Mash, fermentation

Sour mash fermentations must have not less than 20% stiUage added back (backset) to the mash and be fermented for not less than 72 hours. A lactic culture is used and is permitted to develop for a period of not less than six hours. 

Results. The results of this analysis are tabulated below. Contrary to natural growth processes, the distilling process (mashing, fermentation, distillation, and by-product feed recovery) destroyed considerable gibberellin, resulting in a material recovery of only 15%. 

In some cases the processes are combined with the use of enzymes (mash fermentation). A pitting machine can be inserted in the stone fruit processing line ahead of the crusher. 

When the mash ferments sugar it forms alcohol and also carbon dioxide which bubbles up from the mash. As well as alcohol, fusel oil is formed. This is the cover name for the small amounts of impurities made by the yeast. Ideally it would be best if the yeast only formed alcohol but this ideal has not been achieved yet. Every year new types of yeast are developed that in principle ferment faster and above all, cleaner. Fusels are not useful but are formed in such small amounts that they are not harmful, but we want to get rid of them anyway. Both taste and aroma are ruined by fusels. The reason the distillate smells a bit is because the fusels are apparent when there is only alcohol, water and by-products. 

Lettsiti, S. I.K. Phontree W. Thepsingha A. Bhumiratana. Evidence of enzymatic browning due to laccase—like enzyme during mash fermentation in thai soybean paste. Food Chem. 2003, 80, 171-176. 

On storage, beer can become cloudy and form a sediment. Proteins and polypeptides make up 40-75% of the turbidity-causing solids. They become insoluble due to the formation of inter-molecular disulfide bonds, complex formation with polyphenols, or reactions with heavy metals ions (Cu, Fe, Sn). Other components of the sediment are carbohydrates (2-25%), mainly a- and P-glucans. For measures used to prevent cloudiness, see 20.1.8.5. Undesirable microorganisms, e. g., thermophilic lactic acid bacteria, acetic acid bacteria Acetobacter, Gluconobacter) and yeasts, can cause disturbances and defects in various process steps (mashing, fermentation, finished product). 

The pot still process by which malt whislg is made may be divided into four main stages malting, mashing, fermentation, and distillation. 

Adams and Leslie (3) made a study of the maintenance of optimum pH in mashes fermented with B. polymyxa. Control of this factor is necessary because the organism produces acids which will ultimately stop the fermentation. Acidity may be controlled by addition of calcium carbonate but ammonia would be more desirable as a neutndizer in an industrial process because it is easily handled and does not add to the ash in the residue and thus lessen its feed value. The authors showed the use of ammonia to be practicable. Fratkin and Adams (42) studied the use of wheat from which some of the gluten and other fractions of the grain had been removed to give a crude wheat starch. This material was considered because its use would lessen processing difficulties. The addition of malt sprouts was found to be the most effective fermentation supplement. With these added, the crude starch could be fermented with good yields in about 72 hours. 

In 1973, a multistage surface-fermentation process was patented in Japan for the production of acetic acid (42) eight surface fermenters were connected in series and arranged in such a way that the mash passed slowly through the series without disturbing the film of yAcetobacter on the surface of the medium. This equipment is reported to produce vinegar of 5% acidity and 0.22% alcohol with a mean residency time in the tanks of 22 h. 

Fermentative Manufacture. Throughout the years, riboflavin yields obtained by fermentation have been improved to the point of commercial feasibiUty. Most of the riboflavin thus produced is consumed in the form of cmde concentrates for the enrichment of animal feeds. Riboflavin was first produced by fermentation in 1940 from the residue of butanol—acetone fermentation. Several methods were developed for large-scale production (41). A suitable carbohydrate-containing mash is prepared and sterilised, and the pH adjusted to 6—7. The mash is buffered with calcium carbonate, inoculated with Clostridium acetohutylicum and incubated at 37—40°C for 2—3 d. The yield is ca 70 mg riboflavin/L (42) (see Fermentation). 

The most widely available yeast biomass is a by-product of the brewing industry, where the multiplication of yeast during brewing results in a surplus of ceUs. Eor every barrel (117 L) of beer brewed, 0.2—0.3 kg of yeast soHds may be recovered. In the U.S., a substantial fraction is recovered and made available about 40 x 10 kg of brewers yeast aimually. The yeast is recovered from beer by centrifuging and dried on roUer dmms or spray dryers and sold as animal feed or a pet-food supplement. It can be debittered by alkaline extraction to remove the bitter hop residues, and is then sold mainly by the health-food industry. It is available as tablets, powder, or flakes and is often fortified with additional vitamins. Distillers yeast caimot be readily separated from the fermented mash and the mixture is sold as an animal feed supplement. 

A beer with normal alcohol content, but much lower ia caloric coateat, can be made with the help of external, specific enzymes that ate added duriag mashing or fermentation to achieve further breakdowa of carbohydrates. 

Water. The character of the water has a great influence on the character of the beer and the hardness of water (alkalinity) manifests itself by the extent of its reaction with the weak acids of the mash. Certain ions are harm fill to brewing nitrates slow down fermentation, iron destroys the colloidal stabihty of beer, and calcium ions give beer a purer flavor than magnesium or sodium ions (Table 7). 

Concentration of mash, malt water Extract yield, % Fermentable extract, %... 

Infusion Method. Infusion is a classic method for top-fermented beers and is used for ad British types. The whole mash is heated graduady from mashing-in to mashing-off with holding times for the degradation of protein and starch. No part of the mash is boiled and the malt, therefore, must be well-modified to assure the breakdown of ad soluble substances. Because no boiling takes place there is no physical breakdown of the malt, and consequentiy infusion is not as effective as decoction despite the better protection of the enzymes. 

Backset. Backset is the screened aqueous by-product from distillation. It is recycled and added to the cooked grain mash prior to fermentation. 

Beer. Beer is the alcohoHc product arising from the yeast fermentation of saccharified grain mash. It may or may not include stillage from a previous fermentation/distillation (see Beer). 

SourM sh. Sour mash is made with a lactic culture and not less than 20% stillage added back to the fermentor and fermented for at least 72 h. Spirits. Spirits are distilled spirits including all singular whiskeys, gin, brandy, mm, cordials, and others made by a distillation process for nonindustrial use. 

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