Introduction

• The Aviation → pre-Prohibition cocktail = gin, lemon, maraschino liqueur, crème de violette
• Chemists from UC (Cincinnati!) discovered flavor differences btw pure vodkas (comprising only ethanol & water) depend on strength oh hydrogen bonds btw the molecules!
• “The human relationship with alcohol is a hologram for our relationship with the natural world, the world that made us and the world we made.”

Yeast

• Cerevisiae of Saccharomyces cerevisiae derives from cerveza— beer, which it was used to make
• Science of fermentation of beer was simultaneous with research into metabolism, biochemistry, cell bio (Pasteur, Schwann, Koch)
• Phylogeny of yeasts → domesticated initially in Africa 12k years ago, then sake yeasts branch off, then wine → clusters of strains that make same product
• Artificial selective pressures → optimized enzymes in fermentation pathways

Sugar

• Must break starches down to sugar before yeas can ferment it into alcohol (whether grain → beer, rice → sake)
  • Most cultures use some simple sugars directly to produce alcohol (fruit, agave, even horse milk)
  • Japan: koji (Aspergillus niger) turns rice to sugar; turns out to be much more efficient than European method (malting) at doing the same to grains
• Grape = ideal fruit, bc high sugar, grows well, interesting flavors, mostly pulp
  • Few esters (unlike apples), which are destroyed during fermentation → esters created during the process
  • All wine-making varieties = cultivars of same species
• Malting = turning barley to sugars (barley is ideal grain over wheat, corn, oats)
  • Used to make whiskey— basically distilled beer
  • Trick the seed into thinking it’s sprouting → releases enzymes like amylases to break starches into sugars, stop process before the seed metabolizes the sugars (as peat?)
  • Similar to what koji does— when analyzing genome/changes with domestication, found changes to metabolic enzymes involved w production of MSG (umami flavoring in miso, sake)
  • Now some attempts to make beer without malting, using enzymes → more efficient, cheaper

Fermentation

• Yeast evolved to produce ethanol as byproduct perhaps to easily dissipate waste products (evaporates fast?) → happened to be suited to rise of fruits when angiosperms came around
  • Yeast are able to produce and consume ethanol!
• Different strains → different flavors (also dependent on conditions)
  • Yeasts “liberate”/make volatile many of the scent-producing compounds in juice
• Some fermentations also aided by bacteria (rum, esp bc made directly from cane sugar; wines)
• Double dispense → pour an almost full pint of beer (from the tap), let it sit for 3 min, then top it off off: liquid from second pour slips under first foam, pushing it up and sealing the new foam under, slowing CO2 diffusion → stiffer foam

Distillation

• Challenging to maintain consistency of single malt whiskeys— can’t just change ratio of what you’re mixing! Depends a lot on standardization of distillation (≈ factory-like process)
• Distilling = concentrating, gets alcohol content up (after fermentation which usually maxes out at ~15%)
• Basic idea: vaporize the ethanol and interesting stuff (congeners) from water
  • Azeotropic limit = max proof of alcohol at 194.4, when vapor and water have same ethanol concentration
  • Proof just = 2x percent alcohol by volume in the US
• Different spirits distilled in different set ups- batches, continuous, diff numbers of pots or column, cycles
  • Column-bases still → allowed for fractional/continuous distillation, by adding ledges into neck of still
  • Art form = deciding when to make the cut points to keep the middle part that you drink
  • Copper used bc pulls sulfides out of solution

Aging

• Aging in wood gives red wine, Scotch, cognac their “coconutty, round, lush mouthfeel” by adding lactones
• Also many other chemical changes
• Special rules for type of barrels (new vs old, type of wood, charred) to age Bourbon, Scotch in
  • Barrel-making is an art form in itself— choosing the specific tree, heating and cooling to bend wood, ultimately bound & watertight with no nails or glue (just flour)
  • Differences in heat, pressure → spirit loses different amounts of water or ethanol to wood
  • Cellulose and hemicellulose parts of wood break down into sugars, but lignin contains vanillins, other aromatic aldehydes (→ esters when mixed with acids, fruity & tart) and tannins
• How to produce something that tastes old without aging?
  • Add extracts, steep wood chips, higher heat/humidity
  • Roll/rotate barrels for more contact

Smell & Taste

• Extremely hard to describe how things smell— usually by metaphor, but even that’s incredibly individual and subjective
• Very little agreement even between experts when blind-tasting wine
• Aroma and flavor highly influenced by color
• Experts differentiated from novices more by their ability to describe flavor than actually identifying different wines
• Ethanol activates sweet and bitter receptors, but also acts as irritant → nocioception mechanism, independent of taste
• Olfaction is only direct sense, in that what stimulates olfactory neurons is a physical part of what we are smelling
• “Wheels” of flavor/scent give us common language to describe what we sense
  • Can work with panel of tasters and flavor references to establish agreement on aromas → actually can distinguish wines by terroir (regionality/microclimate)
• Ultimate goal = map specific molecules to each flavor → figure out cheaper ways of getting what makes gives spirits their desired taste

Body & Brain

• How to set up random, blinded trial to study effects of ethanol consumption?
  • Use cold vodka/tonic and tonic (people can’t tell difference)
  • Actually have four groups: based on what subjects get and what they expect
  • Expectations (what they perceived to be drinking) = critical to effect of ethanol
• Observable effects of alcohol are very predictable, but unknown mechanism of action for ethanol in the brain