Anti Staphylococcus aureus activity of shikonin @ chitosan nanoemulsion and its effect on the storage quality of pork

Abstract

Shikonin has been used in food production because of its potent bacteriostatic activity and colorability, but it is limited to be widely used because of its poor water solubility. The aim of this study was to prepare shikonin @ chitosan nanoemulsion (NS) to improve the solubility of shikonin and evaluate its antibacterial activity against Staphylococcus aureus (S. aureus) and the effect on storage quality of a pork food model. The results indicated that NS prepared in this study had a particle size of 147.96 ± 0.28 nm, PDI of 0.259 ± 0.007, and zeta potential of −55.37 ± 0.58 mV, which worked well with water as a solvent energy. NS showed good stability and dispersibility after seven days, and significantly damaged S. aureus appearance and biofilm formation. Food application results showed that NS had better activity against S. aureus and better preservation effect without compromising pork meat quality. At the end of the storage period, pork samples with NS coating showed the lowest values of total viable count (TVC) (7.03 ± 0.06 log CFU/g), pH (7.85 ± 0.01), total volatile basic nitrogen (TVB-N) (8.34 ± 0.50 mg/100 g), thiobarbituric acid reactive substances (TBARS) (7.23 ± 0.47 g/kg). NS showed better biocompatibility in acute toxicity experiments in mice, providing a theoretical basis for its application in food preservation.