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Imports and Exports: Microbial-Reduction Techniques Address the Unique Structures of Spices

Between 1973 and 2010, there were 14 outbreaks of foodborne illness linked to contaminated spices worldwide. After several recent large-scale Salmonella outbreaks in the U.S. were associated with contaminated spices, the Food and Drug Administration (FDA) began a major investigation into spice safety.

Since more 80 percent of the spices in American kitchens come from overseas, the agency has placed particular emphasis on imported spices.

“Most spices require tropical or subtropical climatic conditions to grow, so it isn’t possible to grow them in the U.S.,” explained Cheryl Deem, president of the American Spice Trade Association (ASTA). “In the U.S., we grow some onion, garlic and chilies. Canada is a major producer of mustard seed. Virtually everything else is imported and has always been imported.”

In testing shipments of imported spices offered for entry to the U.S. between 2007 and 2010, FDA found that Salmonella was prevalent in nearly 7 percent – a rate twice as high as all other imported food regulated by that agency.

“Many spices are grown in developing countries where sanitation and food-handling practices may not be adequate,” Deem said. “And, as is the case for all foods grown outside, spices can be exposed to animals, birds, dirt, dust, and there is a possibility for contamination.”

In its recently released spice risk profile that addressed other contaminants such as insects and hair, in addition to microbial hazards, FDA laid out the various interventions available for reducing and preventing illnesses.

Salmonella is the main pathogen associated with spice recalls and outbreaks, but a number of other bacteria, including E. coli, Clostridium botulinum, and Listeria, can also be found in spices. FDA reported that, of the 21 spice recalls in the U.S. between 1970 and 2003, all but one contained Salmonella.

The report described how Salmonella and other contaminants can be introduced during primary production, distribution and storage, secondary processing and food manufacturing, and at retail. After that, the report noted, “Salmonella can survive in the natural environment (outside of an animal host) for extended periods and may persist in production environments for years.”

“Spices really do have their own unique food-safety concerns,” said Gillian Dagan, chief scientific officer for ABC Research Laboratories. “If you just think about some of the anatomies of spices, there are lots of nooks and crannies that you really can’t treat with conventional sanitation methods.”

For example, you wouldn’t want to apply anything wet to dried spices or apply heat that would diminish the aroma and flavor of certain spices.

After following Good Agricultural Practices and Good Manufacturing Practices and developing Hazard Analysis Critical Control Point (HACCP) plans for growing, harvesting and processing, microbial-reduction techniques are recommended. The main methods are ethylene oxide gas or propylene oxide gas, irradiation and steam treatment.

Ethylene oxide (EO) or propylene oxide (PPO) are applied under vacuum or under pressure and can kill bacteria, yeast, mold and pathogens without the need for high temperatures. EO is particularly widely used because it usually does not affect appearance or flavor of spices. ASTA estimates that it is used to treat 40 to 85 percent of spices in the U.S., as well as spice packaging material.

Irradiation, a process that involves exposing the spices to radiant energy such as gamma rays or X-rays, has been used on spices for years.

“Irradiation is a tried-and-true way to sterilize that product without changes in flavor and aroma,” Dagan said.

Despite some concerns among consumers that irradiated food is radioactive or could contain free radicals and radiolytic products, the International Atomic Energy Agency (IAEA), the World Health Organization (WHO), and the Food and Agricultural Organization (FAO) of the United Nations have all concluded that the process does not present any toxicological, microbiological or nutritional hazards beyond those of conventional food-processing techniques.

Steam treatment, which is the method of choice for organic companies, introduces a certain amount of heat for microbial reduction but, Dagan noted, “It wouldn’t be as damaging as a regular dry-heat treatment would to the quality of the spice.”

It’s a fairly easy process and can be done in the growing or exporting country. It can be applied to whole or ground spices, but ASTA reports that, in the U.S., steam is commonly used to treat whole-seed spices such as white and black pepper.

“Companies make decisions on which option to use based on the end use of the spice and the requirements of their customers,” Deem said. “ASTA does not have a preference for one above any other, but rather supports having as many options available as possible to allow spice companies to be able to select the option that best meets their need.”

“Something that a spice producer is successful with peppercorn may not work as well for something like a dried oregano or dried basil,” Dagan said. “In all cases, you have to not only evaluate the robustness of the treatment as something that’s going to reduce microbial populations, but you also have to look at if there’s going to be any loss of quality in the product. You have to balance those two things when you evaluate which treatment option to choose.”

FDA is taking various steps to strengthen spice safety and, once finalized, the Food Safety Modernization Act (FSMA) rules on preventive controls for human food facilities and foreign supplier verification programs for importers will provide new tools for controlling contamination.

For growers and producers, “There’s information out there on the proper way to grow, harvest, process and further treat spices,” Dagan said. “I just think it needs to be a cooperative partnership between industry and government to improve all of our practices.”

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