298 94 307/02 Untersuchungen zum Stand der Umsetzung des ...

Teil 3 Seite 6-12
- In- vessel composting of animal b- products (4.3.13.5-p. 329)
- Use of a high carbon source to prevent pungent ammonia odours (4.3.13.6-p. 329)
- Avoiding dusty activities on windy days (4.3.13.7-p. 329)
6.1.15 Use of meat and bone meal as fertiliser
Reference to actual BREF (4.3.14-p.330)
6.1.16 Ancillary site services
6.1.17 Gelatine manufacture
Gelatine is derived from hydrolysis of collagen, the main protein constituent of bones,
skins and connective tissues such as sinews [Leiner, 1965 #203]. The raw materials used
comprise bones, fresh or frozen hides, pig skins and fish skins and chrome tanned
leather. The use of hides and skins submitted to tanning processes is prohibited for the
production of gelatine intended for human consumption [EC, 1999 #85]. The pABP Reg
requires all material destined for gelatine production to be Category 3 material as defined
therein.
There are several processes for the production of gelatine. These depend to some extent
on the raw materials used, although after the de-fatting and demineralisation of bones and
the demineralisation of pig skins, the gelatine extraction steps in some of the processes
using bones hides and pig skins are very similar. The main gelatine manufacturing processes
are summarised in FIG WWW and the individual process steps are described below.
Description of the main gelatine manufacturing processes
The following descriptions should be read, with reference to FIG WWW [GME, 2002
#249].
6.1.17.1 Bone gelatine
1 LIMED BONE PROCESS
A Degreasing
The untreated bones contain a large amount of meat, soft tissue and fat, which has to be
removed. A typical example of the composition of a batch of fresh bones is: water content
46 %, fat 15 %, protein 19 % and minerals 20 %.
The degreasing process is very similar to rendering. The bones are crushed in a pre-
breaker to a maximum of 20 mm diameter, before being degreased, using hot water, at a
temperature of 75 - 90 ºC, for 15 - 30 minutes. A continuous process has been reported,
using a steam jacketed and steam-heated screw conveyor. The turbulent action of the hot
water and the sliding and rubbing of the crushed bone loosens the meat and other soft