Table 4.

Antimicrobial activity of EOs and their active components in combination with other hurdles.

Target microorganisms	EOs or active EO components (Concentration)	Combined treatment	Exposure time, Application	Antimicrobial activity		References
				EO or other treatment alone	Combined treatment
Free
E. coli O157:H7, L. monocytogenes	Citrus sinensis (0.2 μl), Citrus lemon (0.2 μl), Citrus reticulata (0.2 μl)	Mild heat (54 °C)	10 min, Lab culture	No inactivation	More than 5 log cycles inactivation	Espina et al. (2011)
Cronobacter sakazakii (Desiccated and non-desiccated)	Citral (0.3–0.9%)	Mild heat (25–55 °C)	2 h, Infant formula	N/Aa	Complete inhibition	Shi et al. (2017)
Total viable counts, Pseudomonas spp., Lactic acid bacteria, E. coli, Total coliforms, B. thermosphacta, Yeasts and Molds	Thymol (0.4–0.8%) + Carvacrol (0.4–0.8%)	VPb	21 days, Marinated chicken and beef (Shawarma)	0.5–2.9 log reductions	0.8–3.1 log reductions	Karam et al. (2019), Karam et al. (2020)
Total mesophilic counts	Cymbopogon citratus (400 μl)	MAPc (CO2 100%)	21 days, Cabbage and radish sprouts	1.55–2.26 log reductions	Complete inactivation (<1 log) after 14 days	Hyun et al. (2015)
Salmonella	Thyme (0.3–0.9%)	VP, MAP (CO2 50%)	15 days, Minced pork meat	Up to 2.9 log reductions in the first 3 days	1.69–4.05 log reductions in 15 days	Boskovic et al. (2017)
Total aerobic count, B. cereus, C. perfringens	Origanum vulgare (400–32000 ppm)	High pressure CO2 (100 bar/80 °C)	15 min-48 h, Paprika spice	Around 0.3 log reductions and no inactivation of spore population	Significant reductions and spores inactivation	Casas et al. (2016)
Acinetobacter baumannii	Coriandrum sativum L. (0–6 μl/ml)	Chloramphenicol (32–64 μl/ml)	16–20 h, Lab culture	MIC ranged between 1 and 4 μl/ml.	MIC of EO and antibiotic decreased by up to 62.5 times	Duarte et al. (2012)
Acinetobacter baumannii	Myrtus communis L. (0.03–1 MICd)	Polymixin B, Ciprofloxacine (0.03–4 MIC)	24 h, Lab culture	MIC ranged between 0.25 and 4 μl/ml	MIC of antibiotics and EO reduced by up to 1/8 MIC with complete inhibition of microbial counts after 6 h	Aleksic et al. (2014)
L. monocytogenes, E. coli O157:H7	Oregano (0.01%), Lemongrass (0.01%)	Gamma irradiation (0.5 or 1 kGy)	14 days, Fresh cut cauliflower	1.16–3.29 log reductions	Undetectable up to 14 days at 0.5–1 kGy	Tawema et al. (2016)
Yeasts and molds				0.52–2.61 log reductions	Around 2–3 log reductions
Fusarium graminearum	Cananga odorata (0–5 mg/g)	Gamma irradiation (0–10 kGy)	14 days, Maize	Complete inhibition at 3.9 mg/g	Significant reductions at 2.5 mg/g EO combined with 4 kGy irradiation	Kalagatur et al. (2018)
A. niger, P. chrysogenum	Ocimum basilicum (2%)	Irradiation (0–4 kGy)	14 days, Rice	0.42–1.18 log reductions	Up to 5 log reductions	Hossain et al. (2014)
S. Typhimurium	Clove (1.2 mg/ml)	Ultraviolet light-C	N/A, Lab culture	1.8–2.9 log reductions	6.8 log reductions	Silva-Espinoza et al. (2020)
S. Typhimurium	Cinnamomum verum (0–5%)	PEFe (10–30 kV/cm)	60–3000 μs, Pasteurized skim milk	No bactericidal effect	Up to 1.97 log reductions	Pina-Pérez et al. (2012)
Campylobacter jejuni	Oregano (1/4 and 1/2 MIC = 15.625 and 31.25 ppm)	PEF (1–20 kV/cm)	20 μs, Liquids and raw chicken	1.64–3.32 log reductions with varied PEF treatments	EO applied following PEF induced further inactivation of 1.2 log cycles	Clemente et al. (2020)
L. monocytogenes	Thymus vulgaris L. (<0.06–0.50%)	HPP (200–300 MPa)	15 min, Fresh cheese	Around 3.5 log reductions	More than 5 log reductions	Bleoancă et al. (2016)
L. monocytogene, L. innocua	Mentha piperita (0.05 and 0.1 ml/100 ml)	HPP (600 MPa)	300 s, Yogurt drink	More than 5 log reductions	Additional 1 log reduction and reduced HPP treatment	Evrendilek and Balasubramaniam (2011)
S. Typhimurium, L. monocytogenes	Cinnamomum zeylanicum (0.625 μL/mL)	US (24 kHz, 400 W)	0–6 days, Milk	0.7–3.0 log reductions	2.7–4.5 log reductions	Mortazavi and Aliakbarlu (2019)
S. Typhimurium, S. aureus	Zataria multiflora Boiss. (15–30 μl/100 ml)	Nisin (0–0.5 μg/ml at 8 and 25 °C)	21 days, Barley soup	Complete inhibition in 2–12 days	Complete inhibition	Moosavy et al. (2008)
L. monocytogenes	Origanum vulgare L., Thymus vulgaris L., Rosmarinus officinalis L. (50–300 ppm)	Lactic acid (50 ppm)	24 h, Lab culture	32.0–83.48 % inhibition	60.33–99.08% inhibition	Dimitrijevic et al. (2007)
S. epidermidis	Thymol (0.06–16 g/l), Tea tree (0.25–64 g/l), Eucalyptus (0.25–64 g/l)	Chlorhexidine digluconate (0.125–16 mg/l)	24 h, Lab culture	MIC: 0.5–16 g/l	Reduced MIC to 0.5–1 g/l	Karpanen et al. (2008)
S. epidermidis (Biofilms)				MIC: 0.5–64 g/l	Reduced MIC to 0.25–16 g/l
Salmonella enterica serotype Newport	Origanum vulgare, Carvacrol (0.1–0.5%)	Ozonized water (0.01–0.1 mg O3/L)	60–120 min, Iceberg lettuce	1.76–2.09 log reductions	Complete inhibition	Dev Kumar and Ravishankar (2019)
Nano-encapsulated
E. coli O157:H7 Sakai, L. monocytogenes EGD-e	Thymbra capitate nanoparticles (0.1 μl)	Heat (53 °C)	12 min, Lab culture	Up to 0.5 log reductions	Up to 5 log reductions	Merino et al. (2019)
A. niger, A. flavus, A.parasiticus, P. chrysogenum	Thymus vulgaris + Origanum compactum nanocrystals (0.13 and 0.19%)	Irradiation (750 kGy)	8 weeks, Rice	1.19–2.87 log reductions	3.7–4.93 log reductions	Hossain et al. (2019)
E. coli O157:H7	Thyme nanoemulsions (0.375 mg/ml)	USf (127–255 W/cm2)	3–9 min, Lab culture	3.28–4.13 log reductions	5.14–7.42 log reductions	Guo et al. (2020)
S. enterica	Oregano and thyme nanoemulsions (0.025%)	US (continuous and pulsed 200 W)	5–25 min, Lettuce leaves	Up to 2.23 log reductions	Complete inactivation	Millan-Sango et al. (2016)

^aN/A: Not Applicable.

^bVP: Vacuum Packaging.

^cMAP: Modified Atmosphere Packaging.

^dMIC: Minimum Inhibitory Concentration.

^ePEF: Pulsed Electric Field.

^fUS: Ultrasound.