## 3 Results and Discussion  
### Physicochemical Composition  
Physicochemical composition of _Spirulina_ and its combinations with pomeranate peel (S1-S4) is shown in Table 1 Moisture content of ethanolic extracts was measured as a percentage of water relative to dry weight. Moisture content of pomeranate peel from 'Gabsi' cultivar used in this study (S1) was about 74.25 \(\pm\) 0.52% which is slightly higher than those found in other Tunisian cultivars: 'Acide', 'Nebli' and 'Tounsi', whose contents were respectively 67.26%; 72.58% and 72.68% [32]. As illustrated in Table 1, moisture content of sample S2 (_Spirulina_) was 8.25 \(\pm\) 0.07%. This value was higher than _Hawaiien Spirulina_ Pacifica (4.70%) and Algerian _Spirulina_ (5.17%) but lower than the _Spirulina_ moisture content from Chad (8.40%) [33]. In this study, moisture content was less than 10%, which is the recommended condition for long-term storage of _Spirulina_ powders. On the other hand, the combination S4 showed a significant difference (\(p<0.05\)) compared to S2 for moisture content values. The protein content of the studied samples varied significantly (\(p<0.05\)) between 7.68 and 69.54% (Table 1). _Spirulina_ (S2) has the highest (\(p<0.05\)) protein content (69.54%) compared to S1, S3 and S4. These contents are also higher than those found in other _Spirulina_ strains [34; 35]. Amongst others proteins, phycocyanin is a blue coloring agent applied in the food industry and cosmetics, stands out with a well-established antioxidant capacity [36]. For S1 sample, protein content was higher than those found in other Tunisian cultivars 'Acide' (3.96%), 'Nebli' (5.42%) and 'Tounsi' (5.84%) [32], as well as other Turkish cultivars, 'Lefon', 'Seedless', 'Kadi', 'Siyah' and 'Koycegiz', whose contents are 3.19; 3.11; 3.06; 2.67 and 2.58%, respectively [37]. The protein content in S3 sample (54.52%) was found to be higher (\(p<0.05\)) than the other combined sample (S4: 37.42%). As presented in the Table 1, S2 sample showed the highest (\(p<0.05\)) total lipid content (TLC) of 7.18%, for the other samples TLC values were about 0, 5.15 and 2.75 for S1, S3 and S4, respectively. In accordance with our results, [PERSON] et al. [35] found a similar TLC of 7.28% for a _Spirulina platensis_ strain. However, in the same condition of growth, Algerian _Spirulina_ showed lower lipid content [33]. According to [PERSON] and [PERSON] [38], the lipid content in _Spirulina_ ranged between 5 and 8%, but as reported by [PERSON] et al. [39], it could reach 14.3% in an Uzbekistan _Spirulina platensis_ strain. This variability could be related to the differences in culture conditions. In the same context, [PERSON] [40] reported that microalgae lipid production depends on the species and their culture conditions such as nutrients, salinity, light intensity, temperature, pH and even the association with other microorganisms. The total ash content of studied samples was between 5.02% and 10.69%, for S1 and S2 samples respectively. The concentration of ash found in pomeranate peels (S1) was higher than that reported by [PERSON] et al. [32], ranging between 3.71% and 4.97%, and lower than the values presented by [PERSON] et al. [41]. As shown in the Table 1, _Spirulina_ samples (S2) showed ash percentage of 10.69%; this value was comparable to _A. platensis_ from Algeria and higher compared with previous work by [PERSON] et al. [35].