US fruit and vegetable grower and processor Dole Food is planning a US$2.2m upgrade of its Central Oahu pineapple packing plant.

Brian Orlopp, Dole's Hawaii operations general manager, said the aim of the upgrade it to increase efficiency and quality levels, reported the Associated Press.

Many pineapple processors and growers are shifting production to increasingly popular extra-sweet varieties of the fruit. Dole is focusing on its Premium Select brand.

After a 2001 slump in pineapple sales in Hawaii, farm-level sales rose 4% last year.