A CURTIN University study exploring the impact of modified atmospheres in prolonging the life of plums could make the transportation of fresh fruit by sea a more commercially viable—alternative to current expensive air transport.
Professor Sukhvinder Pal Singh found the appearance of chilling injury in Japanese plums pre-treated with the fruit ripening retardant 1-methylcyclopropene (1-MCP) and stored in atmospheres containing low oxygen and high carbon dioxide could be delayed from a maximum of four weeks to eight.
Now a scientist at the National Agri-Food Biotechnology Institute in India, Prof Singh says the plum is a commercially important fruit crop for WA and among the most exported to South East Asian markets.
However chilling injury is a major problem, limiting the fruit’s storage life for refrigerated transportation. Chilling injury is a manifestation of oxidative damage to fruit tissue and symptoms include browning flesh, translucency, mealiness, and flesh bleeding.
The research was part of Prof Singh’s PhD thesis, supervised by Prof Zora Singh and published in Postharvest Biology and Technology.
They used commercially mature fruit from Casuarina Valley Orchard in Karragullen near Perth pre-treated with 1-MCP which is approved for use in WA. The fruit was stored up to eight weeks at zero to one degree in different atmospheres with varying amounts of oxygen and carbon dioxide generated through packaging in low density polyethylene bags.
Testing found the most efficient atmosphere in reducing chilling injury was one per cent oxygen and three per cent carbon dioxide.
Prof Singh says the significance of the findings is two-fold.
“In the current era of consumer-driven markets, consistent supply of a high quality fruit at competitive price is of paramount importance,” he says.
“In order to reduce the transportation cost by air, marine shipment is the viable option, but it may take a few weeks.
“Controlled atmosphere technology in combination with 1-MCP can be used for long distance shipment of fruit without much compromise in quality. Mangoes are currently sea freighted using controlled atmosphere technology from Australia to the United Kingdom and other markets.
“In addition to the commercial importance, this study also provided scientific evidence that the oxidative damage in the fruit tissue resulting from free radicals generated in response to low temperature stress can be minimised and delayed when the fruit is stored under controlled atmosphere.
“In addition, the synergistic effects of controlled atmospheres and 1-MCP, an inhibitor of ethylene action, are more promising in extending the storage life than either of alone.”