ISG Sommelier cheat sheet

Noble grape varieties of Vitis vinifera include Riesling, Chardonnay, Sauvignon Blanc, Semillon, Pinot Noir, Cabernet Sauvignon, Merlot, Syrah, Nebbiolo, and Sangiovese; most other varieties are crosses or minor natives.

Pinot Noir is genetically unstable and prone to mutation, giving rise to clones such as Pinot Blanc, Pinot Gris, and Pinot Meunier.

Cabernet Sauvignon is a spontaneous cross of Cabernet Franc and Sauvignon Blanc, first identified in Bordeaux in the 17th century.

Chardonnay is a cross of Pinot and Gouais Blanc, explaining its affinity with Burgundy soils and its wide clonal diversity.

A wine's structural components are alcohol, acidity, tannin, sugar, and body; balance is the perceived harmony among them, not the absence of any single element.

Tannin in red wine comes from skins, seeds, and stems plus oak; it contributes astringency and bitterness and acts as an antioxidant and preservative.

Fortified wines include Port (fermentation stopped with grape spirit, leaving residual sugar), Sherry (flor or oxidative aging), Madeira (heat and oxidation), and Marsala.

Sparkling wine methods: traditional method (second fermentation in bottle, lees aging, riddling, disgorging), tank/Charmat method, and ancestral method (single fermentation finished in bottle).

The annual vine cycle runs budbreak, flowering, fruit set, veraison, ripening, harvest, and dormancy; veraison is the onset of color change and sugar accumulation.

Grape sugar rises during ripening while titratable acidity falls and pH rises; picking decisions balance sugar (potential alcohol) against acid retention and phenolic ripeness.

Potential alcohol is estimated as sugar (g/L) divided by 16.83 for % v/v, or roughly 0.55-0.6% alcohol per degree Brix.

Terroir combines climate, soil, topography, and human practice; cool climates favor higher acidity and lower alcohol, warm climates favor ripeness and higher alcohol.

Malolactic fermentation converts malic acid to lactic acid via Oenococcus oeni, softening acidity and producing buttery diacetyl notes.

Red wine maceration extracts color, tannin, and flavor; extended maceration increases tannin, while carbonic maceration produces fruity, low-tannin wines.

Sulfur dioxide protects against oxidation and microbial spoilage; free SO2 is the active fraction, and its effectiveness depends on pH (higher pH requires more free SO2).

Brettanomyces contamination produces volatile phenols (4-ethylphenol, 4-ethylguaiacol) perceived as barnyard, leather, or medicinal aromas.

The standard tasting sequence is appearance, nose (condition, intensity, aroma identification), palate (sweetness, acidity, tannin, alcohol, body, flavor, finish), then conclusions on quality and readiness.

Aroma thresholds vary by compound and individual; detection is the lowest concentration perceived, recognition is the lowest identifiable, and both differ from individual sensitivity.

Faults and markers: TCA gives musty/corked notes; oxidation gives sherry-like aldehydes; volatile acidity gives vinegar/nail polish; mercaptans give cabbage/rubber; geosmin gives earthy beetroot.

Blind tasting logic uses structural signatures: high acid plus low alcohol suggests cool climate; high tannin plus high alcohol suggests warm-climate Cabernet, Syrah, or Nebbiolo.

Aroma wheel categories (fruity, floral, vegetal, spicy, earthy, woody, chemical) structure descriptive vocabulary for consistent note-taking.

Serving temperature rules: sparkling 6-8 C, crisp whites 8-10 C, rich whites 10-13 C, light reds 13-16 C, full reds 16-18 C, fortified 14-18 C.

Glassware shape affects perception by directing the aroma stream and contact area; tulip shapes concentrate esters, while wide bowls emphasize alcohol.

Decanting serves two purposes: separating sediment in older wines and aerating young tannic wines; prolonged aeration can flatten fragile older wines.

Classic service sequence: greet, present and open the list, take the order, present the bottle to the host, open and check, pour a taste for approval, then pour around the table, women and elders first in traditional etiquette.

Wine service temperatures and order: serve lighter wines before heavier, dry before sweet, white before red, young before old, and sparkling first unless a specific pairing dictates otherwise.

Standard pour sizes: 125-150 mL for still wine, 100-125 mL for sparkling, 50-75 mL for dessert wine, 25-50 mL for spirits.

Opening sparkling wine: chill to 6-8 C, hold the bottle at 45 degrees, loosen the cage with a thumb over the cork, and turn the bottle not the cork to control release.

Decanting older reds uses a candle or light source to stop pouring when sediment reaches the shoulder of the bottle.

Food pairing principles: acid cuts fat, sweetness balances heat and bitterness, tannin clashes with oily fish and salt, and umami amplifies bitterness and metallic notes.

Wine list design balances by-the-glass viability, price tiers, regional representation, and food menu overlap; by-the-glass wines must survive 2-3 days open.

Responsible service: monitor intoxication signs, offer food and water, arrange transport, and follow local licensing law on refusing service.

Beverage cost percentage equals cost of goods sold divided by beverage sales, multiplied by 100; a common target range is 18-24% for wine programs.

Pour cost is the cost of a single serving divided by its selling price; a 150 mL pour from a 750 mL bottle yields five pours, so bottle cost divided by five approximates pour cost.

Inventory turnover equals cost of goods sold divided by average inventory value; slow turnover ties up capital and risks spoilage for by-the-glass wines.

Menu engineering classifies items by popularity and contribution margin into stars, plowhorses, puzzles, and dogs, guiding pricing and placement decisions.

Pricing strategies include cost-plus, competitive, and perceived-value pricing; wine lists often use tiered markups that decline as bottle price rises.

Key performance indicators include revenue per available seat, average check, wine attachment rate, and gross profit per bottle.

Supply chain risks for wine include vintage variation, currency exposure, freight and glass costs, and allocation limits for high-demand producers.

Staff training and certification programs (WSET, Court of Master Sommeliers, ISG-style curricula) drive upsell performance and reduce service error.

Standard wine alcohol content: 1 g of ethanol yields about 7 kcal; a 150 mL glass at 13% alcohol contains roughly 18 mL ethanol, about 14 g, or roughly 100 kcal from alcohol alone.

A 150 mL glass of dry wine typically contains 0-2 g residual sugar, while off-dry and sweet wines can exceed 10-50 g/L and add meaningful calories.

Moderate drinking definitions vary by country but generally mean up to one drink per day for women and up to two for men; a standard drink is about 10-14 g of pure alcohol.

Red wine contains polyphenols such as resveratrol and procyanidins, but evidence for health benefit is observational and confounded; no medical body recommends starting to drink.

Sulfite sensitivity affects a small subset of people, mainly asthmatics; symptoms range from mild to bronchospasm, and labeling thresholds vary by jurisdiction (commonly 10 mg/L).

Histamine and tyramine in wine can trigger headaches or flushing in sensitive individuals; aged and fermented foods carry similar amines.

Alcohol is a diuretic and impairs judgment and reaction time; food slows absorption, and hydration reduces next-day symptoms but does not prevent liver metabolism.

Allergen labeling for wine may include milk, egg, and fish fining agents, plus sulfites, depending on local regulation.

The EU uses a protected designation system: PDO (protected designation of origin) and PGI (protected geographical indication), roughly corresponding to AOP/IGP in France and DOCG/DOC in Italy.

France's appellation hierarchy runs Vin de France, IGP, and AOP; Italy runs Vino, IGT, DOC, and DOCG; Spain runs Vino, IGP, DO, and DOCa.

The US uses American Viticultural Areas (AVAs); an AVA label requires at least 85% of the wine from that area, while a varietal label requires at least 75% of that grape.

EU labeling rules require varietal labeling at 85% minimum, vintage at 85% minimum, and geographic indication at 85% minimum, with stricter national rules in some countries.

Wine trade flows are shaped by tariffs, free trade agreements, and excise duties; the EU, US, and China are among the largest import markets by value.

The OIV is the intergovernmental scientific body for vine and wine; it publishes statistics, definitions, and resolutions but does not enforce trade law.

New World versus Old World is a cultural and regulatory distinction, not a quality one; climate, tradition, and labeling law differ more than winemaking skill.

Emerging markets include China, India, and Southeast Asia; growth depends on tariffs, distribution, and evolving consumer taste for wine versus spirits.