Quitosana, compostos fenólicos e terpenosno controle da antracnose e qualidade pós-colheita da manga

Abstract

Mango (Mangifera indica L.) has great socioeconomic importance in Brazil. However, production is affected by anthracnose that has caused losses in the main producing regions of the country. Due to the growing concern of society about the excessive use of pesticides, safer and less polluting control measures have been explored. Mango peels extracts, chitosan films or the combination of chitosan with other compounds have shown potential for anthracnose control and postharvest conservation of mango. Therefore, three experiments were performed in this study: the first one aimed to evaluate the in vitro antifungal activity of mango peels extracts using different types of solvents and concentrations on the development of Colletotrichum gloeosporioides; the second experiment evaluated the association of chitosan with phenolic compounds in the development of mango anthracnose caused by C. tropicale and the third experiment aimed to evaluate the potential of applying chitosan coatings associated with phenolic compounds in postharvest ‘Palmer’ mango conservation. ‘Palmer’ mango peels were separated from the pulps and subjected to oven drying and grinding. Subsequently, extracts were obtained in Soxhlet system, using as solvents: methanol, ethyl acetate and hexane. All three extracts were tested at concentrations 0.0; 0.25; 0.5; 1.0 and 2.0 mg / mL by the addition of them in culture medium, where mycelial growth rate index, conidia production and germination were evaluated. Phenolic compounds: citric acid, pyrocathecoic acid, transcinamic acid, gallic acid, caffeic acid, methyl gallate, quercetin and resorcinol at a concentration of 10 mM were incorporated separately into 2% chitosan filmogenic solutions and tested in vitro against C. tropicale. The incidence and severity of anthracnose in mango treated with: chitosan + pyrocathecoic acid, chitosan + citric acid, chitosan + transcinamic acid, chitosan + resorcinol were evaluated. These treatments were also used in the third experiment. Fruits of cv. Palmer were immersed in these solutions and stored in a refrigerated chamber at 14 ºC for 28 days. Every seven days, the fruits were evaluated for fresh mass loss, soluble solids, pH, titratable acidity, firmness, chromaticity, hue angle and lightness of peel and pulp. The methanolic, hexanic and ethyl acetate extracts of mango peel have inhibitory potential in the development of C. gloeosporioides. Hexane extract showed lower conidia production and there was total inhibition of germination when 1 mg / mL ethyl acetate extract and 2 mg / mL methanolic and hexane extracts were used. The association of chitosan with phenolic compounds has antifungal potential and controlls the intensity of anthracnose in mangoes. Total inhibition of growth, conidia production and germination of C. tropicalewas verified with incorporation of chitosan of citric, pyrocathecoic and transcinamic acids. In postharvest conservation of 'Palmer' mango, chitosan coatings associated with phenolic compounds are able to retard fruit ripening and maintain quality.