Correct spelling for the English word "sauerin" is [sˈa͡ʊəɹˌɪn], [sˈaʊəɹˌɪn], [s_ˈaʊ_ə_ɹ_ˌɪ_n] (IPA phonetic alphabet).
Trade name of a German preparation, stated to be a pure active culture of the Bulgarian lactic acid (Massol’s) bacillus.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.