Diseases caused by bacteria

Bacteria ( tiny one -celled organisms) can cause two types of food poisoning - infective food poisoning and toxic food poisoning:

• Infective food poisoning occurs as a result of eating live bacteria that is in the food. The best way to prevent this type of food poisoning is to prevent the growth of the micro-organisms. Examples of bacteria that cause infective food poisoning are Salmonella, Listeria and Escherichia coli.


• In contrast, toxic food poisoning results from toxins that are produced by some bacteria and it is these toxins that cause illness. In general , the toxins cannot be removed or inactivated by cooking. The main food poisoning bacteria that produce toxins are Staphylococcus aureus, Clostridium perfringens and some types of Escherichia coli.

SALMONELLOSIS
Bacteria: Salmonella
Source: Spread when contaminated food (meat, poultry, eggs or milk) is eaten raw or undercooked. Also, when cooked food comes in contact with contaminated raw food, or when an infected person prepares food.
Symptoms: Onset 6–48 hours after eating; nausea, fever, headache, abdominal cramps, diarrhoea and vomiting lasting 2–7 days. Can be fatal to infants and the elderly.
Prevention: Separate raw foods from cooked foods. Thoroughly cook meat, poultry and eggs. Do not leave food for over two hours at room temperature. Refrigerate food at below 5 degree C.

STAPHYLOCOCCAL FOOD POISONING
Bacteria: Staphylococcus aureus
Source: Carried by people on skin in boils, pimples and throat infections; spread when carriers handle food. Staph bacteria produce toxins (poisons) at warm temperatures. Found in meat, poultry, salads, dressings, gravies, cream sauces, cheese, eggs, custards and cream –filled desserts.
Symptoms: Onset 1–8 hours after eating; vomiting, diarrhoea, nausea and abdominal cramps lasting 1–2 days. Rarely fatal.
Prevention: Cooking will not destroy staph poison, so practise good personal hygiene and sanitary food handling. Do not leave perishable food unrefrigerated for over two hours. For quick cooling, place hot food in small containers no more than two centimetres deep, cover when cool and refrigerate.

BOTULISM
Bacteria: Clostridium botulinum
Source: Most common in low-acid foods canned improperly at home. The presence of these bacteria or their poisons is sometimes signalled by clear liquids turning milky, cracked jars, loose or dented lids, swollen or dented cans, or an ‘off’ odour. Found in meat and fish.
Symptoms: Onset 4–72 hours after eating; nervous system disturbances such as double vision, droopy eyelids, trouble speaking, swallowing or breathing. Untreated botulism can be fatal.
Prevention: Carefully examine canned goods and do not use any that show danger signs. Also, cook and reheat foods thoroughly, keep cooked foods hot (above 60 degree C) and cold (below 5 degree C), and divide larger portions of cooked food into smaller portions for serving and cooling.

PERFRINGENS FOOD POISONING
Bacteria: Clostridium perfringens
Source: Called the ‘buffet germ’, it grows rapidly in large portions of food that cool slowly. It grows in warming dishes, which may not keep food sufficiently hot, and in the refrigerator if food is stored in portions that are too large to cool quickly. Found in meat and poultry.
Symptoms: Onset 8–12 hours after eating; diarrhoea, abdominal cramps, headache, chills.
Prevention: Keep food hot or cold. Reheat food carefully, especially soups and casseroles.

CAMPYLOBACTERIOSIS
Bacteria: Campylobacter jejuni
Source: Found in raw milk, eggs, poultry, raw beef, cake icing and water.
Symptoms: Onset 2–10 days after eating; severe diarrhoea, cramps, fever and headache.

Prevention: Pasteurise milk, cook foods properly.

LISTERIOSIS
Bacteria: Listeria monocytogenes
Source: Common in food-processing environments and digestive tracts of humans. Found in untreated water and milk, dairy products, raw meat and seafood.
Symptoms: Onset 2-30 days after eating; fever, flu-like symptoms. Infants may vomit, have trouble breathing; pregnant women, in particular, are at risk.
Prevention: Avoid foods that are not pasteurised.

SHIGELLOSIS
Bacteria: Shigella
Source: Poor sanitary habits spread by touching moist foods. Bacteria multiply at room temperature. Found in poultry, salads and foods that require mixing but not heating.
Symptoms: Onset 1-7 days after eating; abdominal pain, fever and vomiting.
Prevention: Good personal hygiene; refrigerate perishable foods.

BACILLUS CEREUS FOOD POISONING
Bacteria: Bacillus cereus
Source: Found in cooked rice that was not refrigerated and then consumed; pasta, potatoes, meat, milk.
Symptoms: Diarrhoea and vomiting.
Prevention: Refrigerate perishable foods.

HAEMORRHAGIC COLITIS
Bacteria: Escherichia coli
Source: Drinking water contaminated by sewage transmitted to raw food.
Symptoms: Onset 3 -4 days after eating; severe abdominal cramps, diarrhoea, vomiting and fever.
Prevention: Do not consume untreated water; thoroughly cook food.

Questions:

1. Explain the difference between infective food poisoning and toxic food poisoning.

2. Which food poisoning is more dangerous and why? Support your answer with examples.

Food Safety Rules

Follow the below food safety rules:

Cold storage
• Cold food must be 5 °C or colder.
• Frozen food must be frozen hard.
• Check the temperature of fridges and cold storage areas regularly.
• Thaw food in your fridge, away from, and below, cooked or ready to eat food.

Preparation
• Limit the time that high-risk food is in the temperature danger zone and return to the refrigerator during delays.
• If food is kept within the temperature danger zone for a total time of 4 hours or more, throw it out.

Cross- contamination
• Cross-contamination occurs when harmful bacteria or allergens spread to food from other food, surfaces, hands or equipment. This can lead to food-poisoning, to ensure cross - contamination does not occur, make sure you;
1. Keep raw food separate from cooked or ready-to-eat food.
2. Use separate utensils and cutting boards when preparing raw and cooked or ready- to-eat food.

Cooking food
• Use a thermometer to make sure foods are thoroughly cooked and the centre reaches 75 °C.
• Hot food must be kept at 60 °C or hotter.
• Check that only clear juices run from thoroughly cooked minced meat, poultry, chicken or rolled roasts.

Cooling food
• High-risk food must cool from 60 °C to 21°C in the first 2 hours, and then to 5°C or lower in the next 4 hours.
• Once food has cooled to 21°C put it in the refrigerator or freezer.
• Large portions of food take longer to cool. Divide large portions into smaller batches before cooling.

Cleaning
• Use clean, sanitised and dry cutting boards, equipment and utensils.
• Clean and rinse wiping cloths after each use, and change frequently.
• Wash hands thoroughly and regularly.

Answer the following questions:

1.Explain the terms contamination and cross-contamination.
2. List the possible causes of cross-contamination that can occur within the domestic kitchen and ways to minimise the risk.

3. What do you understand by danger zone?

The Australian Army ration packs

Read the following Case Study and answer the questions.



Combat ration pack

There are numerous situations within the Army environment which require diverse catering. These situations vary from group feeding arrangements from a kitchen when soldiers are in barracks, to providing a soldier with a combat ration pack, which can be either individual, or group style, whilst in the field. Army Catering Corps personnel may, where practicable, set up field kitchens during exercises or on operations to provide fresh rations. First let's look at the issues relating to Army rations.

Menu planning

Menus for the rations provided to soldiers are provided on a scientifically formulated basis to meet the nutritional needs of soldiers within the environment in which they are operating. Consideration is also given to providing variety in the soldier's diet.


Ration specifications

These are governed by the Australian Defence Force Food Specifications (ADFFS) and a Defence document known as SUPMAN 4. ADFFS is a detailed document covering food specifications, with SUPMAN 4 detailing a soldier's entitlement, or allowance for rations. Consideration of weight is given to Combat ration packs to minimise the weight a soldier must carry. Normally a soldier will carry only up to three days of rations during exercises or operations; however, this requirement will increase or decrease depending upon circumstances. Combat ration packs have a minimum shelf life of two years.

Meal preparation

Soldiers in the field may eat their rations hot or cold. Each soldier is provided with a small solid fuel stove and cooking containers to heat meals.

Water allowance

Soldiers are encouraged to drink sufficient water to remain hydrated. Thus the requirement for water varies according to environmental conditions. Generally, a minimum of three litres of water is required to sustain a soldier, but this requirement can increase considerably.

Ration contents

A typical combat ration used by a soldier in the field contains three meals for one day. This may include canned or freeze-dried meals, canned fruit, biscuits, coffee or tea making items, toilet paper, matches, and a small can opener. Food technology has changed the contents of these packs over the years. In particular freeze-dried foods and in the future, retort pouch technology.

Preparation of ration packs

The typical chain of events in preparing the packs involves:

*assessment to determine the number of packs needed
*evaluation of any changes to existing contents of different types of pack
*placement of orders to the Defence suppliers
*inspection of the components
*delivery to the ration packing contractor
*packaging
*distribution to meet Defence requirements.

Activity
1. Why is the weight of the ration pack an issue for army personnel?

2. Identify the Hazard Analysis Critical Control Points (HACCP) in the chain of events listed for preparing the ration packs.

3.Research and draw flow charts for the manufacture of:
a) canned meat casserole
b) freeze-dried meat casserole
c) meat casserole using retort pouch technology.

4. Explain why adequate hydration is an issue for army personnel. What are the functions of water in the body?

5. A can opener is the major tool of food preparation for army ration packs.

a) Investigate the functions of packaging and the types of packaging materials available.
b) Design a suitable package for one food item. Consider:
*packaging material
*opening
*resealable lid
*use as a container to eat from.