Objective(s): This study aimed to evaluate the viability of encapsulated probiotics using electrospinning technique. Specifically, the study focused on polyvinyl alcohol-whey protein isolate nanofibers (PVA/WPI) containing Bifidobacterium bifidum. These nanofibers have potential applications in active food packaging to improve food safety and extend shelf life, as well as in medical and pharmaceutical fields. Materials and Methods: PVA/WPI nanofibers were electrospun in varying ratios (ranging from 100:00 to 50:50) and evaluated for their morphology, mechanical properties, FT-IR and DSC characteristics. B. bifidum was also encapsulated in the optimized PVA/WPI nanofibers to assess their encapsulation efficiency and viability, and the antimicrobial properties of the nanofibers were determined using the disk diffusion method. Results: All prepared nanofibers displayed a diameter range of 186.42-612.5 nm, with an inverse relationship between WPI ratio and nanofiber diameter. The PVA/WPI nanofiber with a ratio of 60:40 was found to be the most favorable. DSC analysis showed that adding WPI decreased thermal stability, and the enthalpy of endothermic peaks decreased in nanofibers containing B. bifidum. Mechanical evaluation revealed that adding WPI reduced tensile strength and elongation at break, without significant effects from B. bifidum (P>0.05). Bacterial encapsulation efficiency was 80.58%. Probiotic nanofibers exhibited antimicrobial properties against Listeria monocytogenes (11.00±0.37 mm) and Escherichia coli (9.71±0.06 mm). Conclusion: According to the obtained results, the optimized PVA/WPI nanofiber (60:40) contained suitable morphological, mechanical and thermal characteristics with the highest encapsulation efficiency in regards to B. bifidum (>80%). Probiotics-containing PVA/WPI nanofibers are a suitable platform for medical applications and food industry packaging due to their antimicrobial properties.

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