Estrés por impacto en frutos de zapote mamey (Pouteria sapota) durante el manejo postcosecha

Evaluations of impact stress in sapote mamey [Pouteria sapota (Jacq.) H. E. Moore & Stearn] were carried out in fruits harvested at Jalpa de Méndez, Tabasco, México, over two harvest dates: May and June of 2006. Sapote mamey fruits at physiological maturity were dropped from 0.0, 0.6, 1.2 and 1.8 m, and then evaluated regarding rate of respiration, ethylene production, weight loss and colour (lightness, hue angle and chroma) under laboratory conditions (30 ± 2°C; 85 % RH). Untreated sapote mamey fruits showed the typical climacteric behaviour with peaks of respiration rate and ethylene production between 2 and 3 d after harvest, with values of 65 to 66 mg CO₂ kg^-1 h^-1and 34 and 48 μL C ₂H₄ kg^-1 h^-1, respectively; weight loss was of 8 % after 6 d, and lightness and chroma diminished with ripening. Fruits harvested in May showed higher respiration and hue angle values than those of June; the rest of evaluated variables did not showed statistical differences due to harvest date. Sapote mamey dropped from more than 1.2 m increased respiration (between 15 and 27 %) and ethylene production (between 27 and 56 %) compared to the control; they also had highest weight losses, while lightness and chroma values were lowest than control, and no statistical change occurred in hue angle. Negative effects of mechanical stress by impact were detected with drops greater than 0.6 m.