Gelatine — Frequently Asked Questions

The force in grams needed to depress the surface of a standard gel by a set distance, which is a direct measurement of gel strength rather than an indirect proxy. Commercial grades run from about 80 to 300 Bloom, and higher Bloom means a firmer gel at the same dose, so the grade determines both performance and how much is needed.

The pretreatment before extraction. Type A is produced by acid treatment, usually of pigskin, and has an isoelectric point around pH 7 to 9. Type B comes from alkaline treatment, usually of bovine hide and bone, with an isoelectric point around pH 4.7 to 5.4. That difference in charge behaviour matters in formulations where the gelatine interacts with other charged ingredients.

Because no synthetic polymer has matched it. Gelatine adsorbs onto growing silver halide crystals and controls their size and habit during precipitation, then holds them uniformly suspended in the coated layer. That combination of crystal habit control and colloid stabilisation has resisted substitution, which is why gelatine remains in photographic and X-ray film.

Because they contain proteolytic enzymes, bromelain and papain, which digest the protein chains that would otherwise re-form into the gel network. The enzymes are denatured by heat, so tinned or cooked fruit causes no problem; only fresh or frozen raw fruit does. Kiwi, fig and ginger have the same effect.