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

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 degrees 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 5.15.4 (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 degrees 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. (C) 2017 Elsevier Ltd. All rights reserved.