Chemical composition and bioactive compounds of Cucurbitaceae seeds: Potential sources for new trends of plant oils

3. Results and discussion 
3.1. Chemical composition of Cucurbitaceae seeds
Table 1 shows the chemical composition of ‘Essahli’ pumpkin seeds, ‘Crimson’ 
watermelon seeds, and ‘Ananas’ melon seeds varieties. Significant differences (p< 0.05) were 
observed among Cucurbitaceae seeds in their oil content, protein, total fibre, ash, and sugars. 
Pumpkin seeds possess high levels of oil (35.53%) and protein (40%) in comparison to 
watermelon and melon seeds whose crude oil and protein contents were totalling 19.23% and 
28.44% for the ‘Crimson’ variety and 19.41% and 26.15% for the ‘Ananas’ variety, 
respectively. According to studies conducted by Kulaitienė et al. (2018) and Seymen et al. 
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(2016) the oil content of the Cucurbita pepo L. Lithuanian cultivars and Turkish genotypes 
seeds ranged between 47.24 - 47.43% and 33.04 - 46.97%, respectively. Furthermore, crude 
oil and protein contents of the seeds of the Tunisian Citrullus lanatus ‘Crimson’ variety were 
lower than those reported by Al-Khalifa (1996) for the Iranian, Egyptian, and Chinese 
Citrullus lanatus varieties, which ranged from 20.64 to 21.7%, and 25.29 and 41.58%, 
respectively. Cucumis melo ‘Ananas’ variety’s seeds had lower oil and protein contents than 
those reported by Mallek-Ayadi et al.(2018) for the Tunisian ‘Maazoun’ Cucumis melo 
variety which possessed oil and protein contents of 30.65% and 27.41%, respectively.
The highest oil percentages found in the seeds of the Cucurbita pepo var. ‘Essahli’, 
Citrullus lanatus var. ‘Crimson’, and Cucumis melo var. ’Ananas’ make them fairly ideal for 
many oil industry applications. According to Nyam et al. (2009), differences among oil 
contents could possibly originate from plant diversity, climate conditions, ripening stage and 
the used extraction method. 
Note that Cucurbitaceae seeds examined in our study also exhibited high amounts of 
crude fibre. The highest content was observed in the Citrullus lanatus variety (48.26%).
Interestingly, Cucurbitaceae seeds were found to contain significant amounts of 
minerals, too (Table 1). Phosphorus was the most prevalent element (1471.24 mg/100g, 1124 
mg/100g, and 787.31 mg/100g for Cucurbita pepo, Cucumis melo, and Citrullus lanatus 
seeds, respectively). The phosphorus was followed in descending order by magnesium, 
potassium, and sodium; by potassium, sodium, and magnesium, and by potassium, 
magnesium, calcium, and sodium in Cucurbita pepo var. ‘Essahli’, Citrullus lanatus var. 
’Crimson’, and Cucumis melo var. ‘Ananas’ seeds, respectively. Our findings are in 
accordance with the mineral composition of the melon seeds of the ‘Tibish’ and ‘Maazoun’ 
varieties, in which potassium and magnesium were the major minerals (Mallek-Ayadi et al., 
2018; Siddeeg et al., 2014). The Mineral composition of the seeds of the Egyptian watermelon 
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and pumpkin varieties were rather different than that found in our study. Phosphorus was the 
most prevalent element followed in descending order by potassium, magnesium, and calcium 
(El-Adawy and Taha, 2001). 
3.2. Chemical analysis 
Table 2 shows the physicochemical characteristics of Cucurbitaceae seed oils. The 
specific gravitational value of the watermelon seed oil was lower than those of melon and 
pumpkin seed oils and the values perfectly corresponded with the 0.917 and 0.919 values 
reported by El-Adawyand Taha (2001) for the pumpkin and watermelon seed oils. However, 
the specific gravity values were lower than those reported by Al-Khalifa (1996) for the 
Egyptian, Iranian, and Chinese Citrullus lanatus varieties ranging between 0.9235 and 0.9283 
and those reported by Ramazan et al. (2012) for the Citrullus lanatus vercitroides and