Effects of Elevated CO2 and Trace Ethylene Present Throughout the Storage Season on the Processing Colour of Stored Potatoes

Abstract

Previous short-term trials (9-week duration) have shown that the fry colour of stored potatoes (Solanum tuberosum L.) can be negatively affected by simultaneous exposure to elevated CO2 plus a trace concentration of ethylene gas. In the present study, trials were conducted during each of two storage seasons (2008–2009 and 2009–2010), to examine the effects of long-term exposure to these two gases during the entire November to June storage season. In each year, 0 or 2 kPa CO2 and 0 or 0.5 μl l−1 ethylene were applied in a factorial design to tubers of four processing cultivars (Russet Burbank, Shepody, Innovator and Dakota Pearl). Processing colour of the tubers was evaluated at the start of each trial and at intervals of 4 weeks thereafter. In the three French fry cultivars (i.e. Russet Burbank, Shepody and Innovator), the fry colour of tubers exposed to CO2 + ethylene together was darker than the controls. In the chipping cultivar Dakota Pearl, the gas treatments had only a small effect on chip colour. Fry colour darkening due to an interaction of CO2 × ethylene × time was significant only in Innovator. Processing colour of all cultivars was darkened by these gases, but the magnitude and timing of the responses varied widely between gases, among cultivars and from the start to the end of the season.