Identification and quantification of fructose in different parts of watermelon (citrullus lanatus) by using Reversed Phase High Performance Liquid Chromatography (RP-HPLC) / Nur Shafinaz Mohamad Salin

Watermelon have been part of diet due to its nutritional values and sweetness. Fructose is fruit sugar with low glycaemic index that helps in energy production. Studies have been conducted for sugar analysis in watermelon flesh. However, no study performed in detection of fructose in rind and peel of watermelon. This study was carried out to identify and quantify fructose in flesh, rind and peel of watermelon by using isocratic mode RP-HPLC. Fresh juice and freeze dried samples were injected into NH 2 column at 23°C coupled with refractive index detector at 35°C with flow rate 1mL/min of mobile phase Acetonitrile and water (75:25) and 20μL sample injection. Retention time for fresh juice flesh, fresh juice rind and fresh juice peel were at 8.84, 8.84 and 8.88 min. The retention time for fructose in freeze dried flesh and freeze dried rind sample were, 8.81 and 8.92 min while no detection in freeze dried peel. Standard curve were linear over the concentration range (0.30-5.00mg/mL) with limit of detection and limit of quantification 0.1243 and 0.4144 mg/mL. The concentration of fructose in juice of flesh, rind and peel were 6.20, 1.89 and 0.60 mg/mL while in freeze dried flesh and rind were 13.68 and 37.50 mg/mL respectively. Fructose was successfully separated by using isocratic mode of RP-HPLC and the outcomes indicated that this study method is efficient for identification and quantification for fructose in watermelon parts.