Chitosan–citric acid edible coating to control Colletotrichum gloeosporioides and maintain quality parameters of fresh-cut guava

This study aimed to verify the action of edible chitosan–citric acid (CHI–CA) coating to control Colletotrichum gloeosporioides and maintain quality parameters of fresh-cut guava. Chitosan was obtained from Litopenaeus vannamei shells using high temperature and short exposure times. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of CHI–CA against C. gloeosporioides were determined by macrodilutions at 28 °C/120 h in the absence/presence of CHI–CA (0–10 mg/mL). Scanning electron microscopy was used to evaluate morphological changes in the fungus. Guava slices were coated with CHI–CA (MIC) or 5 mg/mL glycerol (control). Rot incidence and physicochemical, physical, and microbiological factors were determined at 0, 3, 7, and 14 days at 24 °C and 4 °C. Chitosan presented typical structural characterization, 64% deacetylation, and a molecular weight of 1.6 × 10⁴ g/mol. CHI–CA exhibited MIC and MFC values of 5 mg/mL and 10 mg/mL, respectively, and promoted changes in the morphology and cell surface of fungal spores. The fresh-cut guava coated with CHI–CA maintained quality parameters during storage and preserved their sensorial characteristics. Therefore, the use of CHI–CA as a coating is a promising strategy for improving postharvest quality of fresh-cut fruits.