## 3 Results and Discussion
### Oxidative Stability  
In both oils, peroxide value did not exceed the value specified in Codex Alimentarius for refined oils (<10 meq O\({}_{2}\)/kg of fat), although in the quinoa oil, the level of peroxide value was higher. This may mean that quinoa oil was less resistant to oxidation than amaranth oil. The amount of peroxides, as the only indicator, did not clearly indicate the fat's resistance to oxidation. It is advisable to perform other tests characterizing the degree of oxidation. Oil extracted from amaranth seeds was characterized by a longer induction time measured wth the Rancimat test than fat isolated from quinoa seeds (Table 1). Induction time obtained for amaranth oil (6.9 h) was consistent with the results obtained by  
Figure 2: The percentage of palmitic, oleic, linoleic and \(\alpha\)-linolenic acids in the sn-2 position of triacylglycerlycords (TAG) of amaranth and quinoa oil. [PERSON] et al. [40] (6.14 h). In tested amaranth oils, a longer induction time was noticed than for lineseed oil--0.39-0.76 h [10], rapeseed oil--4.76-5.84, and olive oil--4.79-5.26 h [41]. By contrast, quinoa oil was characterized by shorter induction time than hazelnut oil--5.19-8.94 h [41]. The results for oxidative stability of amaranth and quinoa oils measured in the PDSC test at five different temperatures are summarized in Table 3. As expected, the induction time of the tested oils decreased with increase in temperature. The induction time for amaranth oil ranged from 435.26 min (at 100 \({}^{\circ}\)C) to 32.20 min (at 140 \({}^{\circ}\)C), and for quinoa oil ranged from 300.15 min to 20.51 min. The oxidative stability of oils assessed by the PDSC method had only been the subject of a few studies. [PERSON] et al. [42] obtained an induction time of 71.4 min in a study of the cultivar _Amarantus gangeticus_. The PDSC result in an experiment carried out by [PERSON] et al. [32] for quinoa oil was 71 min at 120 \({}^{\circ}\)C. In our study, the PDSC induction time of investigated amaranth and quinoa oils was much longer than in results obtained by [PERSON] et al. [10] in a similar experiment for lineseed oil: 104.20-111.19 min at 100 \({}^{\circ}\)C, 46.19-51.93 min at 110 \({}^{\circ}\)C, 21.20-24.72 min at 120 \({}^{\circ}\)C, 10.48-11.30 min at 130 \({}^{\circ}\)C, 4.33-4.97 min at 140 \({}^{\circ}\)C. On the other hand, studies conducted by [PERSON] et al. [41], also in similar experiment, indicated that rapeseed oils, olive oils and hazelnut oils were characterized by a longer induction time in the temperature range of 100-130 \({}^{\circ}\)C.  
PDSC induction times in whole temperatures range (100-140 \({}^{\circ}\)C) were significantly longer for amaranth oil than for quinoa oil. The free fatty acids present in the oil made the fat more susceptible to oxidation. The investigated quinoa oil was characterized by a  
Figure 3: Melting DSC curves, determined in the temperature range \(-\)80–80 \({}^{\circ}\)C of amaranth (red line) and quinoa (blue line) oils. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Temperature** (\({}^{\circ}\)**C) & \multicolumn{2}{c}{**Induction Time (min)**} \\
**Quinoa** & **Amaranth** \\ \hline
100 & 300.15 \(\pm\) 4.98 \({}^{\mathrm{a}}\) & 435.26 \(\pm\) 6.50 \({}^{\mathrm{b}}\) \\
110 & 169.68 \(\pm\) 3.21 \({}^{\mathrm{a}}\) & 200.50 \(\pm\) 4.60 \({}^{\mathrm{b}}\) \\
120 & 82.82 \(\pm\) 2.10 \({}^{\mathrm{a}}\) & 112.00 \(\pm\) 3.20 \({}^{\mathrm{b}}\) \\
130 & 47.36 \(\pm\) 2.06 \({}^{\mathrm{a}}\) & 62.40 \(\pm\) 2.90 \({}^{\mathrm{b}}\) \\
140 & 20.51 \(\pm\) 1.13 \({}^{\mathrm{a}}\) & 32.20 \(\pm\) 2.20 \({}^{\mathrm{b}}\) \\ \hline \hline \end{tabular} Data denoted by the same letter are not statistically different (\(\alpha\) = 0.05).  
\end{table} 
Table 3: PDSC induction time (min.) in the temperature range 100–140 \({}^{\circ}\)C of oils extracted from quinoa and amaranth seeds. higher level of free fatty acids (measured by acid value), which resulted in lower oxidative stability compared to amaranth oil with lower level of free fatty acids (data not presented).