Brewing and Fermenting

Ingredients in Beer
1. Hops
  1. Female flower cone (Humulus lupulus)
  2. More than 80 varities
  3. Resin
    1. adds the bitterness
    2. iso-a-acids
    3. essential to balance sweetness of malt
  4. Essential oils
    1. Have aroma characteristics
    2. provide, fruity, floral, spicy etc
2. Malt
  1. refers to malted barely
  2. malting is the controlled germination of cereals to activate enzymes used in the mashing process
  3. There are a spectrum of malt types
    1. Base malts
      1. lager (pilsner), ale
      2. Provide enzyme activity for the mash
    2. Toasted malts
      1. Vienna, amber
    3. Darker malts
      1. Brown, chocoloate
    4. Speciality
      1. crystal, caramel
  4. Provides body, and sweetness
  5. Fermentable sugars, e.g alcohol
  6. Variety of flavours, e.g grainy, toasted etc
  7. Other sources of fermentable sugars
    1. Cereal Adjuncts
      1. Rice e.g Budweiser, & Japanese largers
      2. Corn e.g Stella
      3. Cane sugar (sucrose)
      4. Honey, maple syrup, molasses
      5. Why use this? - Cost is cheaper, and to modify beer properties
3. Yeast
  1. Single cell organisms
  2. Eukaryotic cells in fungi kingdom
  3. Ale (top fermenting) e.g Saccharomyces cerevisiae
  4. Lager strains (bottom fermenting) e.g S. pastorianus
  5. Modern Classification and species differentiation achieved by DNA fingerprinting
  6. Different yeast strains important for yeast styles and flavour properties
    1. Hop & aroma flavours
    2. Malt charactertics
    3. Yeast derived flavour e.g fruity esters, tartness (organic acids), spicy, peppery phenolics
4. Water
  1. Alkalinity, pH, hardness, mineral ion all determine beer character and beer style
    1. different mineral ions affect beer flavour accentuating either malt or bitterness
  2. Affects conditions for biochemical reactions during brewing
  3. Important for yeast nutrition and optimal fermentation performance, hence flavour quality
Barley
1. 2-rowed variety
  1. Only central floret is fertile, hence 1 seed at each node
2. 6-rowed variety
  1. All florets are fertile, hence 3 seeds at each node
3. Structure
  1. Husk (hull)
    1. protects the embryo
    2. Important in wort seperation
  2. Aleurone
    1. Source of enzymes, produced in response to hormones from the growing embryo
  3. Endosperm
    1. the starch granules here in the form of fermentable sugars and amino acids
    2. Composed of large + small starch granules
    3. Cell walls within matrix holding the starch granules are composed of beta-glucans, some pentosans, and protein
  4. Acrospire
    1. The plant shoot
  5. Microphyle
The Process
1. Malting
  1. 1st) Steeping
    1. activation of enzymes by steeping with water
      1. increases moisture from11-12% to 42-44%
      2. Grains swell
    2. 1st Immersion
      1. 6-16 hours to raise water content to 3-37%
    3. 2nd) Immersion
      1. 10-20 hours
    4. Air Rest
      1. 12-24 hours
      2. Expose embryos to oxygen
      3. Remove CO2
    5. Chemical Process
      1. Water enters through the grain, through the microphyle and distributes through the endosperm
        The water activates the embryo which produces hormones that migrate to the aleurone
        This stimulates production of enzymes
  2. 2nd) Germinating
    1. Barley spread in a germination box, this:
      1. Dissipates CO2
      2. Keeps temperature constant
      3. Prevents roots from matting
    2. The acrospire grows alongside of the kernel
      1. Pre-existing enzymes are released and new enzymes are created in the aleurone layer. This modifies the endosperm for the acrospire's use
        The enzymes break down the endosprems's protein/carb matrix into smaller carbs, aa's and lipids, also open up the starch reserves
        Modification refers to the degree to which enzymes break down the starch granules
    3. Length of the acrospire will be around 75-100%
    4. A Maltster judges the degree of modification by the length of acrospire
  3. 3rd) Klining
    1. Drying reduces moisture content from 45% to 5%
    2. Kills any microbes
    3. Performed at low temperatures to minimise degradation of enzymes
    4. Stops germination and kills embryo
    5. Inhibits any ongoing enzyme activity
    6. Diastatic Power: the amount of enzymatic starch conversion potential that a malt has
    7. The acrospire and rootlets are knocked off by tumbling
    8. Malts klined at different times/temp to develop different colours + flavours
  4. Initial Steps
    1. Barely cleaned, sized, viability measured, and N content determined
Biochemsitry of malting
1. Starch
  1. Composed of Amylose and Amylopectin
  2. Enzymes involved are: a-glucosidase, a-amylase, b-amylase
    1. a-amylase is main degrading enzyme
      1. Attacks at random in the middle of amylose and amylopectin
        This releases maltose and maltotriose, and dextrins
        Maltose is the main sugar found during mash
      2. More thermostable than b-amylase
  3. Gelatinisation
    1. To achieve gelatinisation mashing includes a conversion stage at 65C for 1 h
    2. Small granules gelatinase at a higher temp than large granules

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Brewing and Fermenting

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	Creado por Shelly Shah hace más de 9 años