Oat milk demand is rising as consumers seek dairy-free alternatives due to lactose intolerance and lifestyle choices. Among plant-based milks, oats stand out for their nutritional benefits, including protein, fats, and β-glucan, which enhances stability. Oat protein (12–20%), mainly globulins, influences texture, solubility, and emulsification. Protein content varies based on oat variety, growing conditions, and processing methods, including heat treatments. This study uses mass spectrometry-based proteomics (LC-MS/MS) to analyze the soluble protein profile of nine commercial oat milk brands. Proteins were extracted, cleaned, and enzymatically digested for identification. The aim was to observe variations in protein composition and levels among commercial oat milks and define differences resulting from the manufacturing processes. Identification of the soluble proteins present in commercial oat milk sets the foundation for understanding and enhancing the nutritional profile of oat milk.
Using Data-Dependent Acquisition (DDA), the number of identified proteins and peptides varied across all oat milk brands. The highest and lowest protein and peptide identification ranges between 51.55% and 66.80%. We identified a total of 244 shared proteins across all brands, and gene ontology (GO) overrepresentation analysis revealed enrichment of proteins with nutrient reservoir, serine-type endopeptidase inhibitor, protein synthesis, 1,4-alpha-glucan branching enzyme, translation elongation factor, and translocase activity.
Quantitative proteomic analysis using Sequential Window Acquisition of All Theoretical (SWATH) MS on oat milk samples resulted in the quantification of 1,070 proteins. Multivariate analysis demonstrated clustering within brands. The identified four key storage protein types, 11S globulins, 7S globulins and globulin 1 protein and avenins, exhibited statistically significant variation among brands. These results provide a new insight into the oat milk proteome and highlight the qualitative and quantitative proteome profile differences between the brands. Our findings hold promise for the potential improvement of oat milk profiles by improving processing methods for desirable quality and nutritional properties.