Milk Fermentation Profiling by HPLC

The profile of milk fermentation was assessed using high performance liquid chromatography (HPLC) as previously described before [22 (link)]. The procedure started by mixing 1 mL of filtered fermented milk with 10 μL Carrez I and 10 μL Carrez II (Sigma-Aldrich; St. Louis, MO, USA). The mixture was centrifuged at 14,000× g for 10 min at 4 °C then filtered (0.45 μm pore diameter) and the supernatant was stored till analysis at −20 °C. Directly before analysis, the samples were diluted 1:25 (v/v) with 0.0085 N sulfuric acid for assessment of the milk fermentation profile of lactose, lactate, and acetate.