Here is an interesting article from the New Haven Register (August 18, 1880) about how bourbon was made. It discusses both sweet mash and sour mash methods of making bourbon. It also lists a couple of laws I had never heard of before including the maximum amount of time for bourbon mash fermenting. I’ve transcribed the article, and back in 1880, it seems the style of writing at the time was run-on-sentences.
Kentucky the Source of the Genuine Bourbon – How it is Made.
About three months ago the Journal was induced to send of its representatives into Kentucky, and while there to make a personal examination of the immense whisky distillery interest of that state. Kentucky has and does now stand head and shoulders over any state in the Union, or, in fact, of ant underneath the sun, for the production of a thoroughly first class fine whisky. After making the rounds of the distilleries in Anderson, Nelsen, Fayette, Franklin and Jefferson counties, and giving the readers of the Journal the result of his personal examination, he then went to Owenboro, Davies county, the home of genuine sour mash whisky.
Davies county claims, and very justly, too, that the fist to produce the genuine hand-made old-fashioned fine copper distilled sour mash whisky. Mr. T. J. Monarch commenced the manufacture of this article as far back as 1808 (?). Since that time fully a dozen first class houses of this kind have been put in operation with wonderful success, and now Davies county produces more first-class fine sour mash whisky than any other county. The revenue paid into the Untied States revenue department for sour mash whisky and tobacco for Davies county doubles that paid by any other county in any state in the Union.
Owensboro, the county seat of Daviess county, is located on the south bank of the Ohio river, and numbers about 15,500 people. Prominent among the other institutions there are about twenty stemming and prizing tobacco establishments; the smallest has a capacity for handling 90,000 pounds while several of the largest have a handling capacity of 2,000,000 pounds a year. This is the most flourishing city in the state of Kentucky, and its prospect for the future are very bright. I made a personal examination of the manner in which sour mash whisky is made in Davies county, the the following results:
The Process of Manufacture
The whiskies made in Kentucky are classed under two general heads, as sweet mash and sour-mash, from the nature of the processes by which they are produced, the distinguishing characteristics of which are in the kind of ferment employed. Sweet mash distillers use only fresh artificial yeast, while in the sour mash process the tub last set for fermentation, or the tub containing the most fresh yeast while at its highest state of fermentation, has yeast taken from it and applied to the small mash-tubs which have already been in mash forty-eight hours, together with rye meal, malt and water mixed thoroughly, and then run off into the fermenter. There it stands seventy-two hours, as required by law, at which period it is ripe and ready for distillation.
The time consumed in the small mash tubs is one of the distinguishing points between sweet and sour-mash whisky, and without the consumption of the this time strictly sour-mash cannot be made. The latter produces a far finer grade of whisky, but at the sacrifice of a number of advantages which somewhat compensate the sweet mash distiller for the inferior quality of his product. These advantages include a yield of from one-fourth to one-third more from the same quality of grain as the result of a more active fermentation, a saving of one-third in time and more than one-third in cost of manufacture, with increased capacity from the same outlay, as the Untied Sates internal revenue laws prescribe that the time of fermentation shall be forty-eight hours in the sweet mash process and seventy two hours in the sour mash. The government classes every distillery under one of these two heads, and requires that each shall use its designated fermenting agent as described above, its officials, on the spot, having personal supervision of the distillery, with instructions to prevent any variation from the prescribed method of precedence. Some sweet mash distillers scald their grains with slop and some with water, the distillation being completed at one operation, without the expense and delay of doubling.
How Whisky is Made
Whisky is generally made from corn or rye, and the unequalled excellence of that produced in Kentucky is undoubtedly due to a certain natural characteristic of the soil, which imparts peculiar quantities to cereals raised on it, and especially to the nature of the water found in certain localities, when it is charges with those alkaline and earthy salts which experience had shown to be indispensable in forming those peculiar principals to which the flavour of fine whisky is due. This is not merely a theoretical assumption but an empirical truth, which has been proven again by the futile efforts which have been made to produce good whisky in other sections which do no possess these natural advantages. The physical characteristics of corn or rye are so entirely different from those of whisky that it would seem difficult to trace the source of changes by which the one is derived from the other; the transformation is effected partly by mechanical means in preparing and handling the materials, partly by a few chemical reactions.
The grain is first ground in a grist mill, and the meal introduced into the mash tubs where, by the agency of heat, the starch granules are ruptured and their contents prepared for the action of the malt. The substance contains a peculiar principle called diastas, by whose agency the starch is, by union with water, altered into glucose, or grape sugar. After this change is complete, the contents of the mash tub are emptied, when ready, into the fermenting vats, where, by the action of ferment, the sugar is decomposed with the formation of alcohols and carbonic oxide, the latter passing off as gas, while the former remains in mechanical union with the water of the beer. The next step is the separation of the alcohols by distillation, resulting in the finished product.
Where 100 bushels are mashed per day about eight tubs are employed in the process. When Bourbon whiskey is to be made a suitable quantity of boiling hot water or slop is introduced, to which is added the proper proportion of corn meal. After mixing, it is set to one side to scald and cold. Before any thing, more can be done the scalded grain must be cooled down, so that when the mash is completed and set for fermentation its temperature will be between seventy and eighty degrees Fahrenheit, according to the temperature of the fermenting room. On the following day the scalded corn meal, which is then found to be caked and of the consistency of cold mush, is broken up by hand and thinned down with cold water. At this stage of the process a small proportion of barley, malt and rye meal is added without being scalded. The diastase if the malt converts, by a chemical change, the starch of the scalded corn-meal into a grape sugar or glucose, which is necessary before there can be any fermentation, which produces alcohol. After the mash has been thoroughly mixed, it is all turned from the small tubs into the fermenting vat, and then the mashing is complete by thoroughly mixing and thinning down with cold water until it fills the vats to within four inches of the top, at a point fixed by law. The mashing process is now complete, and the gravity and temperature of the mash having been taken in accordance with the law, it is set for fermentation. The fermentation now proceeds for seventy-two hours which the time allowed by law in a sour-mash distillery. — Chicago Journal