Bioactive and Nutritional Constituents, In Vitro Functionality, and Food and Therapeutic Potentials of a Syrup Prepared from Oil Palm (Elaeis Guineensis) Sap

A syrup prepared from the sap of the African oil palm (Elaeis guineensis Jacq) was evaluated in vitro, for application as a nutritional, bioactive sweetener and flavouring by determination of its carbohydrate content, sugar, organic acid, and phenolic compositions, and also, its pH, titrable acidity, vitamin C, and functional characteristics at various concentrations. The syrup exhibited high total phenolic content (TPC) (70.82-510.2 mg GAE/L) at the various concentrations studied (5-40% wt/vol). Thirty-four phenolic compounds were identified, with syringic (28.91%), vanillic (24.48%), gallic (17.93%) and ferulic (10.88%) acids as the dominant constituents; 30 others were present in minor and trace concentrations. The various concentrations of palm syrup exhibited acid pH values of 3.2-3.0, high vitamin C (7.67-61.34 mg %) and low titrable acidity (0.31-1.49%), with malic (35.76%), tartaric (21.86%), lactic (16.36%), acetic (12.71%), and oxalic (9.81%) as the major organic acids. Total carbohydrate content was 67.73±0.72%, and glucose (75.69 %) and fructose (19.31%) were the major sugars; sucrose (4.83%) was a minor constituent. The favourable organic acid, carbohydrate, and phenolic profiles, high carbohydrate, vitamin C, and total phenolic contents, high DPPH radical scavenging activity (IC50 = 2.88 g/ml), modest reducing power (IC50 = 25.3 g/ml), and high α-amylase inhibitory activity (IC50 = 0.45 mg/ml) of the palm syrup recommend it as a functional sweetener and flavouring, with possible therapeutic benefits