Beer is one of the most popular beverages, with ~1.95 billion hectolitres produced annually around the globe. As a product from complex agricultural ingredients and processes, the final beer is highly molecularly complex. We used SWATH-MS to investigate the proteomic complexity and diversity of a wide range of commercial Australian beers. While the overall complexity of the proteome was modest, with contributions from barley and yeast proteins, we uncovered a very high diversity of post-translational modifications, especially proteolysis, glycation, and glycosylation. We used newly developed data analysis pipelines to efficiently extract and quantify site-specific PTMs from SWATH-MS data, and showed incorporating these features extended analytical precision. We found that the key differentiator of the beer glyco/proteome was the brewery, followed by the beer style. Targeting our analyses on beers from a single brewery, Newstead Brewing Ltd, allowed us to identify beer style-specific features of the glyco/proteome, and show that abundant surface-active proteins from barley and yeast correlate with foam formation and stability.