Rosemary Essential Oil as a Natural Preservative in Fermented Thick Cream: Effects on Microbial Stability, Physicochemical Properties, and Sensory Quality

Abstract

The present study evaluated the yield, phytochemical composition, antioxidant potential, and antimicrobial properties of Salvia rosmarinus essential oil (REO), as well as its potential application as a natural preservative in fermented thick cream. The essential oil obtained by hydrodistillation (yield: 0.9%) was analyzed by gas chromatography–mass spectrometry (GC–MS), which identified 15 compounds representing 100% of the total composition. The major constituents were 1,8‐cineole (34.26%), camphor (19.7%), and α‐pinene (14.27%). REO exhibited moderate antioxidant activity, with an IC₅₀ value of 1.12 mg/mL, indicating a notable free radical scavenging capacity. Antimicrobial assays demonstrated broad‐spectrum activity against both gram‐positive and gram‐negative bacteria, with inhibition zones ranging from 8 to 22 mm. The lowest minimum inhibitory concentration (MIC) values (0.5% v/v) were observed for Bacillus cereus, Pseudomonas aeruginosa, and Streptococcus bovis, whereas Enterococcus faecium showed the highest MIC (2% v/v), indicating strain‐dependent susceptibility. Incorporation of 0.13% REO into fermented thick cream improved sensory acceptance by enhancing flavor without causing overpowering intensity. Physicochemical and microbiological analyses showed delayed acidification and reduced microbial growth in REO‐treated samples compared with controls, confirming its preservative effect. Collectively, these findings highlight the multifunctional properties of REO as antioxidant activity and antimicrobial agent with acceptable flavor profile, supporting its potential application in food preservation and the development of natural functional ingredients.