Brewing Notes Flashcards
What the does the term Modification mean?
Modification is the term that describes the degree of breakdown during malting of the protein-starch matrix (endosperm) that comprises the bulk of the seed.
Why do moderately-modified malts benefit from a protein rest?
Moderately-modified malts benefit from a protein rest to break down any remnant large proteins into smaller proteins and amino acids as well as to further release the starches from the endosperm.
Do fully-modified malts need a protein rest?
Fully-modified malts have already made use of these enzymes and do not benefit from more time spent in the protein rest regime. In fact, using a protein rest on fully modified malts tends to remove most of the body of a beer, leaving it thin and watery. Most base malt in use in the world today is fully modified.
Most wort proteins, including some enzymes like the amylases, are not soluble until the mash reaches temperatures associated with the protein rest (113-131°F). What are the two main proteolytic enzymes found at this stage of the mash?
The two main proteolytic enzymes responsible are peptidase and protease.
Describe the proteolytic enzyme Peptidase.
Peptidase works to provide the wort with amino acid nutrients that will be used by the yeast
Describe the proteolytic enzyme Protease.
Protease works to break up the larger proteins which enhances the head retention of beer and reduces haze. In fully modified malts, these enzymes have done their work during the malting process.
What is the optimum pH range for proteolytic enzymes during the mash?
optimum pH range is 4.2 - 5.3, and both enzymes are active enough between 113 - 131°F that talking about an optimum range for each is not relevant
What is the standard amount of time for a Protein rest?
20-30 minutes
What are the purposes of the enzymes beta-glucanases/cytases?
beta-glucanases/cytases - part of the cellulose enzyme family, and are used to break up the beta glucans in (un)malted wheat, rye, oatmeal and unmalted barley. These glucan hemi-celluloses (i.e. brambles) are responsible for the gumminess of dough and if not broken down will cause the mash to turn into a solid loaf ready for baking.
What are amylases?
The amylases are enzymes that work by hydrolyzing the straight chain bonds between the individual glucose molecules that make up the starch chain.
What is the temperature most often quoted for mashing?
153°F. This is a compromise between the two temperatures that the two enzymes favor. Alpha works best at 154-162°F, while beta is denatured (the molecule falls apart) at that temperature, working best between 131-150°F.
What can the brewer use to check the conversion rate between starch to sugar?
The brewer can use iodine (or iodophor) to check a sample of the wort to see whether the starches have been completely converted to sugars. As you may remember from high school chemistry, iodine causes starch to turn black. The mash enzymes should convert all of the starches, resulting in no color change when a couple drops of iodine are added to a sample of the wort.
What is the result of running a lower mash temperature, less than or equal to 150°F?
It yields a thinner bodied, drier beer.
What is the result of running a higher mash temperature, greater than or equal to 156°F?
It yields a less fermentable, sweeter beer.
What are two other factors besides temperature that affect the amylase enzyme activity?
grist/water ratio and pH.
What levels of pH do beta and alpha amylase prefer?
Beta amylase is favored by a low wort pH, about 5.0. Alpha is favored by a higher pH, about 5.7.
What are the drawbacks of running low pH level that is favored for beta amylase?
A beta-optimum wort is not a very fermentable wort, leaving a lot of amylopectin starch unconverted; alpha amylase is needed to break up the larger chains so beta can work on them.
What are the drawbacks of running high pH level that is favored for alpha amylase?
an alpha-optimum wort will not have a high percentage of maltose but instead will have a random distribution of sugars of varying complexity.
Why would a brewer add salt to the mash?
Brewing salts can be used to raise or lower the mash pH but these salts can only be used to a limited extent because they also affect the flavor.
Note: Malt selection can do as much or more to influence the pH as using salts in many situations.
How do brewers test pH?
The pH of the mash or wort runnings can be checked with pH test papers sold at brewshops, and pool supply stores.
A lower mash pH (near 5.2) has what benefits?
- Improved enzyme activity during the mash, leading to better conversion of starches to sugars.
- Lower pH in the finished wort which improves yeast health during fermentation, and also inhibits bacteria growth.
- Improved hop extraction rates in the boil.
- Better protein and polyphenol precipitation both during the cold break and post fermentation.
- Improved clarity in the finished beer with reduced chill haze.
- Improved flavor and clarity stability as the beer ages
What are some sources that factor that affect the pH?
- Water Used: The chemical composition of the water is a large driver in mash pH. Calcium, magnesium, carbonates and bicarbonates are all drivers of mash pH. Most water sources are slightly alkaline, so they tend to drive the mash pH above the desired 5.2-5.4 range.
- Malts: Malts tend to be acidic, which means that they lower the mash pH of the overall mixture. Dark malts in particular can be very acidic, which is why many darker beers require little mash pH adjustment. Lighter malts have less buffering capability, so lighter beers often need additives covered blow to drive the mash pH down to the desired level. Unfortunately the acidity of malts varies widely and is not measured and published, so prediction of mash pH in advance is very difficult.
If the pH in your mash is too high what can you add to lower it?
- Lactic Acid – An organic acid produced by bacteria. Many home brew stores sell it in liquid form that is about 88% by weight solution, though this does vary. It is added a little at a time until you reach your target pH.
- Acid Malt – This is typically pilsner malt that has been acidified using lactic acid and contains about 3% acid by weight. Acid malt is primarily used in Germany to comply with strict purity laws (Reinheitsgebot) that prohibit additions other than malt, water, yeast and hops to beer.
- Phosphoric Acid – An inorganic acid widely used in soft drinks. It replaces bicarbonate with phosphate and increases the phosphate content of the wort.
- Hydrochloric and Sulfuric Acid – Used by many commercial brewers, these acids are usually not widely available to the public.
- Buffers such as “5.2 Stabilizer” – These salts lower the mash pH by reacting with phosphates brought in by the malt. They can raise the hardness of the mash water in the process, but they are a great “fire and forget” alternative since you can often add a pre-measured amount of buffer to the mash and achieve the desired range.
How do you avoid oversparging when brewing?
The most common method to avoid oversparging is to monitor the gravity of the runnings and stop sparging when the gravity falls below 1.008 for an average strength beer. Obviously that number would be higher or lower if brewing a very high gravity or low gravity beer. Some brewers with a pH meter also have the option of monitoring the pH of the runnings and stopping when the pH rises above 6.0.
What damage can occur when sparging with excessively hot water?
Sparging at excessively high temperatures can also result in astringency in the finished beer. Sparging at a moderately temperature has some benefits as it improves the flow of wort through the grain bed.
The maximum temperature for sparging is 170 F (77 C). Sparging above that can result in tannin extraction. Some people do use higher temperature sparge additions, but only to raise the temperature of the mash as a whole during the initial phase of the sparge. In no case do you want to raise the grain bed or runnings above 170 F (77 C).
What is a major benefit of bottle conditioning your beer?
The beer achieves a longer shelf-life because the yeast in the bottle consumes the oxygen.
How many gallons of beer is a home brewer allowed to brew?
Since 1979 it has been legal to homebrew up to 200 gallons of beer per family household.
Lautering can be conducted in several ways, but it usually consists of three steps. What are those 3 steps?
mash-out, recirculation, and sparging.
Define Mash-Out when brewing.
Mash-out is the first step during the lautering phase.
Mash-out is the term for raising the temperature of the mash to 170 F prior to lautering. This step stops all of the enzyme action (preserving the fermentable sugar profile) and makes the grain and wort more fluid.
Define the recirculation process when lautering.
Recirculation is the second phase of lautering.
Recirculation, also knows as the vorlauf step, occurs after the grain bed has settled and is ready to be lautered. The first few quarts of wort are drawn out through the drain of the lauter tun and poured back in on top of the grain. This helps settle the grain bed to ensure proper mash filtration and clarity.
Define the sparging process during lautering.
Sparging is the third process of lautering.
Sparging is the process of rinsing the grain bed that has settled at the bottom of the lauter tun in order to extract the remaining sugars. The temperature of the sparge water is carefully controlled so as not to also extract tannins from grain husks.
Discuss an Infusion Mash.
Infusion Mash
In this type of mash, crushed grains are added to water heated at one specific temperature within the range of a saccharification rest. The target mash temperature is then held for the entire period of the mash. This mash is most common when highly modified malts are used and low-protein malts are the dominant part of the grist (crushed grain).
