An apparatus for manufacturing tablets for hot beverage brewing includes a reservoir feeding infusible loose food products, a grinding system for the loose food products to obtain grounds of a given size, a moistening system moistening the grounds to a given moisture content, a mixing and homogenizing system for mixing and homogenizing the grounds to a homogeneous mixture, a weighing system of the homogeneous mixture to obtain a dose of predetermined weight, a forming system forming the dose into a tablet of predetermined volume, an irradiation system for electromagnetic irradiation of the tablet to overheat the particles to a partial baking and/or sintering for compactness and self-supporting ability without an enclosure, and a control system acting on the grinding, moistening, homogenizing, system, forming, and irradiating systems to control particle size, moisture content, homogeneity, weight, volume and compactness parameters of the tablet and change water permeability of the tablet accordingly.