Gigartina pilot scale protein extract BUP

Seaweeds are attracting substantial interest as novel sources of sustainable food protein, as they are established sources of industrial hydrocolloids and have reasonable protein content. In this study we investigate the protein composition and quality of a seaweed protein extract (SPE) from Gigartina radula obtained as a side-stream from industrial carrageenan production. The SPE displayed low (<2%), but pH-dependent, aqueous solubility due to the harsh (heat and extreme pH) employed during extraction. Solubility was improved using buffer and detergent to facilitate proteomic characterization by quantitative LC-MS/MS. Proteomics revealed that the SPE was dominated by proteins related to light harvest and particularly rich in phycobiliproteins (44% relative molar abundance), where phycoerythrin was the most abundant (28%). Based on subcellular localization of identified proteins, the extraction method was evaluated as good for release of cellular protein. The SPE was found to be rich in essential amino acids (36-41%) and particularly in branched chain amino acids (22-24%) and thereby a potential source of nutritional food protein. Using bioinformatic prediction and structural modelling, we found that abundant proteins in the SPE contained high potential, novel emulsifier peptides with amphiphilic properties required to stabilize an oil/water interface. Based on this study, Gigartina could serve as a good candidate for extraction of sustainable and nutritious food protein and possibly be further processed to obtain a hydrolysate with good emulsifying properties for use in foods.