Articles
EFFECT OF POLYAMINES ON QUALITY CHANGES IN PAPAYA AND MANGO FRUITS
Recently, polyamines have been reported to delay senescence and fruit ripening (Galston and Kaur-Sawhney, 1995), and extend shelflife and maintain fruit quality (Kramer et al., 1991). We studied the effect of polyamines on quality changes of papaya and mango.
Fruits of papaya cv. ‘Dampit’ at 10 % yellow (score 2) skin color and mango cv. ‘Arumanis’ at 85 % maturity were used.
Papayas were treated with putrescine at 0, 1, 3, and 10 mM; and with spermidine and spermine at 0, 0.3, 1, and 3 mM. Mango fruits were treated with putrescine, spermidine, and spermine at 0, 0.3, and 3 mM. Fruits of papaya were soaked in the polyamine solution for 30 minutes, while fruits of mango were pressure infiltrated at 0.72 kg/cm2cm for 3 minutes.
Fruits were then stored at room temperature (28°C).
Papaya fruit were observed at 0, 3, 6, and 9 days after treatment (DAT). Measurements were of weight loss, peel color score, fruit firmness (measured by penetrometer), and total soluble solids (TSS, measured by refractometer). Mango fruits were observed at 0, 4, 8, and 12 DAT. Variables observed were weight loss, fruit firmness, TSS, and titratable acidity.
Papaya fruit treated with spermine were firmer than untreated control fruits and showed a lower colour score.
Control fruits and fruits treated with spermine at 0.3, 1, and 3 mM were estimated to reach score 7 (overripe) at 5.2, 7.2, 7.4, and 7.8 days respectively, so that the highest concentration of spermine extended shelflife by 2.6 days.
Fruits treated with spermine had a lower TSS than untreated fruits.
Spermine treatment did not consistently retard weight losses, though they were generally lower.
Spermidine and putrescine had no effect on papaya fruit firmness, fruit color, and TSS, but their highest concentrations caused the least weight loss.
In mango experiments, putrescine, spermidine, and spermine at concentrations of 0.3 and 3 mM gave similar effects in maintaining fruit firmness (Table 1). The three polyamines had no effect on mango fruit weight loss as compared to untreated control (average loss was 17% at 12 DAT). Polyamine effects were not consistent on TSS and titratable acidity.
Pressure infiltration at 0.72 kg/cm2 seems too high.
At 8 DAT some blemish was apparent, while between 8 and 12 DAT, fruit started to rot.
In summary, soaking papaya fruits in spermine delayed softening and the increase of total soluble solid and peel color score, extending shelflife by up to 2.6 days.
Pressure infiltration of polyamines delayed mango fruit softening.
Table 1. Effect of polyamines on mango firmness.
Days = days after treatment.
Means in the same column followed by the same letter as not significant different by Duncan Multiple Range Test.
| Treatment | Depth of Penetration(mm/100 g/10 seconds) |
| 0 Days | 4 Days | 8 Days | 12 Days |
| Control | 8.6 | 20.1c | 34.5c | 51.5c |
| Putrescine | 10.9 | 13.6b | 27.4b | 40.6b |
| Spermidine | 8.2 | 10.5a | 24.5a | 31.0a |
| Spermine | 8.6 | 11.0a | 23.2a | 29.8a |