Pathway no 6 : ACID HYDROLYSE of STARCH

A starch mash is hydrolysed when subjected to high acidity. The acidic hydrolysis of starch has been industrialised in modern times to produce food glucoses by the action of hydrochloric acid on cheap starch (potato, manioc). This pathway proceeds by chemical rather than enzymatic action, even if the acidity of the wort stems, for example, from lactic acid bacteria.

In the production of beer, this method alone very rarely contributes to the release of sugars from the starch.

A) The lactic acid is too weak and the method too long if it acts alone with a pH 4.5.

B) Too high an acidity is incompatible with the subsequent work of the yeasts.

C) Acetic fermentation involves the degradation of alcohol, a process that is incompatible with the purpose of the brewery.

In fact, the pathway no. 6 often cooperates with other traditional techniques for brewing sour beers known in Europe, Africa or Asia. A sour wort hastens the hydrolysis of the starch.

Brewing in sour medium (method no 6)

 

 

 

 

A starchy slurry can be converted into simple sugars by a strong acid medium (pH < 4). This purely chemical technique is applied in industry to produce cheap glucose.

 

It is a method that characterises the brewing of kwas in Russia and braga in Central Europe, a simple infusion of breaded cereals with the addition of sour berries or fruits. It is also used to brew beer with the pith of the sago tree in Indonesia.

 

More generally, the involvement of lactic acid fermentation in traditional brewing methods around the world implies that acid hydrolysis plays a role in the preparation of beers.

Some examples of brewing starting with an acid phase, generally lactic: sake (rice-Japan), Berliner Weisse, Gose and Lichtenhainer (wheat-barley/Germany), kaffir beer (sorghum/South Africa), Lambic (wheat-barley/Belgium), kvas (rye/Russia), braga old acidic beers from Central Europe.

The pathway no 6 is also used to make dried acidic dough in the form of long-life bread patties.This ancient technique (Mesopotamia, Egypt) leads to the baking of breads (bakery) or to the soaking of the dried bread patties (brewery), a preliminary step to the brewing of more or less sour beers. The current vogue for artisanal beers is bringing acidulous beers back in the mainstream. The brewing of these sour beers is based on fully controlled industrial ingredients (malts, laboratory yeasts and lactobacillus, industrial corrective food products, etc.). The acidity is used to enrich a range of tastes. It has little to do with Method 6, which uses acid brewing as the main means of starch hydrolysis instead of malting, for example.

The hydrolysis of starch by voluntary acidification of the mash or wort is not to be confused with their normal acidification resulting from the metabolism of microorganisms (acid PH worts). Generally speaking, all beers are slightly tangy, regardless of the methods chosen to hydrolyse the starch. This property makes the identification of pathway no. 6 problematic in historical documents describing the brewing processes.

 

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01/04/2013  Christian Berger