Potato Review

10 POTATO REVIEW MARCH/APRIL 2020 CUPGRA 2019 CONFERENCE Building resilience W hile conventional ethylene is approved for storage, it is not suitable for all varieties, particularly some processing ones as it can lead to a respiration peak following application and subsequent sugar spike that may lead to fry defects, such as browning, he said. Instead he advised the use of 1-MCP (1-methylcyclopropene), an inhibitor of ethylene, for the processing sector. 1-MCP preferentially blocks the pathways leading to conversion of starch to sugars without impacting sprout suppression. UK registration is anticipated for 2021/22. Data also shows that the effect of the 1-MCP and ethylene combination treatment can be enhanced by the addition of a single, low dose “dormancy modulator”. These results have come from three years of trials which were undertaken by PepsiCo and Cranfield University at both laboratory and pilot scale. Commercially-grown processing varieties with different storage windows and sugar stabilities grown in different areas of the country were assessed for the results of different treatments. Sutton Bridge Crop Storage Research worked on the pilot scale trials to test and validate results. Laboratory experiments undertaken at Cranfield University deduced underlying physiology, building more in-depth understanding of the physiological effects of ethylene on tuber biochemistry. Work was done to assess sprouting from no eye movement to peeping, to 1mm and 3mm sprouts, sensitivity to weight loss, fry colour, as well as targeted metabolomics and next generation sequencing. “This understanding of tuber physiology has allowed us to optimise 1-MCP and ethylene The storage story: Novel alternatives R&D director for field and post-harvest innovation at Pepsico, Mac McWilliam , detailed combinations of physiologically targeted treatments which enable storage duration similar to that achieved by CIPC in processing varieties. timings for consistent results across a range of varieties.” Experiments across different store temperatures and timings have revealed the best results have been when 1-MCP is applied at 1ppm after curing but before pulldown at 8-13 °C, and then ethylene is applied once cold storage has already been established and the tubers have begun to break dormancy ( first sign of eye movement). Moreover, consistent results over three seasons showed 1-MCP significantly reduced sugars and fry defects, reduced eye movement, and also reduced weight loss. 1-MCP is already used extensively in the apple industry under the trade name ‘SmartFresh’ to extend post-harvest storage life, and is currently approved in more than 45 countries world-wide. Only a very small quantity is needed according to Mac. Dr Mark Stalham said the UK is at a competitive disadvantage, as CIPC alternatives such as DMN are available in other European countries and potatoes can be purchased for use in the UK from sources treated with DMN. “Interesting work such as that conducted by PepsiCo on a physiologically targeted ethylene and 1-MCP combination might be able to allow processing growers to become more resilient to the loss of CIPC,” he said. “We also have the possibility of GM-induced resistance to sugar accumulation under cold storage, but to see this technique adopted would require a radical change in consumer perception.” Mark Stalham Cranfield lab