March 2, 2001 - Pathogen Growth Prediction, Optimizing Cooking Key OSU Processing Course

by Beverly Cheng

COLUMBUS, Ohio -- A short course on thermal processing of ready-to-eat products continued Tuesday at The Ohio State University, with sessions on keeping products pathogen-free and optimizing cooking processes. Key presentations covered by The Meatingplace.com included the following:

Equipment and Process Validation for Batch and Continuous Ovens: Tom Betley, food technologist for Alkar Inc., Lodi, Wis.

Products cooked in the same oven often show different results, Betley said, with some product reaching a higher final temperature, for example. The hottest area of an oven is on the bottom at the sides, where the heating equipment is typically located, while the coldest spot in the oven tends to be near the top center, he said. Although some temperature variation is expected from top to bottom in an oven -- usually between 4 and 8 degrees F -- larger differences spell trouble. Worse, an improperly cooked product looks unappealing and can be unsafe to eat.

“Take a smoked product, for example,” Betley said. “When something's not properly smoked, the product nearest the heat [source] will be dark, but near the center (of the oven) it tends to be pale and pink.

”The best way to avoid that is to understand and account for the sources of thermal variation: oven design, product loading, product shape and the actual cooking process, he explained.

There are variations along three dimensions in any oven design, Betley said top-to-bottom, side-to-side and front-to-back. However, processors can control the side-to-side temperature balance by manipulating the oven's rotator dampers, which move air from side to side to avoid a “vacuum” of cold air in the center of the oven.

Betley also warned against overloading, which restricts proper circulation of heat, and noted that a consistently shaped product performs best, and frequent checkups on equipment will help ensure that everything runs smoothly.

Predictive Food Microbiology and the USDA Pathogen Modeling Program: Don Shaffner, lead scientist for the Food Risk Analysis Initiative at Rutgers University.

Shaffner gave an overview of the pathogen-modeling program and explained the math behind the model. The program predicts the rate of pathogen growth in certain conditions, but should not be the only factor in making safety regulations, Shaffner told The Meatingplace.com. “People should use the model to back up their regulatory decisions, not to make them,” he warned.

The model is most useful when combined with input from experienced microbiologists, Shaffner said. “But you have to be careful,” Shaffner pointed out. “You'll get nonsensical predictions if you input nonsensical data.

”USDA's Pathogen Modeling Program, which allows users to choose a pathogen and select conditions to predict its growth, is available by logging onto arserrc.gov

This article reprinted with permission from Meat Marketing & Technology.

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