By Rommel Gerodias
The living dangers in food preparation: choose sources wisely, watch out for toxins, and for goodness’ sake, wash your hands.
Every day we prepare and consume different types of food. Some are presented in different ways, and some are prepared longer than the others. While food flows from receiving, storage, preparation and cooking areas until it reaches the table for consumption, there are hazards along the way that may cause food to become unsafe.
In our May-June 2007 issue, we identified three hazards to food safety: physical, chemical and biological hazards. Of these three, biological hazards present a major threat to food safety.
Biological hazards are microorganisms such as viruses, parasites, fungi and bacteria. Let us study them closely so that we will understand how to deal with them:
Viruses are protein-wrapped genetic material, the smallest simplest known life form. Viruses do not reproduce in food because they require a living host to reproduce; however, they may survive cooking or freezing, and they can be transmitted to people by way of the food, utensils or equipment. They can cause several serious illnesses, including Hepatitis A, which causes inflammation of the liver.
Viruses can contaminate food through foodservice employees’ poor hygiene, contaminated food and water supplies, or shellfish harvested from sewage-contaminated waters. An important defense against food-borne viruses is to practice proper personal hygiene, especially through handwashing.
Parasites are micro-organisms that need a host (supporting organism) to survive. The most common parasite that contaminates food is Trichinella spiralis, a roundworm sometimes found in pigs. If not killed by thorough cooking or proper freezing, its larvae can cause trichinosis, a disease that causes abdominal and muscular pain. Another parasite is the Anisakis roundworm in fish. People who eat raw, marinated, or partially cooked fish such as sushi, may be at risk of becoming infected with this parasite.
Other parasites that may pose significant food and water safety hazards include Cryptosporidium parvum, a parasite that lives in the intestines of cattle and other animals. Drinking water supplies contaminated with high levels of runoff from farms or slaughterhouses have been implicated in outbreaks caused by this parasite. Another parasite is Toxoplasma gondii, which causes toxoplasmosis, an infection of the central nervous system. Individuals with compromised immune systems, such as the very young, or very old, pregnant women, cancer patients undergoing chemotherapy, and HIV-infected people, are most at risk. Toxoplamosis is caused by ingestion of raw or undercooked meat contaminated with this parasite or contaminated with fecal matter. Another parasite that spreads through person-to-person contact or contaminated food or water, Giardia lamblia, is the most common cause of waterborne intestinal diseases. The simplest and most effective way to prevent the disease caused by this parasite is proper handwashing.
Fungi range from microscopic, single-celled plants to mushrooms. Fungi are in the air, soil and water. Molds and yeast are types of fungi.
Individual mold cells are usually microscopic, but mold colonies may be seen as fuzzy growths on food. The main damage caused by molds is food spoilage, but some molds also produce toxins that can cause illness, infections, and allergic reactions. Some toxins survive cooking, such as botulinum toxin. Molds can grow on almost any food, at any storage temperature, and under any conditions. Freezing prevents mold growth, but does not destroy them. If mold is not a natural part of food, such as those in blue cheese, it should be discarded.
Yeasts require sugar and moisture to survive. These are commonly found in food such as jellies and honey. Yeasts spoil food by consuming it. Yeast spoilage appears as bubbles, with an alcoholic smell or taste, pink discoloration, or slime.
Although there are no specific regulations in the Philippines in certifying fish and seafood suppliers, the best food-safety control for fish is to purchase them only from reputable and certified suppliers. Examine incoming deliveries for signs of spoilage and carefully select the kinds of fish that are served, noting the following;
Some species of amberjacks, barracuda and other tropical reef fish may eat smaller fish that, in turn, have eaten smaller fish that have eaten algae carrying ciguatoxin. Ciguatoxin is naturally occurring toxin (which makes it a biological hazard) that is not destroyed by cooking. Ciguatera, resulting from ingestion of fish with elevated levels of ciguatoxin, is characterized by vomiting, itching, nausea, dizziness, hot and cold flashes, temporary blindness, hot and cold sensory reversal, and sometimes hallucinations.
Eating tuna, bluefish or mackerel which has been time-temperature abused can cause scombroid intoxication. Symptoms often resemble an allergic reaction and include flushing of the skin, sweating, a burning or peppery taste in the mouth, nausea, headache, facial rash, hives, edema, diarrhea and abdominal cramps. This illness is caused by histamine, an odorless tasteless chemical that is not destroyed by cooking.
Puffer fish, moray eels and freshwater minnows contain natural toxins.
Many plants such as fava beans, rhubarb leaves, jimson weed and water hemlock have been implicated in food-borne illness outbreaks. Food made from plants–such as honey from bees that gather nectar from mountain laurel, milk from cows that eat snakeroot, and jelly made from apricot kernels–also has been associated with food-borne outbreaks.
Some varieties of mushrooms are naturally poisonous. Since poisonous and non-poisonous mushrooms often look alike, make sure that you use only those purchased from reliable and reputable suppliers. Remember that freezing and cooking do not destroy all plant toxins.
Of all microorganisms, bacteria provide the most common threat to food safety. Bacteria are ling single-celled organisms. They can cause illnesses in two ways: Pathogenic (infectious, disease-causing) bacteria can multiply rapidly in favorable conditions in potentially hazardous foods, while Toxigenic (poisonous) bacteria can produce harmful toxins.
Inside their cells, certain bacteria produce protective thick-walled structures called spores. Spores do not reproduce, but they enable the bacteria to survive some cooking and freezing temperatures and the destructive effects of cleaning and sanitizing solutions.
Generally bacteria thrive in slightly acidic food (pH 4.6–7.5) with enough moisture (Available water,Aw= 0.85 and above), and grow rapidly within the Temperature Danger Zone or TDZ (5 deg. C to 57 deg. C). Potentially hazardous food exposed within the TDZ for more than four hours may already be considered unsafe. It is best to keep food safe by keeping it out of the TDZ and to observe proper cooking temperatures.
Sources: USDA, FDA, FSIS, ServSafe, International HACCP Alliance