At risk or not?

The good news? Baked foods and snacks usually don’t make good carriers for microbes.

“Snack foods have very few microbial problems,” Dr. Plimpton said. “Of course, operating with a ‘safety first and foremost’ approach is essential throughout the food industry. Snacks are no exception, but the incidence of such problems in salty snacks is so low as to be almost non-existent.”

SFA’s general counsel, Martin J. Hahn, partner, Hogan Lovells US LLP, Washington, DC, affirmed her statement. “The bottom line is, snack foods are a very safe category of foods given the manufacturing that delivers a kill step and the low water activity of snacks,” he said.

At the time of this spring’s incident with listeria contamination of ice cream, SFA alerted its members to the situation. It noted that the bacteria won’t grow when water activity is 0.92 aW or lower. “Low-moisture products such as potato chips and nuts, for example, are not typically susceptible to Listeria monocytogenes,” the group stated. “It can be found in soil; however, growth of listeria in a plant environment does require wet conditions.”

Baked products are generally trouble-free from a microbial standpoint, largely because the baker’s oven provides an effective kill step.

“With flour, you have a dry product with a really low risk of microbial contamination,” Dr. Miller said. “Pathogens like E. coli and salmonella in flour are rare. These organisms have human or animal origins. When we find them in the finished flour, it’s almost always due to contamination from an outside source.

“The situation a few years ago with E. coli in raw cookie dough is a rare example,” he continued. “In general, wheat, corn, oats or any cereal grain as it comes in from the field and from storage has low incidence of microorganisms.” There are areas during processing that have higher moisture conditions and could typically allow microbial numbers to increase, Dr. Miller explained.

The biggest risks, however, are with mycotoxins produced by the fungi that grow on grains, according to Dr. Miller.

Dr. Channaiah agreed, “For grain-based products, it’s mainly about fungi.”

Grains grow in the open, subject to natural seasonal differences. “Year-to-year variation is not so much a concern with bacteria, but it certainly is with fungi, which are very sensitive to the environment,” Dr. Channaiah said. “In general, cool and wet conditions can foster fusarium and can lead to DON and vomitoxin present in wheat flour. Wet and humid conditions favor aspergillus growth and the presence of aflatoxins.”