Foil and potatoes can be a dangerous combination

Published: February 01, 1996, By Sacharow, Stanley

I recently came across an interesting article in Food Chemical News (Oct. 9, 1995) with implications for converters of foil intended for foodservice applications. The article dealt with an outbreak of botulism in 1994 caused by holding cooked potatoes in unperforated aluminum foil at ambient temperatures.

It seems that a "reportedly baked" potato wrapped in aluminum foil and held at room temperature for 48 hours was apparently the source of botulism that sent 29 people to the hospital in El Paso, Texas, in April 1994. This was noted by a group of public health officials at a recent American Society for Microbiology conference. The group, led by Fred Angulo, National Center for Infectious Diseases, interviewed 84% of the 235 people who ate at a Greek restaurant April 8 or 9. Of the 29 hospitalized people (none died), all ate either skordalia (cold potato and garlic dip) or eggplant dip.

Angulo's group explained, "Botulism toxin type A was detected in both the skordalia and the eggplant dip. The skordalia contained a potato that was reportedly baked, wrapped in aluminum foil, and then held at room temperature in the foil for 48 hours. No other ingredient in the restaurant was unique in skordalia, and none of the other ingredients tested had botulism toxin. The skordalia apparently contaminated the eggplant dip in the adjacent container via shared utensils."

Six other US botulism outbreaks from cooked, foil-wrapped potatoes held at ambient temperatures have been reported since 1978, the group said, noting:

"The foil provides the anaerobic environment necessary for toxin production. Food preparers and consumers should be alerted to the hazards of holding cooked potatoes wrapped in aluminum foil at ambient temperatures."

In a subsequent telephone conversation with Fred Angulo, I found out that botulism spores are found naturally in potatoes and by wrapping the potato in unperforated foil, an anaerobic state results. Many types of bacteria are heat-sensitive; however, botulism spores actually grow better if "shocked;" they are heat-stable. The combination of anaerobic conditions and the holding of the foil-wrapped potato for 48 hours at room temperature acerbated botulism growth. When the potato was then used in a cold dip and not reheated, the problem arose.

Angulo also told me that funding for the work done on foil-wrapped potatoes at the National Center for Infectious Diseases was provided by the National Potato Board ($5,000).

I'd really like to see Reynolds and/or Alcoa fund a test at a major university (Wisconsin or Rutgers) as to perforated foil versus unperforated foil (as now sold) for baked potatoes. Tests would include botulism-growth temperature conditions and resulting toxicity.

After all, the unperforated foil now sold strictly for potato wrap appears to pose a safety problem. With record profits being enjoyed by the major aluminum foil converters, it's their ethical responsibility to participate in this trial. Just being "updated" on what the National Center for Infectious Diseases does is not enough to safeguard the consumer (and ultimately the entire market).

Note: Clostridum botulinum is a microorganism that produces extremely potent toxins. Without diligent attention to both processing and storage conditions, botulinum type E may result in various food categories being anaerobic - the spore thrives in airless environments and produces its deadly nerve toxin, which results in botulism.

The toxin itself is easily destroyed by mere boiling (or calculated heating cycles). Unless they are killed by extremely high heating conditions, the spores will proliferate into active bacteria.

Botulism type E has also been reported in vacuum-packed, hot smoked, freshwater fish in some countries. Vacuum packaging provides some increase in shelf life, but the possible advantages are outweighed by the risks, since vacuum packaging gives rise to anaerobic conditions, which may accelerate the growth of botulism type E.

Both type A and type E occur in many foods. Although type E is the most toxic, every year people die from both. However, it may be reassuring to note when you shop or eat in a restaurant that the vast majority of botulinum-caused deaths come from improper home processing.