Impact of different food-grade protein extraction methods on the proteomic profile and potential allergenicity of Spirulina (Arthrospira platensis)

Various optimized methods for cell disintegration and protein extraction of algae have been reported, but there is a lack of information regarding the proteomic characterization of the extracted proteins; thus, systematic verification of the protein profiles to find potentially exploitable proteins, while minimizing allergenicity risks, is profitable. The method described in this study was developed to thoroughly investigate the proteome characterization of A. platensis following aqueous protein extraction by high-shear homogenization and pH shift. Liquid chromatography-tandem mass spectrometry was applied to assess the proteome obtained from four protein extraction methods using data-dependent proteome analysis. Overall, 699 proteins were identified; however, each extraction method identified unique proteins. The maximum number of exclusive proteins was observed using a combination of high-shear homogenization and acidic pH. The evaluation of protein abundance revealed a clear distinction between proteins isolated from pH 2 treatment compared to those obtained via neutral or basic pH treatment. The applied extraction methods affected the in silico computed physicochemical properties of the proteins. Using the AllerCatPro database, 12 putative allergenic proteins were detected, the most predominant of which were related to the C-phycocyanin beta subunit (P72508). This study demonstrated that extraction methods affect the detection, physicochemical properties, and potential allergenicity of the obtained proteins. Hence, the extraction methods used to obtain novel proteins must consider these aspects before using them as functional foods.