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

Citrullus lanatus (Thumb) Matsumura & Nakai var. Citroides (Balley) Mansf. All oil samples 
had relatively high iodine values ranging from 109.35 g I
2
/100g for the Cucurbita pepo var. 
‘Essahli’ to 135.39 g I
2
/100g for the Citrullus lanatus var. ‘Crimson’ seed oils. The iodine 
value of the Tunisian Cucurbita pepo seed oil variety was higher than that reported by Nyam 
et al. (2009) for the Cucurbita pepo seed oil, yet lower that those reported by Al-Khalifa 
(1996), Mitra et al. (2009), and Rezig et al. (2012) for the Cucurbita pepo and Cucurbita 
maxima seed oils. Nevertheless, the iodine value of the Citrullus lanatus seed oil was higher 
than those reported by Al-Khalifa (1996) and Mokwala and Shai (2017) for the Egyptian, 
Iranian, and Chinese Citrullus lanatus and sweet, bitter, and weedy Citrullus lanatus Thumb 
(Matsum and Nakai) seed oil varieties, respectively. For the Tunisian Cucumis melo seed oil 
variety, the iodine value was higher than those reported by Nyam et al. (2009) on Bittermelon 
and Kalahari melon seed oils. The high iodine values of Cucurbitaceae seed oils were 
attributable to their abundance in unsaturated fatty acids (Table 3). This indicates that the seed 
oils are convenient for edible and/or drying oil purposes (Meddeb et al., 2017). The 
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saponification values of the C. pepo, C. lanatus, and C. melo seed oil varieties were recorded 
as 176.5 mg KOH/g of oil, 174.2 mg KOH/g of oil, and 178.3 mg KOH/g of oil, respectively. 
These values were lower than those reported by Veronezi and Jorge (2015) for the pumpkin 
(Cucurbita maxima and Cucurbita moschata) seed oils,Nyam et al. (2009) for the Bittermelon 
(Momordica charantia L.) and pumpkin (Cucurbita pepo) seed oils, and by El-Adawy and 
Taha (2001) for the watermelon (Citrullus vulgaris) and pumpkin (Cucurbita pepo) seed oils. 
However, the saponification value of Citrullus lanatus var. ‘Crimson’ was slightly higher than 
that reported by Nyam et al. (2009) on Kalahari melon (Citrullus lanatus) seed oil. High 
saponification values testify to the presence of high contents of high molecular weight 
triacylglycerol, which are useful for soap production (Meddeb et al., 2017). Note that the acid 
and peroxide values of Cucurbitaceae seed oils were low. These values were even lower than 
those determined by the Codex Alimentarius (1982), which stipulated a permitted maximum 
acid value of no more than 10 meq of peroxide oxygen/kg oil for vegetable oils and a 
permitted maximum acid value of no more than 10 mg KOH/mg oil. These results are in 
perfect accordance with those reported by Veronezi and Jorge (2015), Nyam et al. (2009), and 
El- Adawy and Taha (2001). The lower acidity of the Tunisian Cucurbitaceae seed oils 
indicates that they are edible and might have a long shelf life. In fact, the higher acidity index 
is related to the presence of Free Fatty Acids (FFAs), which are much more susceptible to 
oxidation than the fatty acids that are present in the triacylglycerol molecules. For the 
unsaponifiable matters, low contents were observed in the examined varieties. Cucurbita pepo 
var. ‘Essahli’ seed oil showed an unsaponifiable matter content within the range of that 
reported by Rezig et al. (2012), but higher than that reported by El-Adawy and Taha (2001) 
for the Cucurbita maxima and Cucurbita pepo seed oils. For the Citrullus lanatus var. 
‘Crimson’ seed oil, the unsaponifiable matter content was higher than that reported for the 
Citrullus vulgaris seed oil (El Adawy and Taha, 2001). 
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3.3. Fatty acid composition 
Table 3 presents the fatty acid composition of the seed oils of pumpkin, watermelon 
and melon. The analysed oils revealed that there were significant variations (p 
< 0.05) 
in the 
contents of palmitic, stearic, oleic, linoleic, and arachidic acids. These variations induced 
differences in total saturated, monounsaturated and polyunsaturated fatty acids. All the oil 
samples had high amounts of total unsaturated fatty acids (consisting primarily of linoleic 
then oleic acid). They represented 75.2% for the Cucurbita pepo var.’Essahli’, 82.32% for the