Mash, beer

Acetic acid is generally considered an off-flavor in beer. However, a very few sour beer styles feature it as a desirable flavor characteristic, notably Flanders Red Ale and Oud Bruin. However, most sour mash beers, such as Berliner Weisse, depend on the different souring action of lactic acid bacteria a vinegar character is generally considered undesirable in these beers. In contrast to conventional beers, which are fermented by carefully cultivated strains of brewer s yeasts. Lambic beer is produced by spontaneous fermentation. An acetic acid bacterium was isolated from fermenting Lambic beer, and the strain was proposed to be a new species, Acetobacter lambici sp. nov. (Spitaels et al. 2014). 

The basic raw materials for the production of beer are sweet worts formed by en2ymatic hydrolysis of cereal starches. The principal cereal is barley which, after malting, is also the source of en2ymes that hydroly2e starches, glucans, and proteins. In some countries, eg, Germany, the mash biH consists... 

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). 

Upon mashing, small amounts of tannin go into the solution from the malt, and later, during the boiling with hops, more tannin goes into the wort. Tannins from both barley and hops are leucoanthocyanin stmctures, in some cases they are derivatives of quercetin [117-39-5], cathechins are not found. The turbidities in beer, rich in leucoanthocyanins, are composed of peptones, peptides, and condensation products of the tannins of malts and hops. 

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. 

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). 

Particle size and cooking condition for the grain slurry vary depending on the type of distilled spirit that is to be produced. In the case of com grain fermentations, distillers use small size, high temperature, and low beer gallonage (higher starch concentrations) for neutral spirits production at 120—170°C and 76—91 L/0.03 m. Bourbon distillates call for low temperatures (100—150°C) and thinner mash of 95—115 L/0.03 m (saccharified starch slurries) out of flavor considerations. (0.03 m is approximately a bushel). 

If the yeast does not get enough free amino nitrogen, the fermentation will be poor and the beer quaHty inferior. A neutral bacterial protease added at mashing-in can be used to raise the level of free amino nitrogen. This is useful when working with poorly modified malt or with high adjunct ratios. 

ANDERSEN M L and SKIBSTED L H (2001) Modification of the levels of polyphenols in wort and beer by addition of hexamethylenetetramine of sulfite during mashing, J Agric Food Chem, 49, 5232-7. 

J. Gotz, K. Zick, V. Lehmann, D. Grog, M. Peciar, (Analysis of the mixing and flow behaviour of beer mashes in a stirring vessel by means of NMR flow experiments), in preparation. 

Masdil, molecular formula and structure, 5 97t, 118t Mash filter, 3 578 Mash filtration, 3 575 Mashing, in beer making, 3 576-578 Masked polyols, 25 474... 

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