On food and cooking the science and lore of the kitchen ( PDFDrive ) 1412

Once the foam is of the desired thickness, the rest of the beer can be poured in gently along the side of the glass, avoiding aeration and nucleation of new bubbles The glass itself should be clean of any residues of oil or soap, which interfere with foaming (These molecules have water-avoiding ends that pull the similar ends of the bubble-stabilizing proteins out of the bubbles.) By the same token, if a newly poured beer threatens to foam over, it can often be stopped in its tracks by touching the rim with a finger or lip, which carry traces of oil Kinds and Qualities of Beer Beers are a wonderfully diverse group of drinks, and a good beer can be a mouth-filling experience, one that rewards slow savoring There are several qualities worth appreciating: Color, which can range from pale yellow to impenetrable brown-black, and comes from the kinds of malt used Body, or weightiness in the mouth, which comes from the long remnants of starch molecules in the malt Astringency, from malt phenolic compounds Prickly freshness, from dissolved carbon dioxide Taste, which may include saltiness from the water, sweetness from unfermented malt sugars, acidity from roasted malt and from fermentation microbes, bitterness from hops and from darkroasted malts, savoriness from malt amino acids Aroma, from woody, floral, citrusy hops; malty, caramel, and even smoky malt; and from the yeasts and other microbes, which can produce notes that seem fruity (apple, pear, banana, citrus), flowery (rose), buttery, spicy (clove), and even ... malty, caramel, and even smoky malt; and from the yeasts and other microbes, which can produce notes that seem fruity (apple, pear, banana, citrus), flowery (rose), buttery, spicy (clove), and even...to impenetrable brown-black, and comes from the kinds of malt used Body, or weightiness in the mouth, which comes from the long remnants of starch molecules in the malt Astringency, from malt phenolic... Prickly freshness, from dissolved carbon dioxide Taste, which may include saltiness from the water, sweetness from unfermented malt sugars, acidity from roasted malt and from fermentation microbes, bitterness from hops and from darkroasted malts, savoriness from malt