Foods are perishable products, with a limited conservation period that varies according to the product and can be more or less long. Pathogenic microorganisms, viruses, moulds and yeasts are related to the food spoilage process. It is also important to remember that there are certain conditions that accelerate this decomposition, such as light, oxygen, temperature or humidity.
Foods such as fish, meat, milk, bread or vegetables have a short and limited shelf life. Other products, on the other hand, can be kept longer, although this does not mean that they will remain undamaged. Food begins to deteriorate already at the time of harvesting or slaughter. This process can be defined as an unpleasant change in its normal state. Some of these changes are detected through smell, taste or sight, although they are sometimes imperceptible to the senses.
The problem of temperature as one of the most recurrent in the distribution of hot meals to communities, The requirements for the transport of food are different depending on the type of food involved, so firstly the food must be divided into 2 main groups:
• perishable food
• pre-cooked food
The first group includes meat, dairy products and fish, and the second group includes hot meals and ready-made meals. Perishable food will be transported in special vehicles that will have the ATP plate in compliance with the Agreement on the International Carriage of Perishable Goods. Each type of food has its own temperature requirements for transportation, this is also specified in the regulations.
The transport of pre-cooked food is also laid down in a special regulation that ensures that it is not changed in any way during its movement. These foods are not included in the ATP Agreement (as they are not perishable) and it is very important to handle them carefully and to ensure that they are well placed in the vehicle so that they do not lose their air-tightness or become contaminated.
Transporting perishable foods
Remember that perishable goods are those that can deteriorate or lose their properties in a short time with the change of some environmental conditions such as humidity, temperature or pressure. Among perishable foods we find fresh products such as meat, fish, dairy products, fruits and vegetables. For these goods to reach the final consumer in perfect condition, it is necessary to carry out their transport under special safety and control measures.
The specific rules governing the transport of these goods come from the Agreement on the International Carriage of Perishable Foodstuffs and on the Special Vehicles used for such Purposes (ATP), which was adopted in Geneva in 1970. The main objective of this agreement is to ensure that these goods arrive in optimum condition at their destination and that the transport used is in accordance with the regulations contained in the ATP.
Avoiding contamination in food storage and transport
• Receptacles in vehicles and/or containers used for transporting foodstuffs are to be kept clean and maintained in good repair and condition to protect foodstuffs from contamination and are, where necessary, to be designed and constructed to permit adequate cleaning and/or disinfection.
• Receptacles in vehicles and/or containers are not to be used for transporting anything other than foodstuffs where this may result in contamination of foodstuffs by other cargo.
• Where vehicles and/or containers are used for transporting anything in addition to foodstuffs, or for transporting different types of foodstuffs at the same time, there must, where necessary, be effective separation of products.
• Bulk foodstuffs in liquid, granulate or powder form are to be transported in receptacles and/or containers/tankers reserved for the transport of foodstuffs. Such containers must bear either a clearly visible and indelible indication, in one or more Community languages, of the fact that they are to be used for the transport of foodstuffs, or the words “for foodstuffs only”.
• Where conveyances and/or containers have been used for transporting anything other than foodstuffs or for transporting different foodstuffs, there must be effective cleaning between loads to avoid the risk of contamination.
• Foodstuffs loaded into conveyances and/or containers must be so placed and protected as to minimise the risk of contamination.
• Where necessary, conveyances and/or containers used for transporting foodstuffs must be designed to maintain foodstuffs at appropriate temperatures and to allow those temperatures to be monitored.
Vehicle types and temperature during transport
The regulations on the transport of perishable goods stipulate the temperature conditions that must be met during transport depending on the type of food and also explain the type of vehicles that can be used to transport food. We would like to remind you that prepared meals are not considered perishable food and therefore it is not compulsory to transport them in vehicles that meet ATP requirements.
• Isothermal vehicle: The body of these vehicles is completely closed with an insulating material that limits the heat exchange between the interior and the exterior.
• Refrigerated vehicle: This is an isothermal vehicle equipped with a non-mechanical cold source, an isothermal unit that allows the temperature inside the box to be lowered to -20º.
• Refrigerated vehicle: Isothermal vehicle with a mechanical cooling device that allows the temperature of the box to be lowered and left permanently between -12º and -20º.
• Heating vehicle: Isothermal vehicle equipped with a heat production device that allows the temperature inside the box to be raised and kept constant at a value of over 12º. In the following table we summarize the temperature values that the goods must have during loading, transport and unloading depending on the food in question. This value must always be equal to or lower than the one indicated below.
|Temperature for food transport|
|Ice creams -20ºC.|
|Frozen or deep-frozen fish, molluscs, crustaceans -18ºC.|
|Frozen products -18ºC.|
|Frozen butter -10ºC.|
|Other frozen products -12ºC.|
|Red offal +3ºC.|
|Hunting products + 4ºC.|
|Milk in tanks +4ºC.|
|Industrial milk +6ºC.|
|Refrigerated milk products +4ºC.|
|Fish, molluscs and crustaceans in melting ice or at melting ice temperature.|
|Meat and meat preparations (except red offal) +7ºC.|
|Poultry and rabbits +4ºC.|
How does temperature affect food spoilage?
When the temperature is not properly controlled, the risk of food spoiling is greater. Maintaining a product between 5ºC and 65ºC for more than two hours is synonymous with the proliferation of pathogens. At these temperatures, bacteria can double in number every 20 to 30 minutes.
What is the best temperature for food poisoning bacteria to grow at?
Most bacteria will grow more quickly at temperatures between 40 and 140°F (4.4°C and 60°C), replicating in quantity as soon as 20 minutes.This temperature range is often called the “danger zone”.
Causes of food spoilage
Since temperature is one of the main reasons for food spoilage, there are other factors to consider as well, food spoilage is caused by improper handling and storage, although this process is also influenced by other aspects:
• Oxygen: Oxygen, which is essential for life, can have harmful effects on fats, colours, vitamins and other food components. In general, oxygen can provide the conditions for the growth of microorganisms or cause oxidation.
• Micro-organisms: Some bacteria require oxygen to grow (aerobic), while others only grow in the absence of oxygen (anaerobic). They can also be found on the surface of food when air is present. The main sources of microorganisms are air, soil, sewage, and animal waste.
• Enzymes: Certain enzymes are naturally present in food (oxidizing enzymes). These speed up chemical reactions between oxygen and food, leading to their breakdown. One of the most characteristic symptoms is browning of vegetables.
• Moisture: The amount of water in a food influences the appearance, texture and taste. In fresh produce, the water content can be as high as 70% or more of the total weight. Even dry foods, such as flour or cereals, contain a certain amount of water, an aspect that greatly affects the spoilage of food, if not properly preserved. To control this risk, processes such as dehydration (removing a certain amount of water), freezing (changing from a liquid to a solid state) or the use of additives such as salt and sugar are used.
• Light: Almost all foods are exposed to light from natural or artificial sources. This exposure can lead to changes in the color of the food, taste, or vitamin losses. In most solid products, light penetrates the outer layer, so deterioration occurs there. In liquids, on the other hand, penetration is usually greater. Sensitivity to light depends on factors such as intensity, type of light, distance between the light source and the food, duration of exposure or oxygen concentration in the product and temperature.