Extract of Malt.
By J. U. LLOYD.
Read at the Sixth Session of the Thirty-first Annual Meeting of the American Pharmaceutical Association.
When substances of this kind were introduced some five years ago, we were induced by the demand created to make a preparation of malt. In looking at the matter it, then seemed to us that the desideratum was a pharmaceutical one which should embody the soluble constituents of well malted barley. We therefore arrived at the conclusion that there was little if any necessity for a deviation from the regular line of fluid extracts, although the process for making malt extract in Germany resulted in a substance of the consistence of thick honey. Our view of the subject has not been changed. The most practical and feasible process for extracting the desirable principles from malt in our opinion is that of percolation. The product represents all of the valuable constituents of malt if the menstruum is adapted to their extraction. The finished fluid extract is pleasant to the taste; it is rich in diastase.
The action of malt on warm gelatinous starch, whereby the starch is quickly changed into dextrin and sugar, has been familiar since malt liquors have been used. Payen and Persoz (1833) first gave us the name diastase, which they applied to the fermentation principle of germinating malt. This substance is also found in other germinating seeds, sprouting potatoes, etc. This diastase is now generally accepted as the desirable principle of malt, although the glucose certainly is useful as a food, and to us it is by no means certain that other substances than diastase are not present and valuable.
Extract of malt, as introduced into this country, and which, as far as we can learn, was first officinal in the German Pharmacopoeia, was made by bringing a decoction of malt to the boiling point, and then evaporating it to the consistence of a thick extract. Such in substance was the process, and the appearance and characteristics of the preparations sold originally in our country under this name induces us to believe that they were then made in this manner. Until one year ago we do not know that in this country particular attention had been directed to the comparison of values of malt extracts in accordance with their powers to convert gelatinized starch into dextrin and glucose. The perishable nature of diastase was well understood, and yet the makers of malt extracts seemed scarcely to consider it as a prominent factor.
An extract of malt made a few years ago, which was preserved by us in an original bottle, compared with one of recent date made by the same manufacturer, show a great difference in appearance and in properties. This preparation is that of one of the largest manufacturers. We have every reason to believe that the makers endeavor to produce an unexceptionable preparation, and we feel assured that they were as likely as any to have been among the first to consider the value of diastase. Hence it is that we may well believe Mr. Cowdrey to have first directed prominent attention in this country to the ease with which an extract of malt may be dispossessed of its diastase. In his paper read before the Association at its last meeting he stated that a temperature of boiling completely destroyed it. This statement has since been supported by our experiments and by those of others. It is true, also, that a temperature of from 160° Fah. to 180° Fah. will destroy diastase in a very short time, and any continued application of heat at or above 130° Fah. will within a moderate period render it inactive. Hence it is that we now doubt the advisability of applying any heat to a preparation of malt, and we certainly have every reason to believe that pharmacists generally will always be debarred through want of proper facilities from preparing an active malt extract unless it be as a fluid extract.
In the paper of Mr. Cowdrey, and as illustrated. by his experiments, it was stated and shown that 4 drachms of a viscid-like extract of malt could quickly convert into dextrin and glucose 5 drachms of starch which had been boiled with water. (Mr. Cowdrey only exhibited such an extract. He did not give the process by which it was made.) This conversion of gelatinous starch into glucose we have also easily accomplished by means of an equal bulk of fluid extract of malt, although we do not claim that it is desirable to introduce a process into the Pharmacopoeia to represent a proportion of crude material to finished product different from that of the other fluid extracts. It is for the purpose of suggesting a formula for making such a preparation (fluid extract of malt) that we have written this paper, for in the literature which we have at our command on this subject, although the fact is shown that heat will destroy diastase, and that an extract can be made to contain diastase, any reference to the method of preparing such an extract is omitted.
To prepare a fluid extract of malt which will represent as nearly as practical one part of malt to one part of the finished product we have recently followed the process adopted by us with some other substances, which will not bear the application of heat. Tall cylindrical percolators should be used, and a menstruum composed of a mixture of one part of alcohol to four parts of water. (We have found during our experiments that if less amount of alcohol is used, occasional fermentation follows. Hence it is that we suggest the above-named proportion.) The ground malt is moistened with this menstruum, and after one hour is packed carefully into the percolator, and not too firmly. The remainder of the menstruum is then added, and when the percolate appears the exit is closed and maceration conducted for twenty-four hours. Then the percolate is slowly withdrawn until it is equal in weight to three-fourths the amount of malt employed. This product is placed in a tall vessel, permitted to settle, and then decanted. This decanted liquid is the finished fluid extract.
The specimen which we now exhibit was prepared after this process.
In presenting this paper we trust that we will not be considered as participants in the malt controversy which has more or less agitated the pharmacists of some sections of our country during the past year. The substances offered as far as we know under the name of malt extracts, and which our Pharmacopoeia recognizes as a malt extract, are entirely different in appearance from the preparation to which we refer. Our object is simply to bring before the Association a process which can be used by pharmacists with limited conveniences. Any process embodying the application of heat which we have investigated tends, according to our late experiments, to destroy the diastase, and when, by evaporation at a gentle beat, the viscid-like extract is obtained, it will generally be found that, as far as the diastase is concerned, it is in less amount, bulk for bulk, than in the liquid before evaporation, even if it be not altogether wanting. Hence it is that we believe the simple process of percolation is best adapted to the wants of pharmacists generally, and we think such should be the officinal process for making malt extract.