Factors Affecting Shell Cracking in Polished Young Coconuts and Preventive Measures

Abstract

Young coconut shell cracking is a significant problem reported during trimming and polishing. By studying the shell structure, fruit development, pressure inside the shell (internal pressure) of young fruits, dissolved carbon dioxide in the coconut water and cracking incidence, as well as postharvest treatments to manipulate the pressure and carbon dioxide concentration, it was revealed that cracking depended on the physical property of the shell and the internal pressure. Cracking was principally found on the large carpel where the shell was the thinnest. The growing area presenting a high cracking incidence was found to have fruits with a thinner shell than fruits from a nearby area. The younger fruits had a weaker, thinner shell and high internal pressure. Once the fruits were 28 weeks old, the internal pressure dropped to slightly above atmospheric pressure. The level of internal pressure did not depend on rainfall or growing area. However, postharvest heating, dipping in water and exposure to carbon dioxide increased the internal pressure. To reduce shell cracking incidence, it is recommended to delay harvesting to allow shell strengthening, delay the trimming and polishing processes to allow water loss from the fruit and reduce the internal pressure. Dipping fruit in an anti-browning solution should also be brief to avoid water absorption.