Ethylene absorbents influence fruit firmness and activity of enzymes involved in fruit softening of Japanese plum (Prunus salicina Lindell) cv. Santa Rosa.

Introduction. Plum cv. Santa Rosa shows climacteric behaviour and grows profitably under sub-temperate conditions in India. After ripening, it has a very limited shelf life (3–4 days) in ambient conditions [(38 ± 2) °C and at (68 ± 4)% RH]. Hence, there is an urgent need to extend its marketability using recent techniques. Materials and methods. Plums were harvested at the pre-climacteric and climacteric stages of maturity and packed with newspaper shreds (control), KMnO4-impregnated chalks, KMnO4-impregnated newspaper shreds or ethylene-absorbent sachets; then they were transported by road to New Delhi. The biochemical and physiological analyses were carried out at 3-day intervals on plums stored in supermarket conditions [(20 ± 1) °C and at (90 ± 2)% RH] for 15 days. Results and discussion. Untreated fruits had less firmness than those which were packed with ethylene absorbents. The activities of fruit-softening enzymes such as lipoxygenase (LOX), polygalacturonase (PG) and pectin methylesterase (PME) increased rapidly in the control treatment in comparison with plums packed with various ethylene absorbents, the least being either with ethylene-absorbent sachets or with KMnO4-impregnated newspaper shreds. Plums of pre-climacteric and climacteric maturity attained respiration and ethylene evolution peaks on the 9th day and 6th day, respectively. Conclusions. The plums of pre-climacteric and climacteric stages of maturity packed with ethylene-absorbent sachets showed the best results in supermarket conditions in maintaining the firmness, quality and shelf life of plum up to the 12th day and 9th day of storage, respectively. [ABSTRACT FROM AUTHOR]