38 Foamed cereal products.

R. C. HOSENEY. R&R Research Services, Inc., 8831 Quail Lane, Manhattan, KS 66502.

The mouthfeel and texture of cereal products is partially determined by the density of the final product. To control the density and distribution of air cells in the product foam must be produced. A foam is a discontinuous gas distributed in a continuous phase. To leaven the product a foam is necessary. Neither yeast nor chemical leavening can create new gas cells. Thus, to produce a fine foam we must nucleate the system by trapping air during the preparation of the dough or batter. Air is the preferred gas as the nitrogen is not very soluble in water and, thus, will not dissolve in the aqueous matrix. Yeast or chemical leavening can be used to expand the preexisting gas cells. Remixing or punching of doughs will subdivide the larger bubbles to produce a larger number of small gas cells and thus result in a finer grain. The dynamics in the oven as the product is heated is of utmost importance. Overproofing will lead to coalescing of gas cells giving a poor grain. Under proofing also results in a poor grain. The strain hardening of gluten is important in producing a uniform thin cell wall throughout bread. The foam structure must be transformed to a sponge structure or the product will collapse when it is removed from the oven. Puffing of snack products, such as popcorn, uses the starch hila as the nucleation site and water vapor as the driving force to expand the foam. In extrusion, the air trapped in the melt is the nucleation site and once again water vapor drives the expansion.