Differences between Kazak Cheeses Fermented by Single and Mixed Strains Using Untargeted Metabolomics

Area of Science:

• Food Science and Technology
• Microbiology
• Metabolomics

Background:

• Mixed fermentation is known to improve food flavor profiles.
• Kazak cheese is a traditional dairy product where fermentation impacts its quality.
• Understanding the metabolic differences between single-strain and mixed fermentation is crucial for optimizing cheese production.

Purpose of the Study:

• To evaluate the impact of mixed fermentation versus single-strain fermentation on Kazak cheese's volatile and non-volatile compound profiles.
• To identify key metabolites and metabolic pathways responsible for flavor differences.
• To demonstrate the synergistic effects of Lacticaseibacillus paracasei and Kluyveromyces marxianus in Kazak cheese fermentation.

Main Methods:

• Untargeted metabolomics analysis was employed to profile compounds in Kazak cheese.
• Two fermentation strategies were compared: mixed fermentation (L. paracasei + K. marxianus) and single-strain fermentation (L. paracasei).
• Metabolite differences during cheese ripening were analyzed.

Main Results:

• Mixed fermentation significantly increased the abundance of acids, alcohols, and esters compared to single-strain fermentation.
• 397 differentially expressed non-volatile metabolites were identified between the two fermentation types.
• Key flavor compounds in mixed-fermented cheese were linked to ester production and amino acid biosynthesis, involving pathways like nitrogen metabolism and phenylalanine metabolism.

Conclusions:

• Mixed fermentation with L. paracasei and K. marxianus synergistically enhances the formation of flavor compounds in Kazak cheese.
• Metabolomic analysis reveals distinct compound profiles and metabolic activities between mixed and single-strain fermented cheeses.
• This study provides a foundation for developing Kazak cheese with tailored and diverse flavor characteristics.