Identification of phenolic compounds
The amount of phenolic compounds is an important factor when evaluating the quality of different extracts, it involved for their resistance to oxidation and the properties attributed to these antioxidant (Moure et al., 2001). As shown in Table 3 the watermelon rinds contained different types of phenolic compounds, the most abundant one was 4-hydroxybenzoic acid (958.3 μg/g dw) followed by vanillin (851,8 μg/g dw), while the lowest phenolic compounds was coumaric acid 8.8(μg/g dw). On the other hand four phenolic compounds were identified in sharlyn melon peels namely, 4-hydroxybenzoic acid, vanillin, chlorgenic acid, and coumaric acid with amounts ranged from 66.2 to 325.3 μg/g dw. It was clearly noticed that the content of these phenolics was much higher in watermelon rinds than sharlyn melon peels except the coumarie acid.