Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
2.2.8.4 Sweeteners
Starch slurry is the starting raw material for the manufacture of sweeteners or sugar syrups.
These are produced by the action of acids, enzymes or a combination of both, however enzymes
are more commonly used. In a typical process, the starch slurry is heated to gelatinise the starch
and then mixed with acids and/or enzymes and reacted in different liquefaction, saccharification
and isomerisation reactors. The temperature is then raised to around 140 °C. Conversion of the
starch only takes a few minutes. The mass is neutralised and after several stages of purification,
i.e. separation of insolubles, demineralisation and decolourisation, the product obtained is
evaporated. The liquor is usually filtered and treated with active charcoal or ion exchange resins
to remove colour, ash and other minor impurities, e.g minerals. The liquid sweetener resulting
can be sold as such, or dried, or crystallised to produce dry sweeteners.
2.2.8.5 Modified (physical/chemical) starch
The properties of native starch can be changed to produce modified starch. Modification can be
carried out with chemicals, enzymes or physically. The chemicals added can either be dry or
wet, so final drying may be necessary. In the dry chemical modification process, dewatered and
dried native starch is used. The product is chemically modified starch. In the wet process, the
starch slurry, or the re-slurried native starch, is fed directly into the reactor with chemicals and
the reaction takes place in liquid form. The resulting slurry can be washed and/or dewatered
prior to drying. The product is a physico-chemically treated or modified starch.
2.2.9 Animal feed
The compound feed industry consists of two distinct sectors, i.e. animal feed and petfood.
Animal feeds are predominantly dry, while petfoods often have a significant moisture content.
In both sectors, the manufacturing process involves the blending of a range of ingredients such
as cereals, protein sources, vitamins, minerals, fats and oils, to produce nutritionally balanced
foods.
By far the most important moist petfood ranges are those for dogs and cats. These foods are
classified according to moisture, packaging and processing systems, and include moist foods
and semi-moist foods. In the UK, although moist foods currently comprise a major portion of
the market, semi-moist foods are becoming increasingly popular. Moist foods have a moisture
content of 60 to 85 % and are usually preserved by heating. Heat treatment may be applied
before or after packaging. Moist foods can be subdivided into canned foods, premium moist
foods, brawns and frozen meats.
2.2.9.1 Animal feed and dry petfood
The main animal feed types are compound feeds. These consist of a variety of blended
ingredients. The composition is varied depending on the type and age of the animal to be fed,
but typically includes ingredients such as cereals, animal and vegetable proteins, fibre sources,
minerals and supplements such as vitamins, antibiotics and other additives. Some of the
ingredients are co-products and by-products of the FDM sector.
The raw materials are received at the feed mill and may be pneumatically conveyed or
mechanically transferred to bulk storage silos. Some small ingredients which may be mixed in
during the process, such as supplements, may be sent pre-bagged in appropriate quantities.
Ingredients are weighed automatically in modern installations and transferred to holding bins
prior to grinding, typically using hammer mills. After grinding, the ingredients are thoroughly
mixed and any supplements are added. The blend may then be drawn off as meal or mash feed,
or pressed to produce pelleted feed. More commonly, the blend goes on to be manufactured into
feed pellets. Steam is injected into the feed in a process known as conditioning before being
forced through holes in the pelletising die. The resulting pellets vary in size depending on the
intended use. After this stage of manufacture, the pellets are dried and then cooled, typically in
96 January 2006 RHC/EIPPCB/FDM_BREF_FINAL