Type A and Type B Gelatine

The gelatine molecule is capable of being charged in different ways. The isoelectric point (IEP), i.e. the pH at which the gelatine solution is neutral, is determined by the manufacturing process used. Subsequent to acid manufacture, pigskin gelatine (type A) has its IEP at pH 8.0-9.0; in alkaline manufacture (type B), usually the case with split and bone from cattle, the IEP is between 4.8 and 5.4.

For practical purposes, it is important to know that turbidity and loss of firmness can occur if the IEP is identical to the pH of the final product. The IEP also influences the compatibility of gelatine with other hydrocolloids. The pH of the final product is hence an important criterion when it comes to selecting the right type of gelatine.

 

Charge as a function of gelatine type and pH: