Effect of starch-based nanoparticles on the viability and stability of probiotics under adverse conditions

Starch nanoparticles resist digestion in the upper intestine but not in the colon. They are proven to exert prebiotic effects on the human body. Starch-based nanoparticles have generated a great interest in the food and agriculture sector due to their biocompatibility, wide array of natural sources and ease of modification. In the current study, two starch sources (rice and water chestnut) were used to synthesize nanoparticles for the encapsulation of probiotic bacteria. Obtained nanoparticles were characterized for their morphological, molecular, and structural attributes using Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and zeta sizer. Furthermore, free and nano-encapsulated probiotics were subject to simulated gastrointestinal digestion conditions. The average size of rice and water chestnut starch-based nano-capsules ranged from 309 to 427 nm. The encapsulation efficiency was recorded for rice and water chestnut starch as 89% and 95%, respectively. SEM micrographs exhibited entrapment of probiotics in wall materials. The surface of the capsules showed tiny, smooth surface polygonal granules. XRD images showed loss of crystallinity structure following encapsulation. Higher probiotic viability was recorded under simulated gastrointestinal conditions for nano-encapsulated probiotics compared to free probiotics. Conclusively, water chestnut and rice-based starch nanoparticles showed overall the best results regarding the viability of probiotics under stressed conditions.