# Extraction of Pigments from Microalgae and Cyanobacteria--A Review on Current Methodologies
## 10 Final Remarks  
Microalgae and cyanobacteria pigments show great potential for industrial applications, since there is already a commercial market for \(\beta\)-carotene, astaxanthin, and phycocyanin. However, the process of extraction and the available technologies are still associated with a high cost of implementation and operation. In addition, energetic requirements represent a very significant part of the sustainability of the process [84]. As shown in this review, the standardization of a biomass extraction protocol for obtention of the pigments of interest is still a challenge. The variability of microalgae and cyanobacteria composition needs case-by-case optimization. According to [PERSON] et al. [85], extraction can account for up to 60% of overall expenditures. To lower those expenses, it is still required to optimize existing procedures and develop fresh procedures. The main advantages and limitations of the methods discussed in this review for the extraction of pigments from microalgae and cyanobacteria are summarized in Table 2. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Methodology** & \multicolumn{3}{c}{**Advantages**} & \multicolumn{3}{c}{**Limitations**} \\ \hline Classic solvent extraction & \(\bullet\) & Reduced cost in terms of infrastructure and operating & \(\bullet\) & Less efficiency \\  & & & \(\bullet\) & High amount of organic solvents \\  & & & \(\bullet\) & Time-consuming \\ \hline Enzymatic & \(\bullet\) & Specificity & \(\bullet\) & High cost of enzymes \\  & \(\bullet\) & High cell disruption & \(\bullet\) & Requires very controlled process \\  & & & \(\bullet\) & Need of separation of the enzymes \\ \hline Pressure & \(\bullet\) & High cell disruption & \(\bullet\) & High energy requirement \\  & \(\bullet\) & Reduced need of solvent & \(\bullet\) & High cost of infrastructure \\ \hline Wave energy-based & \(\bullet\) & Eco-friendly & \(\bullet\) & High cost of infrastructure \\  & \(\bullet\) & Reduced time of extraction & \(\bullet\) & Hard control of temperature \\  & \(\bullet\) & High extraction rate & \(\bullet\) & Hard up-scaling process \\ \hline Electric fields & \(\bullet\) & Lower energy input & & \\  & \(\bullet\) & Reduced time of extraction & \(\bullet\) & High cost of infrastructure \\  & \(\bullet\) & Reduced need of solvent & & \\ \hline Supercritical extraction & \(\bullet\) & Eco-friendly & \(\bullet\) & High cost of infrastructure \\  & & Optimal temperature below degradation & \(\bullet\) & Hard operating process \\  & & point for pigments & & \\ \hline Cell milking & \(\bullet\) & Non-destructive method & \(\bullet\) & Very sensible process to maintain the culture in continuous production \\  & & \(\bullet\) & Can operate in continuous & \\ \hline Laser & \(\bullet\) & Eco-friendly & \(\bullet\) & Very applicable to small volumes \\  & & Reduced time of extraction & & \\  & & Lower energy input & & \\  & & High extraction rate & & \\ \hline Hydrodynamic cavitation & \(\bullet\) & Eco-friendly & & \\  & \(\bullet\) & Reduced time of extraction & \(\bullet\) & High cost of infrastructure \\  & & \(\bullet\) & Lower energy input & \(\bullet\) & Hard operating process \\  & & \(\bullet\) & High extraction rate & \\ \hline Flotation & \(\bullet\) & Reduced time of extraction & \(\bullet\) & Requires a large amount of salt and \\  & & High extraction rate & & organic solvents \\ \hline High voltage electrical discharge & \(\bullet\) & Reduced time of extraction & \(\bullet\) & High energy requirement \\  & & \(\bullet\) & High cell disruption & \\ \hline Ohmic heating & \(\bullet\) & Reduced time of extraction & & \\  & & Controlled and homogeneous & \(\bullet\) & High energy requirement \\  & & temperature & & \\  & & High cell disruption & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Advantages and limitations of the different methods for extraction of pigments in microalgae and cyanobacteria. Moreover, the use of an optimized extraction method can reduce the necessity of purification.