Viability and stability evaluation of Lactobacillus casei LC03 co-encapsulated with red onion (Allium cepa L.) peel extract

This study aimed to evaluate the effects of adding different concentrations (5, 20, and 40%) of red onion (Allium cepa L.) peel extract to probiotic microparticles on the viability and stability of a Lactobacillus casei LC03 probiotic. The survival of the probiotic under simulated gastrointestinal conditions, its viability in storage, and the resistance of the microparticles to thermal treatments were evaluated, as well as the morphology, size distribution, and encapsulation efficiency of probiotics and compounds in the extract. All microparticle formulations showed high probiotic retention efficiency (>90%). The sizes of the microparticles ranged from 149.29 to 167.05 μm. The treatment containing alginate +20% extract increased probiotic survival under simulated gastrointestinal conditions than the other treatments. It was possible to increase the heat resistance of encapsulated probiotics over free microorganisms. During storage at 25 °C, the alginate microparticles +5 and + 20% extract stood out, whereas the most prolonged period of viability was reached by alginate alone and alginate microparticles +5% extract at 7 °C. At −18 °C, all microparticle formulations remained stable during 90 days of storage. These findings suggest that such microparticles can promote the extended viability and stability of the probiotic L. casei under different conditions. •Microencapsulation provides a controlled release of probiotics.•Microencapsulation increased probiotic survival during simulated gastrointestinal conditions.•Red onion peel extract increased the viability of microencapsulated probiotics.•Low extract concentrations favored the viability of the probiotic.