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
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.