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Maximizing oil yield

21 Nov 2022

Maximising the yield of fruit bunches is, of course, a primary goal of field operations. A second, and equally important goal is to harvest bunches at maximum oil content but before oil free fatty acid content exceeds market requirements.

Whilst it may be necessary to use a minimum ripeness standard of ‘1 loose fruit on the ground before bunch harvest’ in steep terrain (loose fruit scatters over the ground at bunch harvest), in very young mature palms with small bunches (≤5 kg/bunch) and where theft is a significant problem, the recommended optimal ripeness standard is ‘5 loose fruit on the ground before bunch harvest‘.

The graph below shows three important aspects of fruit bunch development:

  1. Bunch water content decreases rapidly during the final 60 days of bunch development (i.e. from 100–160 days after anthesis). Premature harvest means that bunches transported to the mill contain a large amount of water rather than oil.
  2. Fruits in the outer and centre parts of the bunch double in size over the final 100 days of bunch development (60–160 days after anthesis). Premature harvest means that fruits have not developed fully.
  3. Mesocarp oil synthesis takes place over the last sixty days of bunch development (100–160 days after anthesis). Mesocarp oil content continues to increase even after the start of fruit abscission.

In order to maximise oil yield, it is essential to implement the following:

  1. Implement two cycles of pruning per year so that harvesting is unimpeded by the presence of surplus fronds and loose fruits fall to the ground as bunches ripen (and are not trapped in frond butts and unpruned fronds).
  2. Maintain clean weeded circles (1.0 m (young mature palms ≤7 years after planting (YAP) to 1.5 m (> 7 YAP) from the trunk to the outer edge of the weeded circle)so that harvesters can assess bunch ripeness by counting the number of shed loose fruit in the weeded circle (instead of assessing ripeness based on bunch colour).
  3. Establish and maintain ten day harvest intervals so that bunches that are not quite ripe (under ripe bunches) that are not harvested during the present harvest cycle are not over ripe or rotten at the subsequent harvest cycle. Provided ten day cycles are maintained, bunches with 4 loose fruit on the ground will not be over ripe at the following harvest cycle.
  4. Collect all bunches and loose fruit that have fallen into the weeded circle after bunch cutting.
  5. Transport all bunches and loose fruit within 12 hours of harvest. Always transport fruit bunches and loose fruit to the mill at the same time (the mill operates more efficiently when each truck load of crop contains fruit bunches and loose fruit. Oil free fatty acid formation is curtailed during sterilization.

Download the diagram here.

Further reading:

Thomas, R., P’hand Sew, Mok, C., Chan, K., Easau, P. and Ng, S. (1971) Fruit ripening in the oil palm Elaeis guineensis. Annals of Botany, 35, 1219-1225.

Corley, R. (2001) Ripening, harvesting and oil extraction. The Planter, 77, 507-524.

Ng, K.T. and Southworth, A. Optimum time of harvesting oil palm fruit. In: Wastie, R.L. and Earp, D.A. (Eds.) The Incorporated Society of Planters, Kuala Lumpur, Malaysia, 16-18 November 1972, pp. 439-461.

Southworth, A. (1976) Harvesting. In: Corley, R.H.V., Hardon, J.J. and Wood, B.J. (eds.) Oil Palm Research. (Developments in Crop Science (1)), Elsevier, Amsterdam, pp. 469–477.

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