Food Irradiation Updates

Published by Ronald F. Eustice and sponsored  by GRAY*STAR Inc.
February 2016
Food Irradiation Update is published monthly by Ronald F. Eustice, a food quality & safety assurance consultant based in Tucson, Arizona. He can be reached at:
and at 612.202.1016
How often we hear the words "Eat healthy" and are told to eat fruits and vegetables! The problem is that most consumers live in climates where fruits and vegetables are only available during a brief season. In many other countries, phytosanitary rules designed to protect local agriculture prevent importation from countries with pests that can "hitch hike" on imported produce. Irradiation is changing all this by opening up new markets for previously prohibited produce. It's a "Win, Win" situation! Consumers can eat healthier, farmers that produce the product gain market access, farmers in the receiving country are protected from invasive pests and international commerce is enhanced. We all gain.  
Featured Article: Irradiating Insect Pests; International Innovation; By Dr. Peter A. Follett 
Dr. Peter Follett, USDA Scientist & Irradiation Expert 

USDA scientist Dr Peter A Follett discusses his pioneering work on the development of phytosanitary irradiation as an effective postharvest quarantine treatment when exporting agricultural products.

Could you begin by introducing your main research aims and activities?

Along with my colleagues at the US Department of Agriculture-Agricultural Research Service, I work to develop new or improved postharvest quarantine treatments so that Hawaiian farmers can safely export high-quality, fresh agricultural products to the US mainland and other countries. Due to its mild climate, diverse tropical and subtropical agricultural crops and habitats, reliance on imported fresh produce, and popularity as a travel destination, Hawaii has acquired a wide variety of invasive insect pests from around the Pacific Rim. Many of these pests, such as the Mediterranean fruit fly, are not established in mainland US, and therefore quarantine treatments are required by law to prevent their spread in host commodities (fruit, vegetable or ornamental crops) exported to the continental US or elsewhere. Postharvest treatment of fresh commodities with heat, cold, chemical fumigants or irradiation aims to kill any insect pests or hitchhikers and prevent their spread to new areas. It's estimated that new invasive pests cost American farmers $120 billion annually, and are a major threat to agriculture, as well as urban and natural ecosystems.

In what ways does phytosanitary irradiation differ from other types of food irradiation?

Food may be irradiated for several reasons: to reduce food-borne pathogens such as Escherichia coli, Listeria and Salmonella; to inhibit sprouting in tuber and bulb crops such as potatoes, onions and garlic; to extend shelf life by deactivating spoilage organisms; and to control quarantine insect pests in fresh commodities or stored products to reduce contamination and losses. I mostly work in the latter area, developing postharvest, phytosanitary treatments to control insects in fresh and durable commodities. Irradiation is an alternative technology to fumigation, particularly to methyl bromide fumigation. This is the most common method of disinfesting commodities, but has been shown to damage the stratospheric ozone layer.

How widespread is the current use of phytosanitary irradiation?

Hawaii has been a leader in the use of irradiation to export fresh fruits and vegetables, having conducted pilot studies in the 1990s and opened two commercial irradiators in 2000 and 2013. These are designed specifically to treat fresh agricultural products like fruit, vegetables, herbs and flowers. Currently, Hawaii is shipping 10 types of fresh fruit and vegetables to the US mainland using irradiation to control quarantine pests, and the state has approvals for 15 more. Interest from foreign countries in exporting irradiated fresh produce took off in 2006 after the approval of the first ever generic irradiation treatments. During the past eight years, India, Mexico, Pakistan, South Africa, Thailand and Vietnam have all established bilateral agreements with the US for the use of phytosanitary irradiation, and are exporting increasing volumes of fruit (13.6 million kg in 2014) using generic radiation treatments. Other parts of the world are following suit. Australia is exporting an increasing number of fruits and vegetables to New Zealand and Malaysia using irradiation quarantine treatment.

What are the negative effects, if any, of phytosanitary irradiation?

Technically speaking, there are no shortcomings. All insect pests can be controlled by irradiation, and most fresh horticultural commodities can tolerate irradiation treatment without injury at the low doses required to control insects. For this reason, irradiation is superior to other postharvest quarantine treatment technologies. Furthermore, irradiation is probably the most thoroughly studied food processing technology, with hundreds of nutritional and toxicological studies during the past 60 years on a variety of foods. Numerous major health and science organisations have reviewed the literature and endorsed, approved or supported the safety and benefits of food irradiation. Irradiation is approved in more than 60 countries around the world for a wide variety of food products.

Can you share your hopes for the future of phytosanitary irradiation?

For countries that have already approved use of phytosanitary irradiation, fresh produce exports should steadily increase. Consumers should see a wider variety of produce available in the marketplace as countries such as India, South Africa, Thailand, Mexico and Vietnam export increasing volumes of irradiated tropical fruits - including mango, rambutan, guava and dragon fruit - to major markets and gain market penetration. Other countries should come aboard soon given recent successes. The sky's the limit!
Link to article ... 
MYTH of the MONTH: "E-Beam irradiators are faster than Gamma irradiators." By Russell Stein
"E-Beam irradiators are faster than Gamma irradiators."

This statement is incorrect. Processing speed is based on the designed production throughput for an irradiator independent of whether it is E-Beam or Gamma.
There is a fundamental difference of how the radiation is delivered between e-beam irradiation and gamma irradiation.   E-Beam irradiators expose a relatively small mass of product for a relatively short period of time. In contrast, gamma irradiators expose a relatively large mass of product for a relatively long period of time. Typically, the "dose rate" for electrons is much greater compared to that of gamma but the amount of product exposed during irradiation is much greater in a gamma irradiator than in an e-beam irradiator.

This myth was created by only looking at the "dose rate" aspect of productivity and not at the mass of the product being irradiated. For example, using the same product/dose in an e-beam and gamma irradiator of similar production throughput, one could say that the e-beam irradiator irradiates a product in seconds whereas a gamma irradiator takes minutes. This would support the myth.

What was left out of the preceding example was that the e-beam irradiator was only irradiating a box of product in seconds, whereas the gamma irradiator was irradiating a pallet of product in minutes. This breaks the myth.

The "speed" of an irradiator is really its production throughput whether it is e-beam or gamma. Or, on average, how many pounds an hour the unit can produce. Not how many seconds it takes one box to run through the unit.

Technically, the real production rate of an irradiator (speed) is measured in (dose x mass)/time. For example: kGy-kilograms/hour. Both e-beam and gamma irradiators can be designed for any production rate. Like all processing equipment, the design parameters are defined to meet market enough to meet demand at the appropriate cost. 
 Link to article ... 

Russell Stein 
U.S. re-opens doors for Dominican Republic fruit fly host crops; Fresh Fruit Portal; (January 9, 2016): 
USDA/APHIS has lifted import restrictions for a wide range of fruits from Dominican Republic. Irradiation is one of the options.
The U.S. Animal and Plant Health Inspection Service (APHIS) has lifted import restrictions on a range of crops grown in the Dominican Republic, provided they meet certain pest mitigation standards. The issue dates back to March last year when Mediterranean fruit fly was found in the tourism hot spot Punta Cana, prompting U.S. authorities to suspend commercial consignments of any crops that were hosts for the pest.

The initial list included avocados, clementines, grapes, grapefruit, lemons, litchis, longans, sapote, mandarins, mangoes, oranges, papayas, peppers, pummelos, tangelos, tangerines, tomatoes and cactus fruit. In April however, avocados and green tomatoes were removed from that list as they were not deemed Medfly hosts.

Now all these crops will be allowed into the United States, so long as they are from specified regions that do not pose a risk of introducing Medfly.

"The movement of restricted Medfly host material from non-restricted areas must be done in exclusionary containers to prevent the contamination of host material that is destined for export to the United States," APHIS said.

"Shipments must be inspected and accompanied by a phytosanitary certificate that is issued by the Dominican Republic's Ministry of Agriculture and that indicates the province of origin in the Dominican Republic." The service added Dominican Republic-grown mangoes could still be exported under the hot water treatment-based pre-clearance program, or after irradiation treatment.

APHIS Deputy Director of Phytosanitary Issues Management Michael Guidicipietro thanked the Dominican Republic Government for keeping its counterparts informed with reports and weekly updates about its Medfly eradication program.

"We applaud the surveillance and eradication efforts of the Dominican Government, as well as the program of sterile insect release in areas with outbreaks to meet the goal of finally eradicating the insect from the Dominican Republic territory," he said.

Link to article ...
Irradiation preserves blueberry and grape quality; Phytosanitary treatment maintains fruit quality for long-distance transportation, distribution, storage; American Society of Horticultural Science: (January 5, 2015)
Research at Chapman University shows that irradiation can be effective for treating blueberries for export without compromising quality. 
Scientists monitored the effects of irradiation on the quality of three varieties of blueberries and two varieties of grapes treated at phytosanitary dose levels. Results showed that blueberries and grapes have a high tolerance for phytosanitary irradiation and that storage affects quality more than irradiation. Firmness was the primary attribute affected by irradiation for both varieties of grapes. Sensory tests showed that consumers did not have a preference for control or irradiated fruit.

It is often necessary to treat produce for insects in order to transport crops out of quarantine areas. Fumigation with methyl bromide, one of the most common treatments, is in the process of being phased out because of its depleting effect on the ozone layer. Alternately, ionizing irradiation at low doses is being used worldwide as a promising phytosanitary treatment for fruit such as guava, rambutan, and mango.

New research reveals that irradiation can also be effective for treating blueberries and grapes for export without compromising fruit quality.

'Star', 'Jewel', and 'Snowchaser' blueberries and 'Sugraone' and 'Crimson Seedless' grapes were irradiated at a target dose of 400 Gy (range of 400-590 Gy for blueberries and 400-500 Gy for grapes) and stored for 3 and 18 days under refrigeration, plus 3 days at ambient temperatures. "This experiment was designed to simulate the time of ground transport (from California) to Mexico and sea transport from California to Asia," the scientists explained. The fruit was then evaluated for soluble solids concentration, titratable acidity, and weight loss. With respect to these quality attributes, the results showed differences among fruit varieties, but the researchers found treatment effects to be "not significant."
The study also involved sensory tests in which consumers evaluated the fruit on appearance, flavor, texture, and overall "liking." "Firmness was the primary attribute affected by irradiation for both varieties of grapes, but sensory testing showed that consumers did not have a preference for control or irradiated fruit," the authors said. "However, sensory scores for flavor were higher for the irradiated berries than the control berries after storage, suggesting a decline in quality of the control blueberries with time," the scientists noted.

The authors said the research showed that (in terms of quality) irradiation at 400 Gy can maintain blueberry and table grape quality sufficiently to meet transportation, distribution, and storage needs for overseas markets. "Our results show that both blueberries and grapes have a high tolerance for phytosanitary irradiation and that storage affects their quality more than irradiation treatment," they concluded.
Sources Cited: Jonathan Tong, Cyril Rakovski, Anuradha Prakash. Phytosanitary Irradiation Preserves the Quality of Fresh Blueberries and Grapes during Storage. HortScience, November 2015 
New South Wales cherry growers pin hopes on future air freight exports to China; ABC Rural (January 8, 2016):
Australians hope that irradiation of cherries will open China market.
New South Wales cherry growers are hoping to get air freight access to the Chinese market by using irradiation to treat their fruit for pests.

Cherries from mainland Australian growers are only allowed into China by a slow sea journey over 16 days, with the fruit subjected to cold treatment of one degrees, to wipe out pests like fruit fly. But the cold treatment affects the taste and quality of the fruit and cherry growers have been arguing their fruit is well controlled and checked for fruit fly and the cold treatment is not necessary.

Some NSW producers and exporters had little choice this season but to export cherries by ship, but their arrival in China coincided with cheaper cherry imports from Chile.

Growers are frustrated that another bumper cherry season has passed without any air freight access to China, and a large crop of cherries was sold at a discount to domestic consumers in Australia.

Chinese delegation visits Australia
In response to the cherry industry's concerns, the NSW Government has hosted a delegation of Chinese quarantine officials, to inspect cherry regions at Young and Orange.

Dr Fay Haynes, from the NSW Department of Primary Industry's International Engagement group, hoped the visit would smooth negotiations between Australian and Chinese Government officials on market access.

"NSW DPI and cherry growers went to China in September 2015, to the eastern part," Dr Haynes said. "The feedback we got on Australian cherries, was that Tasmanian cherries are beautiful. "And while they like NSW cherries they found them to be of poorer quality. "We know that's a direct result of the cold treatment."
The Chinese quarantine officials from Guangzhou also inspected irradiation facility, Steritech, in Brisbane.
Link to article ...
Australian cherries in short supply for Chinese New Year; Fresh Plaza: (January 21, 2016)
"I think irradiation would be great because it gives the Chinese the security they need and would be great for other markets." Hugh Molloy, Executive Director and General Manager of Antico. 

China may not have as many Australian cherries as it wants in the lead up to Chinese New Year, with export protocols and an early season making it hard to meet demand.

Under the current export protocols, only cherries from Tasmania can be air freighted to China. Mainland cherries, on the other hand, have to go through a cold treatment process and are shipped by boat, taking a minimum of 18 days transit from Australia to China.
Cherry Growers Association CEO Simon Boughey says the current protocols make it hard to keep up with demand from China during the season.

"We can't keep up with demand. The demand out of China is huge but it's mostly Tasmanian growers that supply China and other key Asian markets because cherries can be airfreighted from here," he says.

"The other thing is that the season is running a couple of weeks early, so orchards will be finishing up probably in the first week February. It will be interesting to see what they can provide for Chinese New Year with these conditions."

He says the Cherry Growers Association is working with a number of government departments to get cherries into key Asian markets, including China, but that the process is still too slow to keep up with demand.

"We're also trying to develop markets into China from other growing regions but cold treatment - which mainland growers can currently use to export to China - is just not commercially viable for us. What's commercial is to fly it in and that's what growers are looking for."

Executive Director and General Manager of Antico, Hugh Molloy, says having an airfreight protocol for mainland cherries would make a huge difference for exports to China.

"We are in the best position to offer airfreight, which gives them beautiful fruit, great tasting at fair and reasonable prices," he says, adding that it would offer them a longer season for Australian cherries.

"We could potentially have them taking fruit from earlier October right through February."

Mr Molloy says exploring other export protocol options, such as irradiation, could also offer a solution to these issues.

"I think an irradiation protocol would be great because it gives the Chinese the security they need and would be great for other markets."

For more information:
Simon Boughey
Cherry Growers Association

 Link to article ....
US consumers welcome Australian mangoes; AsiaFruit (January 22, 2016):
Exporters, importers and retailers aim to increase awareness of offering after strong start to campaign.

Irradiation will help Australia market "full-flavoured" tree-ripened fruit to US consumers. 

Australian mango suppliers plan to ship a wider range of varieties to the US this season, as they look to increase consumer awareness of their offerings.
Australian-grown Honey Gold, Kensington Pride and R2E2s will all enter the North American market this season, with programmes kicking-off with the arrival of 6,000 cartons, according to ABC Rural.

Michael Daysh from the Northern Territory Department of Primary Industry travelled to Texas to inspect the arrivals at retail level. Daysh said the fruit made an immediate impact. "The produce manager here says his consumers are asking for them and when they're out of stock, people in his store are looking for them, which is exactly where we want to be," Daysh told ABC Rural.

"Consumers over here are interested and importers are keen to get more volumes next season. They're disappointed that they didn't get as many mangoes from Australia as they had hoped this season, so we could have sold more." After the success of the first full season into the US in 2015, Australian Mango Industry Association chairman, Gavin Scurr, told ABC Rural that Australia could export up to 1m trays of mangoes to the US by 2020.

Daysh agreed there is a huge potential for the offering but added export programmes need to be complimented by strong consumer education programmes, particularly as new varieties are being introduced. "At a consumer level I think they're interested in the different appearances (between the mango varieties), but they're finding them all very sweet relative to the fruit from other countries," Daysh said. "So while the trade and the importers are talking about the difference (in varieties), I don't think it's resonating with consumers just yet.
"They're talking about potentially positioning Australian mangoes as being 'full-flavoured' and 'tree-ripened', marketing things like that, to talk about them having a bigger and better flavour than fruit from other countries.
Also in the News: Sixth Annual Chapman Phytosanitary Conference (March 23-24, 2016):

Sponsored by Chapman University, the USDA and the FAO/IAEC at offered at NO CHARGE.
To register or learn more about the conference click here ... is an excellent source of information on food irradiation.

Food Irradiation Update is published by Ronald F. Eustice and sent to you through the sponsorship of GRAY*STAR, Inc., the manufacturer of the Genesis Irradiator. 
Food irradiation is a cold pasteurization process that will do for meats, produce, and other foods what thermal pasteurization did for milk decades ago.
Ronald F. Eustice, Consultant
Phone: 612.202.1016