Fruit juice processing
Practical Action
Appendix – The Pearson Square
The Pearson Square is a method that processors can use to calculate the amounts of two
components that should be mixed together to give a final known concentration.
For example, it can be used to calculate the amounts of fruit pulp and sugar syrup to make a fruit
drink. The method can only be used for blending two components. When more than two components
are involved, it becomes more complex.
Example of how to use the Pearson Square
You wish to produce a sweetened fruit juice with a final sugar content of 15%. You use orange juice
(that contains 10% sugar), mixed with a 60% sugar syrup (that contains 60% sugar).
1. Draw a rectangle and label the two horizontal lines with the names of the two products to be
blended (fruit juice and sugar syrup)
Orange juice
Sugar syrup
2. Enter the sugar composition of each product in the rectangle as shown below and put the desired
final concentration of sugar in the centre of the box:
Orange juice
10
15
60
Sugar syrup
3. Mix the two components by crossing diagonally through the centre of the rectangle.
Orange juice
10
45
15
60
Sugar syrup
5
4. Following the arrows, subtract the smaller number from the larger one to give two new numbers
(45 and 5) in the opposite corners of the rectangle. These numbers (45% orange juice and 5%
sugar syrup) are the amounts that need to be mixed to give a fruit drink with a final sugar
concentration of 15%.
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