Proper food handling and storage can prevent most foodborne illnesses. In order for pathogens to grow in food, certain conditions must be present. By controlling the environment and conditions, even if potentially harmful bacteria are present in the unprepared or raw food, they will not be able to survive, grow, and multiply, causing illness. Show
There are six factors that affect bacterial growth, which can be referred to by the mnemonic :
Each of these factors contributes to bacterial growth in the following ways:
Identifying Potentially Hazardous Foods (PHFs)Foods that have the FATTOM conditions are considered potentially hazardous foods (PHFs). PHFs are those foods that are considered perishable. That is, they will spoil or “go bad” if left at room temperature. PHFs are foods that support the growth or survival of disease-causing bacteria (pathogens) or foods that may be contaminated by pathogens. Generally, a food is a PHF if it is:
Table 2 identifies common foods as either PHF or non-PHF.
The Danger ZoneOne of the most important factors to consider when handling food properly is temperature. Table 3 lists the most temperatures to be aware of when handling food.
The range of temperature from 4°C and 60°C (40°F and 140°F) is known as the , or the range at which most pathogenic bacteria will grow and multiply. Time-temperature Control of PHFsPathogen growth is controlled by a time-temperature relationship. To kill micro-organisms, food must be held at a sufficient temperature for a sufficient time. Cooking is a scheduled process in which each of a series of continuous temperature combinations can be equally effective. For example, when cooking a beef roast, the microbial lethality achieved at 121 minutes after it has reached an internal temperature of 54°C (130°F) is the same as if it were cooked for 3 minutes after it had reached 63°C (145°F). Table 4 show the minimum time-temperature requirements to keep food safe. (Other time-temperature regimens might be suitable if it can be demonstrated, with scientific data, that the regimen results in a safe food.)
The Top 10 List: Do’s and Don’tsFigure 1 illustrates the top 10 improper food-handling methods and the percentage of foodborne illnesses they cause. Figure 2. Top 10 causes of foodborne illness. Chart created by go2HR under CC BY. [Image description]This section describes each food-handling practice outlined in the top 10 list and the ways to prevent each problem. 1. Improper coolingMany people think that once a food has been properly cooked, all disease-causing organisms (pathogens) have been killed. This is not true. Some pathogens can form heat-resistant spores, which can survive cooking temperatures. When the food begins cooling down and enters the danger zone, these spores begin to grow and multiply. If the food spends too much time in the danger zone, the pathogens will increase in number to a point where the food will make people sick. That is why the process is crucial. Cooked food must be cooled from 60°C to 20°C (140°F to 70°F) in two hours or less, AND then from 20°C to 4°C (70°F to 40°F) in four hours or less. Figure 3. Food Cooling Procedure, used with permission from BC Centre for Disease Control (BCCDC)Even in modern walk-in coolers, large cuts of meat will not cool down properly. Neither will whole poultry. Even large pots (4 L/1 gal. or more) of soup, stews, gravy, etc., can take a day or more to cool to 4°C (40°F). However, you can cool these foods down quickly by using one or more of the following methods depending on the type of food being cooled:
2. Advance preparationAdvance preparation is the cause of many food-poisoning outbreaks, usually because food has been improperly cooled. Often, foods that are prepared well before serving spend too much time in the danger zone. This may happen for one or more of the following reasons:
To prevent problems of advance preparation:
3. Infected personMany people carry pathogens somewhere on or in their bodies without knowing it—in their gut, in their nose, on their hands, in their mouth, and in other warm, moist places. People who are carrying pathogens often have no outward signs of illness. However, people with symptoms of illness (diarrhea, fever, vomiting, jaundice, sore throat with a fever, hand infections, etc.) are much more likely to spread pathogens to food. Another problem is that pathogens can be present in the cooked and cooled food that, if given enough time, can still grow. These pathogens multiply slowly but they can eventually reach numbers where they can make people sick. This means that foods that are prepared improperly, many days before serving, yet stored properly the entire time can make people sick. Some pathogens are more dangerous than others (e.g., salmonella, E. coli, campylobacter). Even if they are only present in low numbers, they can make people very sick. A food handler who is carrying these kinds of pathogens can easily spread them to foods – usually from their hands. is extra dangerous. Ready-to-eat food gets no further cooking after being prepared, so any pathogens will not be killed or controlled by cooking. To prevent problems:
4. Inadequate reheating for hot holdingMany restaurants prepare some of menu items in advance or use leftovers in their units the next day. In both cases, the foods travel through the danger zone when they are cooled for storage and again when they are reheated. Foods that are hot held before serving are particularly vulnerable to pathogens. In addition to travelling through the danger zone twice, even in properly operating hot hold units, the food is close to the temperature that will allow pathogens to grow. To prevent problems:
5. Improper hot holdingHot hold units are meant to keep hot foods at 60°C (140°F) or hotter. At or above this temperature, pathogens will not grow. However, a mistake in using the hot hold unit can result in foods being held in the – between 20°C and 49°C (70°F and 120°F), temperatures at which pathogens grow very quickly. To prevent problems:
6. Contaminated raw food or ingredientWe know that many raw foods often contain pathogens, yet certain foods are often served raw. While some people believe these foods served raw are “good for you,” the truth is that they have always been dangerous to serve or eat raw. Some examples include:
These foods have caused many food-poisoning outbreaks. Always remember: you cannot tell if a food contains pathogens just by look, taste, or smell. To prevent problems:
7. Unsafe sourceFoods from approved sources are less likely to contain high levels of pathogens or other forms of contamination. Approved sources are those suppliers that are inspected for cleanliness and safety by a government food inspector. Foods supplied from unreliable or disreputable sources, while being cheaper, may contain high levels of pathogens that can cause many food-poisoning outbreaks. Fly-by-night suppliers (trunk sales) often do not care if the product is safe to sell to you, but approved suppliers do! As well, many fly-by-night suppliers have obtained their product illegally (e.g., closed shellfish fisheries, rustled cattle, poached game and fish) and often do not have the equipment to properly process, handle, store, and transport the food safely. Of particular concern is seafood from unapproved sources. Seafood, especially shellfish, from unapproved sources can be heavily contaminated with pathogens or poisons if they have been harvested from closed areas. To prevent problems:
8. Use of leftoversUsing leftovers has been the cause of many outbreaks of food poisoning because of improper cooling and reheating (of “hot” leftovers). Leftovers that are intended to be served hot pass through the danger zone twice (during the initial cooling of the hot food and when reheating). Those leftovers intended to be served without reheating, or as an ingredient in other foods (e.g., sandwich filler), go through the danger zone during cooling and then, when being prepared and portioned, often stay in the danger zone for another long period. The time in the danger zone adds up unless the food is quickly cooled and then quickly reheated (if being served hot), or kept cold until serving (if not being served hot). Contamination can also occur with leftover foods when they are stored in the cooler. Improperly stored leftovers can accidentally be contaminated by raw foods (e.g., blood dripping from a higher shelf). To prevent problems:
9. Cross-contaminationYou can expect certain foods to contain pathogens, especially raw meat, raw poultry, and raw seafood. Use extreme caution when you bring these foods into your kitchen. Cross-contamination happens when something that can cause illness (pathogens or chemicals) is accidentally put into a food where not previously found. This can include, for example, pathogens from raw meats getting into ready-to-eat foods like deli meats. It can also include nuts (which some people are very allergic to) getting into a food that does not normally have nuts (e.g., tomato sauce). To prevent problems:
10. Inadequate cookingProper cooking is one of the best means of making sure your operation does not cause a food-poisoning outbreak. Proper cooking kills all pathogens (except spores) or at least reduces their numbers to a point where they cannot make people sick. Inadequate cooking is often done by accident: for example, cooking still-frozen poultry or meat; attempting to cook a stuffed bird using the same time and temperature as an unstuffed bird; using an inexperienced cook. To prevent problems:
Image descriptionsFigure 1 image description: At 100°C (or 212°F), water boils. Above 74°C (or 165°F), bacteria die, although spores and toxins may survive. Food that is being cooked or reheated should hit 74°C (or 165°F). You can hold hot food for service at 60°C (or 140°F). Between 4°C and 60°C (or 40°F and 140°F) is the “Danger Zone.” Keep food out of this temperature range because bacteria will multiply rapidly. Between 0°C and 4°C (or 32°F and 40°F), most bacteria will survive but will not multiply quickly. Water freezes at 0°C (or 32°F). Between 0°C and −18°C (or 0°F and 32°F), most bacterial will survive but not grow. Frozen food is stored at −18°C (or 0°F). [Return to Figure 1] Figure 2 image description:
[Return to Figure 2] A mnemonic to remember the conditions that affect the growth of bacteria: food, acid, temperature, time, oxygen, moisture Temperature zone in which bacteria will grow the fastest: between 4°C and 60°C (40°F and 140°F) Bacteria that require oxygen in order to grow Bacteria that only grow in environments where oxygen is not present Foods that will allow the growth or survival of pathogens OR foods that may be contaminated by pathogens Lowering the temperature of a food from 60°C (140°F) down to 20°C (70°F) in two hours or less AND then from 20°C (70°F) down to 4°C (40°F) in four hours or less Large metal pans that are usually not deeper than 10 cm (4 in.) that are useful for cooling foods Reusable, hollow, plastic, sealable containers that are filled with water, sealed, and then once frozen, can be put in a liquid food to help cool the food quickly Any food that can be eaten without cooking or any other additional preparation, and is expected to be served this way Plastic, latex, or rubber gloves that, when worn while handling food, will eliminate direct hand contact with the food Small plastic or rubber tubes that, when inserted over a finger, will form a waterproof cover over a cut or sore To hold foods at 60°C (140°F) or hotter; at these temperatures, pathogens will not grow The temperature range where pathogens will grow very quickly, between 20°C and 49°C (70°F and 120°F) to apply heat or chemicals on a clean food contact surface (e.g., cutting board, countertop) to destroy most pathogens The temperature taken with a thermometer in the centre of the food; in the case of whole poultry or large cuts of meat, the temperature should be taken in the thickest part of the flesh without the thermometer touching a bone |