Food-related illnesses | Dropping temperature of prepared food poses challenges for processors
TORONTO — As families struggled to make ends meet during the 2008 recession, there was also a spike in food poisoning.
More people were eating leftovers that were not always cooled or reheated properly, said Keith Warriner of the University of Guelph’s department of food science.
The matter of food borne illness was discussed at a symposium hosted by the Canadian Meat Council in Toronto Oct. 3-4.
There are dozens of bacteria, viruses and parasites that can cause disease and secondary infections.
Warriner is studying the bacterium clostridium perfringens, which can make people sick within a day of eating contaminated food.
It will often grow in cooked beans, meat products, thick soups, stir fries and gravy.
Leftovers that aren’t properly cooled and reheated may contain a lot of the bacteria. It is also common when large amounts of food are prepared in advance and not cooled quickly.
There are five different types with the alpha toxin causing most problems in humans. It can cause diarrhea and cramps and last 24 to 48 hours.
Its spores are not killed by boiling so products must be heated to more than 120 C to inactivate them.
Food also needs to be cooled quickly.
“In the good old days what they used to have was an accepted slow decrease in temperature in order to avoid it,” Warriner said.
The new recommendation is for rapid cooling from 55 C to 26 C in two hours and then from that point, drop to four degrees within another two hours.
This can create challenges for food processing because rapid chilling could leave frost traces or change the product quality.
Another way to control it is to add an essential oil like oregano with nitrite at low levels, which seems to work at inhibiting germination without affecting food quality.
The rejection of nitrates and other preservatives in foods has created problems because they acted as a control against pathogens, said Eva Pip of the department of biology, University of Winnipeg.
Describing the many contaminants as “a gang of nasties,” she outlined some of the viruses, bacteria and parasites that can sicken people.
In the case of viruses, only a few cells are needed to cause illness. They account for up to 80 percent of food borne illness in the U.S.
While they are single celled, tiny organisms, they are expensive to isolate and culture in the laboratory and then identify.
Some can remain infectious for days, weeks or years. They can mutate at a rapid rate and recombine to form a highly infectious strain.
They are also more resistant to gamma radiation than bacteria, so sanitizing is difficult.
“The majority of viral meat contamination is caused by infected food handlers. Therefore work hygiene is critical,” she said.
Viral contamination of meat can occur on the farm, processing or at any other stage of handling.
Key problem viruses include norovirus, rotavirus, herpesvirus, retrovirus as well as hepatitis A and E.
Bacteria are a large group of organisms and cause illness on their own or through production of toxins.
There are many types with short life spans but they replicate and rapidly evolve new strains. Many bacterial strains found in the environment are resistant to multiple forms of antibiotics.
There are six groups of E. coli that can sicken people. It is a common bacterium and the strain E.coli O157:H7 can be found in ground meat contaminated during the regular slaughtering process.
There are several species of salmonella and more than 2,000 strains that can cause illness.
“They will vary in the severity and our ability to treat them,” Pip said.
Salmonella invades the intestinal lining and can incubate in six to 72 hours.
Most people recover on their own so the actual number of cases may be under reported. However, it could cause Reiter’s syndrome, arthritis and eye irritation after the infection, making it hard to trace.
Shigella is a group of bacteria that can release toxins and, depending on the species, the illness presents itself in different ways. The onset of sickness ranges from 12 hours to seven days.
Some people are asymptomatic with these infections and can spread it without knowing they are carriers.
Yersinia enterocolitis can take three to seven days after exposure. One study found two thirds of raw pork in the United States carries it. It originates in pig intestines, tonsils and lymph nodes.
“Pork is a big culprit but other meats can harbour this, “ she said.
It can withstand refrigeration. In the past it was often misdiagnosed as appendicitis.
Camplylobacter jejuni often occurs during the slaughter process. It is often found in poultry but can occur in other meats.
Staphylococcus aureus displays multiple antibiotic resistance. It is increasing but the true incidence is not well known.
Clostridium difficile and clostridium botulinum are two other serious infections that are not deactivated with cooking.
Botulism is well known and can be lethal. It is rare but is present in improperly processed meats or in improper home preserving. It is anerobic and can grow in vacuum packaged meats.
The consumer shift to nitrate free meats is increasing the risk of botulism.
Protozoa are often diagnosed as stomach flu. They are single celled organisms like cryptosporidium, giardia, toxoplasma, cyclospora and many others.
Toxoplasma is hard to culture in the lab and most often domestic cats are the source. A common link may be when the family cat sits on the counter where food is prepared.
Parasites like nematodes, trichinella, ascaris and tapeworms can be carried in undercooked meat.