• Olives for pickling are usually hand-harvested to reduce damage to the fruit through bruising.
  • Olives for oil are generally mechanically harvested.
  • The method chosen is also strongly influenced by the size of the grove.

Timing

There are six major influences on the timing of harvest:

  1. Whether the fruit is destined for oil production or pickling.
  2. The ripeness of the fruit.
  3. The requirements and availability of a processor.
  4. The availability of labour or a mechanical harvester.
  5. The quantity.
  6. The quality required.
  • Olives go from green to black during the ripening process.
  • For pickling, timing is determined by fruit size and the colour required.
  • The stage of ripeness at which you harvest determines the character of the oil produced.
  • Fruit picked early, or green, will produce fruity oil with a full bodied aroma.
  • Fruit picked late, or black, will produce milder oil with less aroma or body.
  • The acidity of oil increases as the fruit matures.
  • The optimal harvest time for oil is when the oil yield is optimal and the characteristics required are present.
  • The oil content of the fruit increases as the fruit ripens, but reaches a plateau.
  • This can be determined through chemical analysis, which is expensive.
  • In the field, an expert view is that the best harvesting time for oil is when the skin of the fruit begins to change colour to partially or completely black and when the pulp is still white.

International Olive Oil Council Maturation Index

To assist with determining when harvest olives for oil production the International Olive Oil Council has developed a formula called the Maturation Index.

Randomly draw 100 olives from 1kg of newly harvested olives then calculate the Maturation Index as follows:

n0, n1, n2, ………………..n7 are the number of olives belonging to each of the following eight categories.

0 = the skin is deep or dark green

1 = the skin is yellow or yellowish-green

2 = the skin is yellowish-green with reddish spots

3 = the skin is reddish or light-violet

4 = the skin is black and the flesh completely green

5 = the skin is black and the flesh is violet to half- way to the pit (stone)

6 = the skin is black and flesh is violet almost to the pit (stone)

7 = the skin is black and the flesh is all dark

 

Maturation Index = (0xn0) + (1xn1) + (2xn2) + (3xn3) + (4xn4) + (5xn5) + (6xn6) + (7xn7)

100

 

 

The optimum harvest time for olive oil is when the Maturation Index is 5