Propylene glycol alginate

Propylene glycol alginate (PGA) is a partial ester of alginic acid with propylene glycol. Unlike plain alginates, it maintains its thickening and stabilising properties in acidic conditions (low pH), making it uniquely suited for use in acidic salad dressings, beer foam stabilisation, fruit beverages, and other acidic food systems where sodium or calcium alginates would lose viscosity or gel stability.

JECFA's ADI for propylene glycol alginate is 25 mg per kilogram body weight per day, evaluated in 1975. This numerical ADI (rather than "not specified") reflects the propylene glycol component, which is metabolised to lactic acid through normal metabolic pathways. At typical dietary exposures from food use, no adverse effects have been identified. The alginate component contributes dietary fibre as with other alginates.

Propylene glycol alginate is approved in the EU, US (GRAS), UK, and most global markets. It is particularly prevalent in creamy salad dressings, beer (for foam stabilisation), and acidic fruit-based beverages. For healthy adults there are no safety concerns at typical dietary exposures. It is one of the few hydrocolloids with acid stability, making it technically indispensable in certain product categories.