STJames White, a professor in Cornell University's School of Hotel Administration, startled some listeners here when he announced during a lecture on food-borne disease that bottled mayonnaise is "one of the safest products in the world."
He went to tell a regional meeting of the National Association of Food Editors and Writers that in a restaurant "the cook is 1,000 times more dangerous than the waitress" because "there is no record of food disease coming from an unclean untensil or plate."
Calling man "a remarkably resistant creature," White said there is no avoiding bacteria. The challenge is to control it. "Good sanitation," he said, "is lowering the risks down to whee they are approaching zero." This means taking care to store food, cook it and keep leftovers out of a danger zone that runs from 45 degrees to 140 degrees.
Most of us have heard this advice, but rarely are we given a scholarly explaination of why to take such precautions.
"Temperature control can eliminate 90 percent of the risk," White said. "Contamination is a function of time plus temperature." Therefore meat left at room temperature for "a couple of hours" before it is cooked won't harm a person. But bacteria multiplication ("doubling time" ranges from 10 to 60 minutes, depending on the temperature) could "make it dangerous" within four hours.
"Most bacteria are harmless," White said. "
here can be 20,000 per gram in good quality hamburger. The numbers don't matter. What kind they are does."
Staphylococcus, which causes more than half the attacks of food poisoning, is carried on the skin. It does not grow well in the body. It does grow in foods, however, and gives no warning of off smell, taste or color.
It won't reproduce at temperatures less than 45 degrees and is destroyed when food is heated above 140. Thus the advice is to leave foods in the danger zone between cold and hot for as short a time as possible. White also reminded his audience that there is a cumulative effect if food is brought to room temperature, cooled and then reheated. Once the temperature is right, the slumbering bacteria awaken and begin multiplying once again.
Once the staphylococcus bacteria have reached a per gram count of 5 million, not even pressure cooking will render them harmless. But various forms of preservation can slow or virtually stop the growth rate even in the danger zone. The traditional methods cited by White are adding acid to food (as is done with commercial mayonnaise), salting, smoking or drying it.
Recent research indicates salting and smoking carry their own risks to health, a further cause of confusion to consumers.
In White's view, wood cutting boards are not great health risks. They should be well maintained and sterilized often, but so should those made of plastic or rubber. He also recommends leaving food in original containers and attacks the romantic theory that spices play the role of perservatives in foods of Mexico, India or China.
Microwave users will be interested in another theory he puts forward: Only the surfaces of roasts and other large pieces of meat are contaminated. When cooked in a traditional oven, the surface temperature goes will over 140 degrees, even when the inside remains rare. But as meat in a microwave range cooks evenly throughout, it should be cooked past the rare stage to insure sterilization of surface bacteria. (Contamination in delicatessen meats that led to new federal standards was caused by bacteria-tainted hooks that were plunged into the meat, not by undercooking.)