In Jamaica a distinction is made between the ordinary "clean" or Jamaican rum, and the very highly flavored product, which by way of distinction is known as "German Rum." Various theories have been advanced to account for the difference between the "clean" rum or the ordinary rum, and the highly flavored rums which are produced in this island. The common, belief, as has been expressed, is that the flavoring qualities which distinguish rum from other distilled spirits are peculiar to the sugar cane. They either exist naturally in the products of the cane, or they are produced from pre-existing sources during the processes of fermentation. The essential chemical difference between the ordinary rum of the Jamaican product, and the highly flavored rum, as might be inferred, is in the quantities of esters, or ethers, which they contain. The highly flavored rum contains considerably larger quantities of these ethers than that of the ordinary character; in fact, the quantity is almost twice as great.

Manufacture

The common rum of Jamaica is made in a very simple way, which may be described as follows:

Molasses is used as the base raw material, and in the regular operation of the distillery "dunder" is used in the fermenting tanks, as has already been described. The skimmings which come from the open kettle used in boiling the product are also added to the fermenting tank. The skimmings are supposed to be particularly valuable by reason of increasing the acidity of the fermented mash. Some manufacturers allow the skimmings to stand in tanks until they become sour, while others allow them to trickle through cisterns over cane trash, which produces a rapid oxidizing effect.

In the manufacture of higher flavored rums an attempt is made to produce a greater etherification, and, consequently, a larger production of aromatic substances due to the action of microbes. These additional flavors cannot be regarded as preexisting in the sugar cane, but they are the product of bacterial activity exercised on the original materials. The two organisms which are most active in this respect are the bacillus butyricus and the bacillus amylobacter, and other forms allied thereto. These bacteria are very common and exist frequently in soil and are not difficult to introduce into fermenting solutions. They are mostly produced from spores and are difficult to destroy by the ordinary processes of sterilization.

The bacillus butyricus is an anaerobic organism and it will not develop well unless it is grown out of contact with oxygen. For this reason, in pure cane juices its action is not at all vigorous. Where the cane sugar has been more or less inverted, this bacillus acts with much greater vigor, especially if some albuminous matter be present. The extract of yeast cells adds very much to the activity of these organisms, and in this we see a scientific reason for the use of "dunder." The exclusion of the air from the fermenting tank presents practical difficulties in the production of the maximum activity of these anaerobic organisms. Before the aid of scientific investigation was placed at the disposal of the rum maker, he found that to produce very highly flavored rum he would have to add some material to the fermenting mass, which contained, although he did not know it, a considerable quantity of nitrogenous matter, and this was applied from the "dunder" of the preceding fermented mass. The utilization of these special ferments is another reason why the period of fermentation for rum must be longer than that for the manufacture of whisky or spirits. These bacteria are not of quick action; they move slowly and they require some time to produce their full effect. Hence, the period of the rum production may be well above 72 hours without going too far.

There is a popular impression in Jamaica that good rum cannot be produced in a modern sugarhouse, using modern machinery. While some authors doubt the truth of this belief, it must be borne in mind that modern methods, which take away increasingly large quantities of sugar, must, of necessity, diminish the fermenting value of the molasses, and add thereto, proportionately, very much larger quantities of foreign matters than in the style of molasses formerly made. It is perfectly reasonable to suppose that improved machinery would result in a depreciation in the character of the product.