Antimicrobial Efficacy of Liposome-Encapsulated Citral and Its Effect on the Shelf Life of Shatangju Mandarin

Abstract

Liposome-encapsulated citral was prepared by means of a hot homogenization method. The microstructure, particle size, and zeta potential of the capsules were analyzed by transmission electron microscope and dynamic light scattering, respectively, in which the results showed a good dispersion stability of the citral-loaded liposome. In vitro tests showed that liposome-encapsulated citral significantly (P < 0.05) reduced the populations of Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Penicillium italicum more than free citral. In vivo tests conducted on fresh Shatangju mandarin showed that liposome-encapsulated citral-treated fruit exhibited a decay incidence of 56.67%, which is 42.04% lower than free citral-treated fruit (97.78%) after 26 days of storage at 25°C and 60 to 70% relative humidity. Additionally, fruit treated with citral-loaded liposome significantly reduced weight loss and viable yeast and mold during storage. In summary, liposome-encapsulated citral could be an effective antimicrobial agent to extend the shelf life of the Shatangju mandarin. HIGHLIGHTS

Preparation of Citral Oleogel and Antimicrobial Properties

“…Rhizopus stolonifer growth is illustrated in Figure 7C, and it evidences an incapacity to thrive at concentrations of 3% or higher. The experimental results agreed with the results of a citral liposome inhibition by Chen et al [50]. Citral can inhibit the growth of microorganisms well.…”

Optimization of Cross-Linked Cassava Starch Coating Formulation by Response Surface Methodology and Its Preservation Effects on ‘Shatangju’ Mandarin

“…Vitamin C is extremely unstable, easily soluble in water and easily to be oxidized. It is a very important nutritional component of 'Shatangju' mandarins [Chen et al, 2020]. The changes of ascorbic acid content in 'Shatangju' mandarins can reflect the nutritional status during the postharvest storage.…”

“…Therefore, how to delay the deterioration of the fruit quality and flavor during transportation and storage, inhibit the occurrence of various postharvest diseases, and prolong the storage time are urgent problems to be solved. The main storage and preservation techniques for 'Shatangju' mandarin in China is the use of chemical preservatives, such as pyrimethanil, prochloraz, and iminoctadine triacetate [Chen et al, 2020]. Long-term use of these chemical preservatives will cause microbial resistance on the surface of fruits, leading to their reduced efficacy.…”

Mechanisms and Applications of Citral’s Antimicrobial Properties in Food Preservation and Pharmaceuticals Formulations

“…In a recent study, the antimicrobial activity of citral against C. albicans and some bacteria (E. coli and B. cereus) was enhanced when it was encapsulated in nanostructured lipid carriers (74.8 nm), as citral encapsulates showed lower MIC values than those of the citral emulsion for all microorganisms evaluated [128]. Additionally, Chen et al [129] reported that liposome-citral nanoencapsulates (105.7-238.0 nm) significantly improved the quality of fresh Shatangju mandarins compared to free citral-treated samples by reducing their weight loss and microbial spoilage after storage at 25 • C and 60-70% relative humidity (RH) for 26 d. Nanoemulsions containing citral have also shown outstanding effects when incorporated into coatings as vehicles, such as the case of the study reported by Machado [130], where alginate-based coatings that include citral nanoemulsions, in an optimal concentration between 0.1-0.5%, were a good barrier against microbial attack, while the quality parameters of the fruit were positively affected (e.g., color and respiration rate) during storage for 12 d at 4 • C and 90% RH. Cabbage and chicken skin 0.03 and 0.06% of citral Antimicrobial activity against L. monocytogenes and S. aureus in cabbage.…”