Carvacrol Encapsulation in Chia Mucilage Nanocapsules Enhances Antimicrobial Activity Against Escherichia coli and Preserves Antioxidant Properties in Milk

Carvacrol (CAR) has antimicrobial and antioxidant activity and potential as a food additive, but its intense aroma and high volatility limit its use in foods. Nanoencapsulation has been proposed as a strategy to overcome these limitations. This study evaluated the antioxidant and antimicrobial performance of chia mucilage nanocapsules containing CAR (CMNP) and the effect of nanoencapsulation on CAR content during storage in milk. CMNP and CAR in solution (CS) were added at the Bactericidal Inhibitory Concentration (BIC) and ½ BIC in skim and whole milk. Antioxidant activity was determined by the ABTS (2,2 azinobis (3-ethylbenzothiazoline-6-sulfonic acid) assay, and antimicrobial efficacy was evaluated against Escherichia coli. Samples were stored at 37 °C for 48 h to assess antimicrobial activity under optimal growth conditions for E. coli and at 5 °C for 14 days to simulate refrigerated storage conditions. CAR was quantified by HS-SPME–GC/MS. CMNP increased antioxidant activity compared to the control, showing values similar to CS. At 37 °C, CMNP inhibited E. coli to undetectable levels using ½ BIC in both milks. At 5 °C, the full BIC was required in whole milk, while ½ BIC was sufficient in skim milk. Nanoencapsulation resulted in lower initial CAR content but promoted gradual release during storage at 5 °C and 37 °C. CMNPs show potential to contribute to the microbiological safety and oxidative stability of milk.