The role of some salts applied in combination with wax on the development of postharvest rots was
examined on ‘Tarocco’ and ‘Valencia late’ oranges and ‘Comune’ Clementines. Sodium carbonate and
bicarbonate, potassium carbonate and bicarbonate, ammonium bicarbonate, and potassium sorbate, at
6% concentration (w/v), in combination with a commercial wax, were evaluated for their activity against
naturally occurring postharvest decay. Fruit were stored for one month at 4 ◦C (‘Tarocco’ and ‘Valencia
late’ oranges) or 6 ◦C (‘Comune’ Clementine), followed by one week of shelf life at 20
±
2 ◦C and high RH.
Most decay was from green and blue moulds, caused by Penicillium digitatum and P. italicum, respectively,
with an average incidence of 11% for ‘Comune’ Clementines and 5% for both ‘Tarocco’ and ‘Valencia
late’ oranges. Decay caused by Botrytis cinerea and Alternaria spp. was also observed. The incidence of
postharvest rots on fruit treated with wax alone (11%) was higher than on those treated with water (7%),
whereas in fruit treated with wax combined with different salts, decay incidence was significantly lower
than with wax and water controls. In particular, potassium sorbate incorporated in wax significantly
reduced the incidence of postharvest decay in all tested cultivars. The incidence of decay on fruit treated
with imazalil was low, not exceeding 1%. Salts, except ammonium bicarbonate, interfered with the action
of the wax to retard weight loss. The results indicate that the addition of the salts to wax may be an easy
and effective mode of their application, since no additional equipment is needed.