Background: Myrtus communis L. is a typical aromatic species of the Mediterranean basin, whose leaves are rich in essential oil known for its biological properties. Methods: The essential oil of Tunisian Myrtus communis L. leaves was extracted via hydrodistillation using a Clevenger-type apparatus and optimized using a complete factorial design including three factors with two different modalities and one factor with three modalities, hence the total number of experiments N_total = 2³ × 3¹. This optimization concerns the yield, the terpene composition by GC-MS and the antioxidant activity by the two radical scavenging assays, DPPH and ABTS. Four factors were retained, namely, the type of leaf used (dry or fresh sample), the leaf granulometry (whole or ground), the extraction time (1 h 30 min, 2 h 30 min and 3 h 30 min) and the water volume/plant material ratio (1/4 and 1/10). Results: The dry and whole leaves, duration 3 h 30 min, and V/M 1/10 modalities gave the best yield of essential oil (0.77%). The optimal contents of the majority of the terpene compounds, 1,8-cineole (37.23%), α-pinene (54.79%), myrtenyl acetate (23.43%) and limonene (17.77%), were recorded using the modalities dry and whole leaves, duration 2 h 30 min, V/M 1/10; dry and ground leaves, duration 1 h 30 min, V/M 1/4; fresh and whole leaves, duration 3 h 30 min, V/M 1/4; and fresh and whole leaves, duration 3 h 30 min, V/M 1/4, respectively. The antioxidant activity of the essential oil of myrtle leaves was optimized for the two DPPH (7.477 mg TE/g EO) with the GDL, duration 3 h 30 min, V/M 1/4 and ABTS assays (14.053 mg TE/g EO) with WDL terms, duration 3 h 30 min, V/M 1/10. Conclusions: Optimizing essential oil extraction is of significant interest to the cosmetic, perfumery, and pharmaceutical industries, which are constantly seeking optimal conditions to enhance essential oil yield and to ensure a high concentration of terpenic compounds, valued for their aromatic qualities and diverse biological activities.

Low-moisture cereal products, such as traditional Tunisian coarsely milled barley, represent a vital global and regional dietary staple. However, their post-harvest processing is challenged by contamination with highly resilient endogenous spore-forming bacteria. This study investigated a sequential mild-thermal and UV-C hurdle technology, combining oven temperature (Factor A; 60, 80 and 100 °C) thermal treatment time (Factor B; 2, 6 and 10 min) with UV-C radiation (Factor C; 214.8, 644.4 and 1074.0 mJ/cm²), using a three-factor, three-level Box–Behnken experimental design coupled with response surface methodology (RSM). Three responses were evaluated: microbial logarithmic reduction (Y1), water activity a_w (Y2), and total color difference ΔE (Y3). Statistical analysis confirmed that thermal factors (A: oven temperature and B: thermal treatment time) served as the primary drivers of microbial inactivation, while UV-C light acted primarily at the immediate solid surface, inducing localized photothermal micro-evaporation that significantly affected surface water activity without degrading bulk chromatic properties. Multi-response optimization established an optimal processing window at an oven temperature of 94.5 °C, a thermal treatment time of 8.30 min and, a UV-C dose of 1074 mJ/cm². Experimental validation under these optimal conditions yielded a highly reliable 1.385 ± 0.013 Log CFU/g reduction in naturally occurring, heat-resistant spore-forming bacteria. Concurrently, the product maintained an exceptionally dry state (a_w = 0.34 ± 0) and preserved its natural visual attributes (ΔE= 2.77 ± 0.08). The low validation relative standard errors (RSE < 10% for physical attributes; 15.6% for microbial reduction) demonstrated a good predictive precision and industrial feasibility of the quadratic models.

Fresh-cut fruits are highly perishable and susceptible to bacterial contamination; thus, effective preservation methods are necessary to extend their shelf-life and improve quality. Polysaccharides edible coating loaded with essential oil nanoemulsions have the potential to extend shelf life and improve quality. The effectiveness of this approach is dependent on the properties of the nanoemulsions, such as droplet size (DS) and stability. This study optimized the production of citral (CT) and citronella oil (CTO) nanoemulsions (CT-CTO-NEs) for use in fresh-cut apples, with a focus on the effect of DS on antibacterial efficacy. After testing different combinations of surfactants tween 80 (TW 80) and co-surfactants Propylene Glycol (PG), the results showed that the optimal CT-CTO-NEs had droplets size of less than 500 nm and were stable for 3 weeks at 4ºC. The highest antibacterial activity against Listeria monocytogenes and Escherichia coli was observed with the smallest DS (< 100 nm). This study highlights the importance of DS in the efficacy of essential oil nanoemulsions as an antibacterial coating for fresh-cut fruits. The smaller the droplet size, the better the antibacterial activity.