Plum Coatings of Lemongrass Oil‐incorporating Carnauba Wax‐based Nanoemulsion

Abstract

Nanoemulsions containing lemongrass oil (LO) were developed for coating plums and the effects of the nanoemulsion coatings on the microbial safety and physicochemical storage qualities of plums during storage at 4 and 25 °C were investigated. The emulsions used for coating were produced by mixing a carnauba wax-based solution (18%, w/w) with LO at various concentrations (0.5% to 4.0%, w/w) using dynamic high pressure processing at 172 MPa. The coatings were evaluated for their ability to inhibit the growth of Salmonella Typhimurium and Escherichia coli O157:H7 and their ability to preserve various physicochemical qualities of plums. Uniform and continuous coatings on plums, formed with stable emulsions, initially inhibited S. Typhimurium and E. coli O157:H7 by 0.2 to 2.8 and 0.8 to 2.7 log CFU/g, respectively, depending on the concentration of LO and the sequence of coating. The coatings did not significantly alter the flavor, fracturability, or glossiness of the plums. The antimicrobial effects of the coatings against S. Typhimurium and E. coli O157:H7 were demonstrated during storage at 4 and 25 °C. The coatings reduced weight loss and ethylene production by approximately 2 to 3 and 1.4 to 4.0 fold, respectively, and also retarded the changes in lightness and the concentration of phenolic compounds in plums during storage. The firmness of coated plums was generally higher than uncoated plums when stored at 4 °C and plum respiration rates were reduced during storage. Coatings containing nanoemulsions of LO have the potential to inhibit Salmonella and E. coli O157:H7 contamination of plums and may extend plum shelf life.

Effect of Hydroxypropyl Methylcellulose-Beeswax Composite Edible Coatings Formulated with or without Antifungal Agents on Physicochemical Properties of Plums during Cold Storage

“…It is known that polysaccharides present in the cell wall such as pectin, starch, and hemicellulose mainly contribute to the firmness of the fruit. Degradation of these compounds by hydrolyzing enzymes like pectin methylesterase and polygalacturonase causes softening of the fruit during ripening and storage [15]. The capacity of edible coatings to modify the internal gas composition of the fruit in terms of O 2 and CO 2 concentrations might influence the activities of the cell wall degrading enzymes, reducing fruit softening.…”

“…Plums are climacteric fruits with relatively short postharvest life, usually limited by a high susceptibility to internal breakdown, loss in texture, and postharvest diseases caused by a number of fungal pathogens [14][15][16]. The market life of these fruit varies with the cultivar and storage conditions typically between 1 and 8 weeks [14,15].…”

“…The market life of these fruit varies with the cultivar and storage conditions typically between 1 and 8 weeks [14,15]. Storage at 0-1 ∘ C and 90-95% relative humidity (RH) has been recommended to extend the postharvest life of plums [17], but in some cases cold storage is not sufficient to significantly extend shelf life due to the appearance of chilling injury symptoms.…”

Development of a Microbial Decontamination System Combining Washing with Highly Activated Calcium Oxide Solution and Antimicrobial Coating for Improvement of Mandarin Storability

“…In general, the total polyphenol content in mandarin flesh decreases during storage through the activities of oxidases such as polyphenol oxidase and peroxidase (Kim, Oh, Lee, Song, & Min, ; Meng, Li, Liu, & Tian, ). The maintenance of total polyphenol content in the CaO[W]‐GSE/CW[C] mandarins may be related to blockage of the oxygen supply by the coating and potential CaO deposition, which inhibits the activities of the oxidases (Kim et al., ). The coating of litchi fruit with chitosan was reported to delay the reduction in total polyphenol content in the fruit during storage (Zhang & Quantick, ).…”

Essential Oil Nanoemulsions and Food Applications

“…Recently, lemongrass oil nanoemulsionwas used to evaluate antimicrobial properties, physical, and chemical changes in plums. 33 The nanoemulsion was able to inhibit Salmonella and E. coli population without changing flavor, fracturability, and glossiness of the product. It was also able to reduce the ethylene production and retard changes in lightness and concentration of phenolic compounds.…”