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- Chitosan produced from Mucorales fungi using agroindustrial by-products and its efficacy to inhibit Colletotrichum speciesPublication . Bergera, Lúcia Raquel Ramos; Stamford, Thayza Christina Montenegro; Oliveira, Kataryne Árabe Rimáde; Pessoa, Adjanede Miranda Pereira; Lima, Marcos Antonio Barbosa de; Pintado, Maria Manuela Estevez; Câmara, Marcos Paz Saraiva; Franco, Lucianade Oliveira; Souza, Marciane Magnania Evandro Leite de; Souza, Evandro Leite deThis study evaluated corn steep liquor (CSL) and papaya peel juice (PPJ) in mixture as substrates for thecultivation (96 h, 28◦C, pH 5.6, 150 rpm) of Mucorales fungi for chitosan production, and determinedthe growth-inhibitory effect of the fungal chitosan (FuCS) obtained under optimized conditions againstphytopathogenic Colletotrichum species. All Mucorales fungi tested were capable of growing in CSL-PPJmedium, showing FuCS production in the range of 5.02 (Fennelomyces heterothalicus SIS 28) − 15.63 mg/g(Cunninghamella elegans SIS 41). Highest FuCS production (37.25 mg/g) was achieved when C. eleganswas cultivated in medium containing 9.43% CSL and 42.5% PPJ. FuCS obtained under these conditionsshowed a deacetylation degree of 86%, viscosity of 120 cP and molecular weight of 4.08 × 104g/mol.FuCS at 5000, 7500 and 10,000 ppm inhibited the growth of all Colletotrichum species tested. FuCS alsoinduced alterations in the morphology of C. fructicola hyphae. CSL-PPJ mixtures are suitable substratesfor the cultivation of Mucorales fungi for FuCS production. Chitosan from C. elegans cultivated in CSL-PPJmedium is effective in inhibiting phytopathogenic Colletotrichum species.
- Chitosan–citric acid edible coating to control colletotrichum gloeosporioides and maintain quality parameters of fresh-cut guavaPublication . Nascimento, Julia Idalice Gois; Stamford, Thayza Christina Montenegro; Melo, Natalia Ferrão Castelo Branco; Nunes, Ihasmyn dos Santos; Lima, Marcos Antônio Barbosa; Pintado, Maria Manuela Estevez; Stamford, Tânia Lúcia MontenegroThis 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 ºC and 4 ºC. Chitosan presented typical structural characterization, 64% deacetylation, and a molecular weight of 1.6 × 104g/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.
- Quality of postharvest strawberries: comparative effect of fungal chitosan gel, nanoparticles and gel enriched with edible nanoparticle coatingsPublication . Melo, Natália Ferrão Castelo Branco; Pintado, Maria Manuela Estevez; Medeiros, José Alberto da Costa; Galembeck, André; Vasconcelos, Margarida Angélica da Silva; Xavier, Viviane Lansky; Lima, Marcos Antônio Barbosa de; Stamford, Tânia Lucia Montenegro; Stamford-Arnaud, Thatiana Montenegro; Flores, Miguel Angel Pelágio; Stamford, Thayza Christina MontenegroThis study compared, for the first time, the postharvest conservative action of edible fungal chitosan coatings (gel, nanoparticles and gel-nanoparticle) on the physico-chemical, sensorial and microbiological characteristics of strawberries. The nanoparticles were prepared by an ionic gelation method and characterized by dynamic light scattering and scanning electron microscopy. The antioxidant (DPPH* and ABTS*) activity of the edible coatings and the antimicrobial (macrodilution method) action against phytopathogenic fungi were verified. The nanoparticles had a size of 331.1 nm and a zeta potential of + 34 mV. The gel, nanoparticles and gel+nanoparticles exhibited minimum inhibitory concentration values ranging from 4 to 5, 1.5 to 2.5 and 1.0 + 0.5 to 2.0 + 1.5 g.L−1, respectively. All the edible coatings exhibited antifungal action. All the coatings had high scavenging activity, especially the gel edible coating. The coatings, especially the gel+nanoparticles, decreased the weight loss, microbiological growth, soluble solids, maturity index and moisture loss of the strawberry and preserved the pH values, anthocyanin content, titratable acidity and sensory characteristics. Therefore, the use of chitosan edible coating containing nanoparticles can be a promising strategy to improve the post-harvest quality of strawberries.