Authentication of Indonesian Coconut Sugar Using Stable Carbon Isotopes

Abstract

Indonesian coconut sugar (n = 109 samples) from different local producers was analyzed over a 2-year period. A mean δ13C value of − 25.6‰ ± 0.4‰ was determined for unadulterated (pure) coconut sugar. Seasonal climatic differences of up to ± 0.4‰ increase the standard deviations of coconut sugar (− 25.6‰ ± 0.8‰). Up to 5% w/v of cane sugar is often added during production for seeding purposes which could increase the final coconut sugar δ13C values by up to 0.7‰. Excess C4 sugar (cane or corn sugar) was suggested in 31 coconut sugar samples due to more positive δ13C values (> − 24.8‰). More negative coconut sugar δ13C values (< − 26.4‰) may indicate additives, such as mangosteen sap, commonly used to prevent fermentation of the sugar syrup. A maximum acceptable δ13C value of − 24.1‰ for coconut sugar is proposed which cumulatively accounts for climatic variability and accepted industry seeding practices.