CHILLING INJURY IN SAPOTE MAMEY (Pouteria sapota (Jacq.) H. E. Moore and Stearn). I. CHANGES IN VOLATILES, FIRMNESS AND TOTAL SUGARS

Abstract

Ripening of sapote mamey fruits (Pouteria sapota (Jacq.) H. E. Moore and Stearn) was studied at room temperature (20 °C), during and after storage at low temperatures (5, 10 and 15 °C). Fruits stored for 12 d at 20 °C and 50-60 % relative humidity showed one CO₂ peak (85.3 mL kg^-1h^-1) and one ethylene peak (258.7 µL kg^-1h^-1), as
well as increases in ethanol and acetaldehyde from 21.9 and 6.4 at physiological maturity to 62.7 and 99.7 mg kg^-1 at commercial maturity; increases in total sugars from 82.7 to 267.3 mg g^-1, daily weight losses of 1.02 %, and decrease in firmness from 30 to 1-4 N, were also observed. Storage at 5 °C and 85 % HR for 20 d caused chilling
injury in fruits, measured 8 d after transfer to room temperature, which were associated to increases in respiration and ethylene production of 72.8 and 47.5 %, respectively, as compared to controls; lower ethanol and acetaldehyde accumulation (50 and 46.6 mg kg^-1), as well as a lower total sugar content (200 mg g^-1) and lesser fruit softening (21.8 N). Chilling injury visual symptoms in the flesh were: dark areas in the flesh, failure to ripen, inability to develop the characteristic pulp color, water-soaking areas and hard zones near the seed. Storage at 10 °C caused little chilling injury, while no damage was observed in fruits stored at 15 °C. Weight losses were directly proportional to storage temperature, but after transferring to room temperature the daily weight losses (1.08 %) were similar among treatments.