Lactiplantibacillus plantarum 299V fermented in microcapsules shows enhanced stability and could improve the microbial quality and safety of oysters through bioaccumulation.

In this study, microcapsules of <italic>Lactiplantibacillus plantarum</italic> 299V were prepared using an emulsification/internal gelation technique. Loads of the probiotics were condensed to 9.86 ± 0.13 log CFU/g after 24 h fermentation of the microcapsules. Physical characterization revealed that <italic>L. plantarum</italic> 299V cells were uniformly distributed within the core of the microcapsules, with a mean diameter of 109.81 ± 0.39 µm and a span value of 0.36 ± 0.00, which were comparable to those of the unfermented microcapsules (<italic>p </italic>> 0.05). The viability of <italic>L. plantarum</italic> 299V in the fermented microcapsules was 2.08 ± 0.15 log higher than that of free cells at the end of 5 h simulated gastrointestinal digestion (<italic>p</italic> < 0.05). Oysters were able to accumulate the fermented microcapsules through filter feeding, resulting in a load of probiotics exceeding 6.00 log CFU/g. The presence of <italic>L. plantarum</italic> 299V‐carrying microcapsules in oyster tissues significantly suppressed spoilage‐causing bacteria during 11 days refrigeration storage, suggested by the tested parameters, including total psychrotrophic bacteria, H2S‐producing bacteria, and <italic>Pseudomonas</italic> spp. (<italic>p</italic> < 0.05). Pathogenic bacteria, including <italic>Vibrio parahaemolyticus</italic> and <italic>Salmonella enterica</italic> artificially introduced into oysters, were also significantly suppressed by over 1.00‐log within 4 days compared to control samples (<italic>p</italic> < 0.05). In summary, oysters bioaccumulated with fermented <italic>L. plantarum</italic> 299V‐carrying microcapsules, justified a novel probiotic‐carrying product to exsert the health‐promoting effect of probiotics. This solution could also enhance the microbial quality and safety of oysters during storage. [ABSTRACT FROM AUTHOR]