Understanding Wheat Grain Steaming

Abstract

Wheat grain cooking involves heating and moisture uptake. Stapley et al. (Int. J. Food Sci. Technol. 1997, 32, 355) documented the differences between moisture uptake in boiled and steamed grains. The relationship and coupling between the heat- and mass-transfer processes is investigated here. By determining the moisture−activity diagram arising from the Stapley et al. steaming data (Chem. Eng. Sci. 1999, 54, 965), it is argued for the first time that heat transfer exerts the key controlling influence on the moisture mass transfer in steaming. A heat- and mass-transfer model for grain steaming is developed that extends and improves on the previous model (Chem. Eng. Sci. 1999, 54, 965). This model allows for the coupling of the two processes and the introduction of a dimensionless parameter, as well as providing neater solutions. In steaming, the observed temperature elevation in the grain suppresses the driving force for mass transfer. This study contributes to a better understanding of the cooking operation and will lead to improvements in batch cooking operations in breakfast cereal manufacturing.

Interactions of heat and mass transfer in steam reheating of starchy foods

“…Nevertheless, they regarded the grains as the lumped system that limited the model predictions in locations. Later, Horrobin et al (2003) extended and improved the previous work of Stapley et al (1999) by developing a coupled heat and mass transfer model for steaming by using the equilibrium moisture difference as the driving force on the surface and by using the equilibrium moisture content that varies with grain temperature, in contrast to the partial-pressure driving forces used by Stapley et al (1999). The observed equilibrium moisture level in the grain was highly sensitive to temperature, which supports the theory that heat transfer controls the mass transfer process in steaming.…”

Morphology, structural, thermal and rheological properties of wheat starch–palmitic acid complexes prepared during steam cooking

“…Steamed food is kept separate from boiling water by placing it on a grate but comes into direct contact with hot steam and is different from boiled food. 1 The boiling point of water is exactly the highest temperature of the cooked food under normal pressure. Steaming is a healthy method of cooking and is widely enjoyed around the world.…”