1. Introduction
Young coconut is highly nutritious and is one of the most popular export fruits from Southeast Asian countries (Jarimopas and Ruttanadat, 2007 and Gatchalian et al., 1994). The fruit structurally comprises a green skin, a fibrous husk, and a shell which encloses the flesh and juice. The “Nahm Wahn” (“sweet liquid”) cultivar is generally preferred by consumers because of its taste. The maturity of the young coconut fruit strongly affects the fruit quality. The juice and the flesh of the immature fruit are sour and over-soft (jelly-like) while the over-mature fruit is considered by consumers to be too sweet and hard. However, the properly mature fruit is characterized by juice that is sweet and slightly sour, and has a moderately soft flesh. Competent fruit growers are able to detect changes in physical characteristics, mechanical strength, acoustic and physiological properties as the young coconut matures and changes which are usually imperceptible to the layperson (Jarimopas and Kusol, 2007).