OSU microbiologist gives food the 'acid test' for safety

September 8, 2009
Mark Daeschel

Mark Daeschel tests the pH in a jar of seafood sauce in his lab at Oregon State University. The OSU professor examines newly developed acidified foods that are heat-processed in Oregon to make sure they're safe to eat. He said he evaluated about 150 such products last year. Photo by Tiffany Woods.

CORVALLIS, Ore. – So you've got a secret recipe for barbecue sauce. Your friends can't get enough of it. They urge you to bottle it and sell it. You could make millions, they say.

You put together a business plan, design a logo, and do all that marketing stuff you're supposed to do. But before you can sell what is going to be your key to an early retirement, it has to pass safety standards.

Enter Mark Daeschel. The Oregon State University food scientist aims to make sure that no one gets sick from newly developed acidified foods like mustards, salsas, pickles and salad dressings that are heat-processed in Oregon. About 150 such products passed through his lab last year, he said.

He's the expert that the Oregon Department of Agriculture and the Oregon-based office of the U.S. Food and Drug Administration refer budding entrepreneurs to when they inquire about processing acidified foods.

For the past decade, Daeschel has been what's called a process authority. That's someone whom the FDA recognizes as an expert in evaluating the safety of acidified foods or low-acid canned foods (like beans and corn). Federal regulations require commercial processors of such foods to have these authorities scrutinize their products and processing methods.

Daeschel said that when you're at a grocery store, farmer's market or gift shop and see thermally processed acidified products developed in Oregon in the last 10 years, it's "highly likely" that a sample from a prior batch once passed through his hands. He can't guarantee that he signed off on the product, though, because Oregon companies can ask process authorities outside the state to evaluate their products.

People send Daeschel their million-dollar babies by mailing them or dropping them off at his office.

"I get a lot of products made from secret recipes. Some people don't want to share them. I tell them I have a confidentiality obligation. Sometimes I sign nondisclosure statements," said Daeschel, sitting in his office where he has books with titles like "Botulism" and "Introduction to Parasitology."

Of the approximately 150 products he reviewed last year, about 80 percent passed on their first inspection, he said. The most common product was barbecue sauce, he added.

"Everybody has a recipe for one. It's easy to make," he said. "People just buy ketchup and add garlic, smoke flavoring, onions and maybe some ginger to it."

Salsas were the next most-common product, he said. He also saw a lot of pickles, relishes, bottled tea drinks and hot sauces.

He keeps an extra sample of each product in a cabinet by his office for a couple of years. In case problems arise later, he'll be able to say that at least the batch he tested met the requirements. Some of the products in his cabinet include: a chipotle balsamic drizzle from Phoenix, Ore.; barbecue sauce from Grants Pass; pumpkin butter from Eugene; organic beets pickled in Elmira; peach jalapeño salsa from Albany; chili pepper relish from Coos Bay; and zucchini relish from Oregon City.

In a lab on campus, Daeschel, who has a master's degree in microbiology and a doctorate in food science, makes sure the products are sealed properly. He also reviews a written description of how they were processed, such as pressure-cooked or boiled. He fills out an FDA form that asks for technical things like F and Z values, reference temperature and maximum equilibrium pH.

In the case of jams and jellies he dabs a spoonful onto a refractometer to make sure they contain at least 65 percent sugar to qualify as such foods. Additionally, if something seems not quite right, he'll place a sample under a microscope to look for harmful bacteria like E. coli, salmonella and listeria.

He also pokes an electrical probe into the product to test the pH. The term pH refers to a scale from 0 to 14 that specifies how acidic or alkaline a substance is. The higher the pH, the lower the acidity. Acidified foods, ones to which acid has been added, are generally safer. A product is considered acidified if it has a pH of 4.6 or below. If a food is above 4.6, it can be more dangerous because it might host potentially fatal Clostridium botulinum, which thrives in low-acid environments. The bacteria produce a toxin that paralyzes muscles and is used in wrinkle-smoothing Botox injections.

After a product gets Daeschel's seal of approval, he writes a green-light letter to the FDA. Once the FDA accepts it, the certification is good for life.

But he doesn’t just evaluate products. If they don't pass, he tells the processor how to fix the problem. For example, the pH might need to be lowered, but that might adversely affect the flavor. So Daeschel might recommend using citric acid instead of vinegar.

Daeschel, who has testified as an expert witness in food safety litigation cases, also teaches two- and four-day workshops for individuals who process acidified and low-acid foods. The FDA-approved courses are required for processors of such foods. The next one will be June 21-24 in Corvallis. Participants in the class are certain to hear his mantra: "When in doubt, throw it out."

Author: Tiffany Woods
Source: Mark Daeschel