A process is provided for fortifying a juice beverage with calcium. Fruit juices, including citrus juices, can be fortified. Serial in-line mixers deposit sources of calcium and acid separately into a flow of the juice. An upstream in-line mixer adds a calcium source to the juice flow, such as by high-shear mixing. A downstream in-line mixer adds a food-grade acid powder, such as by high-shear mixing, to the flow of juice into which the calcium had been incorporated. The calcium and acid sources combine within the juice to provide a calcium-fortified juice within which the calcium exhibits excellent solubility and good sensory characteristics, when each property is compared with a successful commercial process for calcium fortification of juices.