FOODBORNE DISEASES Notes
I. Food preservatives are placed in 3 main categories:
1. Antimicrobials which inhibit growth of bacteria, yeasts/molds and viruses;
2. Antioxidants which slow air oxidation of fats that can lead to rancidity; &
3. Types that block natural ripening & enzymatic processes that continue to occur in foods after harvest.
II. Other commonly used food preservatives & ways foods are preserved:
a. Natural food preservatives comes the salt, sugar, alcohol, vinegar used at home while making pickles, jams and juices etc
b. freezing, boiling, smoking, salting are considered to be the natural ways of preserving food. Coffee powder and soup are dehydrated and freeze-dried for preservation
c. Sugar and salt are the earliest natural food preservatives that very efficiently drops the growth of bacteria in food. To preserve meat and fish, salt is still used as a natural food preservative.
d. Chemical preservatives such as: Benzoates (such as sodium benzoate, benzoic acid)
· Nitrites (such as sodium nitrite) give red meats their pink hues & prevent Clostridium botulinum bacteria that spoils meats.
· Sulphites (such as sulphur dioxide) keeps fruits freash, & acts as an antimicrobial
· Sorbates (such as sodium sorbate, potassium sorbate
e. Artificial preservatives are the chemical substances that stops of delayed the growth of bacteria, spoilage and its discoloration.
Types of Artificial Preservatives Food
a. Antimicrobial agents ; b. Antioxidants; c. Chelating agent
In antimicrobial comes the Benzoates, Sodium benzoate, Sorbates and Nitrites.
Antioxidants include the Sulfites, Vitamin E, Vitamin C and Butylated hydroxytoluene (BHT)
Chelating agent has the Disodium ethylenediaminetetraacetic acid (EDTA), Polyphosphates and Citric acid
f. Some common preservatives and their primary activity
Chemical Affected / Organism / Action / Used in FoodsSulfites / Insects & Microorganisms / Antioxidants / Dried Fruits, Wine, & Juice
Sodium Nitrites / Clostridia / Antimicrobial / Cured Meats
Proprionic Acids / Molds / Antimicrobial / Breads, Cakes, Cheeses
Sorbic Acid / Molds / Antimicrobial / Cheeses, Cakes, Salad Dressings
Benzoic Acid / Yeasts & Molds / Antimicrobial / Soft Drinks, Ketchup, Salad Dressings
h. Osmotic pressure: The principle of osmosis is applied. Foods are preserved by adding salts and sugars to them. These chemicals remove the water out of microbial cells causing them to shrink. Thus stopping their metabolism. Jams, jellies, fruit syrups, honey etc. are preserved by high sugar concentration. Fish, meat beef and vegetable products are preserved with salt.
i. Chemical preservatives: The most commonly used are the acids, such as sorbic acid, benzoic acid and propionic acid. These check mainly the growth of yeasts and molds. Sorbic acid is used for preservation of syrups, salads jellies and some cakes. Benzoic acid is used for beverages, margarine, apple cider etc.
Propionic acid is an ingredient of bread and bakery products. Sulphur dioxide, as gas or liquid is also used for dried fruits, molasses and juice concentrates. Ethylene oxide is used for spices, nuts and dried fruits.
j. Radiation:. UV is used in meat storage facilities which reduce surface contamination, on meat products. Gamma rays are also used for some meat products.
k. Anaerobiosis: Packaging of food products under anaerobic conditions - anaerobiosis is effective in preventing aerobic spoilage process. Vacuum packing in an airtight container is used to eliminate air.
l. Controlled atmospheres: Such atmospheres containing 10% CO2 are used to preserve stored food products as apples and pears. This checks fungal growth. Ozone can also be added.
III. Some chemicals used as food preservatives that may be hazardous to our health include:
a. Propyl Gallate
This preservative, used to prevent fats and oils from spoiling, might cause cancer. It's used in vegetable oil, meat products, potato sticks, chicken soup base and chewing gum, and is often used with BHA and BHT (see below).
b. BHA and BHT
Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are used similarly to propyl gallate -- to keep fats and oils from going rancid. Used commonly in cereals, chewing gum, vegetable oil and potato chips (and also in some food packaging to preserve freshness), these additives have been found by some studies to cause cancer in rats. If a brand you commonly buy uses these additives, look for a different variety, as not all manufacturers use these preservatives
c. Potassium Bromate
This additive is used in breads and rolls to increase the volume and produce a fine crumb structure. Although most bromate breaks down into bromide, which is harmless, the bromate that does remain causes cancer in animals. Bromate has been banned throughout the world, except for in the United States and Japan. In California, a cancer warning would likely be required if it were used, which is why it is rarely used in that state.
d. Monosodium glutamate (MSG)
MSG is used as a flavor enhancer in many packaged foods, including soups, salad dressings, sausages, hot dogs, canned tuna, potato chips and many more. According to Dr. Russell Blaylock, an author and neurosurgeon, there is a link between sudden cardiac death, particularly in athletes, and excitotoxic damage caused by food additives like MSG and artificial sweeteners. Excitotoxins are, according to Dr. Blaylock, "A group of excitatory amino acids that can cause sensitive neurons to die."
Many consumers have also personally experienced the ill effects of MSG, which leave them with a headache, nausea or vomiting after eating MSG-containing foods. To find out more about the side effects associated with MSG, as well as a complete
e. Aspartame (Equal, NutraSweet)
This artificial sweetener is found in Equal and NutraSweet, along with products that contain them (diet sodas and other low-cal and diet foods). This sweetener has been found to cause brain tumors in rats as far back as the 1970s, however a more recent study in 2005 found that even small doses increase the incidence of lymphomas and leukemia in rats, along with brain tumors. People who are sensitive to aspartame may also suffer from headaches, dizziness and hallucinations after consuming it.
f. Sodium Nitrite (Sodium Nitrate)
Like diet soda? The aspartame that's used to sweeten it increases lymphomas, leukemia and brain tumors in rats -- even in small doses.
Sodium nitrite (or sodium nitrate) is used as a preservative, coloring and flavoring in bacon, ham, hot dogs, luncheon meats, corned beef, smoked fish and other processed meats. These additives can lead to the formation of cancer-causing chemicals called nitrosamines.
Some studies have found a link between consuming cured meats and nitrite and cancer in humans.
g. Acesulfame-K
Acesulfame-K is an artificial sweetener that's about 200 times sweeter than sugar. It's used in baked goods, chewing gum, gelatin desserts and soft drinks. Two rat studies have found that this substance may cause cancer, and other studies to reliably prove this additive's safety have not been conducted. Acesulfame-K also breaks down into acetoacetamide, which has been found to affect the thyroid in rats, rabbits and dogs.
h. Olestra
Olestra is a fat substitute used in crackers and potato chips, marketed under the brand name Olean. This synthetic fat is not absorbed by the body (instead it goes right through it), so it can cause diarrhea, loose stools, abdominal cramps and flatulence, along with other effects. Further, olestra reduces the body's ability to absorb beneficial fat-soluble nutrients, including lycopene, lutein and beta-carotene.
i. Blue 1 and Blue 2
Blue 1, used to color candy, beverages and baked goods, may cause cancer. Blue 2, found in pet food, candy and beverages, has caused brain tumors in mice.
j. Red 3
This food coloring is used in cherries (in fruit cocktails), baked goods and candy. It causes thyroid tumors in rats, and may cause them in humans as well.
k. Yellow 6
As the third most often used food coloring, yellow 6 is found in many products, including backed goods, candy, gelatin and sausages. It has been found to cause adrenal gland and kidney tumors, and contains small amounts of many carcinogens.
l. Hydrogenated Vegetable Oil
The process used to make hydrogenated vegetable oil (or partially hydrogenated vegetable oil) creates trans fats, which promote heart disease and diabetes. The Institute of Medicine has advised that consumers should eat as little trans fat as possible. You should avoid anything with these ingredients on the label, which includes some margarine, vegetable shortening, crackers, cookies, baked goods, salad dressings, bread and more. It's used because it reduces cost and increases the shelf life and flavor stability of foods.
IV. Some factors that make some foods more sensitive to microbial growth?
a. temperature
b. water content
c. exposure to light
V. 90 percent of the cases of food poisoning each year are caused by the bacteria Staphylococcus aureus, Salmonella, Clostridium perfringens, Campylobacter, Listeria monocytogenes, Vibrio parahaemolyticus, Bacillus cereus, and Entero-pathogenic Escherichia coli. These bacteria are commonly found on many raw foods. Normally a large number of food-poisoning bacteria must be present to cause illness. Therefore, illness can be prevented by (1) controlling the initial number of bacteria present, (2) preventing the small number from growing, (3) destroying the bacteria by proper cooking and (4) avoiding re-contamination.
VI. Microorganisms that can cause food poisoning:
a. Staphylococcus aureus, b. Salmonella,
c. Clostridium perfringens d. Campylobacter
e. Listeria monocytogenes, f. Vibrio parahaemolyticus
g. Bacillus cereus
BacteriaResponsible / Description / Habitat / Types of
Foods / Symptoms / Cause / Temperture
Sensitivity
Staphylococcus aureus / Produces a heat-stable toxin / Nose and throat of 30 to 50 percent of healthy population; also skin and superficial wounds. / Meat and seafood salads, sandwich spreads and high salt foods. / Nausea, vomiting and diarrhea within 4 to 6 hours. No fever. / Poor personal hygiene and subsequent temperature abuse. / No growth below 40o F. Bacteria are destroyed by normal cooking but toxin is heat-stable.
Salmonella / Produces an intestinal infection / Intestinal tracts of animals and man / High protein foods - meat; poultry, fish and eggs. / Diarrhea nausea, chills, vomiting and fever within 12 to 24 hours. / contamination of ready-to-eat foods, insufficient cooking and recontamination of cooked foods. / No growth below 40o F. Bacteria are destroyed by normal cooking.
Clostridium perfringens / Produces a spore and prefers low oxygen atmosphere. Live cells must be ingested. / dust, soil and gastrointestinal tracts of animals and man. / Meat and poultry dishes, sauces and gravies. / Cramps and diarrhea within 12 to 24 hours. No vomiting or fever. / Improper temperature control of hot foods, and recontamination. / No growth below 40o degrees F. Bacteria are killed by normal cooking but a heat-stable spore can survive.
Clostridium botulinum / Produces a spore and requires a low oxygen atmosphere. Produces a heat-sensitive toxin. / Soils, plants, marine sediments and fish. / Home-canned foods. / Blurred vision, respiratory distress and possible DEATH. / Improper methods of home-processing foods. / Type E and Type B can grow at 38o F. Bacteria destroyed by cooking and the toxin is destroyed by boiling for 5 to 10 minutes. Heat-resistant spore can survive.
Vibrio parahaemolyticus / Requires salt for growth. / Fish and shellfish / Raw and cooked seafood. / Diarrhea, cramps, vomiting, headache and fever within 12 to 24 hours. / Recontamination of cooked foods or eating raw seafood. / No growth below 40o F. Bacteria killed by normal cooking.
Bacillus cereus / Produces a spore and grows in normal oxygen atmosphere. / soil, dust and spices. / Starchy food. / Mild case of diarrhea and some nausea within 12 to 24 hours. / Improper holding and stroage temperatures after cooking. / No growth below 40o F. Bacteria killed by normal cooking, but heat-resistant spore can survive.
Listeria monocytogenes / Survives adverse conditions for long time periods. / Soil, vegetation and water. Can survive for long periods in soil and plant materials. / Milk, soft cheeses, vegetables fertilized with manure. / Mimics meningitis. Immuno- compromised individuals most susceptible. / Contaminated raw products. / Grows at refrigeration (38-40o F.) temperatures. May survive minimum pasturization tempertures (161o F. for 15 seconds.)
Campylobacter jejuni / Oxygen sensitive, does not grow below 86o F. / Animal reservoirs and foods of animal origin. / Meat, poulty, milk, and mushrooms. / Diarrhea, abdomianl cramps and nausea. / Improper pasteuriztion or cooking. cross-contamination. / Sensitive to drying or freezing. Survives in milk and water at 39 o F for several weeks.
Versinia enterocolitica / Not frequent cause of human infection. / Poultry, beef, swine. Isolated only in human pathogen. / Milk, tofu, and pork. / Diarrhea, abdominal pain, vomiting. Mimics appendicitis. / Improper cooking. Cross-contamination. / Grows at refrigeration temperatures (35-40o F.) Sensitive to heat (122 oF.)
Enteropathogenic E. coli / Can produce toxins that are heat stable and others that are heat-sensitive. / Feces of infected humans. / Meat and cheeses. / Diarrhea, abdominal cramps, no fever. / Inadequate cooking. Recontamination of cooked product. / Organisms can be controlled by heating. Can grow at refrigeration temperatures.
Hypertext markup by Gretchen Eagle and Dan Lineberger. Http://aggie-horticulture.tamu.edu/extension/poison.html
6. Staphylococcus produces an heat stable toxin_ that is relatively Harmless.
7. An organism normally found in human intestines that can cause food poisoning is bacillus (Escherichia coli) but its growth is usually limited by intestinal Flora (Pyer’s Patches).
8. The most severe type of food poisoning is that caused by E. coli O157:H7
9. A food source of infant botulism is __ Clostridium botulinum
10. List 5 common symptoms of food poisoning:
a. Nausea & Vomiting b. Diarrhea
c. fever & chills d. dehydration
e. bloody stools
11. How is food poisoning different from food infection?
a. Food infection refers to the presence of bacteria, etc within the food.
b. Food poisoning refers to the effect on the body after ingesting such infected food.
12. Salmonellosis is caused by the organism rod shaped, gram negative Salmonella bacteria.
13. Food poisoning by some organisms is more common in the summer months. especially during summer when food may not be kept cold enough to prevent bacteria from growing.