Nanoencapsulation reduces the perception of carvacrol odor, enhances the control of Botrytis cinerea growth and preserves grape quality

Abstract

Botrytis cinerea is the causal agent of gray mold, which is one of the most widespread and destructive fungal diseases that compromises the productivity and quality of grapes produced throughout the world. This work aimed to verify, for the first time, the impact of unencapsulated carvacrol and encapsulated in Eudragit® nanocapsules (Eud-Carv NCs) and chia mucilage (Chia-Carv NCs) on mycelial growth and spore germination of B. cinerea. The impact of these three forms of carvacrol on grape quality parameters, including texture, pH, color, volatile profile and odor perception were also evaluated. All three forms of carvacrol suppress spore germination and mycelial growth of B. cinerea. When used at sublethal levels, the encapsulated forms (Eud-Carv NCs and Chia-Carv NCs) were more effective by inhibiting up to 90 % of fungal growth, while unencapsulated carvacrol suppressed up to 67 %. Both nanocapsules showed no effect on the physicochemical characteristics and volatile profile of the grapes. Furthermore, the odor of carvacrol was not perceived in the grapes treated with both encapsulated forms, since the levels of this monoterpene (9.0 to 11.3 μg/L over 21 days of grape storage) were below the odor threshold (40 μg/L). Conversely, when grapes were treated with the unencapsulated form, carvacrol levels were about 10 times higher than the odor threshold, which negatively impacts the sensory perception of the grape. Therefore, the use of carvacrol encapsulated in Eudragit® and chia mucilage proved to be a promising alternative for preventing B. cinerea infections in grapes.