Temperature in the food industry and Celsius™
Glossary of Celsius related Terms and Guidelines
UK Department of Health Guidelines, Terms and Glossary:
Cook-Chill means a catering system based on the full cooking of food follow by fast chilling
and storage in controlled low temperature conditions above freezing point (0°C to +3°C) and
subsequent thorough reheating close to the consumer before consumption. It can take up to
five days including the day of cooking but no longer as food quality diminishes (Department
of Health, 1993).
Cook-Freeze means a catering system based on full cooking followed by fast freezing storage.
At controlled low temperature conditions well below freezing point (-18°C or below) and
subsequent thorough reheating close to the consumer before prompt consumption
(Department of Health, 1993).
Microorganism growth is minimised when food is stored at a maintained temperature below
freezing point (Department of Health, 1993).
Food Storage Temperature and Life
The recommended Cook-Freeze and long term storage temperature for food is -18°C. Food
Cook-Chill food the storage life should not exceed 5 days with temperatures maintained
below +3°C (Department of Health, 1993).
In Cook-Chill and Cook-Freeze operations initial cooking will ensure destruction of
vegetative stages of any pathogenic microorganisms present. Rapid multiplication of
pathogenic microorganisms occurs between 7°C and 60°C. Subsequently, this temperature
range must be spanned as rapidly as possible to minimise growth during cooling, after
cooking and during thawing or reheating (Department of Health, 1993).
Food Nutrient Retention
Nutrient content in food depends on the quality of the original raw materials, the storage
conditions and the extent and nature of processing. Nutrient deficiency in vegetables increases
proportionally to storage time before preparation and time held in water after preparation.
Retention of nutrients and vitamins occurs if vegetables are cooked quickly and consumed as
soon as possible afterwards. Reductions in nutrition can also be caused by over-cooking and
prolonged delay between reheating and consumption; which can also cause loss of flavour and
palatability. Cook-Chill processes can cause nutrient losses. However, fast chilling can stem
the losses. Retention of nutrients in food can increase if products are stored below -18°C.
Chemical Oxidation can also cause Nutrient deficiencies especially those with unsaturated
fatty acid content (Department of Health, 1993).
Nutrient Content (quality of original raw materials)
Extent and nature of food processing
Nutrient and Vitamin C losses
Prolonged delays between reheating and consumption
Prolonged storages (especially vegetables)
Chemical Oxidation (exposure to oxygen/air)
Poor refrigeration processes
If vegetables are cooked quickly and consumed afterwards.
Storage below -18°C
Foods used as ingredients in meals, including those which have been pre-cooked (Department
of Health, 1993).
Prepared food, i.e. food ready to be used for cooking, should be held at temperatures below
+10°C until the cooking process commences (Department of Health, 1993).
The core temperature is the temperature of the central point of the food product. The time and
temperature of the cooking should be sufficient to ensure that heat penetration to the centre of
foods stuff will result in the destruction of non-sporing pathogens. This is normally achieved
when the core temperature exceeds 70°C. To destroy Listeria monocytogenes the
temperature throughout the food should be held >70°C for >2 minutes. The core temperature
can be read accurately for frozen, chilled and hot products with the McQueen-Cairns Celsius
System (Department of Health, 1993).
Food portioning is dividing food into smaller quantities. After cooking food portioning should
be completed in within 30 minutes for any product in a controlled environment room with the
temperature <10°C (Department of Health, 1993).
Chilling Pre-Cooked Food
Chilling cooked food refers to the cooling process of cooked food to an overall temperature
between 0°C and 3°C. Chilling should occur within 90 minutes of the product leaving the
cooker. This helps preserve food appearance, texture, flavour, nutritional quality and safety of
the cooked food (Department of Health, 1993).
Speed of chilling of a food stuff depends on:
1. Size, shape, weight of food and contruction material of the container;
2. Food density and moisture content;
3. Heat capacity of the food and the container;
4. Thermal conductivity of the food;
5. The design of the chiller;
6. Temperature of the food entering the chiller;
7. Whether the container is provided with a cover (Department of Health, 1993).
Pre-Chilled Food Storage
Chilled foods are much more vulnerable to temperature abuse during storage than frozen
foods. There during storage it is important:
1. That the temperature of the cooked food after chilling be maintained below +3°C
throughout the entire storage and distribution until reheating.
2. That the maximum storage life of chilled products does not exceed 5 days, including
both the day of cooking and consumption. This also applies to where pre-cooked
chilled products are purchased from outside suppliers.
3. Should the temperature of the cooked food in storage exceed +5°C, but not 10°C, and
before reheating, the food should be consumed within 12 hours or destroyed.
4. Should the temperature exceed +10°C, during storage the chilled cooked food should
be destroyed (Department of Health, 1993).
Freezing Pre-Cooked Food
Freezing should take placed <90minutes of the food leaving the cooker. The foods Core
Temperature should reach -5°C within 90minutes of entering the freezing and subsequently
reach a temperature of -18°C. Food that has thawed either partially or completely should not
be re-frozen; and that which has thawed to an unknown temperature destroyed (Department of
Cooked Frozen Food Shelf Life
Frozen food shelf life of cooked food varies with products but in general should not exceed 8
weeks. After the 8 weeks the food can lose nutrients and palatability, and rancidity can occur
in high fat content products (Department of Health, 1993).
Food temperature measurement
No matter what device is used be it the McQueen Cairns Celsius system, electronic
thermometers, PRT probes or infrared surface readers, the temperature of the food will not
necessarily be the same as that of the surrounding air or cryogenic gas. Some temperature
variations are likely to occur at different points in the processes. All records of temperatures
and other monitoring results at critical control should be kept for at least three months.
Indications of temperature abuse should be investigated and corrected promptly. The
McQueen-Cairns Celsius system keeps records of the product signature and date/time stamps
when it was tested (Department of Health, 1993).
Variations in the total aerobic colony are the most useful guide to the hygiene and temperature
control of the process. It is suggested by Department of Health (1993) that one sample of
about 100 grams of each item of food be taken from each batch tested. Samples should be
taken immediately before the food is due to be reheated so that the results reflect any abuse
conditions to which the item sampled has been subjected during storage and transport
following processing (Department of Health, 1993).
Food should generally achieve the following microbiological criteria:
Total aerobic colony count after incubation of agar plates for 48 hours at 37°C - <100,000 per
Salmonella species – not detected in 25g.
Escherichia coli - <10/g
Staphylococcus aureus (coagulase positive) <100 per gram.
Clostridium perfringens <100/g
Listeria monocytogenes – not detected in 25g (Department of Health, 1993).
General Food Industry Terms and Glossary (From Allfoodbusiness.com, 2004):
Calibration - the process of standardizing a temperature monitoring instrument to ensure that
it will measure within a specific temperature range in which the instrument is designed to
operate (Allfoodbusiness.com, 2004).
Chemicals - Chemical food born illnesses are among the most deadly. Chemicals and other
“natural” toxins formed in food include agents such as scombrotoxin and ciguatoxin. Store
cleaning supplies in a different area away from stored food (Allfoodbusiness.com, 2004).
Control (verb) - To take all necessary actions to ensure and maintain compliance with
criteria established in the HACCP Plan (Allfoodbusiness.com, 2004).
Control (noun) - The state wherein correct procedures are being followed and criteria are
being met (Allfoodbusiness.com, 2004).
Control Measures - Actions and activities that can be used to prevent or eliminate a food
safety hazard or reduce it to an acceptable level (Allfoodbusiness.com, 2004).
Corrective Actions - Actions to be taken when the results of monitoring at the CCP indicate
a loss of control (Allfoodbusiness.com, 2004).
Critical Control Point (CCP) - A step at which control can be applied and is essential to
prevent or eliminate a food safety hazard or reduce it to an acceptable level
Critical Limit - A criterion which separates acceptability from unacceptability
Cross-contamination - Cross-contamination is when bacteria spread between food, surfaces
or equipment (Allfoodbusiness.com, 2004).
Detergent - A chemical used to remove grease, dirt and food, such as washing-up liquid
Disinfectant - A chemical that kills bacteria. Check that surfaces are clean of grease, dirt and
food before you use a disinfectant. Chemicals that kill bacteria are sometimes called
germicides, bactericides or biocides (Allfoodbusiness.com, 2004).
Employee - Any person working in or for a food service establishment who engages in food
preparation or service, who transports food or Food containers, or who comes in contact with
any food utensils or equipment.
Equipment- All stoves, ranges, hoods, meat blocks, tables, counters, Refrigerators, freezers,
sinks, dishwashing machines, steam tables and similar items, other than utensils, used in the
operation of a food service establishments (Allfoodbusiness.com, 2004).
Fixed food establishment - A food service establishment which operates at a specific
location and is connected to electric utilities, water, and a sewage disposal system
Food born Illness - A general term often used to describe any disease or illness caused by
eating contaminated food or drink (Allfoodbusiness.com, 2004).
Food born infections - These occur when “enough” of the live bacterial cells that have
reproduced in the food, small intestine, or both are consumed. The severity of the infection
depends on the virulence of the bacteria, resistance of the victim,
and the number of cells that survive digestion (Allfoodbusiness.com, 2004).
Food born intoxications - These result from a poison or toxin produced by reproductive
bacterial cells in food or in the human body. Bacterial toxins have varying resistance to heat;
some can even survive boiling. Other toxins can be a natural part of the food, for example,
certain types of mushrooms (Allfoodbusiness.com, 2004).
Food born Illness Outbreak - The Centers for Disease Control define an outbreak of food
born illness as illness that involves two or more persons who eat a common food, with the
food confirmed as the source of the illness by a laboratory analysis. The only exception is that
a single case of botulism qualifies as an outbreak (Allfoodbusiness.com, 2004).
Food contact surfaces -Surfaces of equipment and utensils with which normally comes in
contact, and those surfaces from which food may drain, drip, or splash back onto surfaces
normally in contact with Food (Allfoodbusiness.com, 2004).
Food poisoning - An illness that occurs when people eat food that has been contaminated
with harmful germs (particularly bacteria and viruses) or toxins (poisonous substances)
Food Preparation - The manipulation of foods intended for human consumption by such
means as washing, slicing, peeling, chipping, shucking, scooping and/or portioning
Food Service Establishment - Any facility, where food is prepared and intended for
individual portion service, and includes the site at Which individual portions are provided
HACCP - A system which identifies, evaluates, and controls hazards which are significant for
food safety (Allfoodbusiness.com, 2004).
HACCP Plan - A document prepared in accordance with the principles of HACCP to ensure
control of hazards which are significant for food safety in the segment of the food chain under
consideration (Allfoodbusiness.com, 2004).
Hazard - A biological, chemical or physical agent or factor with the potential to cause an
adverse health effect (Allfoodbusiness.com, 2004).
Hazard Analysis - The process of collecting and evaluating information on hazards and
conditions leading to their presence to decide which are significant for food safety and
therefore should be addressed in the HACCP plan (Allfoodbusiness.com, 2004).
Kitchenware - All multi-use utensils, other than tableware (such as pots, pans)
Limited Food Service Establishment - Any establishment with a food operation, so limited
by the type and quantity of foods prepared and the equipment utilized, that poses a lesser
degree of risk to the public's health, and, for the purpose of fees, requires less time to monitor
Monitor - The act of conducting a planned sequence of observations or measurements of
control parameters to assess whether a CCP is under control (Allfoodbusiness.com, 2004).
Parasites - These tiny organisms can cause severe illness. Parasites need nutrients from their
host to complete their life cycle. They are always associated with raw or undercooked meat
and fish, including pork, bear meat and others (Allfoodbusiness.com, 2004).
Pathogen - Any disease producing agent, microorganism or germ (Allfoodbusiness.com,
Perishable Foods - Any food of such type or in such condition as may spoil; provided, that
foods which are in hermetically sealed containers processed by heat or other means to prevent
spoilage and properly packaged, dehydrated, dry or powered foods so low in moisture content
as to retard development of microorganism are not considered readily perishable
Potentially Hazardous Food - Any perishable food that is capable of supporting rapid and
progressive growth of infectious or toxigenic microorganisms (Allfoodbusiness.com, 2004).
Safe Temperatures - As applies to potentially hazardous foods, means Temperatures of 41
degrees F or below, or 140 degrees F or above (Allfoodbusiness.com, 2004).
Sanitizer - A two-in-one product that acts as a detergent and a disinfectant
Single-Service Articles - Any cups, containers, closures, plates, straws, place mats, napkins,
doilies, spoons, stirrers, paddles, knives, forks, wrapping materials, and all similar articles,
which are constructed wholly or in part from paper or paper material, foil, wood, plastic,
synthetic or other readily destructible materials, for one time and one person use and then
discarded (Allfoodbusiness.com, 2004).
Step - A point, procedure, operation or stage in the food chain including raw materials, from
primary production to final consumption (Allfoodbusiness.com, 2004).
Tableware - Multi-use eating and drinking items, including flatware, knives, forks, spoons,
glasses, cups, etc.(Allfoodbusiness.com, 2004).
Temperature - a critical measurement for ensuring the safety and quality of many food
products (Allfoodbusiness.com, 2004).
Utensil - Implements such as pots, pans, ladles or food containers used in the preparation,
storage, transportation or serving of food (Allfoodbusiness.com, 2004).
Verification - The application of methods, procedures, and tests, in addition to those used in
monitoring to determine compliance with the HACCP plan, and/or whether the HACCP plan
needs modification (Allfoodbusiness.com, 2004).
Viruses - Viruses grow or reproduce only on living cells. They are often found in untreated
water or sewage-contaminated water, and viruses from human feces on unwashed hands can
infect others by passing the virus to food. Normal cooking may lower the risk of illness but
may not destroy all viruses (Allfoodbusiness.com, 2004).
Allfoodbusiness.com, 2004. Glossary of Food Safety Terms. AllFoodBusiness.com, Caspar,
Wyoming. Viewed 03/12/2008, http://www.allfoodbusiness.com/foodsafety_glossary.php.
Department of Health, 1993; Chilled and Frozen, Guidelines on Cook-Chill and Cook-Freeze
Catering Systems, London: HMSO.