Microbial Growth, Survival, and Cryotolerance in Plant-Based Milk Alternatives: A Study with <i>Listeria monocytogenes</i>

The increasing popularity of plant-based milk products as an alternative to traditional bovine milk has sparked concerns about their safety and nutritional impact. This study focuses on the growth, survival, and cryotolerance behavior of <i>Listeria monocytogenes</i> (strains: ATCC 19115 and RS1) in various plant-based milk substitutes. Samples of almond milk, oat milk, soy milk, and bovine milk, all subjected to ultra-high temperature treatment, were evaluated for their influence on <i>L. monocytogenes</i> growth at 4°C and survival through repeated freezing and thawing cycles. Despite the nutritional differences, the growth rates of two <i>L. monocytogenes</i> strains at 4°C in plant-based milk alternatives and bovine milk displayed similarity (<i>p</i> > 0.05). Both strains of <i>L. monocytogenes</i> demonstrated similar biofilm formation abilities in plant-based milk alternatives and bovine milk. However, <i>L. monocytogenes</i> exhibited different levels of tolerance to repeated freezing and thawing cycles depending on plant-based milk alternatives in which they were grown at 4°C (<i>p</i> < 0.05). In the case of <i>L. monocytogenes</i> ATCC19115, cells cultured in almond milk at 4°C showed a significant reduction in their freezing and thawing tolerance (2.80 log reduction), followed by cells grown in soy milk (2.09 log reduction) when compared with oat and bovine milk (<i>p</i> < 0.05). A parallel trend of tolerance was evident in <i>L. monocytogenes</i> RS1 (2.82 and 3.22 log reduction in almond milk and soy milk, respectively). These findings underscore the need for comprehensive assessments of microbial behavior in emerging food products like plant-based milk alternatives. As these alternatives continue to gain traction, ensuring their safety and stability remains important. With insights into <i>L. monocytogenes</i> growth and survival in milk alternatives, this study will contribute to the evolving understanding of microbial dynamics in response to changing dietary trends.