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In this work the importance of maize pericarp and germ in relation to the overall quality of masa and tortillas was studied. Alkaline-cooking originated alterations in the outer layers of the grain. Its components were hydrated and the pericarp fraction assumed a gummy and sticky texture. During the liming process, some components from the germ, pericarp and tip cap fractions released`maize hull gums', increasing the contents of xylose, galactose and D-glucuronic acid. The presence of gums and insolubilised germ that remained after the traditional washing of the nixtamal improved the viscosity, cohesiveness and adhesiveness of the masa and tortillas as compared to the dry masa and tortillas from nixtamal with the germ removed and from exhaustively washed nixtamal, where most of the hull gums and germ were removed. Fresh tortillas or tortillas stored for 24 h at room temperature prepared using the traditional process of nixtamalisation (washed twice) were more stretchable, elastic and resistant to tearing and cracking than tortillas prepared with exhaustively washed nixtamal or with nixtamal washed twice with the germ removed. Tortillas from nixtamal with the germ removed showed the worst texture, rollability and puf®ng.

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In this paper we describe the use of the open photoacoustic cell (OPC) to obtain the thermal effusivity of transparent liquid samples. The samples used to demonstrate the usefulness of the OPC configuration were distilled water, diffusion pump fluid oil, amaranth seed oil, car oil, glycerol and some solvent liquids, such as trichloroethylene, isopropanol, white gasoline and ethanol.