Solidification of plant essential oils by electrostatic adsorption and Ca2+ crosslinking for pot-stewed duck neck preservation

Abstract

Pot-stewed duck neck (PSDN) is a popular leisure food in China. However, PSDN is rich in nutrients and has high water activity, which can easily cause the oxidation of fat and protein, and microbial growth, resulting in a short shelf life. As a potential preservative, plant essential oils have restricted application due to their poor water solubility, effumability, and easy oxidizability. In this study, the porous starch that had absorbed cinnamon and zanthoxylum essential oils (EOs) was encapsulated by electrostatic adsorption between chitosan and sodium alginate, and solid preservative (SP) was further formed by crosslinking of Ca²⁺ with sodium alginate. Results showed that SP exhibited good encapsulation property and sustained-release effect on EOs. Cinnamon EO showed antibacterial properties and the main component was cinnamaldehyde. Antioxidant property was observed in zanthoxylum EO and the main components were linalool and D-limonene. Subsequently, SP was used to preserve PSDN and stored in modified atmosphere packaging (MAP). Results showed that the SP-MAP treatment provided at least double-time extension of the PSDN shelf life for 3 and 11 days at 25 and 4 ^○C, respectively. The lower values of volatile base nitrogen and thiobarbituric acid indicated that the lipid oxidation of PSDN was delayed. Besides, microbial growth of PSDN with SP-MAP was inhibited with the lowest total viable and fungal counts, and the results of incubation and enumeration of pathogenic bacteria in PSDN samples indicated that Escherichia coli, Bacillus subtilis and Staphylococcus aureus were effectively inhibited during the storage time. Therefore, solidifying essential oils combined with MAP was a promising method to preserve pot-stewed meat products.