Physical defects such as scars, scratches and contamination with latex on the fruit surface, and the hardening of fruit shell, have been identified as the causes of low quality of mangosteen fruit. These defects have limited the fruit to be exported from Indonesia. The objectives of this study were to gain basic understanding of how to defects occur and how they can be prevented and extend shelf life of the fruit.
Field observations showed that scars on the fruit shell occur when the fruit trees grow mainly in low lands areas that are less than 300 m above sea level. The scars that develop from broken tissue of the fruit shell were probably due the high heat intensity from sun light which directly hit the shell surface during the fruit growth. Scratches on the surface of fruit were found to be caused by the improvised harvesting tools such a bamboo stick with spilt top end, which is used twist and hold the fruit. The improved method, which was designed in this study, used an aluminium pipe with one end split into four parts and the inner surfaces of the splits that were covered with rubber sheet, has completely protected the fruit skin from scratching.
The hardening of the fruit shell mainly result from physical impact. These experiments showed that dropping fruit from 50 cm above the ground and application of 2 Kg weight to the fruit were enough to cause hardening of the fruit shell. Shelf life of the fruit at ambient temperature was significantly extended when fruit were individually sealed in stretch- plastic PE film. A shelf life more than 30 days can be achieved for fully matured fruit (red to reddish brown in colour) with this method compared to less than 16 days for non-wrapped fruit.