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J Drying
Teil 3 Seite 6-19
The sterilised concentrated gelatine solution is pumped through a heat exchanger and
cooled to a temperature of less than 30 ºC, to form a gel. The gel is extruded through a
perforated sheet to form spaghetti-like threads. A small pivoting conveyor belt is used to
deposit the “spaghetti” on a large metal wire conveyor belt, which runs through a seg-
mented drying tunnel. In the drying tunnel the gel is dried with clean purified pre-dried
warm air. Each subsequent segment of the tunnel has a higher temperature, ranging from
25 - 30 ºC to 50 - 60 ºC. The drying takes up to 6 hours. The heat for the drier may be
recovered heat from hot water from the evaporator. When the gel enters the drying tunnel
it contains about 80 % water. The dried gelatine contains 9 - 15 % water, usually about
11 %. After drying, the gelatine is crushed and packed for intermediate storage. The
dried noodles are ground and bagged. Each batch is labelled for traceability. Various
grades are blended to meet individual customer requirements. The equipment that comes
into contact with the gelatine is usually made of stainless steel, but in some cases it is
synthetic material.
2 ACID BONE PROCESS
A Degreasing
See description under 1 Limed bone process.
B Demineralisation/acidulation
See description under 1 Limed bone process.
K Acid treatment
After the demineralisation/acidulation process the tank containing the ossein is filled
again, with the same amount of water as the original weight of the bone chips, and is left
to stand in it for about 0.5 – 1 day. The ossein still contains sufficient acid to keep the pH
below 2. The liquid is then removed and the ossein is washed again, one or more times,
to obtain a pH of about 2.5 or above and it is then transferred to the extractors, in a
stream of water.
E Extraction
See description under 1 Limed bone process. For acid bone extraction, the extractors
can be plastic coated.
F Filtration
See description under 1 Limed bone process.
G Ion exchange
See description under 1 Limed bone process. In some acid bone processes the anion
exchanger is placed before the cation exchanger.
H Concentration
See description under 1 Limed bone process.
I Sterilisation