Characterization of pure cheese snacks and expanded granule powders textured by the instant controlled pressure drop (DIC) process

In this study, a new concept of pure cheese crispy snacks has been defined. The process used is the Detente Instantanee Controle (DIC), for instant controlled pressure drop treatment, inserted between two air drying stages. Such cheese snacks can reach low water content (W<3 g H(2)O/100 g dry basis) and achieve high crispness level. A final simple grinding allows expanded granule cheese powders to be obtained. This paper investigates the impact of this process in terms of physical and structural properties such as specific density, expansion ratio, compressibility, etc. Cheese pieces can be expanded to a volume ca. 3,500\% of original size, with a sharp decrease in the specific density of pieces from an initial value of 1,118 +/- 5 kg.m(-3), for untreated samples, which is close to the intrinsic density value, toward 33 +/- 5 kg.m(-3) for the most expanded samples. The values of specific density strictly depend on the DIC processing parameters; the higher the DIC steam pressure, the higher the expansion ratio, and the higher the porosity (results not shown), the lower the specific density of the cheese snacks. The final powder granules can have small size (around 250 mu m), an expanded structure, and thus a low bulk density and a high specific surface area. The results revealed the high capability of the DIC process to produce expanded perfectly dried cheese snacks and powders.