Construction of Oregano Essential Oil Pickering Emulsion/Nanocellulose/Pectin Antimicrobial Coating and Its Application in Mango Preservation
摘要
To improve the compatibility of hydrophilic polysaccharide substrates with oregano essential oil (OEO), an OEO Pickering emulsion stabilized by lauric acid-modified cellulose nanocrystals was prepared and incorporated into a cellulose nanofiber/pectin matrix to develop a mango preservation coating. The emulsion prepared at a 0.45:1 absolutely dry mass ratio between lauric acid and cellulose nanocrystals and a cellulose nanocrystal mass fraction of 1.5% showed uniform droplet size distribution and the emulsification index reached 93.7% after 48 h, reflecting good stability. The Pickering emulsion greatly affected the coating’s microstructure, thereby regulating its barrier performance. The composite coating with 1.5% emulsion loading exhibited the best performance with an oxygen transmission rate of 13.25 cm3/(m2·d), a water vapor permeability of 2.59 × 10-13 g·cm/(cm2·s·Pa), a water contact angle of 76.03°, and 99.69% inhibition against Escherichia coli. In mango preservation trials, the coating reduced the respiratory peak by 14.41%, decreased the mass loss by 3.3% when compared with the control group on day 9 of storage, delayed the browning incidence and the reduction in firmness, and extended the shelf life by over 3 days. In conclusion, the modified cellulose nanocrystals-stabilized Pickering emulsion/nanocellulose/pectin composite coating shows enhanced gas/moisture barrier properties and antimicrobial activity, thereby maintaining postharvest mango quality. It provides an eco-friendly solution for fruit preservation.