Studies on the optimum concentration of glycerine in the preparation and preservation of ragweed pollen extract

Abstract

1. 1. Extracts of low ragweed pollen, prepared in the concentration of 20 grams per 100 ml. of extracting fluid which contained 0, 5, 10, 20, 30, 40, and 50 per cent glycerine by volume, were observed after storage for five and twelve months at refrigerator (4° C.), deep-freeze (−25° C.), and room temperatures (20° C. to 40° C.), as well as heating at 56° C. for forty-five minutes. 2. 2. Each extract was evaluated in terms of appearance of sediment, changes in concentration of PTA nitrogen and reducing substances, and loss of activity in neutralization of skin-sensitizing antibody. 3. 3. The higher the concentration of glycerine, the greater was the protective effect against loss of reagin-neutralization activity at the various temperatures studied. 4. 4. There was essentially no change in PTA nitrogen after heating, regardless of the concentration of glycerine. There was, however, an appreciable loss in PTA nitrogen of the stored extracts, most pronounced in those extracts containing smaller concentrations of glycerine. 5. 5. The loss in bound carbohydrate varied under the different conditions of temperature. There was no change in any extract after heating at 56° C. for forty-five minutes. However, at room temperature, glycerine in the higher concentration showed a protective effect not evident in the lower concentrations. 6. 6. An important observation was the clarity of extracts of high glycerine content in comparison with the sedimentation in extracts containing either no glycerine or glycerine of low concentration. 7. 7. Whereas 30 and 40 per cent glycerine afforded significant protection against deterioration, the greatest protection was observed at the 50 per cent concentration.