Color and clarity, as well as the particle size distribution of gelatin, can be set within a certain range during the production process.
Color and clarity
In solution, gelatin has a typical yellowish color. This can be influenced by thermal treatment during the production process. Modern processes are able to produce brilliant, crystal-clear gelatins. Gelatins of high Bloom value are normally colorless. These are preferred in applications where color influence is not desirable.
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 greatly. Mostly, it is a simple process. An appropriate amount of water at a temperature of 60–80 °C is used and the gelatin is stirred in.
Depending on the equipment used, issues such as lump or foam formation can occur, often combined with a loss of gelling power. This normally happens when dissolution times are too long or too much mechanical energy is applied. 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
- 0.5 mm 35 mesh finely milled
- 0.8 mm 20 mesh standard milled
- 3 mm 6 mesh coarse milled.
The dissolution kinetics of gelatin are the result of three related processes:
1. wetting of the gelatin particles
2. water absorption (swelling) of the gelatin particles
3. dissolution of the swollen gelatin particles.
In principle, low concentration gelatin solutions can be prepared with all types of particles. For highly concentrated solutions, coarse particles are preferred; these tend not to produce lumps and tend to form fewer air bubbles when dissolving. However, 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 gelatin solution increases exponentially with concentration. Thus, when selecting the gelatin concentration to use, the conditions used in the processing plant should be taken into account.