# Application of Cinnamon Essential Oil in Active Food Packaging: A Review
## 6 Cinnamon Essential Oil in Food Industry
### Edible Coatings  
Edible coatings have been mainly used for the preservation of fruits because they are prone to rotting without proper postharvest preservation measures [89]. Common operations used to preserve the post-harvest quality of fruits include cold storage, modified atmospheres, radiation storage, heat treatment, and chemical treatment. Some of these operations may require expensive equipment, while others may affect the quality of the fruit and, consequently, consumer acceptance [90]. During storage and as a consequence of fruit ripening, in addition to changes in their external appearance, changes occur due to water transpiration, respiration, and cellular metabolism, causing a decrease in quality [89]. These changes include weight loss, tissue softening, an increase in total soluble solid (TSS) content, and a decrease in titralable acidity (TA), among others [89; 91; 92]. Weight loss is related to the transpiration process and water loss [66]. The increase in TSSs is caused by the transformation of organic acids into sugar because of cellular metabolism [89] and due to their concentration inside the fruit as a consequence of water loss [93]. Occasionally, microbial contamination can lead to a decrease in this parameter due to the consumption of fruit sugar by microorganisms [69]. TA is a parameter that measures the organic acids in the fruit and, along with TSS, is responsible for the flavor and aroma. All of these changes that occur during storage will affect the taste and acceptability of the fruit [66]. For all of these reasons, coatings seem to be a good alternative for fruit preservation as they promote reduced respiration and moisture loss, controlled gas exchange, and antimicrobial and antioxidant properties [94]. Edible coatings have been applied to multiple fruits such as blueberry, strawberry, mango, pineapple, apple, banana, potato, and melon, obtaining very good results in their preservation and extending their shelf life (Table 2) [66; 69; 89; 91; 92; 95; 96; 97]. [PERSON] et al. [89] applied chitosan coatings enriched with cinnamon EO for mango preservation. Untreated mangoes experienced visible changes in their peel, turning yellow and developing dark spots within three days, whereas coated mangoes did not show these changes until day 12. This effect was attributed to the inhibition of polyphenol oxidase (PPO), an enzyme that catalyzes polyphenol oxidation and color change. Studies have demonstrated that the cinnaldehyde present in cinnamon EO can inhibit the activity of this enzyme [98]. There was also an inhibition of pectin methyl esterase (PME), which is involved in cell wall degradation; thus, reducing its activity prevented mango softening while maintaining its hardness. In addition, the coating reduced water volatilization [69], prevent ing fruit weight loss (only 13.76% compared to 25.16% in uncoated mangoes). Finally, the coating improved nutrient quality by maintaining TSS content, TA, and ascorbic acid levels. Similar effects were found in pineapple, where the application of a chitosan edible coating enriched with 0.5% cinnamon EO resulted in less weight loss compared to untreated pineapples (16.44% vs. 23.42%, respectively), a lower increase in TSS content, the maintenance of pH, and better firmness maintenance. Moreover, all samples showed an increase in mold and yeast population during storage; however, the treated samples exhibited less increase than untreated ones due to the antimicrobial action of cinnamon EO [91]. Generally, it has been observed that increasing the concentration of cinnamon EO in coatings inhibits a wide range of microorganisms. However, the components of EO can affect the quality, color, firmness, flavor, and odor of the coated fruit [95; 96; 91]. Thus, finding the optimal concentration that exerts antimicrobial action without affecting the organoleptic characteristics of the food is necessary.