CHILLING IN SAPOTE MAMEY (Pouteria sapota (Jacq.) H. E. Moore and Stearn). II. CHANGES IN TOTAL PHENOLS AND ENZYMATIC ACTIVITY

Abstract

Ripening of sapote mamey fruits (Pouteria sapota (Jacq.) H.E. Moore and Stearn) at room temperature (20 ºC, 50-60 % RH) and during and after low temperature storage (5, 10, and 15 ºC, 80-85 % RH) was studied. From maturity to ripening fruits stored at 20 °C for 12 d showed a decrease in total phenolics from 1653 to 646 mg kg^-1 and the activity of polyphenoloxidase (PFO) increased from 23.8 to 53.1 U g^-1, and at the same time astringency was reduced. Activities of peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) were increased from maturity to ripening from 383 to 2104, 11.4 to 21 and 6.7 to 28.5 U g^-1 respectively. Soluble protein increased from 82 at maturity to 950 mg kg^-1 when ripe. Storage at 5 ºC delayed the decrease in total phenolics content (555.6 mg kg^-1 ) and PFO activity was inhibited (11.2 U g^-1 ) for 8 d after transferred to 20 ºC; there was a decrease in the activities of CAT (14.5 U g^-1 ) and SOD (6.4 U g^-1 ) as well as of total soluble protein (251.7 mg kg ^-1 ) during the same period. POD was inhibited during storage, but it showed similar activity (2443.4 U g-1) to the control after transfer to 20 ºC. Storage at 10 ºC induced similar effects to those obtained at 5 ºC but at a lower intensity. At 15 ºC the enzyme activities, soluble protein and total phenolics did not show a negative behavior. Therefore, the antioxidant enzymes were negatively affected were by storage temperatures lower than 10 ºC and this was associated with chilling injury in sapote mamey fruits.