The infusion is prepared using traditional methods. The use of only four ingredients (berries, alcohol, water and sugar or honey) produces an excellent liqueur. Its purity and genuineness is guaranteed by the correct recipe and careful timing, by the absence of any dyes or preservatives and above all by so-called "natural flavours", whose aromatic properties can be isolated using physical processes and enzymatic or microbiological techniques. The only difference between present-day procedures and traditional ones lies in the attention given to quality control, made possible by modern technology.As soon as they reach the plant, the berries are washed in cold water to completely eliminate any impurities remaining after initial cleaning. They are then placed in steel silos, where steeping in pure alcohol begins. Some processors prefers to slit berries so that the alcohol can penetrate more easily.Each step in production is carried out at a low temperature so as not to alter the gustatory properties of the finished product. After steeping for the time required, the liquid and solid parts are separated by removing the alcoholic liquid from the silos, leaving the alcohol-soaked berries behind. The latter are later rinsed in pure water to recover the particularly fragrant alcoholic liquid remaining in the berries, which is then added to the previously-extracted "alcoholic fraction". At this point we have an infusion which is technically called the "mass product". It still has a high alcohol content, not less than 50%, which will  remain unaltered until near the end of the production process.Shortly before bottling, the infusion is sweetened with sugar  or honey - or both - and brought to desired strength (not less than 30%) by adding demineralised water. As a last step, natural filters are used to render the liqueur more transparent and sparkling.Sardinian "Mirto" is finally ready for bottling.