Photoacoustic monitoring of water vapour permeability in alkaline-cooked corn pericarp

In Latin American countries alkaline-cooked products (nixtamalised products ) play an important role in the diet of people, Several physical and chemic al changes occur in corn as a consequence of nixtamalisation. Corn pericarp , which determines the quality of corn flour, undergoes a severe degradatio n of its structure and constituents during this process. Knowledge of the w ater vapour permeability in corn pericarp is important because it provides information on the moisture content present inside the grain. In this work, the water vapour permeability in corn pericarp is studied by a recently-pr oposed photothermal configuration. Pericarp was obtained from corn grains b oiled in alkaline solutions containing different amounts of Ca(OH)(2). It i s found that the diffusion coefficient of water vapour in corn pericarp inc reases with increasing Ca(OH)(2) concentration in the alkaline solution. Th is result indicates that a higher diffusion of water vapour occurs due to t he degradation of hemicellulose and lignine in nixtamalised pericarp.