Postharvest curing and storage of New Zealand-grown potato cultivars ('Moonlight' and 'Nadine') for the fresh export market

Tuber quality problems such as skin tears (skinning), rots, browning, shrivelling and weight loss in New Zealand-grown export potatoes have caused significant postharvest losses and insurance quality claims from overseas distributors. These quality issues could be attributed to poor management of curing and subsequent storage conditions. This study investigated the effects of various curing and storage conditions (i.e. duration, temperature and relative humidity (RH)) on tuber quality of two potato cultivars, 'Moonlight' and 'Nadine', that are exported to Fiji. Results have shown that high curing RH (93%) led to significantly lower skin browning, shrivelling and weight loss in both cultivars, and significantly lower tuber rot in 'Nadine' than low curing RH (62%). Shorter curing duration (7 days) yielded significantly lower shrivelling in 'Moonlight', and significantly lower tuber rot in 'Nadine', than longer curing duration (14 days) or control (0 day). Percent weight loss was significantly lower in cured potatoes than in control for both cultivars. Curing temperatures (16 or 26 degrees C) and storage RH (65 or 90%) did not significantly affect the tuber qualities assessed. Therefore, 7 d curing at >90% RH and at least 15 degrees C is recommended for minimising quality problems occurring during transport of these potato cultivars to distant markets.