The Correlation Between Microbial and Physicochemical Properties of Beef Thigh Meat and Particle Size, Polydispersity Index, and Zeta Potential After Treating With Different Concentrations of Sodium Alginate Nanoparticles Containing Lemon Verbena Pla

In the present study, the effect of sodium alginate nanoparticles (SANPs) combined with <i>lemon verbena</i> plant leaf essential oil (LVEOs) (concentrations of 0.25%, 0.5%, and 1% w/v) as an edible coating on the chemical and microbial changes of beef thigh meat during refrigerated storage was investigated. The dynamic light scattering (DLS) and zeta sizer analyses of SANPs incorporating LVEOs yielded the following parameters across LVEO concentrations: at 1%, the hydrodynamic diameter (Z-average) was 32.3 nm with a polydispersity index (PDI) of 0.681 and a zeta potential (ZP) of -39.9 mV; at 0.5%, the Z-average was 88.6 nm with PDI 0.544 and ZP -30.1 mV; at 0.25%, the Z-average was 207.7 nm with PDI 0.465 and ZP -21.7 mV. The data indicate an increasing particle size with decreasing LVEO concentration, with all PDIs below 0.7 and progressively less negative surface charge at lower LVEO content, suggesting reduced electrostatic stabilization at lower concentrations. According to scanning electron microscopy (SEM), the nanoparticles displayed a spherical morphology with smooth surfaces. The current investigation attributes spectral variations within 2800-3000 cm^-1 to C-H modes associated with monoterpenes, whereas the 1000-1100 cm^-1 bands reflect interactions between the C-O-C moieties of the polysaccharide and compounds present in the essential oil. With increasing essential oil concentrations (0.25%, 0.5%, and 1%), the intensities of several bands-particularly those in the -OH and C-H regions-became more pronounced. Thigh meat coated with SANPs + LVEOs (1% w/v) had the lowest microbial growth, 7.66 ± 0.06 log CFU/g for aerobic mesophilic (by 5.2-log reduction compared with control), 6.44 ± 0.07 log CFU/g for coliforms (3.65-log reduction), 6.76 ± 0.30 log CFU/g for lactic acid bacteria (3.67-log reduction), and this treatment also had the lowest degree of lipid oxidation (thiobarbituric acid reactive substances or TBARS value) by 69.5% on Day 20 of storage. It also had the highest sensory score in overall acceptability. These results indicate that SANPs + LVEOs (1% w/v) can be used as an edible coating to enhance the shelf life of meat.