Enzymatic changes in plum (Prunus salicina Lindl.) subjected to some chemical treatments and cold storage.

The objective of the present work is to see the effect of different chemical treatments on pectin methylesterase (PME) activity and softening of the fruits. Purple plums (cv. Satluj) fruits were harvested at colour break stage and treated for 5- minutes in aqueous solutions of salicylic acid at 138, 276 and 414 ppm, Ascorbic acid at 10,000, 20,000 and 30,000 ppm, and Gibberelic acid at 20, 40 and 60 ppm. For control the fruits were dipped in distilled water. Treated fruits were stored at low temperature conditions for 40 days. Physico chemical characteristics and PME activity were determined at 10 day interval. The colour of the fruits improved with respect to a* and b* values progressively throughout the storage, whereas, fruit firmness decreased. Total sugars and PME activity increased before showing a declining trend. Pre-storage application of salicylic acid (414 ppm) significantly delayed colour development. Fruits treated with salicylic acid (414 ppm) retained highest firmness, total sugars and PME activity at the end of storage.