## 3 Results and Discussion
### Physical Properties
#### 3.1.3 Colour  
The chromatic parameters \(L^{\star}\), \(a^{\star}\), \(b^{\star}\), \(C\) and \(h^{\circ}\) of snacks prepared without and with fruit powders addition are presented in Table 2. In general, snacks gained after application of microwaves were lighter (average L* value of 75.6) in comparison to products obtained after frying (average L* value of 73.9), regardless the time of storage. Addition of chokeberry powder resulted in slight decrease in lightness, whereas addition of blackcurrant and cranberry juice powders caused an increase in L* values of snacks gained after microwaving and frying. Storage did not cause a significant change in coordinate L* values in any type of snacks analysed. When the redness was concerned, snacks gained after frying (control and snacks with fruit powders addition) had almost 1.8-times higher values of coordinate a* when compared to products obtained after application of microwaves. The most significant difference in redness between the type of processing applied for snacks obtainment was noted in case of control samples. It can be suggested that frying (stronger processing conditions) led at the same time to greater darkness (L*) and to the generation of redness via Maillard reaction and caramelisation reactions that was previously described by [PERSON] et al. [29] and [PERSON] [30]. Similar observation was made in case of frying and microwave cooking of Jerusalem Artichoke chips [31].  
The addition of fruit powders resulted in an increase in a* values of, on average, 32% after application of microwaves. In the case of frying, the increase was only noticed when chokeberry and blackcurrant powders were used. No significant changes between the control sample and snacks gained with cranberry powder were observed which might suggest stronger degradation of the red components present in cranberry powders during frying.  
The storage resulted in a slight increase in coordinate a* values that was the strongest in case of control samples. This confirmed that progress of Maillard reaction and caramelisation reactions may occur also during the storage of snacks.  
The increase in b* values was the strongest in case of control samples. In general, the yellowness of snacks was stronger after frying when compared to application of microwaves, irrespective to the addition of fruit powders into the pellets. This confirmed a strong impact of processing conditions on the probable occurrence of the newly formed compounds during snacks preparation [32]. In order to track further changes connected with influence of the processing in snacks, the examination of chroma (C*) indicating the colour intensity was done. In the case of the control samples, higher C* values were noticed for samples gained after frying. The addition of fruit powders resulted in an increase in chroma values, except chokeberry. Only in this case, the colour density was the lowest. Similar observation was done for snacks gained after application of microwaves. The hue angle (h\({}^{\text{o}}\)) is defined as a quality attribute of colour [32]. For example, an angel of 0\({}^{\circ}\) represents red hue, whereas angle of 90\({}^{\circ}\) indicate yellow. When the non-stored snacks were concerned, slightly more reddish products were gained after addition of chokeberry powders, whereas the most yellowish were the control samples. No significant changes were noted in h\({}^{\text{o}}\) values between snacks prepared after application of microwaves and frying, except samples with chokeberry powder. In this case, the frying led to the decrease in h\({}^{\text{o}}\) values, thus the samples were more reddish than that gained after application of microwaves. Storage did not cause significant changes in h\({}^{\text{o}}\) values, irrespective to the type of powder used.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Storage Time (Weed)** & \multicolumn{2}{c}{**Control**} & \multicolumn{2}{c}{**Cenberry**} & \multicolumn{2}{c}{**Chokeberry**} & \multicolumn{2}{c}{**Blackeurant**} \\ \hline