Polyvinyl alcohol coating and starch in the post-harvest conservation of avocado

ABSTRACT: This research evaluated whether polymers, individually or in mixtures of PVOH and starch, improve the physicochemical characteristics of avocados for up to eleven days after harvest. Parameters of titratable acidity, respiratory rate, mass loss, total soluble solids and dry matter were evaluated in coated and control fruits. The physicochemical characteristics and preservation of avocado fruits type daisy (Persea americana) for up to eleven days after treatment with 3% starch (S); 2.25% (A) + 0.5% (P); 1.5% (S) + 1% (P), 0.75% (S) + 1.5% (P) and 2% PVOH (P). Glycerol was added to the formulation in a proportion of 30% in relation to the starch. Uncoated fruits were used as controls. The fruits were kept at room temperature (20 ± 5 °C and 70 ± 10% RH), and their analyses occurred before applying the coating (time 0) and on days 4, 7, and 11 of storage - totaling four evaluation times. The data were subjected to homogeneity tests of variances (Hartley test) and normality of residues (Jarque-Bera test). Fruits coated with 2% PVOH had lower respiration rate throughout the experiment, showing that they were efficient in reducing gas exchange between fruits and medium. All coatings reduced the loss of fruit mass and the fruits coated with 0.75% starch and 1.5 PVOH and with 2% PVOH were the ones that most reduced the mass loss. The acidity, firmness and total soluble solids did not differ statistically. PVOH coating was more efficient than starch coating and uncoated fruits during the experiment.