Sodium salts of butyrate, propionate, acetate, formate, and disodium succinate, disodium β-glycerophosphate pentahydrate, and L-ascorbic acid phosphate magnesium salt n-hydrate were purchased from Fujifilm Wako (Osaka, Japan). Sodium isobutyrate and sodium isovalerate were purchased from Kanto Chemical (Tokyo, Japan) and sodium lactate from Sigma Aldrich (St. Louis, MO, USA).