## 3 Results
### Conjugated Diene Content and DPPH Antioxidant Activity of Lipids Extracted from Wafers
Significant effects of storage time and extract addition on the DPPH values were observed. The antioxidant activity of both samples (LWS, LWE) decreased with the wafers' storage time, although the decrease was more pronounced in the LWS samples than in the LWE. The addition of the fruit extract improved the stability of the lipid fraction in the LWE sample because of the active antioxidant compounds contained in the extract. According to the information from producer of the extract, it is composed of maltodextrin and citrus fruit extract. In this study, TPC and TFC of the fruit extract was also tested. TPC equals to 8.84 \(\pm\) 0.42 mg GAE/mL, whereas TFC is 0.823 \(\pm\) 0.038 mg QE/mL. High content of phenolic compounds resulted in high antioxidant activity of the fruit extract measured by the DPPH radical scavenging assay which is 13.68 \(\pm\) 0.18 \(\mathrm{\SIUnitSymbolMicro mol}\) TE/mL. Analyzing the changes of the DPPH value during storage of wafers, at the beginning the antioxidant activity of LWE was 97.4 \(\mathrm{\SIUnitSymbolMicro mol}\) TE/100 g whereas for LWS it was 87.7 \(\mathrm{\SIUnitSymbolMicro mol}\) TE/100 g. Then a significant decrease in DPPH values was observed, and in the 3 rd month, the DPPH values were comparable, i.e., 48.7 and 42.4 \(\mathrm{\SIUnitSymbolMicro mol}\) TE/100 g for the LWE and LWS samples, respectively. After the 3 rd month, the DPPH values of the LWS samples decreased, reaching a value of 20.6 in the 6 th month and then the antioxidant activity was at a constant  
Figure 4: The antioxidant activity of the samples: standard wafers (LWS) and wafers with extract (LWE), measured as DPPH radical scavenging during 13 months of storage. Vertical bars indicate 0.95 confidence intervals, and the same letters indicate a lack of significant differences between data (\(\alpha\) = 0.05). level until the end of storage. In turn, for the LWE sample, the addition of extract increased the antioxidant activity in comparison to LWS sample, and after the 3 rd month of storage the DPPH values were stable until the 8 th month (48.7-51. 3 \(\upmu\)mol TE/100 g). After the 8 th month, the antioxidant activity of LWE decreased with time, reaching a DPPH value of 22.7 \(\upmu\)mol TE/100 g in the 12 th month of storage, which was not significantly different from the LWS sample at the same storage period (\(p>0.05\)) Similarly, after 13 months of storage differences between DPPH value for LWS and LWE were not significant. [PERSON] et al. [10] showed that the DPPH radical scavenging activity of cookies with the addition of saffron extracts decreased during storage. This decrease was lower when comparing to control. Moreover, during the first three month of storage not significant changes were observed in DPPH values for saffron-treated cookies. That indicated the protective effect of saffron was the most pronounced during the first 3 months. In our study the decrease of DPPH values of the sample with fruit extract was the highest at the beginning of storage (0-3 months) and after that time the values stabilized until the 8 th month. All herb extracts, investigated by [PERSON] et al. [12], also showed significant differences in their ability to reduce the initial concentration of DPPH, which was expressed as the IC\({}_{50}\) value, defined as the mass concentration of an antioxidant extract that was required to quench 50% of the initial DPPH under the given experimental conditions. [PERSON] et al. [15] also investigated the effect of raspberry pomace addition to wafers on the DPPH antioxidant activity. They stated that the ability of the ethanol extracts to neutralize the DPPH radical increased with the increasing concentration of freeze-dried raspberry pomace. [PERSON] et al. [27] reported that the DPPH radical scavenging activity of the ethanolic extracts of wafers with the raspberry extract was up to 10 times higher than the control sample and varied in the broad range from 61.89 \(\upmu\)mol/100 g d.w. to 157.44 \(\upmu\)mol/100 g d.w.