Department of Chemistry Faculty of Science and Mathematics, Satya Wacana Christian University, Jalan Diponegoro No, 52-60 Salatiga
RESULTS AND DISCUSSION Yield of Cucumber Seed Oil
The yield of the cucumber seed oil using a continuous extraction method had a greater yield than the yield of the maceration method (Table 1). The continuous extraction method used a soxhlet extraction tool and a solvent that seemed always new, because it was the result of condensation of the vaporized solvent in the soxhlet extractor, resulting in continuous extraction and the solvent used kept on undergoing circulation compared to the maceration method where the solvent was not circulating (Febrina, Rusli, and Muflihah, 2015). The calculation of cucumber seed oil yields was presented in Table 1.
Table 1. The calculation results of the cucumber seed oil yield using continuous extraction method and maceration method
Yield Hexane Maceration Continuous Hexane 𝑥̅ ± SE (% b/b) 13.26 ± 0.99 19.38 ± 0.94
Refinement of Cucumber Seed Oil by Degumming and Neutralization Methods
The oil yielded from the continuous extraction method was refined using degumming and neutralization methods. The selection of oil yielded from the refined continuous method was because the oil from the continuous
method yields a higher yield than the oil yielded by maceration. The addition of 85% H3PO4 as much as 0.15% to the oil was carried out in the degumming process and the addition of 9.5% NaOH was carried out in the neutralization process.
The results of cucumber seed oil yield before and after refinement was presented in Table 2.
Table 2. The results of cucumber seed oil yield before and after refinement Yield Before Refinement After Refinement 𝑥̅ ± SE (% b/b) 19.38 ± 0.94 11.62 ± 0.93
After the refinement process, the yield of cucumber seed oil decreased from 19.38 ± 0.94% to 11.62 ± 0.93%.
The addition of H3PO4 in the degumming process made the phospholipid compound contained in cucumber seed oil which was insoluble in water became soluble in water (Mardani, Ghavami, Heidary-Nasab, and Gharachorloo, 2016). Phosphatides, proteins, resins or metals were gums and impurities which ccould damage oil. Gums and impurities would settle and be washed by adding distilled water which could cause oil yield to decrease (Soetjipto, Anggreini, and
Cahyanti, 2018)b. If after the degumming process there were still gums remained in the oil then the gums which were still
The Physico-Chemical Properties of Cucumber Seed Oil (Cucumis sativus L.)
The physico-chemical properties of cucumber seed oil were shown in Table 3.
Table 3. Comparison of physico-chemical properties of cucumber seed oil before and after refinement with SNI (Indonesian National Standard) of cooking oil
Characteristics Before Refinement
(𝑥̅ ±SE) After Refinement
(𝑥̅ ±SE) SNI 3741 : 2013 Cooking Oil
Aroma Distinct aroma Distinct aroma Normal
Colour Yellow Pale Yellow Pale Yellowish
Water Content (%) 2 ± 0.06 1± 0 Max 0.15
Density (g/mL) 0.96 ± 0.02 0.91 ± 0.01 (-)
Acid Value (mg
KOH/g oil) 4.97 ± 0.71 2.13 ± 0.01 Max 0.6
FFA (%asam oleat) 3.51 ± 0.50 1.50 ± 0 (-)
Peroxide Value
(meqiuv O2/g oil) 0.82 ± 0.18 0.54 ± 0 Max 1
(a) (b)
Figure 2.Cucumber Seed Oil
(a) Before refinement; (b) after refinement (Source: Personal Documentation, 2019)
The oil colour after refinement in Figure 2 (b) turned pale yellow, this was related to the addition of NaOH during the neutralization process. According to Ketaren (1986) that was because NaOH could reduce oil colour. The water content of cucumber seed oil before refinement (2
± 0.06%) was greater than after refinement (1 ± 0%). Conversely, when
compared to SNI, the water content after refinement was still not in accordance with SNI for cooking oil. The water content of oil had to be as little as possible because it could cause hydrolysis reactions that could cause oil to smell rancid (Budiman, Ambari, and Surest, 2012). In addition, water content that was too high in oil could trigger microbial
growth which could reduce the shelf life of oil (Toscano and Maldini, 2007).
The density of cucumber seed oil after refinement has decreased from 0.96
± 0.02 g/mL to 0.91 ± 0.01 g/mL. The decrease was because after refinement, oil lost free fatty acids and impurities so that the fraction weight of the oil component content decreased. Acid value and free fatty acid levels also decreased after refinement due to the use of NaOH in the neutralization process which caused free fatty acids to be reduced (Meilano et al., oxidation process during the evaporation of hexane solvents which resulted in a high free fatty acid content in oil.
Based on the results of the study, the peroxide value after refinement has
decreased. The neutralization process with NaOH could reduce the peroxide value of oil, it was due to the reaction between free fatty acid NaOH and peroxide polymer compounds (Cahyaningtyas, Soetjipto, and Riyanto, 2017). The peroxide value of cucumber seed oil after refinement (0.54 ± 0) has met SNI standards (max 1).
Composition of Cucumber Seed Oil (Cucumis sativus L.) Using Gas Chromatography-Mass Spectrometry (GC-MS) Before and After Refinement The composition of fatty acids in cucumber seed oil before and after refinement was presented in Figure 3 and Table 4. Figure 3 (a) showed that the cucumber seed oil before refinement was identified to have 8 peaks, while in Figure 3 (b) showed that the cucumber seed oil after refinement was identified to have 3 peaks.
(a)
(b)
Figure 3. Chromatogram of Cucumber seed oil.
(a) Before refinement;
(b) After refinement
Table 4. Components of cucumber seed oil before and after refinement
Component Name BM Molecular Formula
Before Refinement After Refinement Retention Time
The result of GC-MS analysis of cucumber seed oil before refinement was dominated by linoleic acid (45.50%) then followed by squalene (22.72%), palmitic acid (21.28%), stearic acid (2.95%) and 9-Octadecanoic acid methyl ester (2.84%) and other components with <2% content.
After refinement, squalene was the dominant compound (53.28%) followed by linoleic acid (25.36%) and palmitic acid (21.37%).
Based on the results of GC-MS analysis before and after refinement, there was a slight difference in the percent content of each compound in oil. The impurity content disappeared after the refinement process, it was caused by the fatty acid content in the oil was washed by NaOH in the process of neutralization, the soapy fatty acids were washed during the washing process together with soap and distilled water (Ratih and Wuriyanti, 2016).
In this study, there was a squalene component, the level of squalene before refinement was 22.72%, retention time was 14.807 minutes, molecular weight 410 and molecular formula C30H50. After the refinement process, squalene content increased to 53.28% with a retention time of 14.826 minutes. The squalene compound itself was one of the
constituents of non-soapy substances and had some functions, among others, were as an antioxidant in skin that experienced oxidative stress due to ultraviolet light, it could reduce the toxicity of the drugs consumed, and had anti-tumor activity (Insani, Suseno, and Jacoeb, 2017).
CONCLUSION
3. The optimum yield of cucumber seed oil was 19.38 ± 0.94% with the continuous extraction method
4. The refinement process did not affect the aroma of oil, on the contrary it affected the colour of the oil to be pale yellow, reducing the value of water oil constituents before refinement was dominated by palmitate acid (21.28%), linoleic acid (45.50%) and squalene (22.72%). While the composition of cucumber seed oil constituents after refinement was dominated by palmitic acid (21.37%), linoleic acid (25.36%), and squalene (53.28%).
ACKNOWLEDGEMENT
The Acknowledgment is addressed to the Ministry of Research, Technology and Higher Education for funding this research through the PDUPT research program grants in 2019-2020.
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