ISHS Acta Horticulturae 343: Physiological Basis of Postharvest Technologies
THE UNDERLYING BIOCHEMISTRY OF THE EFFECT OF MODIFIED ATMOSPHERE AND STORAGE TEMPERATURE ON FIRMNESS DECREASE IN PAPAYA |
| Authors: | H. Lazan, Z.M. Alid, M.K. Selamat |
| Abstract:
The mechanism by which modified atmosphere packaging (MAP) in heat-shrinkable film and storage at moderately low (15C) temperature (MLT) retarded firmness loss in papaya (Carica papaya L. cv. Exotica) fruits was investigated. In papaya, the rapid loss in firmness during ripening at ambient (25C) temperature was associated closely with increase in activity of polygalacturonase (PG), pectimnethylesterase (PME) and B-galactosidase as well as with depolymerization of cell wall pectins. MAP and MLT treatments delayed as well as retarded firmness decrease, with the former being more effective than the latter in retarding texture change particularly when the fruit was stored at the lower-than-ambient (15C) temperature. The efficacy of the different treatments in retarding firmness loss was reflected closely by the varying pattern of the increase in the cell wall hydrolases activity, particularly B-galactosidase, during storage ripening. Besides the cell wall enzymes, depolymerization of wall pectins was also affected by the storage treatments. The overall close correlation between the enzymes activity and variations in fruit firmness with ripening, tissue position and storage treatments suggest that the wall hydrolases may collectively play a significant role in the softening of papaya. | |
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