Fermentation, alcoholic completion

Once the lactic add and alcohol fermentation is complete, the moromi is aged until its moldy odor has disappeared. During this portion of the aging period other flavor molecules, particularly 4-ethylguaiacol and 4-ethylphenol are added to the moromi by Candida versatilis (4), These compounds are the major components contributing to the flavor of soy sauce. The entire moromi process is completed in about six months. 

Amelioration credits remaining after fermentation is complete are used or waived after organoleptic evaluation of the new wines. Each time credits are used, a report must be submitted to the Bureau of Alcohol, Tobacco, and Firearms, Department of the Treasury showing the amount... 

Fumaric Aero Inhibition. Another means of preventing malo-lactic fermentation is to add fumaric acid after alcoholic fermentation is complete (45, 46, 47,48). The inhibition is relative and its extent is dependent on the amount added. The susceptibility to fumaric acid is also dependent on the strain of malo-lactic bacteria tested (49). However, we know of no case where fumaric acid addition at the levels suggested by Cofran and Meyer (45) (about 0.05%) did not delay malo-lactic fermentation under normal winemaking conditions. This includes several experiments from our pilot winery (50). Nevertheless, we have not been hasty to recommend the use of fumaric acid as an inhibitor because 1) of the difficulty in solubilizing the acid in wine 2) we do not know the mechanism of action of its inhibition [Pilone (47, 48) has shown that the bacteria metabolize low levels of fumaric acid to lactic acid but, at inhibitory levels at wine pH, the acid is bactericidal] and 3) of the desirability of minimizing the use of chemical additives. 

Production. Xanthan gum is produced by the microorganism X. campestris, originally isolated from the mtabaga plant. The gum is produced commercially by culturing X. campestris purely under aerobic conditions in a medium containing commercial glucose, a suitable nitrogen source, dipotassium phosphate, and appropriate essential elements. When the fermentation is complete, the gum is recovered from the fermentation broth by precipitation with isopropyl alcohol, and dried, milled, tested, and packed. 

The more concentrated forms of alcoholic drinks such as the spirits whiskey and brandy contain high concentrations of ethanol. These are produced by distillation after the fermentation is complete (Chapter 2, p. 20). 

The complex homogenization system used for this purpose is depicted in Fig. 3B.1. A few months after alcoholic fermentation has completed, the wine is transferred and any lees removed. In Jerez, wines to be biologically aged are fortified... 

Port wine is fermented in shallow receptacles of masonry in which the grapes are trodden and, after fermentation, pressed. Fermentation in Italy, Spain, and the south of France is carried out at 15° to 24° C., and is a top fermentation, but in Germany and with the finer French wines, a bottom fermentation is made at 5° to 12° C. At the higher temperature the fermentation takes from 3 to 8 days, and the wine produced is fiery, high in alcohol, and lacking in delicate aroma. At the lower temperature the first fermentation lasts a few weeks, but yields a wine of delicate flavour. When fermentation is complete, and the wine has become clear, all the yeast aud other suspended matters are deposited oil the bottom of the cask or vat, constituting the lees. From this the young wine is racked, i.e. decanted or siphoned off, and run into a clean cask. 

It is this compound which breaks down into alcohol and carbon dioxide and regenerates the sodium phosphate. The latter can then again combine repeatedly with the sugar, sensitizing it to the breaking down action of the enzyme until the fermentation is complete. It has been shown by careful experiments that during the period of increased fermentation the amounts of alcohol and carbon dioxide produced are stcrchimetrically related to the... 

After 40-60 hours, fermentation is complete, and the product is distilled to remove the alcohol from solid matter. The distillate is fractionated by means of an efficient column. A small amount of acetaldehyde (bp 21 °C) distills first and is followed by 95% alcohol. Fusel oil is contained in the higher-boiling fractions. The fusel oil consists of a mixture of higher alcohols, chiefly 1-propanol, 2-methyl-l-propanol, 3-methyl-l-butanol, and 2-methyl-l-butanol. The exact composition of fusel oil varies considerably it particularly depends on the type of raw material that is fermented. These higher alcohols are not formed by fermentation of glucose. They arise from certain amino acids derived from the proteins present in the raw material and the yeast. These fusel oils cause the headaches associated with drinking alcoholic beverages. 

After alcoholic and malolactic (if applicable) fermentations are complete, wines undergo further processing that potentially influences the growth of microorganisms. One of the most important spoilage issues during storage of red wines, Brettanomyces, is discussed in Section 11.2.2. 

The final stages of fermentation should be closely monitored. When the density drops below 1.000, this measurement is no longer sufficient to measure precisely the evolution of the fermentation. Moreover, the relationship between possible residual sugar and density is complex. When fermentation is complete, wine density can vary between 0.991 and 0.996, according to alcohol content. In addition, free-run wines always have a lower density than press wines, which are rich in extracted constituents. 

The running-off operation consists of recovering the wine which spontaneously flows out of the fermentor by gravity. The wine is then placed in a recipient where alcoholic and malolactic fermentations are completed. 

The History of Enzyme Chemistry.— Four spontaneous natural changes have been known to man ever since he first acquired the power of rational observation. They are (i.) the alcoholic fermentation of sugars (ii.) the lactic fermentation, or souring, of milk (iii.) the acetic fermentation of wine and (iv.) the ammoniacal fermentation of urine. Each is due to the growth of a microscopic organism and its attack on a particular substance or svhstrate. The mechanism of these natural fermentations remained completely obscure until the beginning of the last century. 

After the fermentation is completed, the liquor, known as beer, is withdrawn from the fermentors, passed through heat exchangers, and pumped to the upper section of a beer still (or whisky column ), where the alcohol and other volatiles such as aldehydes are distilled off as the overhead. The bottoms, known as slop or stillage, are processed into animal feeds, known as distillers dried grains, which contain residual sugars, proteins, and vitamins. 

I. "Natural" wines, <14% alcohol. Their nature and keeping quaUties have traditionally depended heavily on complete fermentation and protection from... 

---