A capsule (1) sealed without an internal filter. The capsule includes a cup-shaped body (2) with an outwardly projecting flange (2a), and a flexible lid (3) welded to the flange (2a) to define with the latter a sealed chamber (4) which is impermeable to oxygen and moisture and contains a quantity of granular material (5). The granular material (5) is first compressed inside the chamber (4) in a direction perpendicular to the plane containing the flange (2a), with a compressive load preferably of between 2 and 50 Kg per cm2 of the average cross-sectional area of the chamber (4), so as to form a compact tablet (5) of the material. A vacuum is formed inside the chamber (4) to a degree such that the lid (3) adheres to the upper surface of the tablet (5).
