Only handle food with clean hands. Always wash hands;
- Before handling food
- After handling raw meat and poultry
- After going to the toilet, or changing nappies
- After handling pets
- After gardening
Clean hands are hands that are washed and dried on a clean towel. Wash knives and utensils, and scrub chopping boards between preparation of raw and cooked foods.
- Defrost frozen foods in the fridge before cooking, not on your bench top
- Cool hot foods, covered, for no more than 30 minutes before refrigerating
- Reheat leftovers until steaming hot throughout and do not reheat them more than once
- Chicken, meat patties and sausages need to be cooked thoroughly
Pre-cook these meats before barbecuing. Do not put cooked meat back on the same plate that held raw meat. Ensure there are no traces of pink meat or juices before eating.
Food borne illness is caused by bacteria which are able to multiply very fast in moist, warm conditions where they have a suitable food source. Handling food carefully can stop the bacteria from getting to levels where they cause illness. Cooking food thoroughly helps kill the bacteria and chilling food stops the bacteria from multiplying. Clean hands and utensils and covered food helps stop the bacteria spreading.
- Cover foods before storing in the cupboard or fridge.
- Store raw and cooked foods separately.
Store raw meats in the bottom of the fridge to ensure juices don't drip onto other foods.
- Bacteria causing food borne illness thrive at room temperatures - keep food very cold or very hot.
- A chilly bin is a good way of keeping chilled products cold when taking them home from the supermarket.
- Put a frozen chilly pad with your picnic foods to keep food safe.
Remember to check the use by dates - If in doubt, throw it out!
These days time is short. It is commonplace to allow only 30 minutes to prepare the main meal of the day. We demand convenience and we also want foods with fewer preservatives and additives. We want fresh foods but we only want to shop once a week. With new technology industry has delivered a huge range of fresh ingredients and ready to eat, ready to heat or ready to cook meal solutions. These foods are very convenient but must be looked after properly to keep them safe. The incidence of food borne illness in New Zealand is at an all time high.
Please help to improve the statistics by following some simple rules when handling food in your car, home or garden.
Some foods are harmful right from the start, such as poisonous mushrooms, rhubarb leaves and some berries. Some foods become harmful due to changes that occur in them, such as diseases or contamination with foreign substances. For instance, some grains can become diseased with a fungus that produces very poisonous toxins. Some foods (especially in countries like Africa) become contaminated from unsafe water supplies that may have parasites and diseases in them. The types of harm that can come from food can come from the following sources:
- Bacteria may get into food via soils or water in plants, or via the skin or gut of an animal at slaughter. Depending on the type of bacteria, they may cause illness simply by being present, or they may produce toxins in the food or later in the person who ate that food. In New Zealand, most of our food borne illness is caused by bacteria. These will be discussed in more detail shortly.
- Fungi and moulds can also grow on many food types. Some are not harmful, but others can make toxins in the food which are very poisonous. It is neither safe nor appropriate to sell or serve food that has become mouldy with fungus, unless it is supposed to be, such as with blue cheeses.
- Viruses are becoming a more likely cause of food borne illness in New Zealand. They are most likely to get into food from water or unsafe food handling by an unwell food preparer. More on these later also.
- Parasites such as gut worms, protozoa such as giardia and cryptosporidium and other parasites are likely to get into food from contaminated water or from soil dust, or poor food handling by an ill handler.
- Chemicals are most likely to get into food from cleaning agents, pest control agents or as metals from improper storage in tins and such.
- Some poisons come from the foods themselves, when people wrongly prepare a food which is poisonous, such as decoration with poisonous garden plants. Some poisons are ingested by the food when alive and passed on to humans, such as with shellfish that have eaten toxic algae then becoming poisonous themselves.
Food Borne Illness
There are many types of food borne illness. Illness can be due to spoilage, contamination, infestation, bacterial load or toxins produced by bacteria or moulds.
Let's face it , you're in the food business, you want to make money from your food. It makes sense to have that food look good as well as taste good so that it attracts your customers in the first place. A sandwich that's starting to curl at the corners or a hunk of steak that's green and slimy just aren't attractive - and they might be harmful to eat. Food that doesn't look good may or may not be harmful, but it will certainly turn off your customers anyway.
Food spoilage occurs mainly as a result of chemical reactions involved in the process of aging and decay, through the action of bacteria, or through a combination of both.
In addition, drying, staling, contamination and damage by pests can assist in food spoilage.
Chemical food spoilage in food aging is caused by enzyme reactions natural to the living organism, continuing on after it has been slaughtered or harvested. For example, ripening once picked, continuing on to rot level. Initially these changes in meat make it more tender and flavoursome, but then it continues on to 'sogginess' and putrefaction if not stored at the correct temperatures. Also in meat, the fat may become rancid through oxidation. This causes what is most commonly recognised as 'off' flavours in cooked meat. Fish is much more susceptible, as being a cold blooded animal, it requires much colder temperatures to delay the decay process.
Microbial food spoilage may be due to either bacteria or moulds and yeast, but the more harmful tend to be the bacteria. Food spoilage is caused by changes in the food caused by their feeding on it, and their waste products. However, in many cases the food spoilage is not as harmful as the simple presence of the bacteria. Microbial contamination usually comes from damage to the food. In meat it usually occurs at slaughter when natural bacterial infestation of the skin and intestines of the carcass contaminates the meat itself.
Spoilage isn't necessarily harmful - rubbery carrots aren't likely to cause illness - but it might be and you can't always tell.
To avoid food spoilage, eat it fresh, store it refrigerated, cook it soon after purchase, eat it soon after cooking. Choose fruit and vegetables with clean, intact skins, meat that isn't slimy, green or smelly, and other foods that aren't mouldy or dusty.
There are three possible types of contamination to be avoided.
- Physical contamination
- Chemical contamination
- Microbial contamination
Physical contamination is basically the presence of some foreign object that shouldn't be there. It could be harmful, like a piece of broken glass; or it could be merely offensive, like a freshly washed slug on your salad. Many foreign object contaminations can be both harmful and offensive, such as hairs, broken fingernail, dead insects and many others that you can't even tell what they were! It doesn't matter - if it looks like it shouldn't be there it will offend your customers and you could be liable for an Offence against the Food Hygiene Regulations or the Food Act.
Be aware that even something harmless but offensive can make people violently ill - the body recognises WRONG! - EJECT! and deals with it on a subconscious level. You just lost a customer, and many of that person's friends as well.
Chemical contamination usually comes from inappropriate storage of cleaning solutions and pest control poisons. Make sure any non-food items are always stored in a marked container so that they cannot be mistaken for anything else. They must also be stored somewhere away from food and food items so that any leakage of the containers cannot contaminate any food or food item.
One restaurant was brought to a close forever by making a whole night's customers very ill indeed by contaminating food with dishwashing liquid because it had leaked from one shelf down to another and contaminated a commonly used ingredient.
Microbial contamination is the most common form of contamination and the most potentially harmful. Contamination could be by bacteria, viruses, yeasts and moulds or other microscopic "bugs". Some foods will be naturally laden with bacteria, such as raw meats, but most foods get their microbial contamination from the food handler, pests or from cross-contamination from other food items via things such as knives, cutting boards and slicers that have not been properly used. (More about prevention of cross contamination later).
Illness resulting from excessive bacterial growth can be of two types:
Food infection is illness caused by the presence of the bacteria itself, usually due to multiplication of the bacteria to large numbers over a length of time. Illness may not occur until some time after consumption of the contaminated food. Symptoms of the illness will be specific to that bacteria.
Food poisoning is illness caused by toxins released from the bacteria. Illness is likely to be more severe and have a more rapid onset. Prevention of bacterial contamination and control of growth are essential because some of these toxins are resistant to average cooking temperatures.
Moulds may also cause food spoilage activity, but still be desirable and harmless to eat, such as in blue cheeses. Meats, breads and sweet foods are also likely to be attacked by moulds. These are not generally harmful, but like bacteria, moulds can release toxins - especially those found on nuts and cereals, so it is best not to eat them.
In New Zealand, our biggest cause of unsafe food is bacteria. If you prevent and/or control the harm from bacteria, you will probably control the other potentially harmful sources. In some cases you will be preventing them getting into the food in the first place. Or, you may be controlling their numbers so that they are not harmful, or you may be actively killing them off. Whatever the circumstance, food must be ensured to be safe to eat at all times.
High and Low Risk Foods
Different foods carry different risks of becoming harmful to eat depending on factors such as water content, sugar levels, acidity, salt content, protein levels, natural bacterial load, exposure to air and how we prepare and eat them. Foods may be considered to be stable, semi-perishable, perishable, raw or cooked. For example:
Toast is more stable than bread because the lower moisture content doesn't support mould and bacterial growth as well. Similarly, raw meat will rot faster than cooked meat – but here's the trick – the cooked meat is more risky as it is likely to be eaten as is, whereas the raw meat is likely to be cooked and rendered safe. You must consider foods that are ready to be eaten as is the most risky as any abuse of them may not be over ridden before they are eaten.
High risk foods include:
- Cooked meat and poultry
- Cooked meat products such as pies, gravy, sauces, soups and stocks
- Processed meat products
- Some meat cuts eaten raw or rare
- Milk , cream, custards and other dairy products
- Cooked rice
- Eggs, especially if raw, egg products, custards, mayonnaise
These foods are readily perishable due to being excellent food sources for bacteria and therefore prone to spoilage and infection. Many of the bacteria associated with these foods are also toxin producing, leading to food poisoning also
Lower risk foods include:
- Jams and chutneys
- Pickled foods
- Foods preserved in brine (salt)
- Dry foods such as flour and grains
- Foods preserved in alcohol or oil
This is because bacteria need a warm (room temperature), moist environment to survive in that provides some food source. Bacteria cannot live in any food that is high in sugar, acid, salt, alcohol or oil.
Some bacteria need a supply of oxygen, some mustn't have it so it is difficult to use air supply as a control tool for food safety.
Food preservation by drying, salting and smoking, sweetening and acidifying provides environments that bacteria cannot survive in. But they must be done properly to avoid toxin production. Preservation by heating as in canning and pasteurisation kills off the harmful bacteria. Sealing to prevent re-contamination is essential. In some countries, food is preserved by irradiation. Although there has been shown to be no residual radiation, with excellent preservation results, this is not allowed in New Zealand or its imports.