Concentrated juice is the liquid from a fruit which requires adding water before it's drinkable. You can make juice concentrate at home without using artificial ingredients. The method you use depends largely on the type of fruit you're using. For example, various berries and cherries are simple: press the fruit to extract the juice and then strain it. The juice is already in concentrated form. For other types of fruits, there are two home methods you can use to make juice concentrate.
Boiling Method (lower-water content fruits – apples, pears, grapes etc.)
Wash, peel and slice the fruit. If you're using grapes, they don't need to be peeled or sliced, however, you should remove the stems.
Place the fruit and sugar to taste (amount varies by fruit and preference) in a pan and add water until the fruit is covered. Heat to boiling and cook for about 30 minutes or until the fruit is soft and pulpy.
Strain the liquid into another container, repeating the process until the juice is free of particulate. Add water to taste when you're ready to drink.
Freezing Method (high-water content fruits – oranges, grapefruits, etc.)
Express the juice from the fruit into a container. This can be done by hand squeezing or by using a juicing device. Strain the juice to remove seeds or any unwanted pulp.
Pour the juice into a narrow-necked container such as a jug. Cover and place in your freezer until the juice is completely frozen.
Remove the cover and suspend the container over another container large enough to contain the melted juice. Allow the juice to thaw only to the point where the juice has dripped out but the water content is mostly still contained within the jug as a block of ice. Repeat the freezing and thawing process twice more to attain a concentrated juice.