Beer: Fermentation Methods Flashcards
(28 cards)
What must happen before fermentation can commence?
Starch must be converted to sugar.
What are the two most important aspects of the brewing process?
- The brewer must first derive the wort, a sugar-rich liquid, from malted grain.
- Then the brewer must ferment the wort.
What are the ingredients required for the brewing process?
Typically, the raw ingredients required for this process are water, yeast, hops, and a starch source.
Why are hops important?
Hops, the dried flower clusters that provide flavor and bitterness to beer, have both preservative and antiseptic qualities that inhibit bacterial growth.
What is the 1561 BAvarian Purity Law?
(Reinheitsgebot), which codified the three ingredients authorized for beer production as barley, hops, and water. The action of yeast in fermentation was at the time undiscovered, and wheat, a component of Hefe-Weizen and white beer styles, was reserved for the production of bread.
What is the first step in the modern brewing process?
The first step is to create the malted barley, or malt. Barley—the cereal grain of choice for most beers—is steeped in water for approximately two days to promote germination of the grain.
What happens after the barley begins to germinate?
Once the grain begins to germinate, or sprout, it is transferred to compartments with controlled temperature and moisture levels. As the sprout grows to nearly an inch in length, the enzyme amylase is produced.
What does the enzyme amylase do?
Amylase converts the starchy carbohydrates of the grain into the fermentable sugars maltose and dextrin.
The sprout has now been converted to “green malt” What is the next step?
This “green malt” is then roasted with hot air in a kiln to suppress further growth. The style of beer desired will determine the length and degree of roasting. Highly roasted black malts, for example, are used for porter-style beers, whereas pale malt, dried at low temperatures and very light in color, is used for pale ales.
After the grain has been malted to the desired level what needs to happen next?
The malt is ground, or cracked, in a mill to produce grist. The grist is combined with hot water in a mash tun. The mashing process lasts one to two hours, converting and extracting sugar from the malt, and results in the wort, which is rich in flavor, sugar, and color.
Once the wart liquid has been made what is the next step?
The wort liquid is drawn off the grains and filtered into the brew kettle, or copper. Additional sugar and flavor can be extracted from the spent grains by sparging—rinsing with fresh water—although this may lead to unwanted bitterness in the finished brew.
What is Sparge?
Additional sugar and flavor can be extracted from the spent grains by sparging—rinsing with fresh water—although this may lead to unwanted bitterness in the finished brew.
What is done with the Sparge?
The sparge is combined with the wort in the copper, and hops are added.
What happens once the wort, sparge and hops have been combined?
The wort is then brought to a sustained, roiling boil for at least one hour. Boiling the wort stabilizes and sterilizes the brew, darkens the color, and causes excess water to evaporate.
What happens to the hops as the wort is boiling?
Hops contribute more bitterness the longer they boil, but they also lose aroma in the process.
What might a brewer do to retain hop aromas and flavor?
In order to retain fleeting, volatile hop aromas, the wort may pass through a hopback chamber prior to chilling. Fresh hops encounter the hot wort and contribute fresh aroma. The wort is then strained, leaving spent hops behind, and chilled to an appropriate temperature for fermentation.
What is the key difference in the brewing process which differentiates lagers from ales?
Wort destined to become lager beer is cooled to a lower temperature than wort for ale production, and the two styles require different yeasts for fermentation.
What is the yeast required for lagers?
Bottom-fermenting yeast (Saccharomyces pastorianus, formerly called Saccharomyces carlsbergensis) is used for lagers and results in a more delicate, cleaner beer. With bottom-fermenting yeasts, which tend to clump together at the bottom of the vessel, the fermentation process is slower and occurs at lower temperatures.
What is the yeast required for ales?
For ales, a top-fermenting yeast (Saccharomyces cerevisiae) is added to the wort. Top-fermenting yeasts prefer warmer temperatures and result in fruity and richly flavored beers. Ale fermentation is quick, usually lasting less than a week.
What is the final step before bottling or cask?
After fermentation, the beer is transferred to conditioning tanks or casks, and it is often pasteurized prior to bottling. Cask ales sold as draught beers are unpasteurized, and bottle-conditioned beers are unfiltered and undergo partial fermentation in the bottle.
What is Lambic?
Lambic beers, a unique specialty of Belgium, are spontaneously fermented in open-top containers with native wild yeasts.
What are the native yeast varieties used for fermentation of Lambic beer?
Brettanomyces bruxellensis and Brettanomyces lambicus.
What is the general style of Lambic?
Classic lambics are almost vinous in character, distinctively sour, and aged prior to release—often up to three years in cask. Aged hops are used, resulting in a final brew that contains little hop flavor and aroma. Generally, lambics are blended before release.
How is Gueuze beer made?
Gueuze is a style produced by mixing one-year-old lambics with beers that have aged for two to three years. The blend, which contains fermentable sugars from the young lambic, is then refermented in the bottle, giving the beer its sparkle and the moniker Brussels Champagne
