This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
All fluid extracts or essences and tinctures, when prepared with highly concentrated spirits, separate part of their extractive matter or dissolved oils in the cold, but especially when mixed with aqueous solutions or "carbonated waters," causing either a separation in flakes of the dissolved matter or a milky appearance, as in the case of essences when particles of oil separate. These extracts, essences and tinctures, therefore, must be made water soluble. That means to prepare them in such a strength as to be readily miscible with water or any aqueous liquid.
There is a difference between extracts, esseuces and tinctures made for the druggist, confectioner, or carbonator.
When the druggist flavors alcoholic medicines he can employ them more concentrated. The confectioner also can use the flavors in concentrated solution for the preparation of most all of his products. Not so for preparing his dispensing syrups, except he does not lay any particular stress on the bright appearance of the dispensed drinks, on account of being consumed immediately and while effervescing, yet when the "milki-ness" would not be so apparent. However this could go with his essences, his extracts and tinctures must have the same requirements as those used for bottling purposes: they must yield clear and bright syrups; too much concentrated extract would separate extractive matter on the admixture with syrup, and cause turbidity, with all its consequences.
The carbonator requires for all his purposes water-soluble flavorings. For preparing water-soluble essences or cutting essential oils we refer to the chapter on same. In this chapter we append directions how to prepare water-soluble extracts or tinctures, and such alcoholic essences that have been bought. The water solubility of these ingredients is an important point in the manufacture of carbonated beverages that should not be overlooked.
To make extracts and tinctures water soluble they are sometimes prepared with diluted alcohol, in order to readily yield clear solutions with aqueous liquids and avoid the separate treatment for making them water soluble. However, in most cases the employment of weak alcohol leaves the principal properties of the drug behind and undissolved in the drug, which, by using strong alcohol, would have been dissolved and made water soluble by the proper treatment. On the other hand, the diluted alcohol dissolves matters which are not required and better left behind, and which the strong alcohol does not extract, as they are only soluble in water or diluted alcohol. It is therefore advisable to prepare the fluid extracts with alcohol of sufficient strength, as specially directed for each case, also to prepare the tinctures as the respective formula will re-quire. Such preparations as have been made with stronger alcohol, and need therefore to be reduced to become miscible with water or remove resinous matter, treat as follows:
Take the fluid extract (except ginger, which we propose to dilute further), and proceed as follows: Into a half-gallon bottle put
Fluid ext, ginger .... 1 pint
Powdered pumice stone . . . . 4 oz avoirdupois
Pour the fluid extract into the bottle and add to it the pumice, shake well occasionally during several hours, and then slowly add the water in portions of about four fluid ounces, with plentiful agitation, and alternate periods of rest and subsidence. Continue this at intervals during twenty-hours, then filter, and upon the mass in the filter pour water until two pints are obtained. If the filtrate thus obtained is not quite clear it may be shaken with a little more pumice.
It is important to know that no alkaline should be used to make the extracts, etc., water soluble, as the action of fruit-acids used to acidulate the beverages creates a slight ebullition, and there ensues turbidity and flakiness, if the alkaline, which has absorbed a considerable amount of resinous matter from the mixtures, is not most carefully removed.