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From: Food Quality & Safety magazine, December/January 2011

Tools For Better Food Safety Testing

Evolving tools and methods help reduce foodborne illnesses

by John Ricardi

Is our food really safe? The plethora of contamination events over the past few years certainly begs the question. The first major contamination event occurred in 1998 when Sara Lee recalled 35 million pounds of various meat products. Recalls were pretty quiet for about eight years, and then:

  • In 2006, E. coli was found in packaged spinach that sickened 300 people in 26 states and caused three deaths.
  • In 2007, Tyson recalled 40,000 pounds of beef in 12 states due to E. coli contamination.
  • In 2008, Topps Meats recalled 21 million pounds of beef due to E. coli contamination; the company closed as a result. Also in 2008, there were recalls of lettuce and spinach due to Salmonella contamination.
  • In early 2009, King Nut had a massive recall for Salmonella-contaminated peanuts that sickened 399 people in 42 states.
Low-temperature electron micrograph of a cluster of E. coli bacteria magnified 10,000 times.
Low-temperature electron micrograph of a cluster of E. coli bacteria magnified 10,000 times.

Over the past three months, several incidents have been reported. Between November 2009 and January 2010, more than 2.8 million pounds of meat products were recalled due to contamination by E. coli or Salmonella. In February, 225 people in 44 states were sickened by Salmonella in imported black pepper that was used to prepare salami and other types of Italian sausage made by a Rhode Island company.

CDC Numbers

In 1999, the Centers for Disease Control and Prevention (CDC) stated that 76 million people are infected annually with bacterial contamination, resulting in 325,000 hospitalizations and 5,000 deaths. At that time, the bacteria most responsible for contamination were Campylobacter jejuni, E. coli 0157:H7, Listeria monocytogenes, and Cyclospora cayetanensis.

Most authorities contend that there is significant under-reporting, and the statistics have increased dramatically; the only major contamination event reported prior to the CDC report was the Sara Lee incident. Also, almost all recent contamination events can be attributed to E. coli, Salmonella, or Listeria.

Most people believe the growth in the number and magnitude of contamination events can be attributed to several factors, including:

To add to the dilemma, a report recently released by a former U.S. Food and Drug Administration economist indicated that food-related illnesses are estimated to cost the United States $152 billion annually in health- care and other losses.

  • the increased globalization of food sources;
  • the lack of federal regulations regarding food quality; and
  • the desire of food processors to increase revenue and profits, leading them to reduce quality controls that ensure safe food.

To add to the dilemma, a report recently released by a former U.S. Food and Drug Administration (FDA) economist indicated that food-related illnesses are estimated to cost the United States $152 billion annually in healthcare and other losses.

Our government is taking some actions, but they are probably not enough to make a significant difference. President Obama has requested a 30% increase in funding in 2011 for FDA food safety programs. According to the agency, the budget will invest approximately $1.37 billion to strengthen food safety efforts, up $318.3 million from 2010. By contrast, the Food Safety Inspection Service’s budget would receive a less than 2% increase ($18 million) to $1.046 billion, compared to $1.028 billion in 2010.

The increase in contamination events prompts these questions: How can contamination be prevented, and how is testing done today? Researchers are constantly investigating treatment methods that would kill bacteria before the food product is shipped to the consumer, but, so far, none have been successful without adversely affecting the taste or structure of the food product. At present, inspection is the only viable method.

About 80% of testing is done the way most of us learned in high school biology. A meat sample is shipped to a test lab, where a “scraping” is cultured in a petri dish in accordance with established methods. In roughly 24 to 72 hours, any bacteria present in the sample will appear in the petri dish. A trained microbiologist will take a sample, place it on a glass slide, and examine it under a microscope, identifying and determining the number of bacteria present.

Considering transportation time and test lab queues, results may not be available for a week or more. Even if a contamination event is recorded, a confirmation test is done before any action is taken. Because food processors do not “hold” inventory, a confirmed contamination results in a recall. When you couple this with the fact that only small samples are taken for examination, it is quite possible a contaminated product could elude the inspection process.

Table 1. There are a variety of features and costs associated with identification test systems available on the market.
click for large version
Table 1. There are a variety of features and costs associated with identification test systems available on the market.

PCR Systems

Several companies have developed quicker methods, the most popular being a type of DNA testing called polymerase chain reaction (PCR) diagnostic systems. PCR systems entered the market more than 10 years ago, but in a conservative, cost-conscious industry, acceptance has been slow. According to an industry consulting firm, rapid microbial identification processes only make up about 20% of all testing done. In 2007, this represented more than 630 million tests, a growth rate of about 10% a year. PCR systems typically perform an identification in 36 to 48 hours with greater than 90% accuracy at a cost per test of about $10. Some new systems can complete the whole process in 10 hours, but the cost can be as high as $45 per test, and the capital cost can exceed $40,000.

The specific reagents or chemicals and the sample equipment needed to perform an identification are the most important drivers for test costs. A novel test method uses the principles of multi-angle laser light scattering combined with proprietary algorithms to perform an identification. The entire identification process takes less than 10 minutes, and because no chemicals or reagents are used, cost per test is about 10 cents. The capital cost of the system is significantly cheaper than the lowest priced PCR system. Although other rapid methods have a cost per test as low as $2, they are compromised in either accuracy or specificity. Table 1 (below, left) summarizes the features and costs of many of the identification test systems available today.

Independent agencies validate most rapid test methods. The AOAC Research Institute is probably the one most respected in the industry. The institute created a test protocol that rigorously tests a method for accuracy and robustness. Two different sources perform the accuracy testing. If an inconsistency in the test results occurs, either the testing is redone or a “referee” within the AOAC Research Institute, along with input from the two test sources, decides if the method should be certified.

Cost-effective, reduced-time inspection systems are highly desired, with the goal of preventing contaminated food from ever reaching the consumer. Improved food test methods will not solve all contamination problems, but they will certainly reduce the number of annual illnesses, thereby reducing healthcare costs.

Ricardi is executive vice president and COO at Micro Identification Technologies. Reach him at j.ricardi@micro-identification.com.

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