Sugar components of coconut sugar in Indonesia: study digest
A 1992 study of Indonesian coconut sugar found that sucrose was the dominant measured sugar in samples from Malang, Yogyakarta and Denpasar, while glucose and fructose varied substantially by location. Water activity was also measured, linking sugar composition with the moisture state of the products.
The samples were analysed and compared with later research on coconut sugar and relevant quality standards. Because the original report was small and geographically limited, its findings describe those specific samples rather than Indonesian coconut sugar as a whole.
What the 1992 study examined
Hari Purnomo analysed coconut sugar produced as a cottage-industry product in three Indonesian locations: Malang in East Java, Yogyakarta in Central Java, and Denpasar in Bali. The study focused on three sugars—sucrose, glucose and fructose—and on water activity, a measure of how much water in a food is available for chemical reactions and microbial growth. The archive record for this paper is PAN 19930319960.
How the sugars and water activity were measured
Sugars were extracted using boiling 85% ethanol and analysed by high-performance liquid chromatography. Water activity was measured with a Novasina sensor. The findings apply only to the tested samples, not all Indonesian coconut sugar.
Results differed among the three Indonesian locations
Location | Replicates | Sucrose (%) | Glucose (%) | Fructose (%) | Water activity / moisture |
Malang | 8 sugar; 3 Aw | 70.85 | 3.00 | 2.92 | Aw 0.69; 13.5% moisture on DM |
Yogyakarta | Not specified | 78.97 | 3.45 | 3.12 | Aw 0.69; 13.2% moisture |
Denpasar | Not specified | 70.52 | 8.96 | 9.00 | Aw 0.63; 10.8% moisture |
Yogyakarta had the highest reported sucrose concentration at 78.97%. Malang and Denpasar were similar in sucrose at 70.85% and 70.52%, respectively. The strongest contrast was in reducing sugars: Denpasar contained 8.96% glucose and 9.00% fructose, roughly three times the levels reported for Malang and Yogyakarta. Denpasar also had the lowest reported water activity, 0.63.
How these figures compare with later work
Later research confirms that coconut sugar composition varies with sap quality and processing. A 2018 East Java study found differences in sugar composition depending on preservative use, while a 2020 HPLC study identified sucrose, glucose and fructose as the principal sugars in coconut sap.
The Philippine National Standard specifies 78–89% sucrose, 2-3% glucose, 1-4% fructose and water activity no higher than 0.60. The 1992 Yogyakarta sucrose value met this later range, while Malang and Denpasar values were lower. However, standards developed in another country and period cannot establish whether the historical samples were defective.
Why processing can change coconut sugar chemistry
Coconut sugar is produced by concentrating coconut palm sap. Fermentation, heating, evaporation and sucrose inversion can affect its chemical composition. A 2007 study examined volatile compounds in coconut sap, syrup and sugar, while a 2019 analysis documented commercial product variability and possible added ingredients.
The differences observed in 1992 cannot be attributed to location alone. Sap quality, collection conditions, preservatives, heating and storage may also influence sugar composition.
What the study can and cannot tell us
The study provides an early analytical snapshot of Indonesian coconut sugar. Sucrose dominated in all three locations, while Denpasar samples contained considerably more glucose and fructose.
Water activity was 0.69 in Malang and Yogyakarta and 0.63 in Denpasar. These values describe water availability rather than total moisture content. Later standards should not be applied retrospectively as acceptance criteria for the 1992 samples.
It does not establish a single composition for all Indonesian coconut sugar.
It does not identify why the three locations differed.
It does not evaluate health outcomes or prove that coconut sugar is nutritionally superior to other sugars.
Its reported moisture and water-activity values should be interpreted in the context of the analytical methods and processing practices of the period.
Frequently asked questions
What was the main sugar in the Indonesian coconut sugar samples?
Sucrose was the largest of the three measured sugars in samples from all three locations. The reported means were 70.85% in Malang, 78.97% in Yogyakarta and 70.52% in Denpasar. Glucose and fructose were much lower in Malang and Yogyakarta but notably higher in Denpasar.
Which location had the highest glucose and fructose values?
Denpasar samples had the highest reported reducing-sugar values: 8.96% glucose and 9.00% fructose. Those concentrations were substantially above the values reported for Malang and Yogyakarta. The study did not experimentally determine which production, raw-material or storage factors caused this difference.
How were the sugars measured?
Researchers extracted sugars from coconut sugar samples using boiling 85% ethanol. Sucrose, glucose and fructose were then quantified by high-performance liquid chromatography (HPLC) with a Bondapak silica column and an acetonitrile–water mobile phase. Water activity was measured separately using a calibrated Novasina humidity sensor to assess the samples' moisture-related properties.
What does water activity mean in this study?
Water activity describes the availability of water for chemical reactions and microbial growth rather than simply the total amount of water present. The reported values were 0.69 for Malang and Yogyakarta and 0.63 for Denpasar, alongside moisture estimates reported for the samples.
Do these results describe all coconut sugar sold in Indonesia?
No. The paper analysed samples from three locations and was not designed as a nationally representative survey. Later research shows that coconut-sugar composition can vary with sap, processing conditions, preservatives and product quality. The 1992 figures are best treated as measurements of the tested samples.
Sources
- Purnomo, H. “Sugar components of coconut sugar in Indonesia.” ASEAN Food Journal 7(4), 200–201 (1992).
- Philippine National Standard PNS/BAFS 76:2016. Coconut Sap Sugar — Specifications.
- Somawiharja, Y. et al. “Indigenous technology of tapping, collecting and processing of coconut (Cocos nucifera) sap and its quality in Blitar Regency, East Java, Indonesia.” Food Research 2(4), 398–403 (2018). DOI 10.26656/fr.2017.2(4).075.
- Asghar, M.T. et al. “Coconut (Cocos nucifera L.) sap as a potential source of sugar: Antioxidant and nutritional properties.” Food Science & Nutrition 8(4), 1777–1787 (2020). DOI 10.1002/fsn3.1191.
- Wrage, J., Burmester, S., Kuballa, J., Rohn, S. “Coconut sugar (Cocos nucifera L.): Production process, chemical characterization, and sensory properties.” LWT 112, 108227 (2019). DOI 10.1016/j.lwt.2019.05.125.
- Srikaeo, K., Thongta, R. “Effects of sugarcane, palm sugar, coconut sugar and sorbitol on starch digestibility and physicochemical properties of wheat based foods.” International Food Research Journal 22(3), 923–929 (2015).
- Saraiva, A. et al. “Coconut Sugar: Chemical Analysis and Nutritional Profile; Health Impacts; Safety and Quality Control; Food Industry Applications.” International Journal of Environmental Research and Public Health 20(4), 3671 (2023). DOI 10.3390/ijerph20043671.
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