Exploring obsorne fractionation method to establish protein solubility profile of red and brown macroalgae

Abstract: Macroalgae could help to overcome the environmental/health issues associated with exploitation and consumption of conventional proteins (i.e. meat, dairy). Macroalgal protein extraction represents a challenge and studies exploring the solubility profile of macroalgal proteins through Osborne fractionation, widely explored in plant proteins, are lacking till date. The establishment of a solubility profile of macroalgal proteins through Osborne fractionation method can facilitate the selection of solvent of extraction and maximize protein recovery. Hence, the authors investigated Osborne fractionation in Chondrus crispus and Alaria esculenta belonging to red and a brown macroalgal species, respectively.

Objective:
To determine the protein content of extracts obtained from C. crispus and A. esculenta using various solvents sequentially (water, salt, alcohol and alkali solutions) to establish optimum solubility profiles for macroalgal protein extraction.



Methods:
Macroalgal samples were extracted at macroalgae:solvent ratio of 1:50 for 1 h sequentially with water, 5% NaCl, 70% ethanol and 0.1M alkali solutions. Protein contents were analysed using both Dumas and Bicinchoninic Acid assay (BCA) methods.

Results
For C. crispus, water achieved the highest protein (19.12 ± 0.25% by Dumas, 8.53 ± 0.14 mg BSA equivalent/100 mg dried extract (de)) followed by alkali (6.51 ± 0.11% by Dumas, 4.07 ± 2.01 mg BSA equivalent/100 mg de). For A. esculenta, alkali achieved the highest protein content (13.05 ± 0.11% by Dumas and 10.62 ± 0.29 mg BSA equivalent/100 mg de) followed by water (9.64 ± 0.47% by Dumas and 5.02 ± 0.25 mg mg BSA equivalent/100 mg de).

Significance of your research to the AOCS membership:
Within the ‘Protein and Co-Products Division’ of AOCS, these results will help researchers to choose optimum extraction conditions and solvents for isolation of proteins when working with different macroalgae for their future use as functional foods/feed ingredients.