was not related