**4. Conclusions**

The present work revealed interesting results of chitosan hydrochloride-based coatings on the safety of horticultural fresh products, such as lettuce and kiwifruits. Commercial grade chitosan hydrochloride was selected here as a polymer for food coating and its film-forming properties, physico-chemical and morphological characteristics, as well as antimicrobial response against *B. cinerea* and *P. c.* subsp. *carotovorum* were investigated. The results underlined the film-forming capability of this grade of chitosan, which maintained its physico-chemical characteristics after dissolution in water and which formed a thin and well-distributed coating on both kiwifruit and lettuce. The in vitro antimicrobial assays showed that both the mycelial growth of *B. cinerea* and the bacterial growth of *P. c.* subsp. *carotovorum* were totally inhibited by the presence of CH, whereas in vivo antimicrobial properties were proved for 5–7 days on lettuce and until 20–25 days on kiwifruits demonstrating

that chitosan-based coating is able to contrast gray mold frequently caused by the two selected plant pathogens during the postharvest phases of both fruit or vegetable products. On *B. cinerea*, chitosan has also shown to inhibit the spore germination and this is an additional positive function that this organic material can express with respect to this dangerous pathogen [42]. Chitosan applications, in combination with essential oils, were also recently tested with respect to different bacterial plant pathogens and so our study assumes a particular relevance to improve sustainable strategies able to reduce the negative impact of different plant pathogens during postharvest phases [43]. The obtained results contribute to the idea and need of novel greener strategies and approaches for food quality and safety preservation. By using natural compounds, like chitosan hydrochloride, interesting opportunities emerge to limit the damage caused by dangerous plant pathogens on vegetable and fruit production after harvesting, reducing or avoid remarkable economic losses and preserving final products.

**Author Contributions:** Elena Fortunati, Giorgio Mariano Balestra, Josè Maria Kenny, and Luigi Torre conceived and designed the experiments; Elena Fortunati, Geremia Giovanale, and Francesca Luzi performed the experiments; Elena Fortunati, Angelo Mazzaglia, and Giorgio Mariano Balestra analyzed the data; Elena Fortunati and Giorgio Mariano Balestra wrote the paper.

**Conflicts of Interest:** The authors declare no conflict of interest.
