A good formula for a vanilla extract is the following:
| Vanilla | 1 ounce |
| Tonka | 2 ounces |
| Alcohol, deodorized | 32 fluidounces |
| Syrup | 8 fluidounces |
Cut and bruise the vanilla, afterwards adding and bruising the Tonka; macerate for 14 days in 16 fluidounces of the alcohol, with occasional agitation; pour off the clear liquid and set aside; pour the remaining alcohol on the magma, and heat by means of a water bath to about 168° F., in a closely covered vessel. Keep it at that temperature for 2 or 3 hours, then strain through flannel with slight pressure; mix the two portions of liquid and filter through felt. Lastly, add the syrup. To render this tincture perfectly clear it may be treated with pulverized magnesium carbonate, using from 1/2 to 1 drachm to each pint.
To Detect Artificial Vanillin In Vanilla Extracts
Vanilla beans contain 4 to 11 per cent of this rosin. It is of a dark red to brown color and furnishes about one-half the color of the extract of vanilla. This rosin is soluble in 50 per cent alcohol, so that in extracts of high grade, where sufficient alcohol is used, all rosin is kept in solution. In cheap extracts, where as little as 20 per cent of alcohol by volume is sometimes used, an alkali—usually potassium bicarbonate—is added to aid in getting rosin, gums, etc., in solution, and to prevent subsequent turpidity. This treatment deepens the color very materially.
Place some of the extract to be examined in a glass evaporating dish and evaporate the alcohol on the water bath. When alcohol is removed, make up about the original volume with hot water. If alkali has not been used in the manufacture of the extract, the rosin will appear as a flocculent red to brown residue. Acidify with acetic acid to free rosin from bases, separating the whole of the rosin and leaving a partly decolorized, clear supernatant liquid after standing a short time. Collect the rosin on a filter, wash with water, and reserve the filtrate for further tests.
Place a portion of the filter with the attached rosin in a few cubic centimeters of dilute caustic potash. The rosin is dissolved to a deep-red solution. Acidify. The rosin is thereby precipitated. Dissolve a portion of the rosin in alcohol; to one fraction add a few drops of ferric chloride; no striking coloration is produced. To another portion add hydrochloric acid; again there is little change in color. In alcoholic solution most rosins give color reactions with ferric chloride or hydrochloric acid. To a portion of the filtrate obtained above add a few drops of basic lead acetate. The precipitate is so bulky as to almost {714} solidify, due to the excessive amount of organic acids, gums, and other extractive matter. The filtrate from this precipitate is nearly, but not quite, colorless. Test another portion of the filtrate from the rosin for tannin with a solution of gelatin. Tannin is present in varying but small quantities. It should not be present in great excess.
To Detect Tonka In Vanilla Extract.
Vanilla Substitute.
| Vanillin | 1 ounce |
| Alcohol | 6 quarts |
| Water | 5 quarts |
| Syrup | 1 quart |
| Caramel sufficient to color. | |