Apart from a number of other parameters, the following properties of gelatine / gelatine solutions can be set within a certain range during the production process: color and clarity - these can be of importance for certain applications - and particle size distribution.
Color and clarity. From colorless to yellowish depending on requirement.
In solution, gelatine has a typical inherent yellowish color. This can be influenced by thermal treatment during the production process. Modern processes are able to produce brilliant, crystal-clear gelatines.
Gelatines of high Bloom value are normally colorless. These are preferred for products where color influence is not desirable.
Particle size. An important criterion for the user.
In almost all production processes the first step is dissolution. A very important parameter for this process is the milling process and the corresponding particle size distribution.
The technology used for dissolution varies a lot. Mostly, it is a simple process. An appropriate amount of water at a temperature between 60 - 80°C is used and the gelatine added under stirring. Depending on the equipment used, a number of problems can occur. The most frequent problem is the formation of lumps and foam, often in conjunction with exceptional loss of gelling power. This is normally due to too long dissolution times or too high mechanical energy, e.g. by turbo-stirrers and the like.
GELITA supplies a broad spectrum of specific milling grades that are precisely adjusted to the requirements of the customer.
The available particle sizes are:
• 0.1 mm 140 mesh "dust" milling (Staubmahlung)
• 0.5 mm 35 mesh finely milled
• 0.8 mm 20 mesh standard milled
• 3 mm 6 mesh coarse milled
The dissolution kinetics of gelatine are the result of three related processes:
1.) Wetting of the gelatine particles
2.) Water absorption (swelling) of the gelatine particles
3.) Dissolution of the swollen gelatine particles
In principle, gelatine solutions of low concentration can be prepared with all types of particles. For highly concentrated solutions coarse particles should be preferred; these tend not to produce lumps and can be dissolved with less formation of air bubbles. However, it should be taken into consideration that they take up water more slowly, require more time to swell and take longer to dissolve.
It should also be taken into consideration that the viscosity of a gelatine solution increases exponentially with concentration. Thus, in selecting the gelatine concentration to use, the conditions used in the processing plant should be taken into account.