Impact of Free and Nanoencapsulated Essential Oil on the Physicochemical, Microbial, and Sensory Properties of Siahmazgi Cheese.

This research investigated the effects of incorporating essential oil (EPEO) on the qualitative and sensory characteristics of Siahmazgi cheese, a traditional Iranian cheese prepared from ewe's milk or a combination of ewe and goat's milk. This study analyzed various concentrations of EPEO, namely 0, 0.1%, 0.3%, and 0.5% (w/w), in both free and nanoencapsulated forms over 90 days. Initially, the nanoemulsion of EPEO was characterized by examining zeta potentials (ZPs) and microstructure. The resulting nanoemulsion capsules exhibited a spherical shape, with ZPs ranging from -0.74 ± 0.04 mV to -0.42 ± 0.05 mV. Subsequently, the influence of EPEO on Siahmazgi cheese was assessed through an analysis of its textural properties, including hardness, adhesiveness, and cohesiveness, as well as its chemical composition (specifically salt content), microbiological parameters (total bacterial counts, mesophilic bacterial counts, molds, and yeasts), and sensory characteristics (odor, taste, texture, and overall acceptability). The findings indicated that EPEO did not significantly alter the cheese's hardness but increased adhesiveness and decreased cohesiveness. Over time, both hardness and adhesiveness exhibited an upward trend, whereas cohesiveness diminished, all while maintaining a stable salt content. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were found to be 3.5 and 5 mg/mL against and , respectively. Furthermore, EPEO effectively reduced the counts of molds, yeasts, and total mesophilic bacteria in the treated cheese samples and improved flavor and overall acceptability, with the highest sensory ratings observed for the 0.3% (w/w) nanoencapsulated treatment over the 90-day observation period. In summary, the incorporation of EPEO demonstrates significant potential as a natural additive for enhancing the qualitative and sensory attributes of Siahmazgi cheese.