Captain Cook, HI — The Big Island features five volcanoes, black sand beaches and eight different climate zones. And, it produces world-famous Kona coffee and macadamia nuts.
“Mac” nuts, as they’re called here, are actually native to Australia. They were introduced to Hawaii in the late 1880s and gradually became an important export crop by the 1950s. The trees are evergreens, which can reach 30-40 feet in height.
The nuts are enclosed in a husk that splits open when mature, and they are typically manually harvested from the ground, and sometimes the tree. They are dried, husked, shelled and roasted, although some are dehydrated and sold as “raw.”
Hawaii annually produces about 50 million pounds of macadamia nuts, with nearly all of those coming from the Big Island, according to John Cross, president of the 53-member Hawaii Macadamia Nut Association. In addition to his association work, Cross helps to manage 1,200 acres of macadamia trees for the Hilo-based Edmund C. Olson Trust.
Like most U.S. food producers these days, macadamia nuts growers and processors are focused on providing a safe commodity for consumers and complying with requirements of the Food Safety Modernization Act (FMSA). They are also concerned about recent macadamia nut-related recalls and are exploring ways to limit Salmonella on their product.
“I am sympathetic to this trend toward a raw food diet, but as an industry, we’ve got to figure out how to get a raw macadamia treated so it is contaminant-free,” Cross said recently.
The U.S. Food and Drug Administration (FDA) posted at least a dozen recalls in 2015 involving macadamia nuts, and another three have been announced so far in 2016. All of this year’s recalls to date involved nuts from Mahina Mele Farm south of Captain Cook. The farm also had a recall in August 2015 of one lot of macadamia nuts and nut butters due to potential Salmonella contamination.
Mahina Mele Farm’s first voluntary recall this year, on Jan. 21, involved three lots of macadamia nuts and nut butters distributed to retails stores in Alaska, California, Hawaii, Maryland and Virginia between Oct. 21 and Nov. 25, 2015. The second, on Feb. 3, 2016, expanded that initial recall and covered all lots currently on the market.
On Feb. 5, 2016, Living Tree Community Foods in Berkeley, CA, issued a recall of macadamia nuts and nut butters sold under its own label but supplied by Mahina Mele Farm. Those products were shipped from the company’s California facility between Dec. 11, 2015, and Feb. 3, 2016.
All three recalls targeted “raw” macadamia nuts, not roasted ones, and were prompted by FDA testing.
“It was a random sample that they took off the shelf, and we’ve been working with the FDA real closely for the last few weeks. There was no Salmonella found in my facility or in any of the nuts after that lot,” said Kollette Stith, who owns and operates the family farm with her husband, Jason Stith. “What we are assuming happened is that the temperature must have dropped in our dehydrators, so it must have gotten below 140 degrees.”
Stith said that Salmonella bacteria are killed if the nuts are held at 140 degrees F for at least 15 minutes. There were no alarms on the farm’s dehydrators at the time of the recalls, but she said they have since been installed when equipment was replaced.
After the recent recalls were announced, Cross issued a statement on behalf of his association members. The statement reads:
“All of the Hawaiian Macadamia Industry processors roast their macadamia nut kernel. No ‘raw’ kernel is sold into the market. The processors roast to the highest standards as dictated by Good Manufacturing Practices, (GMPs). This assures the buyers and consumers of roasted Hawaiian macadamia nuts the safest, healthiest, and best tasting nut possible.”
Ways to limit Salmonella
Roasting macadamia nuts — either in oil or by dry-roasting — will kill Salmonella, but not everyone wants them roasted. The challenge is how to safely limit pathogens and contaminants on the nuts without ruining the delicate flavor.
One method under consideration is PPO, propylene oxide gas, a chemical fumigant now being used to pasteurize almonds. Another is steam treatment, which is used on almonds sold under the organic label, as well as using radio waves and infrared heat processes.
“PPO will probably take care of that raw food supplier, but it will not take care of the raw food organic supplier. It’s a chemical. That’s where we have an issue. If you’re an organic grower, you do not have that option,” Cross said.
Harvesting from the ground
One factor that may make macadamia nuts more vulnerable to contamination is the method of harvest, said Aurora Saulo, professor and extension specialist in food technology at the College of Tropical Agriculture, University of Hawaii-Manoa.
“They let the macadamia nuts in their husk and shell fall on the ground before they are harvested, and that increases the risk because they are in contact with other foreign matter,” she said. “It has to be treated even before it’s shelled, so you can see how some of that contamination can come in.”
According to a 2012 report compiled for the Food and Agriculture Organization of the United Nations (FAO), outbreaks involving Salmonella and enterohemorrhagic E. coli (EHEC) have been linked to consumption of tree nuts.
“Significant evidence suggests that one source of contamination is the orchard itself. Many nuts are harvested directly from the orchard floor after being mechanically or hand shaken, cut from the tree by hand and then thrown to the ground, or allowed to fall naturally. This results in significant mixing of the nuts with soil and plant debris. Contaminants picked up at harvest may then be spread to the edible kernels before or during shelling. Moisture may also play a role in amplification of contaminants if the harvested and dry product is not protected from irrigation water or rainfall.”
At Mahina Mele Farm, Stith said Salmonella contamination could possibly occur from the presence of birds and geckos, but FDA took “hundreds of swabs” at her facility and got no positive test results. Consequently, she believes that the problem stemmed from the older dehydrators.
She also said that she does not support the idea of using PPO as a processing technique for macadamia nuts.
“I don’t need to pasteurize if I can just get them to temperature. I don’t really think that we need to adulterate our food any more,” Stith said, adding that a sample of each batch of the farm’s macadamia nuts is tested for safety before the lot is shipped out.
In an October 2015 presentation to HMNA members, Saulo noted that additional PPO trials are scheduled this fall, along with testing and validation of the roasting process. She said the trials will be done by researchers at Oregon State University and the University of California-Davis.
Macadamia nut growers and processors say they are trying to comply with applicable FSMA provisions, at least to the extent that they are currently understood on the state level.
Lynn Nakamura-Tengan, an Extension educator with UH-Manoa’s College of Tropical Agriculture, is part of a safety outreach team that recently made the rounds of the islands for informational sessions with growers. She said growers and processors need to know about water testing requirements and how to understand the results. She said they also need to learn manageable ways to apply good agricultural practices (GAPs) under FSMA.
“The challenge is getting them the detailed information that they want without knowing what FDA is thinking,” she said. “We want to respond to the growers and the growers want to meet their regulatory requirements, but our hands are kind of tied because we don’t want to make interpretations for FDA and then they come back with a different interpretation.”
Nakamura-Tengan added that once an approved FSMA curriculum is available from FDA, the state hopes to begin train-the-trainer sessions this fall with a full program launch planned in 2017 so growers will be able to get their GAP certificates of compliance.
Meanwhile, UH-Manoa Extension staff plan to restructure their self-help GAP resources for Hawaii’s growers.
Individual macadamia nut growers and processors in Hawaii are adapting to meet the challenges of producing a safe product. Mahina Mele Farm has installed new dehydrators with alarms that link to the owners’ phones so time and temperature can be more accurately monitored.
The Hawaii macadamia nut industry is exploring methods of post-harvest treatment so the risk of pathogens and other contaminants will be as low as possible.
Growers and processors are systematically testing their product and paying attention to federal and state regulations. However, they worry that FDA will require pasteurization of macadamia nuts before they may legally be sold into the marketplace, similar to what happened with almonds back in 2007.
There is also speculation that FDA may be focusing more attention on testing samples of macadamia and other tree nuts for pathogens given the increased number of recalls in the recent past. Whether the federal agency will ramp up regulations by requiring pasteurization is uncertain at this point. The FDA’s Honolulu office did not respond to requests for comment.
Saulo emphasized that adequate guidelines are already available and just need to be fully understood and consistently followed.
“It’s just a really different way of looking at food safety now,” she said. “Before, it was more reactive and you see something and react to it. Now it’s more planning and addressing the issues, and what are the controls you are going to do? It’s a different way of thinking.”
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