# Microencapsulation of Natural Food Antimicrobials: Methods and Applications
## 3 Microencapsulation of Natural Food Antimicrobials
### Essential Oils
The antimicrobial activity of all the formulations and both free CO and active solid liquid microparticles against _Candida pseudointermedia_ and _Penicillium paneum_ increased over 28 days of storage at 25 and 45 \({}^{\circ}\)C. Inhibition zones obtained for free CO against both strains were higher than for encapsulated CO, whereas microparticles formed from saturated and unsaturated lipid mixtures displayed good antimicrobial efficiency [85]. Increased antimicrobial activity of free and encapsulated CO over storage time could be attributed to an increase in both coumarin and O-methoxy cinnamaldehyde concentrations after a possible degradation of the cinnamic acid. Encapsulation of EOs such as EG and cinnamon bark in \(\beta\)-CD increased their antimicrobial activity at lower concentrations as a result of the enhanced water solubility of these substances, which improves their accessibility to the antimicrobial primary sites located at the membrane and inside the cytoplasm of bacteria [90]. The antimicrobial properties of free and encapsulated EG, clove bud extract, cinnamon bark extract and a 2:1 trans-cinnamaldehyde:EG within \(\beta\)-CD prepared through freeze drying against _Salmonella enterica_ serovar _Typhimuriumium_ LT2 and _L. innocua_ have been evaluated. The microencapsulation of cinnamon bark extract in \(\beta\)-CD showed the highest inhibitory effect (59%) on the growth of both studied pathogens (MIC: 166 \(\upmu\)g/mL) compared to free cinnamon bark extract (MIC: 400 \(\upmu\)g/mL for _S. typhimurium_ and 500 \(\upmu\)g/mL for _L. innocua_) [90]. Encapsulation of various bioactive agents via liposomes is considered a promising method for enhancing the shelf-life of food products, mainly due to the significantly increased antimicrobial activity. Thymol and carvacrol, as monoterenes, have a stabilization effect on the PC/Chol (cholesterol) liposome membranes. Physicochemical properties of liposomes, such as charge, size and composition, along with compounds present in bacterial cells, have important effects on the antimicrobial activity of monoterenes. Additionally, cellular transport can be promoted by using liposomal formulation, which can lead to the release of active substances inside the cell. The antimicrobial activity of free and encapsulated EOs derived from _Origanum dictannus_ (wild and organically cultivated specimen) pure thymol and carvacrol and carvacrol mixtures with thymol (6/1) and \(\gamma\)-terpinene (3/1) in PC/Chol liposomes (PC/C: 10/2 and 5/1) has been assessed against four Gram-positive bacteria, four Gram-negative bacteria and three human pathogenic fungi [91]. The diffusion technique revealed two important facts, including the higher effectiveness of pure compounds (thymol and carvacrol) compared to oils and increasing antimicrobial activity upon encapsulation. Despite its encapsulation in a small amount (25.0 \(\times\) 10\({}^{-8}\) g/mL) in liposomes, the antimicrobial activity of carvacrol was equal or increased compared with pure natural compounds (6.0 \(\times\) 10\({}^{-3}\) g/mL) [91].