Study on compositional changes of king coconut (<em style="mso-bidi-font-style: normal;">Cocos nucifera </em>var. aurantiaca) water and kernel during maturation  and evaluation of optimum quality characteristics targeting commercial applications

Abstract

King coconut (Cocos nucifera var. aurantiaca) is a tropical nut with notable nutritional and medicinal values. King coconut water (KCW) and king coconut kernel (KCK) are sweet and refreshing. They undergo several changes during maturation. The objective of this study was to assess the physico-chemical changes of KCW and KCK with maturity. Three different maturity stages (6, 7, and 8 months) of the variety aurantica, known locally as ‘Nawasi Thembili’ were studied for several physico-chemical parameters. Whole nut weight (g), nut-circumference (cm), colour (water/kernel) (*L), nut-water volume (mL), kernel weight (g), and kernel thickness (mm) were assessed as physical parameters, while pH, total soluble solids (oBrix), titratable acidity (as % ascorbic acid), total sugars (g/100g; g/100mL), and minerals (mg/L; mg/kg) were analysed as chemical attributes. Sugars were estimated using Agilent 1260 HPLC and ICP-MS was used to measure the mineral profile. Results revealed that all the tested physical parameters of KCW and KCK increased significantly (p < 0.05) with maturity. The pH, TSS, total sugars, and acidity of KCW increased significantly (p < 0.05), while mineral content decreased significantly (p < 0.05) with maturity. However, the TSS and minerals of KCK decreased significantly (p < 0.05) with maturity and a higher sucrose content was reported in KCK compared to KCW at later maturity. The Ca+2 and Mg+2 were prominent in both KCW and KCK. The study concluded that the physico-chemical characteristics varied widely with the maturity of king coconuts. The selection of optimum harvest maturity to match the preferred attributes of intended applications is suggested.