Integrierte Vermeidung und Verminderung der Umweltverschmutzung

2.1.7 Processing by the removal of heat (G)
2.1.7.1 Cooling, chilling and cold stabilisation (G.1)
2.1.7.1.1 Objective
Chapter 2
Cooling is used to reduce the temperature of the food from one processing temperature to
another or to a required storage temperature. Chilling is a processing technique in which the
temperature of a food is reduced and kept at a temperature between -1 and 8 °C. The objective
of cooling and chilling is to reduce the rate of biochemical and microbiological changes in
foods, to extend the shelf-life of fresh and processed foods, or to maintain a certain temperature
in a food process, e.g. in the fermentation and treatment of beer. Cooling is also used to promote
a change of state of aggregation, e.g. crystallisation. The objective of cold stabilisation is to
precipitate out tartrates in wines, or fatty acids in spirits before bottling.
2.1.7.1.2 Field of application
Cooling, chilling and cold stabilisation are widely used in the FDM sector.
Chilling is used for preservation of a lot of perishable foods. In the wine sector, cooling and
chilling are applied to clarify the must before fermentation. Cold stabilisation in used in the
beer, wine and spirit sectors. Beer is cold stabilised to precipitate the protein-polyphenol adduct.
The beer is kept between -2 and -3 ºC for at least 12 hours.
2.1.7.1.3 Description of techniques, methods and equipment
Cooling of liquid foods is commonly carried out by passing the product through a heatexchanger
or cooler or by cooling the vessels. The cooling medium in the cooler can be
groundwater, water recirculating over a cooling tower, or water, eventually mixed with agents
like glycol, which is recirculated via a mechanical refrigeration system or ice-water system.
In cryogenic cooling, the food is in direct contact with the refrigerant, which may be solid or
liquid carbon dioxide, or liquid nitrogen. As the refrigerant evaporates or sublimates, it removes
heat from the food, thereby causing rapid cooling. Both liquid nitrogen and carbon dioxide
refrigerants are colourless, odourless and inert.
The supply of chilled foods to consumers requires a sophisticated distribution system, involving
chilled stores, refrigerated transport and chilled retail display cabinets. Chilled foods can be
grouped into three categories according to the storage temperature [225, Hendley B., 1985]. A
fourth category is applied to winemaking.
• -1 to 1 °C for fresh fish, meats, sausages and ground meats, smoked meats and fish
• 0 to 5 °C for pasteurised canned meat, milk and milk products, prepared salads, baked
goods, pizzas, unbaked dough and pastry
• 0 to 8 °C for fully cooked meats and fish pies, cooked or uncooked cured meats, butter,
margarine, cheese and soft fruits
• 8 to 12 °C for the wine industry. The must is kept at this temperature for 6 to 24 hours.
The equipment used for freezing (see Section 2.1.7.2) can also be used for cooling and chilling.
Cold stabilisation is a technique for chilling wines before bottling to cause the precipitation of
tartrate crystals. For spirits, this technique consists of bringing the spirit to a temperature of
between -1 and -7 ºC, depending on the operators, and possibly performing a stabulation, i.e.
storing at low temperature, in tanks at constant temperatures for between 24 and 48 hours. A
cold filtration, around -1 ºC, allows the fatty acid esters to be retained. For wines, three
techniques can be employed; cold stabilisation by batch and stabulation, continuous cold
stabilisation, and cold stabilisation by crystal seeding. The two last techniques are the most
widely-used. There can be many variations on these basic schemes.
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