90 Chilled foods 4.9 Refrigerated transport 4.9.1 General requirements Refrigerated transport of chilled foods must be seen as a total operation involving the movement of chilled goods from one fixed storage area to another The operation involves a of events, of which the actual movement of goods in a road vehicle, intermodal freight container, rail wagon, ship or aircraft is only a part. Temperature maintenance throughout the chain is essential for success, and the finest transport equipment cannot compensate for poor handling at loading, wrong packaging and stowage, or inadequate product cooling(Frith 1991). The term refrigerated transport may itself be misleading, in that frequently it should be temperature-controlled transport. In cold winter onditions, it may be necessary to heat chilled foods in order to prevent freezing damage, and for many fresh tropical fruits quite moderate temperatures can roduce irreversible chilling damage. For example, bananas should not be allowed to cool below about 13C. In areas of the world having severe winter conditions, heating requirements can be considerable. The distinction between efrigeration'andtemperature controlis important for equipment users, who may not appreciate that a wrong temperature-setting on transport equipment may ead to foodstuffs being heated, whereas in many static stores it would only lead to lack of refrigeration In general, transport equipment is designed to maintain temperature, and not to provide cooling. Whilst foodstuffs can be cooled to some extent during transport, this is a slow and non-uniform method of attempting to cool, and it should not be depended upon Pre-cooled foodstuffs should be loaded under temperature-controlled conditions wherever possible. In some cases, packaging designed for horizontal airflow coolers may not allow further cooling in transport, where vertical airflow is usual The range of transport refrigeration equipment is wide, as are the needs for transport. At its simplest, it could be an insulated box containing water ice. At its most complex, it might be an intermodal freight container with integral refrigeration machinery. This equipment is capable of maintaining either frozen or chilled goods at any selected temperature between -25C and +30C ambient temperatures from -20oC to +50oC. Most frequently it will be a road vehicle designed either for local deliveries or for long distance or bulk distribution(Fig. 4.5) The temperature control requirements for chilled foods are more difficult to achieve than those for frozen foods. Typically, it may be necessary to maintain cook-chill products between 0oC and 5C, and for many products closer tolerances are required, whereas with frozen foods there will be an upper limit mperature, perhaps -18C, but no lower limit. To ensure temperature uniformity in a load of chilled foodstuffs, relatively high rates of continuous air circulation and high levels of temperature control are necessary, and careful stowage within the vehicle may be needed to achieve this4.9 Refrigerated transport 4.9.1 General requirements Refrigerated transport of chilled foods must be seen as a total operation involving the movement of chilled goods from one fixed storage area to another. The operation involves a ‘chain’ of events, of which the actual movement of goods in a road vehicle, intermodal freight container, rail wagon, ship or aircraft is only a part. Temperature maintenance throughout the chain is essential for success, and the finest transport equipment cannot compensate for poor handling at loading, wrong packaging and stowage, or inadequate product cooling (Frith 1991). The term ‘refrigerated transport’ may itself be misleading, in that frequently it should be ‘temperature-controlled transport’. In cold winter conditions, it may be necessary to heat chilled foods in order to prevent freezing damage, and for many fresh tropical fruits quite moderate temperatures can produce irreversible chilling damage. For example, bananas should not be allowed to cool below about 13ºC. In areas of the world having severe winter conditions, heating requirements can be considerable. The distinction between ‘refrigeration’ and ‘temperature control’ is important for equipment users, who may not appreciate that a wrong temperature-setting on transport equipment may lead to foodstuffs being heated, whereas in many static stores it would only lead to lack of refrigeration. In general, transport equipment is designed to maintain temperature, and not to provide cooling. Whilst foodstuffs can be cooled to some extent during transport, this is a slow and non-uniform method of attempting to cool, and it should not be depended upon. Pre-cooled foodstuffs should be loaded under temperature-controlled conditions wherever possible. In some cases, packaging designed for horizontal airflow coolers may not allow further cooling in transport, where vertical airflow is usual. The range of transport refrigeration equipment is wide, as are the needs for transport. At its simplest, it could be an insulated box containing water ice. At its most complex, it might be an intermodal freight container with integral refrigeration machinery. This equipment is capable of maintaining either frozen or chilled goods at any selected temperature between
25ºC and 30ºC in ambient temperatures from
20ºC to 50ºC. Most frequently it will be a road vehicle designed either for local deliveries or for long distance or bulk distribution (Fig. 4.5). The temperature control requirements for chilled foods are more difficult to achieve than those for frozen foods. Typically, it may be necessary to maintain cook-chill products between 0ºC and 5ºC, and for many products closer tolerances are required, whereas with frozen foods there will be an upper limit temperature, perhaps
18ºC, but no lower limit. To ensure temperature uniformity in a load of chilled foodstuffs, relatively high rates of continuous air circulation and high levels of temperature control are necessary, and careful stowage within the vehicle may be needed to achieve this. 90 Chilled foods