## 3 Results and Discussion
### Amino Acid Composition
\begin{table}
\begin{tabular}{c c c c c c} \hline  & & _Spirulina_ sp. & & & _Isochrysis_ sp. & \\ \hline \multirow{6}{*}{**Essential amino acids**} & \multicolumn{2}{c}{_Spirulina platensis_} & \multicolumn{2}{c}{_Spirulina platensis_} & \multicolumn{2}{c}{_Isochrysis_ T-_Iso_} & \multicolumn{2}{c}{_Isochrysis_ T-_Iso_} \\  & \multicolumn{2}{c}{**Whole Biomass**} & \multicolumn{2}{c}{**Protein Extract**} & \multicolumn{2}{c}{**Whole Biomass**} & \multicolumn{2}{c}{**Protein Extract**} \\  & \multicolumn{2}{c}{**(g/kg)**} & \multicolumn{2}{c}{**(g/kg)**} & \multicolumn{2}{c}{**(g/kg)**} \\ \hline
**Essential amino acids** & Isoleucine & 10.42 & 1.84 & 12.05 & 0.45 \\  & Leucine & 25.53 & 2.31 & 17.63 & 0.55 \\  & Valline & 15.2 & 1.96 & 15.86 & 1.05 \\  & Phenylalanine & 32 & 2.63 & 12.3 & 0.54 \\  & Tyryptophan & 6.73 & 15.79 & 0.69 \\  & Hidsidine & 20.44 & 1.53 & 7.12 & 0.69 \\  & Lysine & 8.98 & 0.13 & 4.54 & 0.64 \\  & Threonine & 7.16 & 0.94 & 16.91 & 0.64 \\  & Methionine & 4.92 & - & 2.51 & - \\
**Non-essential amino acids** & Alanine & 24.37 & 1.33 & 50.88 & 1.84 \\  & Glycine & 3.92 & 0.55 & 12.45 & 0.14 \\  & Proline & 1.14 & 0.22 & 18.32 & - \\  & Tyrosine & 29.55 & 2.81 & 12.01 & 0.45 \\  & Asparatic acid and & 6.08 & 1.08 & 7.43 & 0.69 \\  & Glutamic acid and & 54.79 & 2 & 11.01 & 0.89 \\  & Arginine & 15.12 & 1.79 & 20.98 & - \\  & Serine & 8.65 & 0.56 & 10.14 & 0.59 \\  & Cysteine & 17.18 & 2.51 & 6.19 & 1.16 \\
**Total free amino acids (FAA)** & & 292.18 & 24.19 & 254.12 & 9.68 \\
**EAA** & & 131.38 & 11.34 & 104.71 & 3.92 \\
**NEAA** & & 160.8 & 12.85 & 149.41 & 5.76 \\ \hline \end{tabular}
\end{table} 
Table 2: Free amino acid contents of the whole alga and protein extracts. The protein content of the _Spirulina_ sp. Extract, in terms of TAA and FAAs, was greater following extraction than that of _Isochrysis_ sp., despite the fact that both whole microalgae have similar total and free amino acid profiles. Both microalgae contained a greater percentage of FAA (292.18 g/kg and 254.12 g/kg for the _Spirulina_ sp. and _Isochrysis_ sp., respectively) than TAAs (63.76 g/kg and 57.98 g/kg for _Spirulina_ sp. and _Isochrysis_ sp. respectively). The extraction process increased the TAA content of the _Spirulina_ sp. protein extract, but the _Isochrysis_ sp. protein extract contained less than 10% of the available TAA in this microalgae. The _Isochrysis_ T-_Iso_ species does not contain a cell wall. The protein extraction process used was not suitable for this species, and this warrants further investigation. The yield of protein obtained from _Isochrysis_ sp. in this study was similar to that achieved previously with pressurized liquid extraction using water, where approximately 18% of the protein was recovered [25]. Furthermore, there were inconsistencies observed between the determined protein content (% values) and the TAA content for the two extracts. Both contained >70% protein (i.e., >700 g/kg), but the total AA content was 7% (i.e., 70 g/kg). Therefore, for _Spirulina_ sp., the discrepancy was a factor of 12, while for _Isochrysis_ sp., it was a factor of 108. This may be due in part to the protein determination method used and discussed and the nitrogen conversion factor used.