## 3 Results and Discussion
### Evaluation of Different Extraction Techniques on the Yield and Purity of Obtained Extracts
#### 3.1.4 Comparison of Different Extraction Techniques on the Yield and Purity of Obtained Extracts  
Table 1 compares the highest obtained yields and corresponding purities under the tested conditions described in Sections 3.1.2-3.1.4. The results showed PC recoveries of 53%, 63%, and 54% for maceration, homogenisation, and freeze-thaw cycles, respectively. While homogenisation achieved the highest yield, the extract's purity was significantly lower than the other methods. In contrast, maceration and freeze-thaw provided comparable yields, but maceration produced extracts with considerably higher purity. When considering purity and yield, maceration stood out among these techniques due to its simplicity, low energy consumption, and ease of implementation. While effective for small-scale laboratory experiments, freeze-thaw extraction could be considered unsuitable for industrial-scale implementation due to its high energy consumption and time requirements. On the other hand, homogenisation could offer a better potential for scalability due to its mechanical efficiency and shorter processing times. However, the high energy consumption, protein denaturation, and additional costs required for the purification steps would limit its applicability [25]. For these reasons, maceration was selected for the next part of the study, where a larger-scale extraction was performed, as described in Section 2.3.3. From the serial extraction experiments, it was determined that three cycles were sufficient to recover 97% of PC. The larger-scale maceration with three extraction cycles yielded an extract with high PC and APC content (Table 1). The total  
Figure 4: Freeze–thaw extraction yield of phycocyanin and allophycocyanin from _A. platensis_ using different number of extraction cycles (**A**). Yield values are expressed as mg/g of _A. platensis_. Purity of the crude extracts obtained after the different number of cycles (**B**). Image of obtained extract after 3 freeze-thaw cycles (**C**). Values are expressed as mean \(\pm\) standard deviation, n = 3. Different lowercase letters indicate significant differences (\(p\) < 0.05). PBP content under these conditions reached 80.8 mg/g of biomass, corresponding to a PC content of 5.5% \(w/w\). However, as anticipated, increasing the number of extraction cycles led to decreased extract purity (Table 1). The results obtained in this study are consistent with those reported in the previous literature, where phycocyanin contents typically ranged from 2.6% to 9.2% \(w/w\) depending on species, biomass form (fresh or dried), solvent type, and extraction conditions. For instance, [PERSON] et al. reported PC contents between 12 and 217 mg/g of biomass depending on the cell disruption technique, applied temperature, and solvent characteristics [43]. While this study's total PBP content may be lower than that of previous studies, the focus should be more on extraction efficiency than content. Thus, the high recovery (\(\sim\)96%) achieved under the optimal conditions in this study further strengthens the rationale for applying simple, conventional techniques for extracting PBP. However, maceration may not be considered the most efficient method for industrial-scale extraction due to the typically extended extraction times and high amounts of solvent required. Nevertheless, this technique could play an important role for small- to medium-size cosmetic companies, as it is a cost-effective method requiring minimal equipment and operational costs [44]. Moreover, another advantage of this technique lies in its ability to ensure quality and purity by gently extracting bioactive compounds under mild conditions, preserving the structural integrity of thermolabile pigments such as phycocyanin, thus potentially benefiting niche cosmetic brands which prioritise natural and organic ingredients with an antioxidant and anti-inflammatory function [40; 45]. These attributes align well with the industry's emphasis on the quality of natural extracts, especially for premium formulations.