Relationship between Physical Properties and Mono- and Multilayer Water Contents of a White Wheat Baked Product at Various Temperatures and Relative Humidity

The relationship between physical properties and water content of monolayers (Wm) and multilayers (MC) was investigated for baked white wheat flour products with different gelatinization levels at various temperatures (5, 20, 40 degrees C). As the temperature increased from 5 degrees C to 40 degrees C, the region of relative humidity (RH) for brittle narrowed to low RH and that for softening widened. Irrespective of the temperatures tested here, brittle occurred at low RH and hardening at middle-high RH. The RH region of brittle corresponded well to the RH region of Wm during the desorption process, whereas softening corresponded to the MC region. Especially, baked white wheat products with a high gelatinization level became harder at the RH region for MC, and softening started at the MC region. Therefore, the water contents of the Wm and MC regions may be intimately involved in changes in the physical properties of baked white wheat products, irrespective of the temperatures tested here.