This industrially based peanut study provides practical information for processors that can be used as guidance for a 5-log reduction of salmonella.

Cary, NC (July 3, 2014) – Salmonella contamination can occur at any point in handling and processing of peanuts and is usually traced back to human or animal sources. To help mitigate the risks associated with product contamination, a recent study conducted jointly by Bühler Aeroglide and the USDA, Agricultural Research Service has verified that processors of peanuts can use industrially relevant parameters in the dry roasting process for acceptable salmonella reduction.

Published in Peanut Science, Bühler Aeroglide offers the first study to predict log reductions in peanut dry roasting using industrial dry roasting parameters. Bühler Aeroglide Process Engineer Dan Poirier led the study using a laboratory scale roaster at the company's Cary, NC Technical Center. Contributing on the project were Research Leader Tim Sanders, Ph.D., and Food Technologist Jack Davis, Ph.D., of the USDA Agricultural Research Service at North Carolina State University in the Department of Food, Bioprocessing and Nutrition Sciences in Raleigh, NC. The roaster simulated the parameters of Bühler Aeroglide's AeroRoast industrial peanut roaster. The study provides the first scientific documentation for reducing salmonella in real world conditions for dry roasting peanuts. The abstract can be found here:

"We've been advancing down this path for several years," said Poirier. "Our customers have asked for help in achieving the highest log reduction of salmonella. Our goal with this research was to give the industry guidance on specific parameters that can be followed to achieve a critical control point for salmonella reduction."

Validation is a term used by the food industry that refers to proving that a process is delivering the required level of pathogen reduction. The current USFDA requirement in almonds is a minimum 4-log reduction of pathogens. A 5-log reduction is often the target for peanuts and pistachios, even though this is not required by USFDA.

In order to determine the reduction of salmonella in a specific set of roaster conditions, peanut processors use 'challenge tests' usually performed in conjunction with testing laboratories such as Deibel Labs or JLA Global. Sample mesh bags of product inoculated with a salmonella surrogate are passed through the roaster and organism reduction is determined. A peanut processor can easily spend $5k to $8k per test and multiple tests may be required to validate equipment. Bühler Aeroglide's study will help processors determine appropriate roaster conditions before validation and thus significantly reduce the number of iterations and hence the cost of validating their equipment.

"We hear about salmonella outbreaks on a regular basis now and the industry is getting better at tracking contamination when it happens," said Bühler Aeroglide Food Safety Manager Steve Blackowiak. "But we all have a moral responsibility to global food production as we work together to proactively support safe food processing. We know that by improving air flow capacity, cool spots as well as hot spots can be eliminated. During the roasting process, when air flow is evened out across the entire product bed according to specific controlled parameters, the result is better uniformity in roast color and moisture, combined with a safer food product."

Bühler Aeroglide manufactures dryers, ovens, roasters, toasters, and hot air expansion systems for the food, feed and industrial product markets. Since 1940, the company has been providing innovations for a better world in the form of high-quality thermal processing equipment. As a business unit of Bühler, Aeroglide is headquartered in Cary, NC, and provides sales and service for its industry-leading equipment in more than 140 countries around the world. For more information about Bühler Aeroglide, call +1 919 851 2000, or visit


For more information, please contact:

Nick Manley, Marketing Communications

Bühler Aeroglide, 100 Aeroglide Dr., Cary, NC USA 

Phone +1 919 278 2864, Fax +1 919 851 6029, E-mail