CONSERVAÇÃO PÓS-COLHEITA DE PÊSSEGOS COM APLICAÇÃO DE REVESTIMENTOS ADITIVADOS DE EXTRATO DE ERVA-MATE

Abstract

Peach is an important climacteric tropical fruit consumed in many countries, being an important source of vitamins and nutrients for human diet. However, inadequate postharvest conservation can influence peach quality and cause a high level of fruit losses. The experiment was conducted with the objective of testing the potential of the application of glycerol-based coatings or cassava starch, supplemented with yerba mate extract (Ilex paraguariensis St. Hill) in the postharvest conservation of peaches. For the first year of evaluation, fruits cv. Della Nona and the treatments used were:uncoated fruits, fruits with glycerol-based coatings supplemented with yerba extract at 0 g L-1 (G+0%E), 5 g L-1 (G+5 %E), 10 g L-1 (G+10%E) and 15 g L-1 (G+15%E) and fruits with cassava starch-based coatings supplemented with yerba extract at 0 g L-1 (F+0%E), 5 g L-1 (F+5%E), 10 g L-1 (F+10%E) and 15 g L-1 (F+15%E). The fruits were stored for 20 days at 1 ° C with 95% relative humidity (RH). In the second year of experimentation were used peaches cv. Kampai were evaluated in the following treatments: control (fruits treated with distilled water), glycerol-based coatings supplemented with yerba extract at 0 g L-1 (G+0%E) and 15 g L-1 (G+15%E) and fruits with cassava starch-based coatings supplemented with yerba extract at 0 g L-1 (F+0%E) and 15 g L-1 (F+15%E). The fruits were stored for 13 days at 1 ° C with 95% relative humidity (RH). To evaluate the postharvest quality of fruits, physicochemical analyzes were performed, including soluble solids (SS), titratable acidity (TA), ratio (SS/TA), weight loss, firmness, staining and anthocyanins. To evaluate the in vitro effect of the coatings on fungus growth Monilinia fructicola, causal agent of brown rot, conidia germination and the area under the mycelial growth curve (AUMGC) were evaluated. In order to evaluate the in vivo brown rot control, the fruits were inoculated with the M. fructicola fungus and evaluated for incidence (%) and infection index (%) and the peroxidase and polyphenoloxidase enzymes. It was observed that the use of coatings reduced the loss of mass by 49% and soluble solids content and increased fruit firmness, delayed browning of the fruit epidermis and evolution of red and yellow coloration. The addition of the doses of the aqueous extract of yerba mate influenced the postharvest quality of the fruits and the effectiveness of the coatings. For the fruits coated with glycerol the lower doses of yerba mate reduced the loss of mass and the soluble solids content and for coloring the doses of 0 g L-1, 5g L-1 and 15g L-1 delayed the browning of the epidermis and evolution of red coloration. In the coating of the fruits with cassava starch, the addition of 5 g L-1 and 15 g L-1 of the yerba mate extract promoted greater firmness of the fruits and the dose of 5 g L-1 lower soluble solids content, for color the yerba mate increased darkening of the epidermis and accelerated the evolution of the red coloration. For peaches cv. Kampai treatment with glycerol presented greater conservation of physical-chemical characteristics in the storage period in relation to those coated with cassava starch. The treatment with glycerol promoted greater red color development in the fruits, which coincides with the results of anthocyanins. The coatings were not efficient in the in vitro control of M. fructicola, being that the higher doses promoted higher AUMGC and for germination of conidia the dose of 10% of the extract was more efficient in the control of the pathogen. In the in vivo control the F + 15% treatment completely inhibited the development of brown rot in the peaches in cv. Della Nona, for peaches cv. Kampai, the lowest incidence and infection rate were observed for the highest dose of yerba mate extract, for both glycerol and cassava starch. For the enzymes, the use of coatings promoted increased peroxidase activity.