# Microencapsulation of Natural Food Antimicrobials: Methods and Applications
## 4 Food Applications of Encapsulated Antimicrobials
### Meat and Fish Products  
Ready-to-eat (RTE) meat products are prone to contamination by various foodborne pathogens, such as _L. monocytogenes_, _S. typhimurium_ and _E. coli_ O157:H7, mainly during post-processing stage. Different chemical preservatives, such as nitrite, nitrate and sodium chloride, are applied to meat products to produce an inhibitory effect against the growth of these pathogens, except for _L. monocytogenes_, which cannot be inhibited by these chemicals during storage at the refrigeration temperature [117]. However, clove essential oil showed strong inhibitory effects on the growth of _L. monocytogenes_ in meat and cheese [110]. This EO exhibited a broad spectrum of antimicrobial activity against pathogenic microorganisms, which is related to the presence of phenylpropanoids, including eugenol, \(\beta\)-caryophyllene and \(\alpha\)-humulene. Taking into account that, on the one hand, the taste of food could be changed or even surpass acceptable flavor thresholds with the addition of high clove oil concentrations and by treating food for a long period of time, and on the other hand, that incorporation of low amounts of clove EO cannot effectively inhibit the growth of pathogens [118], microencapsulation could be an effective alternative able to overcome these drawbacks. Clove oil microcapsules obtained by spray drying within \(\beta\)-CD and porous starch wall material have been successfully applied to various meat products, such as cooked fish, cooked chicken, cooked pork and cooked beef. Active microcapsules have strong resistance and strong antifungal activity when the fungicidal concentration is above 0.070% [110]. The propolis coproduct can be also used as a natural active agent for extending meat shelf-life, but the unpleasant taste due to its phenolic compounds limits its direct application in food matrices. Storage stability of burger meat was improved by the addition of spray-dried propolis coproduct extract microcapsules. The lipid oxidation of meat burgers containing microencapsulated propolis coproduct extract was inhibited after 14 days of frozen storage (\(-15\pm 0.6\)\({}^{\circ}\)C) as evaluated by the increase in malondialdehyde levels. These burgers meat also showed scores close to the ideal grades for color, appearance and texture [119]. Microencapsulation can prevent inactivation of natural antimicrobial peptides such as nisin through a proteolytic reaction with the glutathione present in the meat products. It is of the utmost importance that we inhibit the growth of foodborne pathogens in pork products, including Norovirus, _Salmonella_ spp., _Campylobacter_ spp., _Toxoplasma gondii_ and _E. coli_ O157:E7 because of its high consumption. In this context, free nisin or encapsulated nisin in alginate--cellulose nanocrystal microbeads were used to coat cooked ham slices initially contaminated with _L. monocytogenes_[28]. The meat was then stored under vacuum packaging at refrigeration temperatures. After 28 days, the concentration of _L. monocytogenes_ increased to more than 6 log CFU/mL for the control without treatment. Free nisin (63 \(\mu\)g/mL) had an antibacterial effect as it limited the  
increase to approximatively 3 log CFU/mL. However, the effect was better for meat coated with encapsulated nisin (63 \(\mathrm{\SIUnitSymbolMicro\mathrm{g}}\)/mL) as no growth occurred after 28 days [28]. Coconut shell liquid smoke is a natural preservative containing phenol, carbonyl and organic acids responsible for its antibacterial activity. The quality of tilapia, a type of fish, can be preserved by applying natural bioactive agents to inhibit the activity of perishable psychrophilic bacteria. Application of microencapsulated liquid smoke by spray drying it on cold-stored Tilapia (_Oreochromis nilicticus_) meat resulted in a 1.45 log cycle reduction in total plate count (TPC) for treatment containing 1.5% of microcapsules compared to the control sample after 9 days of storage [112].