Investigation of Freezing and Freeze-Drying for Preserving and Re-Using a Whole Microbial Cheese Community

Area of Science:

• Food Microbiology
• Microbial Ecology
• Biotechnology

Background:

• Traditional cheese production relies on complex microbial ecosystems for unique flavor profiles.
• Maintaining the biodiversity of these microbial communities is essential for preserving cheese quality.
• Limited effective protocols exist for the long-term preservation of these valuable microbial consortia.

Purpose of the Study:

• To develop and evaluate methods for stabilizing entire microbial communities from smear-ripened cheese.
• To assess preservation techniques without isolating or multiplying individual microbial species.
• To ensure the viability and functionality of the microbial community post-storage.

Main Methods:

• A simplified microbial community, mimicking cheese maturation metabolism, was used in three cheese productions.
• Cheese samples were treated with maltodextrin or saline solution and subjected to freezing (-20°C, -80°C) or freeze-drying.
• Microbial survival was quantified using colony-forming unit assays, and differential scanning calorimetry analyzed physical stability.

Main Results:

• Freezing at -80°C yielded the lowest loss of microbial culturability (<0.8 log unit).
• Freezing at -20°C and freeze-drying showed higher losses in microbial viability.
• Ripening bacteria were identified as the most sensitive members of the microbial community to preservation methods.

Conclusions:

• Long-term preservation of intact cheese microbial communities is achievable.
• -80°C freezing is the most effective method identified for maintaining microbial viability and function.
• The study demonstrates the successful re-use of a stabilized microbial community for cheese production, preserving its characteristics.