How and what is concentrated apple juice made of?

Fresh juice is squeezed from the fruit and is then heat-treated to remove a large percentage of the water that it naturally contains. The resulting 'juice' is about six times more concentrated than it was when first squeezed.

Juice is concentrated in this way because it is easier, and cheaper, to transport the resulting smaller volumes than it would be to ship the original volumes of liquid.

Once the concentrate has arrived at its destination, water is added to return it to the original dilution.