Mashing Flashcards
Enzyme action produces these sugars during mashing. Enzymes enable the breakdown of larger molecules into smaller molecules. In mashing. Enzymes from the malt help break down the starch from grist into sugars.
Temperature, pH, and the ratio of water to grist, all affect how the enzymes in the mash work.
Mash tun
Insulated vessel maintains temp
- grist hydration
- no heating
- mash stand
- conducts mashing and wort separation
-water to grist ratio 2.1:1-2.5:1
Mash conversion vessel
-mash is mixed
- water to grist ratio 2.5:1-3.5-1
-heating elements on vessel
-controlled temperature increase
- only conducts mashing
- grist fully hydrated
Temperature
Starch exists in grist as granules. These granules do not allow water in until gelatinised. When we heat them to their gelatinisation temperature, the granules are disrupted (broken open on a microscopic level), allowing water to enter the disrupted starch granule. Once the water is in, the enzymes can access the starch and help break it down into sugars. If we do not reach the temperature at which the starch granules gelatinise, we cannot convert the starch in the mash.
The final temperature rise before mashing out is set to denature the enzymes, and thus stop conversion. We also do this to lower the wort’s viscosity and make wort separation as easy as possible.
Time
It is therefore essential to set a time for each temperature stand, to allow enzymes to produce the wort we need. If we leave a certain mashing step for too long, the enzyme reactions could go too far. If the starch degrading enzymes go too far, they can break down more of the longer chain carbohydrates (dextrins) that help give the beer its body. We would thus end up with a thin tasting beer. If the enzymes that break down proteins go too far, we can lose the proteins. These proteins also give us body and help give the beer a good head of foam. As time is money, we also do not want to delay the next brew with mash stands that are longer than necessary!
Water to grist ratio
The water to grist ratio, also called the mash thickness, must be controlled. This is because it too affects the enzymes’ action. Enzymes are protected to a greater degree from denaturing at higher temperatures in a thicker mash. As mash becomes thinner, it becomes more dilute. This means that a thinner mash has a lower concentration of enzymes and starch. Since the enzyme concentration is lower in a thinner mash, starch is broken down at a slower rate. The mash in a mash tun is thicker than mash in an MCV.
pH
The mash pH also affects how our mashing enzymes work. As with temperature, each enzyme has a pH at which it works most effectively. We cannot adjust the pH several times during mashing as we do with temperature. We therefore aim for a pH at which all of our enzymes work well. We will return to the factors that affect pH later.
Optimum pH range
5.2-5.4
Maltose
Main sugar in the grist, 2 units of glucose
- ferments quickly
Maltotriose
Less present, 3 units of glucose
- ferments slowly
Dextrin
Many glucose, cannot become maltose
- WIll NOT FERMENT
Glucose
Small amounts, 1 unit of glucose
Amino acids and proteins
Peptides/proteins: larger chains of amino acids
-broken down by protease in the mash
- used by year to build new yeast cells in fermentation
Lipids
Used by yeast to build new cell membranes and for nourishment
- too much will oxidise the final product
Definition of an enzyme
An enzyme if a catalyst. A catalyst is something that makes a chemical reaction happen faster and more easily. Enzymes are made up of proteins.
Starch degrading enzymes
Starch exists in the mash in two forms: amylose and amylopectin. In barley, the starch is present at around 25% amylose and 75% amylopectin. Amylose is a straight chain and amylopectin is formed of branched chains.
Starch in the mash
Amylose: 25% of barley, straights chain
Amylopectin: 75% of barley, branched chains
Alpha amylase - a amylase
Liquefaction, 72*, 5.2 pH
- attacks random points in the starch chain, chipping into random chunks, some fermentable and some not.
Beta amylase- b amylase
Saccharification, 63*, 5.25 pH
- attacks ends of the starch chain, creating very fermentable maltose.
Dextrins
Are the carbohydrate chains that are to long for b-amylase cannot turn into maltose. They are to big for yeast to ferment and we believe that they contribute to the fullness of the beers palate.
Beta glucanase
Breaks down B-glucans, 40-50* stand
Proteases
-work on proteins rather the starch
-break proteins down into polypeptides, peptides and acids.
-protein and polypeptide as possible can only be a good thing. However, this is not true. Some proteins and polypeptides are essential for stabilising the foam on the head of our beer and adding fullness to the palate
- work best at cooler temperatures 50-54*
Starch conversion test importance
Converting starch to sugar is arguably the most important aspect of mashing. If we do not achieve it we are wasting money. We can conduct this test to know if the conversion is complete or if we need ti leave the mash to convert longer.
