Salmonella-free peanut processing

SALMONELLA contamination is a common problem in the peanut industry, sometimes leading to product recalls or much worse consequences. In 2013 for instance, former executives of the Peanut Corporation of America were indicted on charges related to salmonella-tainted peanuts and peanut-containing products, which sickened more than 700 people across the United States. 

But the risks associated with salmonella contamination can be mitigated, as shown by a pioneering study conducted by Bühler Aeroglide and the USDA, Agricultural Research Service. It verifies that processors can use industrially relevant parameters in the dry roasting process for acceptable salmonella reduction. It predicts log reductions in peanut dry roasting using industrial dry roasting parameters.

The study, which appears in Peanut Science, was led by Bühler Aeroglide process engineer Dan Poirier, who used a laboratory scale roaster at the company’s Technical Centre in North Carolina. Also 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 AeroRoast industrial peanut roaster

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.

“We’ve been advancing down this path for several years,” said Mr 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 the company’s 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 colour and moisture, combined with a safer food product.”Lebron XIV 14 Glow