INS 330 is citric acid (E330 in Europe), the same acid that makes lemons and limes sour. A label that prints “Acidity Regulator (INS 330)” names both the job and the substance: citric acid is there to set and hold the acidity of the food. Commercial citric acid is not squeezed from citrus fruit; it is made by fermenting sugars with the mould Aspergillus niger.
In sweet snacks, citric acid sharpens fruit flavours and balances sweetness. In jams and jellies it also matters for texture, because pectin gels set properly only within a certain acidity range. It is one of the most widely used food additives and is permitted under Codex.
On SeekSnack it appears in this form on Euro Choco Pie with Marshmallow and Raspberry Jam, listed right after the gelling agent pectin (INS 440).
