Changes in fruit colour and composition of dokong (Lansium domesticum Corr.) during maturation

S. Ahmad Tarmizi, Y. Norlia, M. Pauziah and S. L. Tham

Abstract

Dokong harvested at 4, 7, 11, 14 and 17 days after fruit yellowing stage were monitored for changes in colour and chemical characteristics. Fruit yellowing (FY) is the stage at which all dokong fruit in a bunch have yellowish-green pericarp. The pericarp changed from yellowish green to intense yellow (higher b* and C* values) on the fourth day, dark yellow (lower L* value) on the seventh day, and light yellow (higher L* value) on the 11th day. At 14 or 17 days after FY, the fruit turned brownish yellow (hue ≤ 83°). The colour or hue angle of the fruit was negatively correlated with total soluble solids (–0.68) and the ratio of total soluble solids to total titratable acidity (–0.73) but positively correlated with total titratable acidity (0.65). These correlations indicated that the sweetness of the fruit aril increased as the pericarp changed from yellow to brownish yellow.The change in the yellow colour of the fruit can be an acceptable harvesting index for dokong. As the pericarp colour changed, there was an increase in fruit weight and sugar content of aril up to about 18 g and 10% respectively on the 11th day and remained constant thereafter. This change in total sugars content paralleled the increase in total soluble solids. However, total titratable acidity showed a decreasing trend as the fruit matured, and at 14 days after FY only 0.7% was present. Based on taste evaluation, fruit harvested at 4 and 7 days after FY were sourish though acceptable, whereas fruit harvested at 11 and 14 days were sweeter and more preferred.

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