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Unformatted text preview: Quality of Beer Package Foam Gushing Clarity Color Flavor Stability Safety & wholesomeness Not mutually exclusive malt water Flavor adjuncts hops yeast Flavor threshold: concentration at which a substance becomes detectable Pain - the trigeminal sense Carbon dioxide Threshold about 1 g/L Cask ales ~2 g/L (1 vol) Packaged beers 5~6 g/L (2.5-3 vol) Nitrogen - softens the palate (and suppresses hop) - typically less than 50 mg/L mouthfeel Sweetness Residual or added sugars (primings) Sourness Beer pH range 3.9 - 4.6 (excluding Lambic/gueuze) low pH more sour Acids mg/L Typical Flavor Descriptor level threshold 175 2.2 8 2.0 15 0.1-0.5 2-12 30-200 0.5-1.5 0.03-0.1 Acetic Butanoic Pentanoic 2-methylbutan -oic Octanoic Salt Sodium potassium Bitterness Iso--acids from hops Iso--acid light MBT Intensity of flavor Time Hop aroma At least 340 different compounds Malt Biscuity Sweet, nutty Toffee, caramel Nutty, caramel Mocha, treacle Smoky, coffee Burnt, smoky Color Typical flavor Pale ale 4.5-4.8 Cara Pils 25-35 Crystal 100-300 Amber 40-60 Chocolate 900-1200 Black 1250-1500 Roasted barley1000-1550 Vicinal diketones mg/L Typical Flavor Descriptor level threshold .01-.4 .9 .07-.15 Diacetyl Pentanedione .01-.15 Esters mg/L Typical Flavor Descriptor level threshold 30 Ethyl acetate 10-60 Isoamyl acetate 0.5-50 1 Phenylethyl acetate .05-2 3 Sulfur compounds Typical level 1-20 10-100 .1-3 5-20 .001-.1 7.5 50 .01 30 5 g/L Flavor Descriptor threshold Hydrogen sulfide Dimethyl sulfide Dimethyl disulfide Methyl thioacetate MBT perceived DMS n n n n n n n n n n n measured DMS perceived DMS n n n n n n n n n n n measured phenylethanol sugar sugar Cell components pyruvate acetaldehyde ethanol Esters Sulfur compounds acids yeast diacetyl Phenolic Wild yeast Precursor Weizenbier yeast 4-VG Drinkability Balance intensity bitterness ribes sweet Papery/ cardboard time Minimizing flavor instability Low oxygen Low temperature Reluctance - c.f. labeling Sulfur dioxide Quality of Beer Package Foam - gushing Clarity Color Flavor Stability Safety & wholesomeness Not mutually exclusive Foam Parameters - formation - carbon dioxide content, nucleatio sites - retention - protein, bitterness content - lacing (cling) - bitterness content - texture, whiteness Forming a foam - big increase in surface area of liquid Counter to surface tension (think of a drop of water on a clean surface) Surface active molecules go into bubble wall and make a framework that counters surface tension boiling Denatured protein, exposed hydrophobic interior Bitter acid hydrophilic Foams from soaps and detergents hydrophobic Mixed protein and fat/soap/detergent means death to foam CO2 N2 far less soluble Doesn't go so easily from bubble to bubble Foams much more stable Gushing Presence of nucleation sites Proteins from Fusarium Particles in the beer - e.g. slithers of glass, oxalate Agitation Haze Insoluble (or potentially insoluble) materials not properly removed in the process Haze forming materials Yeast Spoilage organisms Oxalic acid Cell wall polysaccharides from barley Starch Proteins and polyphenols Protein - remove with silica hydrogel or tannic acid or papain Polyphenol - remove with PVPP The malting and brewing processes and Color, foam, haze Barley proteolysis release of foaming proteins from storage proteins; release of amino acids "carbohydrolysis" release of sugars from cell walls Green malt "melding" of sugars and amino acids to form melanoidins (color) Kilned malt The malting and brewing processes and Color, foam, haze extraction of proteins and polyphenols isomerization of bitter acids; precipitation oxidation of polyphenols to produce color fermentation loss of foam material cold conditioning precipitation of coldsensitive polypeptide; stabilizers Malt Sweet wort Boiled wort Green beer Finished beer Beer: Tap into the Art and Science of Brewing Today's reading assignment: Pages 65-80 ...
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This note was uploaded on 04/17/2008 for the course FST 003 taught by Professor Charliebamforth during the Winter '08 term at UC Davis.
- Winter '08