<b>Improving probiotic preservation through phycocyanin enriched skim milk as a protective drying medium</b>

The viability and functionality of probiotics are strongly influenced by environmental stressors encountered during processing and storage. This study aimed to evaluate the effects of phycocyanin supplementation and drying in skim milk, followed by vacuum desiccation at 50 °C, on three probiotic strains: Limosilactobacillus reuteri, Lactiplantibacillus plantarum, and Lacticaseibacillus casei. Probiotic viability, metabolic activity, and surface properties were monitored over 12 months of storage at room temperature, refrigeration, and freezing, with assessments performed every three months. Results showed that phycocyanin supplementation markedly improved survival, particularly at room temperature, with increases of up to 2 log CFU/g. Drying in skim milk further enhanced stability and promoted biofilm-forming ability. Additionally, phycocyanin positively affected metabolic activity and cell surface interactions. Overall, these findings demonstrate that combining phycocyanin supplementation with vacuum desiccation in skim milk represents an effective approach for enhancing long-term probiotic preservation under diverse storage conditions.