Chitosan treatment for the control of postharvest decay of fruit

Gianfranco ROMANAZZI, Marche Polytechnic University

Chitosan, an N-acetylated derivative of the polysaccharide chitin, is a biopolymer which has been the object of considerable interest for applications in agriculture, biomedicine, biotechnology, and the food industry due to its biocompatibility, biodegradability, and bioactivity. Research to reduce fungicide applications by the discovery of new natural antimicrobials is needed to meet a growing consumer demand for food without chemical preservatives. Chitosan was reported to prolong storage life and control decay of several fruit and vegetables. The biopolymer has a triple mechanism: it i) has film-forming properties that affect host physiology, reducing gas exchanges and then delaying respiration and ripening, ii) inhibits the growth of decay-causing fungi and iii) induces defense response in the host tissues. The thickness of the chitosan coating, the viscosity of the solution and the antimicrobial activity depended on the acid used to dissolve the biopolymer, and chitosan acetate proved to be the best. Several commercial chitosan formulations are available on the market as biostimulants, and the active ingredient chitosan hydrochloride was approved for use as basic compound for plant disease management (Reg. EU n. 563/2014 of 23/05/2014). In our trials, we tested the effectiveness of chitosan formulations to improve shelf life of fresh fruit (strawberries, sweet cherries, table grapes) and investigated the changes in gene expression occurring in fruit tissues, confirming the triple action in the improvement of fruit and vegetable shelf life, and contributing to a sustainable management of postharvest diseases of fresh produce for both integrated and organic agriculture.

 
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