Sachets are made from at least one thin and flexible film (10, 18) of a water-soluble and edible polymeric material, the film and/or films being shaped to define a sachet and filled with a food material (16), and being sealed to form a peripheral seal by RF welding between opposed electrodes (12, 20). The film may be of starch. The sachet and contents are added to water, without needing to be cut open, before being eaten or drunk, or cooked. For example the food material might be coffee powder or dried soup, or a mixture for making bread; the film dissolves readily and is substantially tasteless. RF welding provides reliable seals despite any powder on the surfaces of the film.