September, 1997

Workshop focuses on erecting safety barricades against attacking bacteria

The first of four national fresh juice safety meetings focused on strengthening the defenses of a vulnerable industry.
The first documented outbreak of contaminated juice dates to 1923, but an increase in well-publicized outbreaks has vaulted the industry into a tenuous situation.
Reducing risk is the top priority, said David Armstrong, director of the National Center for Food Safety and Technology in Summit-Argo, Illinois, where the August meeting was held. The risks are greatest from three pathogens, including bacteria (such as E. coli and salmonella), parasites (Cryptosporidium) and viruses (hepatitis A).
The juice industry is vulnerable to outbreaks because only a low level of contamination is needed to cause major problems, the severity of the disease and the survival of pathogens under acidic conditions at refrigerator temperatures.
Reducing risk will require the industry to practice rigorous sanitation and good management practice (GMP) standards, said Armstrong. These include paying strict attention to personal hygiene, animal and manure control, avoiding use of drops, washing fruit and sorting fruit.
Food and Drug Administration microbiologist Kelly Bunning outlined how citrus juice manufacturers have also had their problems. Contaminated orange juice has produced outbreaks of gastroenteritis, typhoid fever and hepatitis A. A salmonella outbreak in 1995 proved to be the first such occurrence from a citrus-processing facility. The bacteria came from tiny tree frogs that had made their way into the juice vat.
Barring the existence of a kill step (a way to eliminate bacteria found during sampling), Bunning said the key is to control the avenues that lead to contamination. A study of orange juice discovered higher bacteria populations as the condition of the fruit deteriorated.
In the laboratory, research is underway at an accelerated pace to learn more about how to counteract E. coli and other bacteria and on ways to produce a pasteurized and flavorful product.
Don Splittstoesser, professor emeritus at Cornell University's Department at Cornell University, said E. coli was "the meanest one of the group" of pathogens, and his focus is getting it out of cider through a logarithmic kill step. This kill step is measured in terms of "log" or "D". One log equals the death of 90% of the pathogen, which equals one D. An FDA subcommittee on microbiological food safety has recommended processors have the ability to perform a five-log kill step on any detectable bacteria.
"Logarithmic kill does not give you complete sterility, but it gives you a level you can live with. Perhaps five-log is something we can live with," he said.
The second track of research at Cornell and elsewhere is pasteurization, and specifically on a minimal heat treatment to kill the pathogen while retaining the taste of the product. Cornell has recommended pasteurization at 160 F. for 10 seconds. This will not result in shelf-stable cider but will extend the shelf life and knock out the E. coli, said Splittstoesser.
Much attention has been given to the research of additives to the cider. Splittstoesser believes sulfur dioxide has promise. Already common in wines and hard cider, it is generally regarded as a safe food additive. Higher pH hampers the effectiveness of sulfur dioxide.
"No one has used it yet in cider, but they should," said Splittstoesser. "We think it can work, especially for the smaller producer who cannot afford pasteurization. It inhibits the oxidation of fruit products and that gives us the flavor we like in cider. So you have to let browning develop before you add sulfur dioxide. If you add it immediately, you will get a clearer, poor tasting juice."
Cornell researchers have applied ultraviolet light to household water to see if it can kill the E. coli. The verdict - it can, but 80 to 145 minutes of UV light are required to reach the desired 5D kill step, and that's too slow. Another possibility is Velcorin, an additive used in wine and sports beverages. This material works, but the monitoring equipment is extremely expensive. The same problems exists with irradiation.
Juice manufacturers need to think beyond cleanliness and concentrate on sanitation, said Bruce Schmidt from Ecolab, Inc.
"All it takes is one careless person, and the results can be disastrous," he said.
Sanitation is purely a matter of safety - the quality of the product does not enter into the mix, he said. Sanitation is accomplished by what is called the "4 x 4" formula, which are four steps modified by four factors. The four steps include a pre-rinsing, washing, post-rinsing and sanitizing. The four factors are concentration of the cleaning agent, water temperature, the time required and the amount of mechanical or manual force.
All sanitizers used on food processing equipment are registered materials under the Federal Insecticide, Fungicide and Rodenticide Act, in the same manner as ag chemicals.
Other speakers described how apple industry organizations, state government and grower groups have responded to the crisis. The speakers included Jerry Wojtala of the Michigan Department of Agriculture, Randy Graham of the Illinois Horticultural Society and Shirley Bohm of the Illinois Department of Public Health.