Facile green preparation of Cr2O3 nanoparticles combined with probiotics in hydro-beads to produce integrated yoghurt

Abstract

The current study deals with the green synthesis of chromium oxide nanoparticles (Cr2O3-NPs) by using fig leaf extract as a capping and reducing agent for chromium. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and Dynamic Light Scattering (DLS) were employed to characterize the fabricated Cr2O3 nanoparticles. The purity and crystallinity of Cr2O3-NPs were determined using the X-ray diffraction technique. The viability of probiotics in presence of synthesized Cr2O3-NPs concentrations of (0.1, 0.2, 0.3, and 0.4 mg/100 mL) was evaluated and the data showed probiotics have the ability to tolerate and grow at low concentrations. The microencapsulated hydrogel was achieved using sodium alginate and Arabic gum then loaded with probiotics (Lactiplantibacillus plantarum, Ligilactobacillus salivarius) and 0.0, 0.1 and 0.2 mg of Cr2O3-NPs/100 mL. The addition of Cr2O3-NPs did not affect the encapsulation yield and the hydro-beads were non-spherical, irregular, and unequal in shape with a rough appearance. All hydro-beads after exposure to gastrointestinal conditions have the recommended level for probiotics to have a healthy impact. Also, the produced hydro-beads were added to produce integrated yogurt. The yogurt samples were evaluated chemically, microbiologically, and sensory during 21 days of cold storage. The probiotics in yogurt persisted stable in the same log cycles with slight improvement during the last two weeks. All yogurt treatments' protein, acidity, dry matter, and fat levels increased during storage. Yogurts with hydro-beads containing Cr2O3-NPs showed a lower pH than controls. The overall acceptability of all yogurt treatments was unaffected by green synthesized Cr2O3-NPs levels.