What causes an extract to become cloudy and develop sediment?
Allergenic extracts from certain species have a tendency to form “precipitates”. These form when proteins or other substances in the extract coagulate and form visible clumps. Short ragweed is one of the species most likely to precipitate, however many other species exhibit this property.The more concentrated extracts have a greater tendency to form precipitates. A 1:10 aqueous extract is more likely to precipitate than a 1:20 glycerinated extract of the same species. Similarly, a 100,000 PNU extract is more prone to forming sediments than is a 10,000 PNU preparation of the same source material. Based on some limited data on a few extracts, when precipitates are removed by filtration, the allergenic potency appears to be unchanged suggesting that the precipitates do not include any important allergens. However, precipitated product is not suitable for use.Manufacturers do not ship extracts that have visible precipitates.
