Storage of salads follows the same principles as for any other potato crop type, although extra care is required with ventilation to minimise water loss. For successful storage, it is important to produce a healthy and blemish free salad crop.
Like all potato types, unless the salad crop is destined for rapid marketing with un-set skin, it is important to harvest only when the skin has fully set. This will protect against damage and reduce the risk of water loss during storage. The salad variety Charlotte may require longer for skin set than other salad varieties.
In general, as salad crops tend to be higher value and more sensitive to any loss of water, salads should be stored in purpose built potato stores with good insulation, effective ventilation and temperature control, ideally using refrigeration.
Priorities after harvest are drying the crop and curing the crop. Both can be achieved at the same time especially for salad crops which tend to be lifted earlier under warmer conditions.
As with all box storage, efficient ventilation for drying, cooling and maintaining an even temperature relies on good box layout and ensuring air passes through pallet apertures and not down the sides of boxes. Avoiding over-filling boxes is also important. Efficient ventilation is more important for salad crops as small tubers in boxes leave less air space between tubers for air movement. Where the soil content of boxes is high, ventilation efficiency is reduced
Early after harvest, a decision should be made about the length of storage of salad stocks for marketing. Where marketing is planned before the New Year, attention to detail with salad stocks is less critical. Where longer term storage is required, more care is required in storage of salad crops.
Especially for longer term storage, once drying and curing have been completed, temperature pull-down to target temperatures should be achieved as quickly as possible. Typical pull down rates are between 0.25oC to 0.5oC a day.
Target temperature for salads is around 3oC unless very long term storage is planned where a temperature of 2.0oC to 2.5oC will be more suitable. Where these latter low temperatures are used, this is best achieved in stores with efficient refrigeration.
Once tubers are at the target temperature, the principal concern is to minimise variation in temperature across a stack of potatoes by regular, but not excessive, ventilation. The frequency of ventilation to sustain temperatures within 1oC or less across the stack varies depending on the efficiency of the ventilation system and the store layout etc. Typically, 10 to 20 minutes every 2 hours is sufficient in good stores but in modern stores the frequency of ventilation can be less. It is important to avoid excessive moisture loss from salad potatoes as this will affect marketability and the use of VFD (inverter) fans for ventilation allows the speed to be reduced during the steady state period of storage.
Regular monitoring of tuber temperature and visual inspection for condensation will confirm the effectiveness of ventilation.
It is important when handling salads out of store that damage is limited. Ideally, tubers should be warmed from their holding temperature to 6oC or 8oC before grading.