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Unformatted text preview: FST 3 Winter 2009 Introduction to Beer and Brewing - with a mention of wine Charlie Bamforth firstname.lastname@example.org Quality of Wine - Name - Legs, tears, church windows - Color - Flavor (aroma, bouquet) 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-α-acids from hops Iso-α-acid MBT light 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 µg/L Flavor Descriptor threshold Hydrogen sulfide Dimethyl sulfide Dimethyl disulfide Methyl thioacetate MBT perceived DMS n n n n n n n n nn 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, nucleation sites - retention - protein, bitterness content - lacing (cling) - bitterness - 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 proteins polyphenols Grape versus Grain Today’s reading assignment: Pages 106-128 ...
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- Spring '08