When apples are cut, the new surfaces quickly go brown. Although nitric oxide can delay this browning it is thought to be impractical to include exposure to the gas in a commercial processing operation. An alternative is to use diethylenetriamine-nitric oxide (DETANO), which releases nitric oxide at the surface of cut tissues.
In the research described here, Granny Smith apples were sliced and the slices dipped into solutions of DETANO for different periods and at different pH at 20 degsC. The slices were dried after treatment and stored at 0 degsC in plastic containers equipped with vents to lessen CO2 accumulation.
Slices were also placed in an atmosphere containing nitric oxide for two hours before storage at 0 degsC. Post-harvest life was defined as the time required for slices to develop unacceptable browning in storage.
The optimum treatment was to dip slices in a solution of 10mg per litre DETANO at pH6.5 (phosphate buffer) for one minute. This increased post-harvest life by about six days relative to dipping in water.
Furthermore, the same solution could be used on five slice batches without losing effectiveness. Buffering the solution pH was necessary to stop the slices' acidity from degrading the DETANO prematurely.
Use of the Nitric Oxide-donor Compound, Diethylenetriamine-nitric Oxide (DETANO), as an Inhibitor of Browning in Apple Slices by Pristijono, Wills and Golding (2008). Journal of Horticultural Science & Biotechnology 83 (5): 555-558. The authors' abstract of their manuscript can be seen in full at www.jhortscib.com.