Gelatin Processing Aids

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Complete Process Essentials

Gelatin is a water soluble high molecular weight protein (20 to 250 KD) prepared by the thermal denaturation of collagen, isolated from animal skin and bones, with very dilute acid. It can also be extracted from fish skins.

Membrane filtration is used for:

• Purification
• Concentration
• Deashing
• Water Recovery

Raw Materials for Extracting Gelatin

• Pigs (Pigskin)
• Cattle - split
• Cattle Bones - Ossein
• Fish Skins

World Production of Gelatin

• Edible
• Gelatin Desserts, Gummed candies, marshmallow, wine fining or clarification and prepared meat products.
• Pharmaceutical
• hard and soft capsules, stabilizers for oil emulsions and glycerinated gelatin for suppositories
• Photographic
• paper coating and as a component in silver halide emulsion coatings
• Technical
• Micro-encapsulation, bacteriological culture media and in emulsion polymerizations.

Gelatin World Market 2003

Production in metric tons Percent by raw materials Pig skin 117,950 Bovine Hides 81,650 Bones 76,750 Other 1,950   Total 278,300 Production in metric tons Percent by Regions Western Europe 117,800 Eastern Europe 4,950 North America 60,500 South America 43,050 Asia 49,500 Other 2,500   Total 278,300

Grades of Gelatin

• Bloom Strength - measurement of the strength of a gel formed by a 6 2/3 % solution of the gelatin, at 10 ºC for 18 hours. (Grades Available: 50, 75, 100, 125, 150, 175, 200, 225, 250, 300 Bloom)
• A standard viscosity range is associated with each bloom level gelatin (between 10 - 2 cP for 6 2/3 % solution at 60 ºC )
• Clarity
• Micro-biological evaluation, inorganic ash, clarity, moisture content and heavy metal content.

These parameters depend on raw materials, extraction step, processing techniques especially thermal treatments.

Acid Manufacturing Process

The acid process is mainly used with pigskin and fish skin and sometimes bone raw materials. It is basically one in which the collagen is acidified to about pH 4 and then heated stepwise from 50°C to boiling to denature and solubilize the collagen. Thereafter the denatured collagen or gelatin solution has to be defatted, filtered to high clarity, concentrated by vacuum evaporation or membrane ultra-filtration treatment, to a reasonably high concentration for gelation and then drying by passing dry air over the gel. The final process is one of grinding and blending to customer requirements and packaging. The resulting gelatin has an isoionic point of 7 to 9 based on the severity and duration of the acid processing of the collagen which causes limited hydrolysis of the asparagine and glutamine amino acid side chains.

Alkali Manufacturing Process

The alkali process is used on bovine hide and collagen sources where the animals are relatively old at slaughter. The process is one in which collagen is submitted to a caustic soda or lengthy liming process prior to extraction. The alkali hydrolyses the asparagine and glutamine side chains to glutamic and aspartic acid relatively quickly, with the result that the gelatin has a traditional isoionic point of 4.8 to 5.2, however, with shortened (7 days or less) alkali treatment, isoionic points as high as 6 are produced. After the alkali processing, the collagen is washed free of alkali and treated with acid to the desired extraction pH (which has a marked effect on the gel strength to viscosity ratio of the final product). The collagen is then denatured and converted to gelatin by heating, as with the acid process. Because of the alkali treatment, it is often necessary to demineralise the gelatin solution to remove excessive amounts of salts using ion-exchange or ultrafiltration. Thereafter the process is the same as for the acid process - vacuum evaporation, filtration, gelation, drying, grinding and blending.

Manufacturing Process for Gelatin