The changes of chemical composition and antioxidant activity of coconut sap during heating process

Maillard reaction may lead to the forming of the brown color of granulated coconut sugar during sap heating. It has been proven that Maillard reaction products (MRPs) have antioxidant activity. It is, thus, necessary to verify that the Maillard reaction occurs during the heating of the sap. This verification would be valuable to figure out the antioxidant potency of granulated coconut sugar in future studies. Reducing sugar as well as free amino acid content of the sap decreased in the first 10 min of heating from 3.78 to 1.73 db and from 0.09 to 0.04 db, respectively. About 77.98 of free amino acid levels of the coconut sap decreased. Such reduction was an indicator of the occurrence of the carbonyl-amino reaction, which was deemed as the initial Maillard reaction. The reaction was also demonstrated by the absorption band at 1635.64 cm^-1 denoting the presence of C=O which could correspond to Amadori compounds evaluated by FTIR. The Maillard reaction occurred during the heating process of sap resulting in the increase of antioxidant activity evaluated by the DPPH method and Fe²⁺ chelating activity. This increase might be due to the reductone compounds formation at the intermediate Maillard reaction. © 2020 Elsevier B.V., All rights reserved.