The effect of atmospheric components in potato storage on tuber characteristics

Many potato stores are well-sealed units. This provides little opportunity for ambient air exchange which would remove the carbon dioxide (CO₂) produced by respiring tubers. The sprout suppressant ethylene stimulates tuber respiration, leading to the possibility of elevated CO₂ levels in store. It was suspected that insufficient ambient air exchange would affect tuber quality (taste, texture and fry colours) and influence the development of disease and non-pathogenic disorders (e.g., blackheart). However, at the time the research was commissioned, there was little publicly available information on the changes in CO₂ levels that can occur in stores and the subsequent consequences for potato quality.  

The project had three main components:

• Understanding the range of carbon dioxide levels within working potato stores over a storage season
• Defining the effects of carbon dioxide and ethylene on taste and texture attributes of potato tubers
• Investigating the potential effects of high carbon dioxide concentrations on disease risk in stored tubers

Results

In total, 19 stores were monitored for CO₂ levels. The levels recorded had no apparent effects on taste, texture or appearance of the tubers as most were used to supply supermarket contracts for high quality pre-pack potatoes. There was, however, an elevated weight loss (>6%) observed.

To define the effects of CO₂ and ethylene on taste and texture attributes, three cultivars, Maris Piper, Marfona and Estima were exposed to different levels of CO₂  atmosphere (from ambient to 6%) in store. To understand the potential interactions between CO₂ and ethylene used for sprout suppression, the trials were carried out with and without ethylene at 10 ppm. There was no evidence that CO₂ and/or ethylene gases adversely affected tuber taste or texture.

Altering the CO₂ level of the storage atmosphere (from ambient to 10%) within the incubation environment had different effects on different pathogens. Infection with both Pectobacterium carotovorum and Phoma exigua increased with increasing CO₂ dioxide concentration whereas infection with Fusarium sulphureum decreased with increasing CO₂ concentration.