Clove (Syzygium aromaticum) extract as a natural bio-preservative in milk: antimicrobial and organoleptic evaluation, Екстракт гвоздики (Syzygium aromaticum) як натуральний біоконсервант у молоці: антимікробна та органолептична оцінка

<jats:p>The food industry increasingly struggles to achieve product biological safety while avoiding artificial chemical preservatives that raise significant health concerns among consumers. The purpose of this study was to determine the optimal concentration threshold of ethanolic clove (Syzygium aromaticum) extract that maximizes bacterial control in refrigerated bovine milk while successfully preserving its baseline organoleptic attributes. To achieve this, serial dilutions of ethanolic and aqueous extracts were evaluated via the agar well diffusion method against Staphylococcus aureus and Escherichia coli, and inoculated milk samples stored at 4±1°C were monitored for Total Aerobic Count alongside descriptive sensory analysis using a nine-point hedonic scale. The experimental results demonstrated that the untreated control group exhibited the highest microbial load, reaching 6.29 and 7.17 log CFU/mL on Day 1 and Day 2 of storage, respectively. Conversely, the incorporation of clove extracts resulted in a significant, concentration-dependent reduction in bacterial profiles (p&lt;0.05). Milk formulated with the maximum 100 % extract concentration demonstrated the highest antimicrobial efficacy, maintaining the lowest Total Aerobic Count values at 3.65 and 4.36 log CFU/mL. The agar well diffusion assay further verified that the ethanolic extract possessed a significantly more potent antibacterial activity compared to the aqueous variant, yielding superior zones of inhibition of 22 mm against Staphylococcus aureus and 21 mm against Escherichia coli, whereas the aqueous variant produced moderate zones of 20 mm. Notably, at the lowest 25 % concentration, neither extract displayed any detectable inhibitory activity. In the sensory evaluation, the inclusion of the ethanolic extract at 25 %, 50 %, and 75 % concentrations caused no statistically significant modifications (p&gt;0.05) in milk aroma, color, or consistency. However, the 100% concentration level induced a critical organoleptic trade-off, significantly compromising product flavor (decreasing from 8.6±0.54 to 7.4±0.19) and overall acceptability (decreasing from 8.6±0.54 to 7.4±0.24). In conclusion, the 75 % concentration of ethanolic clove extract represents the mathematically established optimum for dairy bio-preservation, achieving sufficient bacterial control – reducing the Total Aerobic Count to 4.42 log CFU/mL on Day 1– without triggering consumer rejection.</jats:p>