Pre-storage application of polyamines improves shelf-life and fruit quality of mango

Mature green mango (Mangifera indica L. cv. 'Kensington Pride') fruit were dipped for 6 min in aqueous' solutions containing different concentrations (0, 0.01, 0.5, 1.0 mM) of various polyamines (PAs) including spermine (SPM), spermidine (SPD) and putrescine (PUT), with 0.01% 'Tween-20' as a surfactant, to investigate their effects on shelf-life and fruit quality. Treated fruit were air-dried (22 degrees +/- 1 degrees C), packed in Ecopax trays and stored in a cool room (13 degrees +/- 1 degrees C, RH 85 +/- 5%) for 3 or 4 weeks. Following storage, fruit were allowed to ripen to the eating soft stage (score 4) at ambient temperature (22 degrees +/- 1 degrees C). Pre-storage dip application of PAs retarded development of mean fruit softness (10.3%) and visual colour (26.3%), and reduced weight loss (6.8%) during storage without significant (P <= 0.05) reductions in ethylene production and respiration rate. During ripening of 3 week-stored fruit, 0.5 mM SPM-treated fruit exhibited significantly (P <= 0.05) lower mean respiration rates compared with the control. Application of PAs significantly (P <= 0.05) increased fruit firmness and ascorbic acid content, while reducing carotenoids, total soluble solids (TSS)/acid ratio and Hue angle of ripe fruit compared with the no-PA treatment. In conclusion, pre-storage dip application of PAs improved the shelf-life of mango fruit without impairing fruit quality.