Functional and Antimicrobial Properties of Camel Milk-Based Kefir: Physicochemical Stability and Biopreservation Potential

Camel milk possesses unique nutritional and therapeutic properties, yet its valorization through fermentation remains limited, particularly in arid and semi-arid regions. This study aimed to assess the functional and antimicrobial potential of kefir produced from camel milk using kefir grains as a natural fermenting agent, without the addition of selected probiotic strains. Raw camel milk was aseptically collected, mildly pasteurized, and fermented at 22 °C for 48 hours using 5% kefir grains. For comparison, traditional spontaneously fermented products—lfrik (camel milk) and lben (cow milk)—as well as cow milk kefir, were prepared under similar fermentation conditions. Physicochemical parameters, including the pH, titratable acidity, total solids (TSs), and water activity (aw) were measured. Microbial viability was assessed through enumeration of lactic acid bacteria (LAB) on MRS agar. Camel milk kefir exhibited a final pH of 3.8–4.3, titratable acidity of 0.73% lactic acid equivalent, water activity of 0.992, and total solids of approximately 10%. These values remained stable after 24 hours, indicating fermentation completion. During 15 days of cold storage at 4 °C, LAB counts were maintained around 7 log CFU/mL, demonstrating good microbiological stability. Challenge tests performed with Listeria monocytogenes CECT935 and Staphylococcus aureus ArFMSA019 revealed significant antimicrobial activity, with reductions of approximately 3 log CFU/mL and 4 log CFU/mL, respectively, after exposure to the kefir matrix. These results highlight the potential of camel milk kefir to ensure its own microbial stability and safety during storage through the action of its naturally occurring fermentative microbiota, without the need for added preservatives or antimicrobial agents, and without having direct antimicrobial effects on the consumer.

Funding: The authors would like to express their gratitude to the EU PRIMA program and the Moroccan Ministry of Higher Education, Scientific Research and Innovation (MESRSI) for their support of the Pas-Agro-Pas project [Grant number PRIMA/0016/2022].