Carvacrol-loaded chitosan nanoparticles maintain quality of fresh-cut carrots

Abstract

Abstract The effects of carvacrol-loaded chitosan-tripolyphosphate nanoparticles (Np-EO) on the physicochemical, sensory and microbial quality of fresh-cut (FC) carrot slices stored up to 13 days at 5 °C were studied. Np-EO was compared to samples treated by NaOCl (100 mg L − 1 ), Np (chitosan-tripolyphosphate nanoparticles without carvacrol) or individual chitosan (0.5%) and carvacrol (0.5%) solutions. Np-EO achieved the best sensory scores also avoiding carvacrol-related off-flavours found with the carvacrol solution. Furthermore, whitening of FC carrot slices was highly reduced in Np-EO samples. Np-EO reduced microbial levels in FC carrot slices by 0.6–3.0 log units on processing day compared to untreated (control) samples. Np-EO allowed to reduce the microbial growth in FC carrot slices during the first 9 days of storage similarly to carvacrol solution. Furthermore, Np-EO highly controlled microbial loads at the end of storage showing 2.3 (lactic acid bacteria), 6.1 (yeasts and moulds) and 5.1–5.4 (mesophiles, psychrophiles and Enterobacteriaceae ) lower log CFU g − 1 units compared to control samples. Conclusively, Np-EO highly maintained microbial (2–6 lower log CFU g − 1 units compared to control), sensory (up to 2.5 better scores than control) and physicochemical quality of FC carrot slices than control for 13 days at 5 °C. Industrial relevance Natural essential oils industrially extracted from plants are potential alternative substances with high antimicrobial properties when tested in vitro . However, their microbicidal efficacy is greatly reduced due to their low solubility in washing solutions of fresh-cut products. Accordingly, chitosan-tripolyphosphate nanoencapsulation of essential oils such as carvacrol is a great opportunity to increase the antimicrobial properties of carvacrol to be used in fresh-cut fruit and vegetables alternatively to conventional NaOCl sanitation.