Raw milk kefir: microbiota, bioactive peptides, and immune modulation

Area of Science:

• Microbiology
• Immunology
• Food Science

Background:

• Kefir, a fermented milk drink, is known for its potential health benefits.
• The impact of milk processing (raw vs. heated) on kefir's microbiota, peptidomics, and anti-allergic properties requires further investigation.

Purpose of the Study:

• To characterize the microbiota and peptide composition of raw and heated milk kefirs.
• To evaluate the anti-allergic effects of these kefirs in a murine food allergy model.

Main Methods:

• Kefir production from raw and heat-treated milk using a defined starter culture.
• Microbiota analysis via amplicon sequence variants.
• Peptide profiling using mass spectrometry.
• Assessment of anti-allergic effects in a mouse model (ovalbumin-induced allergy).

Main Results:

• Raw milk kefir harbored a more diverse microbiota, including additional yeast species, compared to heated milk kefir.
• Fermentation significantly increased peptide diversity and intensity in both kefirs, with heating negatively impacting peptide profiles.
• Only raw milk kefir demonstrated suppression of allergic skin responses and modulated T-cell activation (Th1 cells) and Interferon-gamma (IFNg) production.

Conclusions:

• Raw milk kefir possesses specific characteristics, including a richer microbiota and peptide profile, contributing to its enhanced anti-allergic properties.
• Heating milk diminishes the potential health benefits of kefir related to allergy modulation.
• Raw milk kefir shows promise as a functional food for managing food allergies.