Food Safety
Elahe Divsalar; Hossein Tajik; Rahim Molaei
Abstract
In this research, the white postbiotics (P) powder of Leuconostoc mesenteroides and white zinc carbon dots (Z-CDs) from zinc acetate, which were prepared in our previous studies, were used. Hydroxyl, carbonyl, and carboxyl groups in the P were confirmed by FTIR spectra to affect the functions, ...
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In this research, the white postbiotics (P) powder of Leuconostoc mesenteroides and white zinc carbon dots (Z-CDs) from zinc acetate, which were prepared in our previous studies, were used. Hydroxyl, carbonyl, and carboxyl groups in the P were confirmed by FTIR spectra to affect the functions, antioxidant, and antimicrobial capabilities. Antioxidant activity of P was confirmed based on DPPH (IC50 values, 0.28 mg/mL) and FRAP (total antioxidant capacity, 73.5 nM of Fe2SO4/L) methods. The antimicrobial properties of P solutions at concentrations of 150, 300, and 450 mg/mL were evaluated through the agar well diffusion assay against Escherichia coli, which showed acceptable antimicrobial effects. E. coli was sensitive at 4 °C and 25°C in photodynamic treatments. The effects of P (300 mg/mL), Z-CDs (5 mg/mL), and their combination (Z-CDs-P) as additives in fresh pasta filata cheese were studied by aerosolization method. The results showed that the highest inhibitory effects were observed in P, Z-CDs-P, and Z-CDs420nm-Ps treatments; so that E. coli reached 1 log10 CFU/g on days 18, 14, and 12, respectively. We concluded that the aerosolization method of P and CDs had a novel antibacterial activity and can be used for the packaging of cheese.
Food Packaging
Negar Nikfarjam; Roghayieh Razavi; Mehran Moradi; Rahim Molaei
Abstract
Despite the relatively short history of the discovery of carbon dots (C-dots) and the development of their applications, methods for producing nanodots based on green chemistry have consistently attracted the attention of scientists. In this study, green C-dots were synthesized from onion juice using ...
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Despite the relatively short history of the discovery of carbon dots (C-dots) and the development of their applications, methods for producing nanodots based on green chemistry have consistently attracted the attention of scientists. In this study, green C-dots were synthesized from onion juice using a simple hydrothermal method (200°C, 4 hours), and their optical properties, particle size distribution, and morphology were subsequently evaluated. The antibacterial activity of C-dots was assessed against pathogenic bacteria Escherichia coli (Gram-negative) and Listeria monocytogenes (Gram-positive), with minimum inhibitory concentrations of 8 mg mL-1 and 4 mg mL-1, respectively. Furthermore, the synthesized C-dots were incorporated into nanocellulose using an ex-situ method to produce modified bacterial nanocellulose (BNC) films with both antimicrobial and ultraviolet (UV) protective properties. The carbon dot-embedded nanocellulose demonstrated enhanced UV-blocking capabilities and greater inhibitory activity against Gram-positive bacteria compared to Gram-negative bacteria, highlighting its potential as a promising nano-biomaterial for food packaging applications.
